SC480 amplifier
Leura
Anyone who built the ETI-480 like to make some comments on this replacement
amplifier? or simply on ETI-480 only?
Craig
I built these modules and had a hell of a time building them. See
http://groups.google.com search for "ETI 480"
I would highly recommend that if you want to build it, then build the
SC version. It is so much better than the ETI version (from reading
the Jan 03 article).
Wait until hopefully a kit for the SC 480 is out (don't hold your
breath though) and build that one.
And as a final word, for the money I spent on the stereo ETI 480, I
could have spent a bit more and bought myself an entry level home
theatre amplifier with all the bells and whistles.
Building kits isn't like it used to be :(
Craig
Hughie
all, this amp kit is still available at Dickie Smith's. (both amps and
power boards.) I have 2 boards built, still here if you want them?
am in Perth
I have a few trannies for the ETI, and am going to use them on the new
SC amps
Leura
Low Distortion Stereo Amplifier kit from Altronics; Pro Series 3 Amplifier
kit from Jaycar and ETI480 (SC480) from Dick Smith.
Does anyone have some comments on their sonics? Which one sound better to
you?
"Hughie" <mc...@pacific.net.au> wrote in message
news:1da909e0.03012...@posting.google.com...
Phil Allison
"Leura" <nos...@antispam.net> wrote in message
news:jt7Z9.10406$7y2....@news-server.bigpond.net.au...
> At the moment, there are 3 amp kits in shops I like to know compare. Ultra
> Low Distortion Stereo Amplifier kit from Altronics; Pro Series 3 Amplifier
> kit from Jaycar and ETI480 (SC480) from Dick Smith.
>
> Does anyone have some comments on their sonics? Which one sound better to
> you?
** The Pro Series 3 ( mosfet ) is a very respectable home amp - you get
a complete kit that if built properly works like a bought one - only at
about 1/3 the price.
......... Phil
Johnny
>At the moment, there are 3 amp kits in shops I like to know compare. Ultra
>Low Distortion Stereo Amplifier kit from Altronics; Pro Series 3 Amplifier
>kit from Jaycar and ETI480 (SC480) from Dick Smith.
>
>Does anyone have some comments on their sonics? Which one sound better to
>you?
I'd give the original ETI480 a big miss. Its a design that looks to
have some serious issues to me, especially with the bias stability.
The new SC480 looks like a pretty good design. However I'd like to
see some SOA limit circuitry and failing that, a DC protection relay
would be a really good idea.
However it really dosen't make sense to build your own power
amplifier. You can buy amps like Rotel RB-970 or similar second-hand
for less money that you can buy the bits for a SC480 based DIY amp.
regards,
Johnny.
Phil Allison
"Johnny" <joh...@NOSPAM.hotmail.com> wrote in message
news:3e350f9...@news.optusnet.com.au...
> I'd give the original ETI480 a big miss. Its a design that looks to
> have some serious issues to me, especially with the bias stability.
** That is an odd remark - the OP stage is common emitter which takes the
devices out of the thermal bias loop. There is a BD139 Vbe multiplier right
on the heatsink - looks maybe overcompensated to me.
The one I built for my sub ( as opposed to dozens I have serviced)
suffered from parasitic oscillation induced distortion - which was a pig to
find and fix.
........... Phil
Johnny
wrote:
>
>"Johnny" <joh...@NOSPAM.hotmail.com> wrote in message
>news:3e350f9...@news.optusnet.com.au...
>
>
>> I'd give the original ETI480 a big miss. Its a design that looks to
>> have some serious issues to me, especially with the bias stability.
>
>
> ** That is an odd remark - the OP stage is common emitter which takes the
>devices out of the thermal bias loop.
If you are talking about temp related Vbe variations of the output
devices, then you are right. However there is a lot more than that
going on, because this is an "Output stage with gain". The local
feedback resistors make the bias current very dependant on the current
gain, Hfe of the output devices, since the base current for these must
flow though the local feeback resistors. There is also no
low-impedance path to discharge the dynamic base currents of these
output devices, due to b-e charge during switch-off and also the
miller charge from b-c. Its very difficult to say what will happen to
the bias voltage and switching distortion during slewing of the output
voltage, because:
1) These dynamic currents for each of PNP and NPN output devices will
not match (ie not complementary)
2) The miller capacitances of the output transistors are voltage
dependant.
I think that output stages with gain are a very bad idea for these
reasons. The added feedback loop also needs frequency compensation as
you pointed out, and it seems like there may be issues there too.
regards,
Johnny.
Phil Allison
> On Mon, 27 Jan 2003 22:49:10 +1100, "Phil Allison" <bi...@bigpond.com>
> wrote:
>
> >
> >"Johnny" <joh...@NOSPAM.hotmail.com> wrote in message
> >news:3e350f9...@news.optusnet.com.au...
> >
> >
> >> I'd give the original ETI480 a big miss. Its a design that looks to
> >> have some serious issues to me, especially with the bias stability.
> >
> >
> > ** That is an odd remark - the OP stage is common emitter which takes
the
> >devices out of the thermal bias loop.
>
>
> If you are talking about temp related Vbe variations of the output
> devices, then you are right.
** Ok - so you now agree the bias is more stable than with common
collector stages.
However there is a lot more than that going on, because this is an "Output
stage with gain". The local feedback resistors make the bias current very
dependant on the current gain, Hfe of the output devices, since the base
current for these must flow though the local feeback resistors.
** The feedback network has no effect on the bias in the OP devices since
changes in bias current have no effect on the voltage at the output there is
nothing to feed back.
The current in the BD139/140 is set by a Vbe multiplier that is
thermally tracks the pair - also the large value (33 ohm) emitter ballast
resistors keeps a pretty steady 12 mA in this pair.
The OP devices are driven from a 47 ohm source impedance and the
actual bias current will depend on their temperature and current gain but to
a lesser extent than is the case with a common collector stage driven by
emiter followers - ergo the bias current is stable.
> There is also low-impedance path to discharge the dynamic base currents
of these
> output devices,
** Huh? What does the 47 ohm do?
due to b-e charge during switch-off and also the
> miller charge from b-c. Its very difficult to say what will happen to
> the bias voltage and switching distortion during slewing of the output
> voltage, because:
> 1) These dynamic currents for each of PNP and NPN output devices will
> not match (ie not complementary)
** No PNP /NPN pair is perfectly complementary.
The 3055/2955 pair is reasonable.
> 2) The miller capacitances of the output transistors are voltage
> dependant.
** They always are.
>
> I think that output stages with gain are a very bad idea for these
> reasons.
** Your "reasons" are all a bit shakey.
The added feedback loop also needs frequency compensation as
> you pointed out, and it seems like there may be issues there too.
** The 100 nF caps across the 2 x 220 ohms are doing what ?
.............. Phil
Greg
>At the moment, there are 3 amp kits in shops I like to know compare. Ultra
>Low Distortion Stereo Amplifier kit from Altronics; Pro Series 3 Amplifier
>kit from Jaycar and ETI480 (SC480) from Dick Smith.
>
>Does anyone have some comments on their sonics? Which one sound better to
>you?
>
The Pro three would be an excellent choice. I have a friend who had a
pro series amplifier 7-8 years ago. I don't think it was the series 3,
but it was fantastic. The mosfet devices are truly rock solid and
stable.
If I had the money, I'd love the Pro 3 in my room.
Phil Allison
"Greg" <sp...@spam.aa> wrote in message
news:bqjc3v8kj2upjjtn3...@4ax.com...
** Words of wisdom.
........... Phil
Johnny
wrote:
>
>"Johnny" <joh...@NOSPAM.hotmail.com> wrote in message
>news:3e36205c...@news.optusnet.com.au...
>> On Mon, 27 Jan 2003 22:49:10 +1100, "Phil Allison" <bi...@bigpond.com>
>> wrote:
>>
>> >
>> >"Johnny" <joh...@NOSPAM.hotmail.com> wrote in message
>> >news:3e350f9...@news.optusnet.com.au...
>
>
> However there is a lot more than that going on, because this is an "Output
>stage with gain". The local feedback resistors make the bias current very
>dependant on the current gain, Hfe of the output devices, since the base
>current for these must flow though the local feeback resistors.
>
>
> ** The feedback network has no effect on the bias in the OP devices since
>changes in bias current have no effect on the voltage at the output there is
>nothing to feed back.
Bias stability is not just about what happens under zero-input
conditions. Bias stability is important for minimising the crossover
non-linearity and switching distortion of the amplifer.
What I expect will happen with the ET480, is under certain load
conditions, the output stage will cross-over without any bias current
though the output stage, generating gross switching distortion.
>> There is also low-impedance path to discharge the dynamic base currents
>of these
>> output devices,
>
>
> ** Huh? What does the 47 ohm do?
True, but when it comes to reducing switching distortion this is not
as good as a Emitter follower driver stage.
>> due to b-e charge during switch-off and also the
>> miller charge from b-c. Its very difficult to say what will happen to
>> the bias voltage and switching distortion during slewing of the output
>> voltage, because:
>
>
>> 1) These dynamic currents for each of PNP and NPN output devices will
>> not match (ie not complementary)
>
>
> ** No PNP /NPN pair is perfectly complementary.
>
> The 3055/2955 pair is reasonable.
When they are put in a local feedback loop that has gain, and are less
directly biased by a loop consisitng of feedback resistors and what is
essentially a current source, these differrences of PNP vs NPN are
going to have a much bigger effect on bias stability and switching
distortion produced by the amp..
The 3055/2955 pair can only be described as vaguely complementary.
When you look at large signal distortion, you need to consider
non-linearity on the output transistors Hfe (which is very non-linear
for the 3055). This non-linearity is magnified by the impedance of
the local feedback resistors in the case of the ETI480.
>> 2) The miller capacitances of the output transistors are voltage
>> dependant.
>
>
>** They always are.
Variations between DC base currents and dynamic currents have the
same consequences. See above reasoning.
>> I think that output stages with gain are a very bad idea for these
>> reasons.
>
>
> ** Your "reasons" are all a bit shakey.
More common output stage topologies have big advantages. I advocate
using a voltage source that directly references the b-e junctions of
the driver and/or output transistors and ballast resistors. This is
the best way to minimise switching distortion and crossover
non-linearity. If you want to learn more about the topic, Doug Self
has written a very detailed analysis of this in his book.
>The added feedback loop also needs frequency compensation as
>> you pointed out, and it seems like there may be issues there too.
>
>
> ** The 100 nF caps across the 2 x 220 ohms are doing what ?
Aparrently this wasn't having the desired effect in the amp that you
built. Again, the HF stabilty for local osciallations depends on the
instantaneous operating conditions of each side of the output stage.
They will be different for the NPN and PNP sides of the circuit which
makes a bizzare design such as the ETI480 even more marginal and
difficult to stabilise.
regards,
Johnny.
Phil Allison
** What you suspect is of no value - what do you know ????
>
>
> >> There is also low-impedance path to discharge the dynamic base
currents
> >of these output devices,
> >
> >
> > ** Huh? What does the 47 ohm do?
>
> True, but when it comes to reducing switching distortion this is not
> as good as a Emitter follower driver stage.
** Huh? An emitter follower cannot drive in reverse.
>
> >> due to b-e charge during switch-off and also the
> >> miller charge from b-c. Its very difficult to say what will happen to
> >> the bias voltage and switching distortion during slewing of the output
> >> voltage, because:
> >
> >
> >> 1) These dynamic currents for each of PNP and NPN output devices will
> >> not match (ie not complementary)
> >
> >
> > ** No PNP /NPN pair is perfectly complementary.
> >
> > The 3055/2955 pair is reasonable.
>
> When they are put in a local feedback loop that has gain, and are less
> directly biased by a loop consisitng of feedback resistors and what is
> essentially a current source, these differrences of PNP vs NPN are
> going to have a much bigger effect on bias stability and switching
> distortion produced by the amp..
** The local feedback loop has NO effect on bias stability.
If you think it does then say how.
>
> The 3055/2955 pair can only be described as vaguely complementary.
** Like Johnny can be only be described vaguely - since he is anonymous.
> >> 2) The miller capacitances of the output transistors are voltage
> >> dependant.
> >
> >
> >** They always are.
>
> Variations between DC base currents and dynamic currents have the
> same consequences. See above reasoning.
** Autistic bull - not reasoning.
>
> >> I think that output stages with gain are a very bad idea for these
> >> reasons.
> >
> >
> > ** Your "reasons" are all a bit shakey.
>
> More common output stage topologies have big advantages.
** You have not got the slightest clue. There are any number of very
high performance common emitter OP amps - there is large advantage in
terms of bias stability.
I advocate
> using a voltage source that directly references the b-e junctions of
> the driver and/or output transistors and ballast resistors. This is
> the best way to minimise switching distortion and crossover
> non-linearity.
** Horse poo - care to check out a Murray design amp ?
> If you want to learn more about the topic, Doug Self
> has written a very detailed analysis of this in his book.
** How fucking patronising - so you have read the self appointed one's
drivel.
>
> >The added feedback loop also needs frequency compensation as
> >> you pointed out, and it seems like there may be issues there too.
> >
> >
> > ** The 100 nF caps across the 2 x 220 ohms are doing what ?
>
> Aparrently this wasn't having the desired effect in the amp that you
> built. Again, the HF stabilty for local osciallations depends on the
> instantaneous operating conditions of each side of the output stage.
> They will be different for the NPN and PNP sides of the circuit which
> makes a bizzare design such as the ETI480 even more marginal and
> difficult to stabilise.
** With a tiny change ( not needed on most examples) it is a stable as a
rock.
Bet you have never actually seen nor tested one.
.............. Phil
Gradenko
> Low Distortion Stereo Amplifier kit from Altronics; Pro Series 3 Amplifier
> kit from Jaycar and ETI480 (SC480) from Dick Smith.
>
> Does anyone have some comments on their sonics? Which one sound better to
> you?
>
If its sonics your after, give the Aska kits a look. I've been
following them on harmonicdiscord forums and they seem to receive
nothing but favourable reviews, usually when pitted against far more
expensive opponents.
http://www.aksaonline.com/
http://www.harmonicdiscord.com/forums/viewforum.php?f=42
I haven't built one yet but I'm planning on starting 3 x 100w mono
blocks shortly.
Trevor Wilson
"Gradenko" <bsi...@iinet.net.au> wrote in message
news:96af8377.03012...@posting.google.com...
**You should also consider some of the Silicon Chip alternatives.
--
Trevor Wilson
www.rageaudio.com.au
Trevor Wilson
"Trevor Wilson" <tre...@rageaudio.com.au> wrote in message
news:3e36d539$0$31038$afc3...@news.optusnet.com.au...
**I should have added, that at the prices AKSA charge, you could consider a
fully built, commercial alternative, like the ME200.
--
Trevor Wilson
www.rageaudio.com.au
Eric Lindsay's spam trap
(Johnny) wrote:
>>At the moment, there are 3 amp kits in shops I like to know compare. Ultra
>>Low Distortion Stereo Amplifier kit from Altronics; Pro Series 3 Amplifier
>>kit from Jaycar and ETI480 (SC480) from Dick Smith.
>However it really dosen't make sense to build your own power
>amplifier. You can buy amps like Rotel RB-970 or similar second-hand
>for less money that you can buy the bits for a SC480 based DIY amp.
Jaycar kit prices for the SC480 is $45 each, plus $30 for the
power supply, and $40 for a transformer, so that runs to $160,
and you still need heat sinks, wiring, connectors, and a case (if
you intend to use a case). Of course if you have a decent junk
box, you'd probably do considerably better.
--
Eric Lindsay http://www.ericlindsay.com/guff
Airlie Beach Qld Australia - Great Barrier Reef entry
Psion & Epoc site http://www.ericlindsay.com/epoc
Leura
> Jaycar kit prices for the SC480 is $45 each, plus $30 for the
> power supply, and $40 for a transformer, so that runs to $160,
> and you still need heat sinks, wiring, connectors, and a case (if
> you intend to use a case). Of course if you have a decent junk
> box, you'd probably do considerably better.
>
> --
> Eric Lindsay http://www.ericlindsay.com/guff
> Airlie Beach Qld Australia - Great Barrier Reef entry
> Psion & Epoc site http://www.ericlindsay.com/epoc
I could not find SC480 on Jaycar catalogue. You need about double your money
to get the transformer. But anyway, it seems that building a SC480 is not
that cost effective than Jaycar Pro Series 3 ($599 including everything),
regardless of the sonics.
Greg
>
>I could not find SC480 on Jaycar catalogue.
<SNIP>
What he is probably saying is that the Feb edition of SC is saying the
kit is available from Jaycar at $45. But I havn't read the Feb SC yet.
Greg
Lindsay's spam trap) wrote:
>Jaycar kit prices for the SC480 is $45 each, plus $30 for the
>power supply, and $40 for a transformer, so that runs to $160,
>and you still need heat sinks, wiring, connectors, and a case (if
>you intend to use a case). Of course if you have a decent junk
>box, you'd probably do considerably better.
300VA toroidal 30V transformer $76
2x SC480 $45
2x heatsinks ~$45
Capacitors 4x 4700uf 50V $20
Rocker switch ~$5
IEC fused socket $5.90
Binding posts ~$15
Rca sockets ~$6
Rack case ~$100
Hookup wire ~$3
Heatsrink tubing ~$3
There you go. $368.90
Of course you need tools like a heat gun, drill and bits, and nibbling
tool etc. If you don't, then expect to pay over $400.
I would go for the Pro series amp. Or you could spend a bit more and
buy a cheap home theatre reciever. But then again, you wouldn't have
the enjoyment of building a amplifier.
Johnny
Lindsay's spam trap) wrote:
>On Mon, 27 Jan 2003 10:59:41 GMT, joh...@NOSPAM.hotmail.com
>(Johnny) wrote:
>
>>>At the moment, there are 3 amp kits in shops I like to know compare. Ultra
>>>Low Distortion Stereo Amplifier kit from Altronics; Pro Series 3 Amplifier
>>>kit from Jaycar and ETI480 (SC480) from Dick Smith.
>
>>However it really dosen't make sense to build your own power
>>amplifier. You can buy amps like Rotel RB-970 or similar second-hand
>>for less money that you can buy the bits for a SC480 based DIY amp.
>
>Jaycar kit prices for the SC480 is $45 each, plus $30 for the
>power supply, and $40 for a transformer, so that runs to $160,
>and you still need heat sinks, wiring, connectors, and a case (if
>you intend to use a case). Of course if you have a decent junk
>box, you'd probably do considerably better.
Your estimates for a suitable transformer, capacitors, rectifers are
too low by about $30. An amp without a case would be unsafe.
Items left out include the following:
Case
RCA input terminals
Cabling
Banana sockets for output.
Heatsink insulators and compound.
Mains switch.
Mains fuse holder and fuse.
IEC socket / mains cable.
Fasteners
By the time you add it all up it will cost as much as a good second
hand amp.
regards,
Johnny.
Leura
"Greg" <sp...@spam.aa> wrote in message
I would guess that a cheap home theatre receiver is not in the same league
as these kits in terms of sonics. What I am looking into is to build a kit
amp to "upgrade" my cheap receiver amps (not so cheap. I am using 8 years
old Denon receiver)
Do you think I will be better off building such kit amps, comparing to
consumer home receivers (about $5000 range), speaking of sonics?
Greg
speaking of sonics?
>
I dunno what you mean by "sonics".
Greg
>I would guess that a cheap home theatre receiver is not in the same league
>as these kits
I really couldn't say about quality. Comparing kits to home theatre
amplifiers. I have taken a brief look at the circuitry of my home
theatre amplifier and must say it can't be that bad. I will let others
comment on comparing original kits to those made bulk in China.
Cheers,
Greg........
Trevor Wilson
**That is a tough call. The actual topology used in most decent HT receiver
power amp stages is not all that bad. In some cases, it is quite good. The
topology used in many cheap ones, is utterly appalling. Where most HT amps
fall down, is in two critical areas:
Preamp stages.
Power supplies.
Building an amplifier, for the complete novice is an incredibly
time-consuming task. It is simply not worth it for anyone not requiring an
education. Good quality power amps are available from a number of sources,
at very respectable prices.
--
Trevor Wilson
www.rageaudio.com.au
Gradenko
> > "Gradenko" <bsi...@iinet.net.au> wrote in message
> > news:96af8377.03012...@posting.google.com...
> > > following them on harmonicdiscord forums and they seem to receive
> > > nothing but favourable reviews, usually when pitted against far more
> > > expensive opponents.
> > >
> > > http://www.aksaonline.com/
> > > http://www.harmonicdiscord.com/forums/viewforum.php?f=42
> > >
> > > I haven't built one yet but I'm planning on starting 3 x 100w mono
> > > blocks shortly.
> >
> > **You should also consider some of the Silicon Chip alternatives.
>
> **I should have added, that at the prices AKSA charge, you could consider a
> fully built, commercial alternative, like the ME200.
I haven't looked at Silicon Chip designs and I don't intend to.
Sonically, I think Hugh has a hit on his hands. Shallow words from
someone who hasn't even heard the product yet, but I have faith in his
design :-) If I was building a pro audio or subwoofer amp I may
consider other cheaper designs.
I have considered the ME range. I really should get around to
listening to one but even so, they are far out of my price range. The
model you mention, the ME200, isn't a power amp and is twice the price
of a Aska kit. A comparison between a Aska 100 and ME200 would be
interesting.
Leura
> I haven't looked at Silicon Chip designs and I don't intend to.
> Sonically, I think Hugh has a hit on his hands. Shallow words from
> someone who hasn't even heard the product yet, but I have faith in his
> design :-) If I was building a pro audio or subwoofer amp I may
> consider other cheaper designs.
>
> I have considered the ME range. I really should get around to
> listening to one but even so, they are far out of my price range. The
> model you mention, the ME200, isn't a power amp and is twice the price
> of a Aska kit. A comparison between a Aska 100 and ME200 would be
> interesting.
The total cost of Aska is also a little over $1000 + your own labor. So
these two amps are the same money wise. However, a kit of a price tag of $45
is still very attractive.
I don't know if Trevor can point me to any technical writings about the
design of ME amps. One of the good things for kit is that one can know the
design of the amp.
Trevor Wilson
"Gradenko" <bsi...@iinet.net.au> wrote in message
news:96af8377.03012...@posting.google.com...
> "Trevor Wilson" <tre...@rageaudio.com.au> wrote in message
news:<3e36e129$0$8831$afc3...@news.optusnet.com.au>...
> > > "Gradenko" <bsi...@iinet.net.au> wrote in message
> > > news:96af8377.03012...@posting.google.com...
> > > > If its sonics your after, give the Aska kits a look. I've been
> > > > following them on harmonicdiscord forums and they seem to receive
> > > > nothing but favourable reviews, usually when pitted against far more
> > > > expensive opponents.
> > > >
> > > > http://www.aksaonline.com/
> > > > http://www.harmonicdiscord.com/forums/viewforum.php?f=42
> > > >
> > > > I haven't built one yet but I'm planning on starting 3 x 100w mono
> > > > blocks shortly.
> > >
> > > **You should also consider some of the Silicon Chip alternatives.
> >
> > **I should have added, that at the prices AKSA charge, you could
consider a
> > fully built, commercial alternative, like the ME200.
>
>
> I haven't looked at Silicon Chip designs and I don't intend to.
**You should. Some are vastly more sophisticated than the AKSA products. And
considerably less expensive too. Even if you fitted some of the mythical
parts which are fitted to the AKSA products, you'd still come out ahead.
> Sonically, I think Hugh has a hit on his hands.
**Certainly financially, anyway. Don't forget: Nobody will admit to their
own, handcrafted kit amplifier (ie: AKSA) as sounding sub-standard. Because
they poured their heart and soul into it, it will always sound better than
any commercial product, in spite of any kind of reality.
Shallow words from
> someone who hasn't even heard the product yet, but I have faith in his
> design :-) If I was building a pro audio or subwoofer amp I may
> consider other cheaper designs.
**One recent Silicon Chip design (forgot the code number) is very
impressive, indeed. Sophisticated topology and sensible component choice. It
is one which should be considered by any home constructor.
>
> I have considered the ME range. I really should get around to
> listening to one but even so, they are far out of my price range.
**Utter nonsense. The ME200 has a RRP of $1295.00. The aproximately
equivalent AKSA is $690.00 (no discounts available) PLUS freight PLUS power
supply PLUS case PLUS labour costs, etc. The ME200 comes with a full parts
and labour 5 YEAR warranty. The AKSA comes with a 3 DAY warranty. By the
time you build an AKSA, you'll spend at least $1,000.00, excluding any
labour costs and you'll still have an amplifier which does not equal the
ME200 in a number areas. If you want to save money, look at some of the
Silicon Chip designs. They're mucyh less expensive.They also employ output
stage VI limiting. The AKSA does not. One component failure, one crossed
speaker cable, or faulty assembly and you're screwed.
The
> model you mention, the ME200, isn't a power amp and is twice the price
> of a Aska kit. A comparison between a Aska 100 and ME200 would be
> interesting.
**The ME200 IS a power amp and, by the time you add a power supply, case,
etc, the cost of the AKSA closely approaches the ME200. And here is the rub:
The ME200 carries a full, 5 year parts and labour warranty, backed by a
company with a 27 year history. Don't forget that pesky TCO (Total Cost of
Ownership) thing, that computer guys are so fond of quoting. How much do you
think you'll get for your old AKSA amplifier, when you tire of it? You know
the one. Built in some Chinese sourced, Disk Smith generic case, with
Letraset labelling on the front. Now look at the second hand prices of a
typical ME amplifier. An 18 year old ME550 (originally $1200.00) will
typically fetch $800.00 second hand. An ME75(b), which originally sold for
around $1500.00 in 1983, would fetch around $1200.00 today. Let's not even
get into the absurdly high prices of the AKSA preamp kits.
--
Trevor Wilson
www.rageaudio.com.au
Trevor Wilson
> >
> > I haven't looked at Silicon Chip designs and I don't intend to.
> > Sonically, I think Hugh has a hit on his hands. Shallow words from
> > someone who hasn't even heard the product yet, but I have faith in his
> > design :-) If I was building a pro audio or subwoofer amp I may
> > consider other cheaper designs.
> >
> > I have considered the ME range. I really should get around to
> > listening to one but even so, they are far out of my price range. The
> > model you mention, the ME200, isn't a power amp and is twice the price
> > of a Aska kit. A comparison between a Aska 100 and ME200 would be
> > interesting.
>
>
> The total cost of Aska is also a little over $1000 + your own labor. So
> these two amps are the same money wise. However, a kit of a price tag of
$45
> is still very attractive.
**Correct, on both counts. The $45.00 kit is very reasonable. The AKSA does
not appear to be so.
>
> I don't know if Trevor can point me to any technical writings about the
> design of ME amps. One of the good things for kit is that one can know the
> design of the amp.
**The design outline of the ME is available in some detail, on my own site
and ME's site.
Go to White Paper
or
I'm not sure where it is on the ME site.
In any case, the White Paper is far from finished. It contains a goodly
number of errors and ambiguities. However, I will be happy to answer any
questions you may have regarding the design. As will Peter Stein, if you ask
him.
Briefly, the ME200 (and all ME amplifiers and preamps) are fundamentally
different to pretty much every other amplifier on the market (including the
AKSA).
Some highlights include:
*Zero Global NFB.
*Carefully matched components (1% or better for transistors)
*Careful layout.
*Large power supplies (directly opposite to HT amps and AKSA amps).
*Multiple small capacitors in power supplies.
*More output devices than is necessary.
*No relays of switches in the signal path.
*No capacitors in the signal path.
*VERY low open loop output impedance.
*Excellent distortion figures (considering the fact that no Global NFB is
used)
*Common Emitter output stages.
Etc.
--
Trevor Wilson
www.rageaudio.com.au
Leura
As the ME amps are not kit amps, I guess I have no access to schematics. I
believe you have listened to Aksa. Can you tell me what are the difference
in sonics between ME and Aksa?
"Trevor Wilson" <tre...@rageaudio.com.au> wrote in message
news:3e37b6cd$0$2327$afc3...@news.optusnet.com.au...
Leura
> **You should. Some are vastly more sophisticated than the AKSA products.
And
> considerably less expensive too. Even if you fitted some of the mythical
> parts which are fitted to the AKSA products, you'd still come out ahead.
>
A bit more detail on your comments on the two designs? Have you built one
Aksa and why do you think the parts of Aksa mythical?
> > Sonically, I think Hugh has a hit on his hands.
>
> **Certainly financially, anyway. Don't forget: Nobody will admit to their
> own, handcrafted kit amplifier (ie: AKSA) as sounding sub-standard.
Because
> they poured their heart and soul into it, it will always sound better than
> any commercial product, in spite of any kind of reality.
>
In what areas Aksa sounds sub-standard?
> Shallow words from
> > someone who hasn't even heard the product yet, but I have faith in his
> > design :-) If I was building a pro audio or subwoofer amp I may
> > consider other cheaper designs.
>
> **One recent Silicon Chip design (forgot the code number) is very
> impressive, indeed. Sophisticated topology and sensible component choice.
It
> is one which should be considered by any home constructor.
>
The last Silicon Chip kit (Jan03) is SC480, a replacement of ETI480. The
second last one (Nov02) is Ultra Low Distortion.
Which one did you mean?
> >
> > I have considered the ME range. I really should get around to
> > listening to one but even so, they are far out of my price range.
>
> **Utter nonsense. The ME200 has a RRP of $1295.00. The aproximately
> equivalent AKSA is $690.00 (no discounts available) PLUS freight PLUS
power
> supply PLUS case PLUS labour costs, etc. The ME200 comes with a full parts
> and labour 5 YEAR warranty. The AKSA comes with a 3 DAY warranty. By the
> time you build an AKSA, you'll spend at least $1,000.00, excluding any
> labour costs and you'll still have an amplifier which does not equal the
> ME200 in a number areas. If you want to save money, look at some of the
> Silicon Chip designs. They're mucyh less expensive.They also employ output
> stage VI limiting. The AKSA does not. One component failure, one crossed
> speaker cable, or faulty assembly and you're screwed.
>
In this case, I guess you have read Aksa schematics. Can you make some
comments specifically which areas you think Aksa is not good.
> get into the absurdly high prices of the AKSA preamp kits.
>
Why do you think Aksa preamp is "absurdly high prices", considering ME
preamps are all over $1200?
Gradenko
> > Sonically, I think Hugh has a hit on his hands.
>
> **Certainly financially, anyway. Don't forget: Nobody will admit to their
> own, handcrafted kit amplifier (ie: AKSA) as sounding sub-standard. Because
> they poured their heart and soul into it, it will always sound better than
> any commercial product, in spite of any kind of reality.
All comparisons and reviews I've read on ASKAs have always been by a
third party. I've never read Hugh play his own fiddle.
> Shallow words from
> > someone who hasn't even heard the product yet, but I have faith in his
> > design :-) If I was building a pro audio or subwoofer amp I may
> > consider other cheaper designs.
>
> **One recent Silicon Chip design (forgot the code number) is very
> impressive, indeed. Sophisticated topology and sensible component choice. It
> is one which should be considered by any home constructor.
Sophistication isn't necessarily what I'm after in a power amp. AKSA's
have been designed to be simple for a reason - every extra component
in the amp has the potenial to impart undesired musical qualities.
Its the reason AKSA doesn't employ protection circuitry or other such
niceties as found on commercial amps. A benefit in building a kit amp
is the user isn't assumed to be a complete dolt, they know the amps
opertating limitations :-) I did a quick search on groups.google.com
and found that Hugh has been over most of these topics with yourself
already. I have no desire to start another amp vs amp war, so lets
leave it there.
> The
> > model you mention, the ME200, isn't a power amp and is twice the price
> > of a Aska kit. A comparison between a Aska 100 and ME200 would be
> > interesting.
>
> **The ME200 IS a power amp
My mistake. The following page on your web site
http://www.rageaudio.com.au/mesales.htm , links ME200 to the ME240's
page (an integrated amp). Slightly confusing, as I missed the print
about the ME200 below its specifications.
I must mention, I always found your comments useful and incitful,
without much hint of commercialism that others complain about.
However, I did notice that it didn't take too long for this thread,
which made initially no mention of ME amps, to turn into a sales
pitch. Discuss benefits of various amp designs by all means, but
perhaps leave the salesman efforts for the showroom.
Trevor Wilson
> Hi Trevor, I have read the whitepaper. Thank you.
>
> As the ME amps are not kit amps, I guess I have no access to schematics. I
> believe you have listened to Aksa. Can you tell me what are the difference
> in sonics between ME and Aksa?
**I can't say, since I've not heard the AKSA. As for schematics for the ME,
you would need to ask Peter Stein. He may, or may not, be willing to supply
them. I can describe the basic topology, however. It uses simple, low
distortion gain stages, with lots of local NFB and no Global NFB. Some
highlights:
*Dual differential inputs.
*Perfectly symmetrical from input to output.
*Current sources are used on differential pairs, to reduce distortion (not
used on the AKSA)
*Common Emitter outputs.
--
Trevor Wilson
www.rageaudio.com.au
Trevor Wilson
> >
> > **You should. Some are vastly more sophisticated than the AKSA products.
> And
> > considerably less expensive too. Even if you fitted some of the mythical
> > parts which are fitted to the AKSA products, you'd still come out ahead.
> >
>
> A bit more detail on your comments on the two designs? Have you built one
> Aksa and why do you think the parts of Aksa mythical?
**I havn't built an AKSA. They're too expensive, for a kit amp. The Silicon
Chip products are far more cost effective, sophisticated and carry the same
warranty. Mythical, was a poor choice of words. I find a number of problems
with some of the concepts espoused by the AKSA site. Small power
transformers, small amounts of filter capacitance, input coupling caps, lack
of VI limiting, the suggestion that no decent log pots exist, lack of
current sources, etc.
>
>
> > > Sonically, I think Hugh has a hit on his hands.
> >
> > **Certainly financially, anyway. Don't forget: Nobody will admit to
their
> > own, handcrafted kit amplifier (ie: AKSA) as sounding sub-standard.
> Because
> > they poured their heart and soul into it, it will always sound better
than
> > any commercial product, in spite of any kind of reality.
> >
>
> In what areas Aksa sounds sub-standard?
**I did not mention the sound of the AKSA. I suggested that any AKSA builder
would have difficulty in admitting that their handiwork respresented
anything but the best sounding product available. I know this, from my own
experience in building kit amplifiers, many years ago. I also know it from
others, who have built their own products. Objectivity goes out the window.
I am equally certain that the AKSA amp sounds as good as the kit amps
published by Silicon Chip, et al.
>
>
> > Shallow words from
> > > someone who hasn't even heard the product yet, but I have faith in his
> > > design :-) If I was building a pro audio or subwoofer amp I may
> > > consider other cheaper designs.
> >
> > **One recent Silicon Chip design (forgot the code number) is very
> > impressive, indeed. Sophisticated topology and sensible component
choice.
> It
> > is one which should be considered by any home constructor.
> >
>
> The last Silicon Chip kit (Jan03) is SC480, a replacement of ETI480. The
> second last one (Nov02) is Ultra Low Distortion.
> Which one did you mean?
>
**The Ultra Low Distortion amp. It's topology is quite sophisticated.
> > >
> > > I have considered the ME range. I really should get around to
> > > listening to one but even so, they are far out of my price range.
> >
> > **Utter nonsense. The ME200 has a RRP of $1295.00. The aproximately
> > equivalent AKSA is $690.00 (no discounts available) PLUS freight PLUS
> power
> > supply PLUS case PLUS labour costs, etc. The ME200 comes with a full
parts
> > and labour 5 YEAR warranty. The AKSA comes with a 3 DAY warranty. By the
> > time you build an AKSA, you'll spend at least $1,000.00, excluding any
> > labour costs and you'll still have an amplifier which does not equal the
> > ME200 in a number areas. If you want to save money, look at some of the
> > Silicon Chip designs. They're mucyh less expensive.They also employ
output
> > stage VI limiting. The AKSA does not. One component failure, one crossed
> > speaker cable, or faulty assembly and you're screwed.
> >
>
> In this case, I guess you have read Aksa schematics. Can you make some
> comments specifically which areas you think Aksa is not good.
**The lack of current sources.
*The lack of VI limiting.
*Common Collector outputs.
*The suggestion that small power supplies should be used.
>
> > get into the absurdly high prices of the AKSA preamp kits.
> >
>
> Why do you think Aksa preamp is "absurdly high prices", considering ME
> preamps are all over $1200?
**Points:
1) The ME14 preamp is $1400.00. (And whatever discounts/trade-ins the
purchaser can organise)
1a) The approximately equivalent AKSA product is $1200.00. (NO discounts, NO
trade-ins)
2) The ME14 comes complete with an attractive (personal taste issues aside,
of course), custom manufactured case, front panel and knobs.
2a) The AKSA does not come with case, knobs, or front panel. Most builders
will probably choose a Chinese sourced, Dick Smith, generic case.
3) The ME14 has a frequency response of DC - 550kHz +/- 0.1dB
3a) The AKSA has a frequency reponse of 15Hz - 80kHz +/- 3dB. ( Afigure
which suggests phase shifts will occur, within the audio band)
4) The ME14 has a THD figure of less than 0.005% from 20Hz to 20kHz.
4a) The AKSA has a THD figure, which is hard to decipher. It is considerably
higher than the ME14.
5) The ME14 has a S/N ratio of better than 95dB.
5a) The AKSA has unspecified S/N figures. Based on THD measurements, it may
well be much worse than the ME14.
6) The ME14 has a potential resale value which is a significant fraction of
it's original purchase price (based on past performance).
6a) The resale value of the AKSA is likely to be minimal (based on the
resale value of most other kit set amplifiers).
7) The ME14 comes with a full 5 YEAR, parts and labour warranty.
7a) The AKSA comes with a 3 DAY limited warranty.
8) The ME14 is available from a number outlets, many of whom will allow
in-home demonstartions.
8a) The AKSA is available from one supplier who, presumably, does not allow
in-home demos, before purchase.
For an extra $200.00, the ME14 offers tangible and substantial benefits.
Most likely, easily audible ones, too.
--
Trevor Wilson
www.rageaudio.com.au
Trevor Wilson
> "Trevor Wilson" <tre...@rageaudio.com.au> wrote in message
news:<3e37b41d$0$21720$afc3...@news.optusnet.com.au>...
>
> > > Sonically, I think Hugh has a hit on his hands.
> >
> > **Certainly financially, anyway. Don't forget: Nobody will admit to
their
> > own, handcrafted kit amplifier (ie: AKSA) as sounding sub-standard.
Because
> > they poured their heart and soul into it, it will always sound better
than
> > any commercial product, in spite of any kind of reality.
>
> All comparisons and reviews I've read on ASKAs have always been by a
> third party. I've never read Hugh play his own fiddle.
**His web site, asdie, you're probably correct. That was not my point. It is
the kit builder (not the designer) who cannot usually make objective
judgements. I know this from personal experience. I built many kit
amplifiers, over the years. I always felt that they were far better than the
commerical alternatives. In those days (the early 1970s), kit amplifiers
were real viable alternatives to the much more expensive commerical
products. Sometime in the 1970s, I took the time to perform an honest
comparison to a good commerical product (Marantz 1200B). It blew away my
handcrafted kit amplifiers, in every meaningful way. It also had resale,
when it came time to sell it.
>
>
>
> > Shallow words from
> > > someone who hasn't even heard the product yet, but I have faith in his
> > > design :-) If I was building a pro audio or subwoofer amp I may
> > > consider other cheaper designs.
> >
> > **One recent Silicon Chip design (forgot the code number) is very
> > impressive, indeed. Sophisticated topology and sensible component
choice. It
> > is one which should be considered by any home constructor.
>
> Sophistication isn't necessarily what I'm after in a power amp.
**The sophistication in the Silicon Chip amplifier, translates to better
performance. And that better performance is available at a signifantly lower
cost than the AKSA. If I were in a position to build an amp, the Silicon
Chip, Ultra Low Distortion amp, would be my choice.
AKSA's
> have been designed to be simple for a reason - every extra component
> in the amp has the potenial to impart undesired musical qualities.
**Nonsense. SOME extra parts (current sources, f'rinstance), impart lower
levels of distortion and therefore less impact in the final result. SOME
parts do impact negatively. However, a good designer will have figured that
out first. The designer of the Silicon Chip product knows his stuff.
> Its the reason AKSA doesn't employ protection circuitry or other such
> niceties as found on commercial amps.
**No. The reason why AKSA does not employ VI limiting, is because the
designer has not yet learned how to make VI limiting circuits which exhibit
no sonic problems. Those issues have been addressed by several designers
(Peter Stein included). The absence of VI limiting is a serious omission. I
have been servicing such amplifiers, for many years. They show a higher
proportion of failures (by a large margin) than other amplifiers, which
employ protection devices.
A benefit in building a kit amp
> is the user isn't assumed to be a complete dolt, they know the amps
> opertating limitations :-) I did a quick search on groups.google.com
> and found that Hugh has been over most of these topics with yourself
> already. I have no desire to start another amp vs amp war, so lets
> leave it there.
**Check out the Silicon Chip product, if you want the experience and fun of
building. It is cheaper and better performing. You can also install some of
the exotic components and still come out way ahead. If you want the best
performance, a long and meaningful warranty, good resale and attrative
styling, fit and finish, then the ME makes a sensible alternative.
>
>
>
> > The
> > > model you mention, the ME200, isn't a power amp and is twice the price
> > > of a Aska kit. A comparison between a Aska 100 and ME200 would be
> > > interesting.
> >
> > **The ME200 IS a power amp
>
> My mistake. The following page on your web site
> http://www.rageaudio.com.au/mesales.htm , links ME200 to the ME240's
> page (an integrated amp). Slightly confusing, as I missed the print
> about the ME200 below its specifications.
**Fair enough. The specs on the ME240 and ME200 are identical.
>
>
> I must mention, I always found your comments useful and incitful,
> without much hint of commercialism that others complain about.
> However, I did notice that it didn't take too long for this thread,
> which made initially no mention of ME amps, to turn into a sales
> pitch. Discuss benefits of various amp designs by all means, but
> perhaps leave the salesman efforts for the showroom.
**Perhaps. I apologise. It is my opinion that the AKSA products are
over-rated and over-priced, whilst the Silicon Ship kits are under-rated and
under-priced, whilst the ME products are simply ignored.
--
Trevor Wilson
www.rageaudio.com.au
Eric Lindsay's spam trap
wrote:
>>
>> Jaycar kit prices for the SC480 is $45 each, plus $30 for the
>> power supply, and $40 for a transformer, so that runs to $160,
>> and you still need heat sinks, wiring, connectors, and a case (if
>> you intend to use a case). Of course if you have a decent junk
>> box, you'd probably do considerably better.
>
>I could not find SC480 on Jaycar catalogue. You need about double your money
>to get the transformer. But anyway, it seems that building a SC480 is not
>that cost effective than Jaycar Pro Series 3 ($599 including everything),
>regardless of the sonics.
The last part of the project only appeared in February. The
prices I gave were from the most recent Jaycar price list in
Silicon Chip, February 2003. They are new products.
KC-5345 SC-480 shortform using TO-220 $44.95 or
KC-5346 SC-480 (using TO-3) $44.95
KC-5347 Power supply $29.95
MM-1095 28v-0-28v CT transformer $39.95
Given that comes to $160, and I'd tend to expect it more likely
to be built into speakers, hidden away, or in a cheaper case, I'd
figure it to be around half the cost of the much more complete
and attractive Pro Series 3. I don't think they are really aimed
at the same audience.
I'm not at all sure it isn't easier in that power range, and
depending on the quality required, to go for a straight audio
opamp design (LM3876 maybe?)
Leura
I have not read the ME schematics so that I can not make any comments on the
design and I have not listened to any ME amps so that I am not sure ME is
better than others, say Aksa.
You have not studied Aksa schematics and listened to any Aksa. How do you
know it's not designed "sophisticatedly" and doesn't sound good, or better
than ME? (sophistication is not complexity)
"Trevor Wilson" <tre...@rageaudio.com.au> wrote in message
news:3e384270$0$21720$afc3...@news.optusnet.com.au...
Trevor Wilson
> Hi, Trevor,
>
> I have not read the ME schematics so that I can not make any comments on
the
> design and I have not listened to any ME amps so that I am not sure ME is
> better than others, say Aksa.
**A valid conclusion. You should attempt to do a comparison. See you local
ME dealer. He may be able to laon you one, for comparison with the AKSA.
Then, you will know for sure.
>
> You have not studied Aksa schematics and listened to any Aksa. How do you
> know it's not designed "sophisticatedly" and doesn't sound good, or better
> than ME? (sophistication is not complexity)
**I HAVE looked at an abridged version of the AKSA schematics and have read
through the information on the AKSA site. From that, I know that the level
of sophistication is not as high as (say) the Silicon Chip Ultra Low
Distortion amplifier. AKSA, for instance, eschews commonsense distortion
reducing devices, such as current sources, which the Silicon Chip amp does
not. As to whether the AKSA SOUNDS any better than the Silicon Chip amp, I
can't say. Looking at the specs and topology, it is logical to deduce that
the Silicon Chip amp will sound better (ie: Nuetral, uncoloured,
transparent, etc) than the AKSA, IF there is any sound difference. There is
most certainly a cost difference, in the Silicon Chip amp's favour. And, as
I have stated several times, the lack of VI limiting devices, is a real
worry, IMO. In short I would be very surprised to learn that the AKSA is
better than the Silicon Chip amp, in a blind trial.
--
Trevor Wilson
www.rageaudio.com.au
Patrick Turner
Trevor Wilson wrote:
Trevor, I doubt you could actually describe how a basic ME amp works,
beyond the above utterly useless over simplistic explanation.
Of course if you had all the ME schematics posted at your website, with detailed
explanations
that would give folks who doubt the effectiveness of the design
something to focus on, and also allow easy servicing or modding.
The AKSA power amp is very simple in that it has a normal
input differential pair; and a gain transistor which is bootstrapped off the
output
pair of transistors. I seem to remember the output stage is
darlington emitter follower connected, using modern flat pack transistors.
The design goes back to 1970? anyway, its older than the ME design,
and although it is an old topology, it uses modern transistors,
and I haven't heard a bad report yet about it.
It uses plenty of global NFB, permissable because
there are only 3 stages, wheras ME's design couldn't have such simplicity,
since so many more stages are in the amp.
I leave you all to decide which sounds best.
I haven't a clue.
I am sure Hugh might provide a copy of the AKSA schematic
to anyone wise enough to read and understand such a thing.
There is an Altronics kit cat no K5150 which could be what folks might be
thinking
of building.
I tried to build this kit for a subwoofer project and had to spend two days
redesigning the board
layout, changeing the circuit to a Turner Audio design, to prevent
this horrid kit producing clouds of smoke and HF oscillations,
and remaining thermally stable.
I have never encountered such a dog of kit.
Its got common emitter output stages like TW says is so great,
but I think CE transistor output stages are crap.
Meanwhile, I have repaired ME amps which came to
me with many burned out parts. Like many things, they are fixable.
There are conditions where active current protection is of limited use.
Many things can and do go wrong with SS amps from time to time,
generally due to wrong speaker connections, or partially shorted speakers
and at low levels some protection is as useful as tits on a bull, because a few
amps of output into a lousy load starts everything frying in the output stage
well before fuses blow, current limits work, or protection relays trip, or
thermal
sensors send a message.
The only guard against all mishaps is to have a microprocessor chip
which shuts the amp down if it detects a load which is too low,
along with everything else.
I would be surprised if the leading edge designs in the world
didn't have such sophisticated protections.
But the cost of such things is high since their complexity is
greater than the amp itself.
Active protection could be achieved without a microprocessor chip,
but somewhere in the earth return line there has to be a small resistance
to sense the current.
This has to be compared to the output voltage, and if Vout is small,
and I out is high, the circuit turns off the power rail supplies.
Patrick Turner.
Trevor Wilson
"Patrick Turner" <in...@turneraudio.com.au> wrote in message
news:3E38EB10...@turneraudio.com.au...
>
>
> Trevor Wilson wrote:
>
> > "Leura" <nos...@antispam.net> wrote in message
> > news:KeRZ9.3760$Tu2....@news-server.bigpond.net.au...
> > > Hi Trevor, I have read the whitepaper. Thank you.
> > >
> > > As the ME amps are not kit amps, I guess I have no access to
schematics. I
> > > believe you have listened to Aksa. Can you tell me what are the
difference
> > > in sonics between ME and Aksa?
> >
> > **I can't say, since I've not heard the AKSA. As for schematics for the
ME,
> > you would need to ask Peter Stein. He may, or may not, be willing to
supply
> > them. I can describe the basic topology, however. It uses simple, low
> > distortion gain stages, with lots of local NFB and no Global NFB. Some
> > highlights:
> > *Dual differential inputs.
> > *Perfectly symmetrical from input to output.
> > *Current sources are used on differential pairs, to reduce distortion
(not
> > used on the AKSA)
> > *Common Emitter outputs.
>
> Trevor, I doubt you could actually describe how a basic ME amp works,
> beyond the above utterly useless over simplistic explanation.
**Without posting an actual schematic, it is difficult to describe an
amplifier's topology, in words.
>
> Of course if you had all the ME schematics posted at your website, with
detailed
> explanations
> that would give folks who doubt the effectiveness of the design
> something to focus on, and also allow easy servicing or modding.
**Servicing is already easy. Since ALL transistors are matched to within 1%
tolerance for hFE and VBE, replacing devices is already beyond the reach of
most techs. Since the construction is modular, a module needs only to be
removed and sent to the factory, for correct servicing. As for schematics,
both ME and myself have seen a goodly number of amplifiers which have been
serviced very badly, by allegedly competent service people, over the years.
In several cases, the protection systems have been disabled, because the
techs could not figure out how to repair them! Little wonder that ME prefers
to see their products returned to the factory (or authorised agents) for
service.
>
> The AKSA power amp is very simple in that it has a normal
> input differential pair; and a gain transistor which is bootstrapped off
the
> output
> pair of transistors. I seem to remember the output stage is
> darlington emitter follower connected, using modern flat pack transistors.
>
> The design goes back to 1970? anyway, its older than the ME design,
> and although it is an old topology, it uses modern transistors,
> and I haven't heard a bad report yet about it.
> It uses plenty of global NFB, permissable because
> there are only 3 stages, wheras ME's design couldn't have such simplicity,
> since so many more stages are in the amp.
>
> I leave you all to decide which sounds best.
> I haven't a clue.
**I'll agree with that.
>
> I am sure Hugh might provide a copy of the AKSA schematic
> to anyone wise enough to read and understand such a thing.
**I think you need to buy an amp, before a schematic will be supplied. I
could be wrong.
>
> There is an Altronics kit cat no K5150 which could be what folks might be
> thinking
> of building.
> I tried to build this kit for a subwoofer project and had to spend two
days
> redesigning the board
> layout, changeing the circuit to a Turner Audio design, to prevent
> this horrid kit producing clouds of smoke and HF oscillations,
> and remaining thermally stable.
> I have never encountered such a dog of kit.
> Its got common emitter output stages like TW says is so great,
> but I think CE transistor output stages are crap.
**You are entitled to your opinion. Why do you think that they are crap?
>
> Meanwhile, I have repaired ME amps which came to
> me with many burned out parts. Like many things, they are fixable.
> There are conditions where active current protection is of limited use.
**When would that be?
> Many things can and do go wrong with SS amps from time to time,
> generally due to wrong speaker connections, or partially shorted speakers
> and at low levels some protection is as useful as tits on a bull, because
a few
> amps of output into a lousy load starts everything frying in the output
stage
> well before fuses blow, current limits work, or protection relays trip, or
> thermal
> sensors send a message.
>
> The only guard against all mishaps is to have a microprocessor chip
> which shuts the amp down if it detects a load which is too low,
> along with everything else.
**Whilst a micro has it's uses, it is not necessary to provide adequate
protection for an amplifier. Analogue systems work just fine.
>
> I would be surprised if the leading edge designs in the world
> didn't have such sophisticated protections.
> But the cost of such things is high since their complexity is
> greater than the amp itself.
**You're kidding, of course. Micros are very cheap. Interfacing them with
the outside world is not that difficult. Have a look at the Feb issue of
Silicon Chip. They feature a very powerful, 8 PIN mini DIP micro, which
sells for 3 bucks. It probably has plenty of power to be used as a
protection system for amplifiers.
>
> Active protection could be achieved without a microprocessor chip,
> but somewhere in the earth return line there has to be a small resistance
> to sense the current.
> This has to be compared to the output voltage, and if Vout is small,
> and I out is high, the circuit turns off the power rail supplies.
**Alternatively a couple of transistors could be used to shunt Base drive
away from the output devices. Much in the same way that designers have been
doing for the last 40 years. Whilst it is very effective and very safe (I
can send you a copy of a Marantz service manual, where short circuit testing
is part of the required test procedure, for all repaired amplifiers), it can
impose some nasty sonic artefacts. Naturally, amplifiers which have the VI l
imiters outside the feedback loop need not suffer this drawback.
--
Trevor Wilson
www.rageaudio.com.au
Leura
local suppliers as standard parts. This is no good as it makes it almost
impossible to upgrade the transformer. I feel the kit supplied transformer
(150VA) is not big enough.
Is it a businees decision or techinical decision to use this special PS
transformer?
Trevor Wilson
> SC480 uses a 28-0-28 PS transformer, which is not available from any major
> local suppliers as standard parts.
**Jaycar P# MM-1095. I regard Jaycar as a major supplier.
This is no good as it makes it almost
> impossible to upgrade the transformer. I feel the kit supplied transformer
> (150VA) is not big enough.
**Use two.
>
> Is it a businees decision or techinical decision to use this special PS
> transformer?
**With any new kit, there is likely to be some delay, before parts become
common. It would seem that Silicon Chip have collaborated with Jaycar (and
probably DSE and Altronics, as well) to ensure ready availability of the
critical power transformers for this project.
--
Trevor Wilson
www.rageaudio.com.au
Patrick Turner
Trevor Wilson wrote:
Servicing SS is only easy when the schematics are easily available.
All SS servicing should be easy, with no reliance on sending the amp away
for repairs.
And it is a pity ME has a negative view about repair folks other than
themselves.
There are not many competent repair places which would disable protection
systems.
Please advise ME to provide better online info about their products.
>
>
> >
> > The AKSA power amp is very simple in that it has a normal
> > input differential pair; and a gain transistor which is bootstrapped off
> the
> > output
> > pair of transistors. I seem to remember the output stage is
> > darlington emitter follower connected, using modern flat pack transistors.
> >
> > The design goes back to 1970? anyway, its older than the ME design,
> > and although it is an old topology, it uses modern transistors,
> > and I haven't heard a bad report yet about it.
> > It uses plenty of global NFB, permissable because
> > there are only 3 stages, wheras ME's design couldn't have such simplicity,
> > since so many more stages are in the amp.
> >
> > I leave you all to decide which sounds best.
> > I haven't a clue.
>
> **I'll agree with that.
>
> >
> > I am sure Hugh might provide a copy of the AKSA schematic
> > to anyone wise enough to read and understand such a thing.
>
> **I think you need to buy an amp, before a schematic will be supplied. I
> could be wrong.
I got one from Hugh, without buying a kit, via email.
All makers of all electronics should be able to send whatever info one wants.
Pigs will fly before they get around to doing this.
>
>
> >
> > There is an Altronics kit cat no K5150 which could be what folks might be
> > thinking
> > of building.
> > I tried to build this kit for a subwoofer project and had to spend two
> days
> > redesigning the board
> > layout, changeing the circuit to a Turner Audio design, to prevent
> > this horrid kit producing clouds of smoke and HF oscillations,
> > and remaining thermally stable.
> > I have never encountered such a dog of kit.
> > Its got common emitter output stages like TW says is so great,
> > but I think CE transistor output stages are crap.
>
> **You are entitled to your opinion. Why do you think that they are crap?
I have my reasons, too complex to describe here.
But there are no universal outright advantages of common emitter output stages
in SS amps. Its just one way out of many to configure the output transistors.
Everyone, including people who sell ME, say their own
preffered topology is the best way, but alas, there is zero corellation
to absolute sonic superiority under all conditions.
Variety in amplifier design exists because there IS NO best way to do things,
just different ways.
>
> > Meanwhile, I have repaired ME amps which came to
> > me with many burned out parts. Like many things, they are fixable.
> > There are conditions where active current protection is of limited use.
>
> **When would that be?
The ones that allowed the failure of the pile of blown up SS amps in my shed.
It should be impossible to blow any SS amp up any time,
regardless of the way it has been abused, or what has failed
spontaneously within the circuitry, due to old age.
But shite happens......
>
> > Many things can and do go wrong with SS amps from time to time,
> > generally due to wrong speaker connections, or partially shorted speakers
> > and at low levels some protection is as useful as tits on a bull, because
> a few
> > amps of output into a lousy load starts everything frying in the output
> stage
> > well before fuses blow, current limits work, or protection relays trip, or
> > thermal
> > sensors send a message.
> >
> > The only guard against all mishaps is to have a microprocessor chip
> > which shuts the amp down if it detects a load which is too low,
> > along with everything else.
>
> **Whilst a micro has it's uses, it is not necessary to provide adequate
> protection for an amplifier. Analogue systems work just fine.
>
> >
> > I would be surprised if the leading edge designs in the world
> > didn't have such sophisticated protections.
> > But the cost of such things is high since their complexity is
> > greater than the amp itself.
>
> **You're kidding, of course. Micros are very cheap. Interfacing them with
> the outside world is not that difficult. Have a look at the Feb issue of
> Silicon Chip. They feature a very powerful, 8 PIN mini DIP micro, which
> sells for 3 bucks. It probably has plenty of power to be used as a
> protection system for amplifiers.
Complex they are, and yes, I guess the modern micros are cheap,
I forgot that, but really, many amp protect systems leave a lot
to be desired, and I should never ever get a blown up SS amp to repair...
>
> > Active protection could be achieved without a microprocessor chip,
> > but somewhere in the earth return line there has to be a small resistance
> > to sense the current.
> > This has to be compared to the output voltage, and if Vout is small,
> > and I out is high, the circuit turns off the power rail supplies.
>
> **Alternatively a couple of transistors could be used to shunt Base drive
> away from the output devices. Much in the same way that designers have been
> doing for the last 40 years. Whilst it is very effective and very safe (I
> can send you a copy of a Marantz service manual, where short circuit testing
> is part of the required test procedure, for all repaired amplifiers), it can
> impose some nasty sonic artefacts. Naturally, amplifiers which have the VI l
> imiters outside the feedback loop need not suffer this drawback.
You entirely miss my point. I am well aware of shunting the base drive
to prevent the output transistors producing more than a certain
maximum current, usually less than the rated maximum.
But if a shorted speaker cable exists without the owner knowing,
and he, or his wife or kids use the system, they mightn't realise that
one channel sounds bad, at a low level, there is only a watt or two output.
But a few amps is being delivered
to the shorted speaker cable, usually frayed wires touching at
speaker or amp connections, and perhaps intermittently and this current is too
low to
trigger the over current protection you mention, or blow fuses, or trigger any
other protect circuit.
Thus say 2 amps x 50 volts on the rail, ie, 100 watts, is being
dissipated in heat in the output transistors, which can heat up and fuse
into a solid short circuit, before the thermal detect has time to work,
and then perhaps a fuse will blow, after the damage is done.
This is very common cause of SS amp failure.
Tube amps will also overheat their tubes in the same manner from the same cause,
but posibly the owner might notice a pair of red hot anodes,
but usually his wife of kids won't,
and the only proper protection is some method of
detecting when there is twice the usual DC flow in the tubes sustained for more
than 4 seconds. This is easy with class AB tube amps, but difficult
with nearly class B tube amps and surely more difficult with ALL SS amps
which are very nearly pure class B.
Load value detection is of course the best, but seldom used..
Patrick Turner.
Trevor Wilson
**Servicing ANYTHING is only easy when the schematics are available.
> All SS servicing should be easy, with no reliance on sending the amp away
> for repairs.
**And that is why ME make their construction modular. A module is removed,
sent to the factory, where it is serviced correctly and economically. Since
ME products are the only products ME's service personel repair, they are
very familiar with the product. As such repairs can often be effected faster
than the time taken to dispatch service data to a third party repairer,
fault diagnosed, parts ordered, delivered, then fitted. Then, of course, all
ME power amps should be run for at least one hour, whilst bias adjustments
are made.
> And it is a pity ME has a negative view about repair folks other than
> themselves.
**They (and I) just judge it on the evidence of appallingly badly repaired
products. A couple of months ago, I received an ME in for service, which had
been worked on by one of Sydney's most prestigious repair centres. Not only
were unmatched output devices fitted (dumb), thus compromising performance,
but the output devices were not securely mounted to the heatsinks (really,
really dumb). The final repair bill was huge. It would have been much
smaller, had the owner returned it to myself, or to the factory. This is
just one example.
> There are not many competent repair places which would disable protection
> systems.
**Well, the one which performed that particular little trick, was one of
Sydney's most prestigious repair centres. I have seen the results of their
disabling of protection systems, in ME amps, several times. Such actions
disgust me (and ME).
>
> Please advise ME to provide better online info about their products.
**That would be Peter Stein's decision. I guess, if he could assured that
the repairer would actually take the time to service ME products properly,
use correctly matched semiconductors and generally take good care and not
reveal proprietory information, then he would be inclined to send service
data. Again, that would be Peter Stein's decision.
**Some do, some don't.
**So, they're not actually crap, then? Just different.
>
> >
> > > Meanwhile, I have repaired ME amps which came to
> > > me with many burned out parts. Like many things, they are fixable.
> > > There are conditions where active current protection is of limited
use.
> >
> > **When would that be?
>
> The ones that allowed the failure of the pile of blown up SS amps in my
shed.
>
> It should be impossible to blow any SS amp up any time,
> regardless of the way it has been abused, or what has failed
> spontaneously within the circuitry, due to old age.
>
> But shite happens......
**Sure it does. It is possible to damage ANY amplifier, if one is determined
to do so. Active VI limiting, however, is an excellent way to mitigate most
damage.
**Of course many amps are inadequately protected. It costs money to provide
adequate protection.
**That can certainly happen. It is not difficult to provide thermal
protection, however. A well designed amplifier will have the thermal sensors
mounted very close to the output devices. Companies like Rotel, have thermal
protection, though it is placed at some distance from the output devices.
> This is very common cause of SS amp failure.
> Tube amps will also overheat their tubes in the same manner from the same
cause,
>
> but posibly the owner might notice a pair of red hot anodes,
> but usually his wife of kids won't,
> and the only proper protection is some method of
> detecting when there is twice the usual DC flow in the tubes sustained for
more
> than 4 seconds. This is easy with class AB tube amps, but difficult
> with nearly class B tube amps and surely more difficult with ALL SS amps
> which are very nearly pure class B.
> Load value detection is of course the best, but seldom used..
**Actually, such things ARE used in a great many mass market amps. It is
simple enough to do, since many have a micro on-board, with plenty of unused
ports.
--
Trevor Wilson
www.rageaudio.com.au
Leura
major
> > local suppliers as standard parts.
>
> **Jaycar P# MM-1095. I regard Jaycar as a major supplier.
>
Jaycar is a major supplier but the MM-1095 is the supplied EI transformer I
referred, which I don't like and trying to replace. I was thinking of two
330 VA Avel toroidals to replace them but could not find a Avel 28-0-28 one
or any similar branded ones from Jaycar, Dick Smiths, Altronics, Farnnel and
RS.
> This is no good as it makes it almost
> > impossible to upgrade the transformer. I feel the kit supplied
transformer
> > (150VA) is not big enough.
>
> **Use two.
>
Do you mean two for one channel? If so, it's not a good idea for a hi-fi
amp.
Trevor
> Jaycar is a major supplier but the MM-1095 is the supplied EI transformer
I
> referred, which I don't like and trying to replace. I was thinking of two
> 330 VA Avel toroidals to replace them but could not find a Avel 28-0-28
one
> or any similar branded ones from Jaycar, Dick Smiths, Altronics, Farnnel
and
> RS.
> > > This is no good as it makes it almost
> > > impossible to upgrade the transformer. I feel the kit supplied
> > >transformer (150VA) is not big enough.
> > **Use two.
> Do you mean two for one channel? If so, it's not a good idea for a hi-fi
> amp.
Why? It's actually a benefit if you use seperate rectifiers and capacitors
as well.
How many continuous watts output per channel are you trying to achieve? Do
you really need 600 VA of transformers anyway?
Trevor.
Trevor Wilson
> > > SC480 uses a 28-0-28 PS transformer, which is not available from any
> major
> > > local suppliers as standard parts.
> >
> > **Jaycar P# MM-1095. I regard Jaycar as a major supplier.
> >
>
> Jaycar is a major supplier but the MM-1095 is the supplied EI transformer
I
> referred, which I don't like and trying to replace. I was thinking of two
> 330 VA Avel toroidals to replace them but could not find a Avel 28-0-28
one
> or any similar branded ones from Jaycar, Dick Smiths, Altronics, Farnnel
and
> RS.
**That was not your original question. If you have the cash to burn on an
Avel transformer (for whatever reason), then you could probably get a
specialist maker to wind a transformer for you. BTW: Toroidals do not
possess any magical qualities which make them better than an euivalently
rated EI type, except that they radiate less field. Being roughly cubic
shaped, an EI tranny may have better space efficiency too.
>
> > This is no good as it makes it almost
> > > impossible to upgrade the transformer. I feel the kit supplied
> transformer
> > > (150VA) is not big enough.
> >
> > **Use two.
> >
>
> Do you mean two for one channel? If so, it's not a good idea for a hi-fi
> amp.
**Why?
--
Trevor Wilson
www.rageaudio.com.au
Patrick Turner
Trevor Wilson wrote:
>
> BTW: Toroidals do not
> possess any magical qualities which make them better than an euivalently
> rated EI type, except that they radiate less field. Being roughly cubic
> shaped, an EI tranny may have better space efficiency too.
The problem with toroids is that many samples one puchases are not mechanically
quiet, and the turns per volt insufficient and the B at which the tranny runs,
usually about 1.2 Tesla, means the core is partially saturating,
even though it runs cooler than a larger E&I tranny.
Jaycar toroidals and many which are made in Oz by so called specialists
are also crap due to the same reasons I mention.
The toroidal core has a high iron U, and thus the magnetising
current is usually low, but with a rectifier circuit, they go noisy.
Nearly all toroids are not varnish or epoxy impregnated
which makes the noise problem worse.
So, I have given up ever trying to get Oz wound trannies,
since the only way I can get a quiet tranny which runs cool
is to wind them all myself, using Oz made GOSS material which
at $8 per kg is twice the price of plain NOSS E&I which
gets much hotter, but which most tranny winders here try to use to cut costs
and leave you with a hot running tranny with a high magnetising current.
In a 4 kG tranny the extra material cost for GOSS is only
$16, and I bet volume winders get the GOSS at a cheaper rate than I pay.
Of course there is another price to pay for quiet cool trannies if
one wants quality, and that is size and weight.
If the turns per volt are arranged for B = 0.7 Tesla,
and we want low copper losses, the core has to be bigger.
But a large well made cool running quiet power tranny
will last 50 years at least, and have better overload tolerance.
I laugh at the Jaycar specs which allow for a 60C rise from ambient
for their power trannies.
In mine, even ones which pull 550 watts from the mains, the T rise
is negligible after 4 hours, and such a tranny will have only
4 watts of iron losses.
The other thing wrong with toroidals is that their weight rests on the wires,
and unless the winder has been extremely careful to never allow
a crossed over turn within a layer the chances are a shorted turn will result.
So quality control with toroids is critical.
For a 100 watt largely class B SS amp, the idle power is only
15 watts perhaps, and many mainstream product with 2 x 100 watt channels have
trannies rated at 50 watts for both channels.
This is because the amps are rarely if ever used above an average power level
of
10 watts each, with clipping on peaks limiting any further power use.
Thus such a scheme works OK, but does not test very well,
or last very long under sine wave full power conditions
wth both channels driven at 1 dB under clipping into the rated
load of 8 ohms, let alone 4 ohms.
The toroid does not seem to have penetrated the mainstream market place
to any great extent, since they are labour intensive compared to
E&I trannies using welded GOSS cores with special preformed
concentric pre wound bobbins to allow physical isolation between P&S windings.
Labour content of a power tranny
in a factory doing 10,000 units per day is about 0.2 manhours.
(And a spare one still averages a cost of $180; don't ever think makers don't
make a profit
selling spares.)
Patrick Turner.
Phil Allison
>
> Trevor Wilson wrote:
>
> >
>
> > BTW: Toroidals do not
> > possess any magical qualities which make them better than an euivalently
> > rated EI type, except that they radiate less field. Being roughly cubic
> > shaped, an EI tranny may have better space efficiency too.
>
> The problem with toroids is that many samples one puchases are not
mechanically
> quiet, and the turns per volt insufficient and the B at which the tranny
runs,
> usually about 1.2 Tesla, means the core is partially saturating,
** There are lies, damn lies and the BS Pat posts.
Bet he has never measured the magnetising current of a toriodal -
it is tiny.
E-cores are the ones that operate in permanent saturation.
> even though it runs cooler than a larger E&I tranny.
> Jaycar toroidals and many which are made in Oz by so called specialists
> are also crap due to the same reasons I mention.
** False reasons so no crap.
> The toroidal core has a high iron U, and thus the magnetising
> current is usually low, but with a rectifier circuit, they go noisy.
> Nearly all toroids are not varnish or epoxy impregnated
> which makes the noise problem worse.
** Only if some 1/10 th wit draws half wave current off the output.
.............. Phil
Patrick Turner
Phil Allison wrote:
> "Patrick Turner" <in...@turneraudio.com.au> wrote in message
> news:3E3A22C7...@turneraudio.com.au...
> >
> > Trevor Wilson wrote:
> >
> > >
> >
> > > BTW: Toroidals do not
> > > possess any magical qualities which make them better than an euivalently
> > > rated EI type, except that they radiate less field. Being roughly cubic
> > > shaped, an EI tranny may have better space efficiency too.
>
> >
> > The problem with toroids is that many samples one puchases are not
> mechanically
> > quiet, and the turns per volt insufficient and the B at which the tranny
> runs,
> > usually about 1.2 Tesla, means the core is partially saturating,
>
> ** There are lies, damn lies and the BS Pat posts.
Ah, how many trannies do you wind and sell to make part of your living?
>
>
> Bet he has never measured the magnetising current of a toriodal -
> it is tiny.
It is indeed sometimes small because the mu of the iron is high, up to 40,000.
This means the impedance curve for the iron shows that for B=0.7 T,
the primary Z is very high, ie, the inductance of the primary
coil is high.
But at 1.2 T, this high Z has begun to plummet.....
When you look at the current flow using a series R of 10 ohms in a typical
toroid operating at 1.2 Tesla or more, the current isn't sinusoidal.
But loweing the B to 0.8 T or lower removes this distortion current,
caused by PARTIAL saturation.
Same goes for cores of E&I.
The GOSS Sankey E&I lams I recently bought measured a mu of 17,000
when assembled in a large 550 watt wkg tranny.
Iron losses were 4 watts, less than many toroids, at 0.7 Tesla.
> E-cores are the ones that operate in permanent saturation.
I am not discussing E-cored transformers.
I am discussing normal 2 phase domestic amp transformers.
Should you wish to show how an E cored tranny will be great stuff in a small
domestic amp, then go ahead.
>
>
> > even though it runs cooler than a larger E&I tranny.
> > Jaycar toroidals and many which are made in Oz by so called specialists
> > are also crap due to the same reasons I mention.
>
> ** False reasons so no crap.
?
> > The toroidal core has a high iron U, and thus the magnetising
> > current is usually low, but with a rectifier circuit, they go noisy.
> > Nearly all toroids are not varnish or epoxy impregnated
> > which makes the noise problem worse.
>
> ** Only if some 1/10 th wit draws half wave current off the output.
Gees Phil, you are as thick as a brick today.
I recently TRIED to use a Jaycar tranny, as a temporary measure
so the client could use this amp during the Xmas New yr break but
he could not accept the amp
because it was too noisy, and it has a full wave rectifier.
When I replaced the offensive Jaycar product with something I wound myself
with GOSS E&I, the noise was indetectable with my ear 50 mm away from the
tranny.
Regulation was fine, and the idle current was 1/3 of the toroid.
I recently contacted a supposedly reputable Sydney company about
winding a toroidal tranny which was quiet, and had a low temperature rise,
and qualities they were prepared to guarantee.
I got a 4 line reply email saying that they could do a toroidal but the T rise
would be 49C.
I emailed back , asking them to contact me when they learn how to
wind quality transformers, and are competent enough to prove it routinely.
That mob just hasn't a clue, or else they just were not interested in
a small quantity of work.. Their website indicates otherwise.
But also their website has no prices, details are missing, no mention of
guarantees of the specs, so I half expected rubbish, and its all they can do.
Patrick Turner.
Phil Allison
> > > The problem with toroids is that many samples one puchases are not
> > mechanically> quiet, and the turns per volt insufficient and the B at
which the tranny
> > runs, > usually about 1.2 Tesla, means the core is partially saturating,
> >
> > ** There are lies, damn lies and the BS Pat posts.
>
> Ah, how many trannies do you wind and sell to make part of your living?
** The FUCKWIT cannot even comprehend my insult !!!!!!!!!
> > Bet he has never measured the magnetising current of a
oriodal -
> > it is tiny.
>
> It is indeed sometimes small because the mu of the iron is high, up to
40,000.
> This means the impedance curve for the iron shows that for B=0.7 T,
> the primary Z is very high, ie, the inductance of the primary
> coil is high.
> But at 1.2 T, this high Z has begun to plummet.....
>
> When you look at the current flow using a series R of 10 ohms in a typical
> toroid operating at 1.2 Tesla or more, the current isn't sinusoidal.
> But loweing the B to 0.8 T or lower removes this distortion current,
> caused by PARTIAL saturation.
** So the LYING SHIT has never actually measured it - as I said.
> Same goes for cores of E&I.
> The GOSS Sankey E&I lams I recently bought measured a mu of 17,000
> when assembled in a large 550 watt wkg tranny.
> Iron losses were 4 watts, less than many toroids, at 0.7 Tesla.
>
>
> > E-cores are the ones that operate in permanent saturation.
>
> I am not discussing E-cored transformers.
** YOU JUST DID - YOU ARE A LIAR !!!!!!!!!!!
> I am discussing normal 2 phase domestic amp transformers.
> Should you wish to show how an E cored tranny will be great stuff in a
small
> domestic amp, then go ahead.
** On planet Turner the laws of physics are all different.
> >
> > > The toroidal core has a high iron U, and thus the magnetising
> > > current is usually low, but with a rectifier circuit, they go noisy.
> > > Nearly all toroids are not varnish or epoxy impregnated
> > > which makes the noise problem worse.
> >
> > ** Only if some 1/10 th wit draws half wave current off the
output.
>
> Gees Phil, you are as thick as a brick today.
** Stop pulling your cock Pat.
>
>
> I recently contacted a supposedly reputable Sydney company about
> winding a toroidal tranny which was quiet, and had a low temperature rise,
> and qualities they were prepared to guarantee.
> I got a 4 line reply email saying that they could do a toroidal but the T
rise
> would be 49C.
> I emailed back , asking them to contact me when they learn how to
> wind quality transformers, and are competent enough to prove it routinely.
> That mob just hasn't a clue, or else they just were not interested in
> a small quantity of work.. Their website indicates otherwise.
> But also their website has no prices, details are missing, no mention of
> guarantees of the specs, so I half expected rubbish, and its all they can
do.
** If you want low temp rise then simply overspecify.
They would have though you were a fuckwit for not realising that -
Pat.
They would also have been dead fucking right.
............... Phil
Patrick Turner
statements from PA that it is no wonder so many folks here at
Aus.hi-fi would love to see PA get off the group,
and go fishing.
Patrick Turner.
Phil Allison
> Below is an error filled post so full of sanity challenged
> statements from PA that it is no wonder so many folks here at
> Aus.hi-fi would love to see PA get off the group,
> and go fishing.
** The obove is another idiot post from Pat the Autistic.
If he ever had a logical thought it would die from lonliness.
.............. Phil
Steve
news:3e350f9...@news.optusnet.com.au...
> On Mon, 27 Jan 2003 10:02:55 GMT, "Leura" <nos...@antispam.net> wrote:
>
> >At the moment, there are 3 amp kits in shops I like to know compare.
Ultra
> >Low Distortion Stereo Amplifier kit from Altronics; Pro Series 3
Amplifier
> >kit from Jaycar and ETI480 (SC480) from Dick Smith.
> >
<SNIP>
> However it really dosen't make sense to build your own power
> amplifier. You can buy amps like Rotel RB-970 or similar second-hand
> for less money that you can buy the bits for a SC480 based DIY amp.
First up, I have no electronics skill whatsoever. I've been looking at the
SC-480 as a solution to my amplifier issues for 2 reasons. First is cost, as
I've yet to find an amplifier that can provide similar power at a similar
price. Secondly (and perhaps more importantly), I have a very odd
installation requirement, and unless I can find an amplifier with a very low
profile (100mm maximum) then I figure a modular design like the SC480 kits
would be more suitable.
Mind you, my opening statement also means I need to find someone in Brisbane
to build it for me. Anyone care to take the job on? Or at least tell me what
NOT to buy?
Steve
Dale
--
Please remove "WWW" when replying via email
"Steve" <st...@mag.net> wrote in message
news:3e6849fa$0$12816$afc3...@news.optusnet.com.au...
> "Johnny" <joh...@NOSPAM.hotmail.com> wrote in message
> news:3e350f9...@news.optusnet.com.au...
> > On Mon, 27 Jan 2003 10:02:55 GMT, "Leura" <nos...@antispam.net> wrote:
> >
> > >At the moment, there are 3 amp kits in shops I like to know compare.
> Ultra
> > >Low Distortion Stereo Amplifier kit from Altronics; Pro Series 3
> Amplifier
> > >kit from Jaycar and ETI480 (SC480) from Dick Smith.
> > >
> <SNIP>
> > However it really dosen't make sense to build your own power
> > amplifier. You can buy amps like Rotel RB-970 or similar second-hand
> > for less money that you can buy the bits for a SC480 based DIY amp.
>
> First up, I have no electronics skill whatsoever. I've been looking at the
> SC-480 as a solution to my amplifier issues for 2 reasons. First is cost,
as
> I've yet to find an amplifier that can provide similar power at a similar
> price. Secondly (and perhaps more importantly), I have a very odd
> installation requirement, and unless I can find an amplifier with a very
low
> profile (100mm maximum) then I figure a modular design like the SC480 kits
> would be more suitable.
## Rega amps may be able to help. Perhaps also the budget ME.
Dale
Aussiemale
you.
I have been trained in electronic assembly to mil spec and have won silicon
chip's circuit notebook multimeter prize.
Hope you find someone to make it for you.
"Steve" <st...@mag.net> wrote in message
news:3e6849fa$0$12816$afc3...@news.optusnet.com.au...
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Trevor
> news:3e350f9...@news.optusnet.com.au...
> > On Mon, 27 Jan 2003 10:02:55 GMT, "Leura" <nos...@antispam.net> wrote:
> >
> > >At the moment, there are 3 amp kits in shops I like to know compare.
> Ultra
> > >Low Distortion Stereo Amplifier kit from Altronics; Pro Series 3
> Amplifier
> > >kit from Jaycar and ETI480 (SC480) from Dick Smith.
Be careful, the ETI 480 and SC480 are two completely different designs.
> First up, I have no electronics skill whatsoever. I've been looking at the
> SC-480 as a solution to my amplifier issues for 2 reasons. First is cost,
as
> I've yet to find an amplifier that can provide similar power at a similar
> price. Secondly (and perhaps more importantly), I have a very odd
> installation requirement, and unless I can find an amplifier with a very
low
> profile (100mm maximum) then I figure a modular design like the SC480 kits
> would be more suitable.
> Mind you, my opening statement also means I need to find someone in
Brisbane
> to build it for me. Anyone care to take the job on? Or at least tell me
what
> NOT to buy?
Don't buy the original ETI 480! The SC480 is much better.
Of the 3 you mention, the first two are available as complete kits with the
later ULD version having a low profile case. (the original design was built
in a computer case)
The SC480 is only available as a PCB module to my knowledge, so power
supply, pre-amp and case etc. is up to you. It is not as powerful as the
other two either and uses much cheaper output transistors, but the total
cost will be much lower if that is what you want.
If you aren't prepared to build it yourself though, I can't see how you can
save any money. There are single rack unit power amps available that fit
your requirements.
Trevor.
Steve
news:1047040937.651895@teuthos...
> I was in Brisbane up until last march - I could have possibly done it for
> you.
> I have been trained in electronic assembly to mil spec and have won
silicon
> chip's circuit notebook multimeter prize.
>
> Hope you find someone to make it for you.
Steve
news:3e6890d1$0$16256$afc3...@news.optusnet.com.au...
> If you aren't prepared to build it yourself though, I can't see how you
can
> save any money. There are single rack unit power amps available that fit
> your requirements.
Yeah, that's the problem isn't it. You only save money if you DIY. And of
course anything rack-mounted will be more expensive just because it usually
has a professional use. Surely there's a low-end consumer market for amps
that are low-profile - I'd much rather buy off-the-shelf if I could but it's
all too big and covered with useless controls and settings.
Trevor
Don't automatically assume a rack mount unit will be more expensive, prices
start at around $500 for 100W per channel new.
A lot of pro gear now uses switch mode power supplies and fan cooling
though.
Trevor.