Phil Allison is dumb on OPTs.
Patrick Turner
on OPTs and using mains trannies as such,
and there is no reason for me to reply.
All the posts were insult laden, repititious, and without any good
design ideas about OPTs.
Even Phil's friend, Andre Jute, would roundly condemn
any idea that decent performance with tubed PP with 2 x 6L6 is possible
using mains derived toroidals, even those with "special" twin 240v
windings to make the P a bit bigger.
Andre rightly has said a lot in favour about Plitrons which are
toroidals.
They are a little more expensive, but they come with the right number of
turns per volt to suit tube usage.
Meanwhile, Phil Allison hasn't a clue about how to wind a really
decent OPT fit for use with 2 x 6L6, or any other tubes.
We should simply assume he is pig ignorant on the subject
until he prooves otherwise.
Good OPT design cannot be summed up in a series of simple one liners,
interspersed with insults.
We can assume PA has never designed, wound, and tested an OPT.
For more about decent OPT design theory, turn to the RDH4,
wherin there is all one needs to know about OPTs,
but there is nothing about using toroidal transformers.
Exactly how to wind toroidal OPTs with all the formulae
to get a predictable result is a little thin on the Web, or in the old
books,
because toroidals were never wound in the old days en-masse;
they have only come into vogue because modern winding machines
can wind them more cheaply than an E&I transformer.
Nearly all toroidals wound are mains transformers.
The makers of E&I trannies responded to calls from their bean counter
staff
to reduce E&I tranny costs further by winding bobbins with a primary,
and another with a secondary, and the two bobbins are slid together
offering excellent isolation.
GOSS E&I core material has been improved to the point
where interleaving the laminations isn't needed, the bundle of Es and Is
is simply butted together and welded. Even with an effective air gap,
the core U is still high enough to keep the magnetising current low
enough.
There are no human hands involved in the process, and transformers
for 1,001 purposes stream off production lines like sausages from a
sausage machine.
With a little refinement, and 10 minutes longer of machine time,
decent OPTs could be made en-masse, but demand is infinitessimally small
compared to mains trannies for SS amps, so we have to pay through the
nose
for OPTs.
Even so, the cost of a replacement mains transformer for a Marantz SS
hi-fi amp
is quite high. The big companies like their profits to be high when they
sell spares.
Patrick Turner.
Form@C
<snip>
>
> For more about decent OPT design theory, turn to the RDH4, wherin there is
Unfortunately I'm not likely to be able to find that easily around here.
It *may* be available via a reference library but that's about it. I
suspect it is probably rather advanced for me at the moment too... ;-)
<snip>
>
> With a little refinement, and 10 minutes longer of machine time, decent
> OPTs could be made en-masse, but demand is infinitessimally small
>
That sums up the whole problem in a nutshell. Supply & demand. If I buy
(what appears to be) Sowter's cheapest EL34 UL p-p 6k6 a-a transformer it
is over 124ukp +carriage. To put that into perspective, it is over half my
total income for a 3-day week. A 110+110:9+9 mains torroid is about 17ukp
delivered. For that difference in price I can live with a 7W limit and a
steep bass roll-off at anything up to 200Hz! ;-) I have a pair of "guitar
amp" transformers which are about 4k a-a IIRC (I can check, but have no
other info). I suspect that they would be worse than mains torroids at the
top end - and there may not be much bass either with only a 32mm
lamination stack.
On the whole, I think it has been worth asking the question, even if Mr
Allison's opinion of me has sunk somewhat... I'll not let it worry me. ;-)
Oh - my SE 6L6 amp sounds quite pleasant now... Unfortunately, that has
what appear to be "music centre" OPTs, probably intended for EL84s. Such
is life...
--
Mick
http://www.nascom.info for Nascom & Gemini information
Also at http://www.mixtel.co.uk where the collection started.
Currently deserting M$ for linux... :-)
Phil Allison
"Form@C" <mi...@mixtel.co.uk> ...
Patrick Turner wrote:
>>
> >
> > For more about decent OPT design theory, turn to the RDH4, wherin there
is
>
> Unfortunately I'm not likely to be able to find that easily around here.
** That book was written in 1952.
Modern, machine wound, plastic wrap insulated, low cost toroidals came
out much more recently.
The transformer game has changed - the Turneroid is yet to catch up.
................ Phil
Form@C
I will certainly be looking at torroids in some form. Even if I can't get
"hi-fi" quality out of them it doesn't really matter. That isn't my field
- I can't afford it! I like building with valves though; that's the
attraction for me. I'll ask around for custom winding as you suggested. If
the price isn't prohibitive I'll get one (or probably two) wound with
dual primaries of as many turns as they can comfortably manage, put my
own secondary on top by hand, and give them a spin to see (hear! - but
"spin" sounds more apt for torroids!) how they work. I don't have much in
the way of test gear, but since I'm only building for *me* the test
results would mainly be just for academic interest. I might be able to do
a response curve of sorts for the amp if I can persuade my old scope &
kit-built oscillator to function. :-) Steve Bench's notch filter for
distortion measurements may get built too.
Phil Allison
"Form@C" <mi...@mixtel.co.uk
>
> I will certainly be looking at torroids in some form. Even if I can't get
> "hi-fi" quality out of them it doesn't really matter.
** You easily can - hard to get otherwise.
> I'll ask around for custom winding as you suggested.
** Just ask that a secondary winding *equal in turns* to the primary one
be fitted.
Go for an 80 VA core size - the turns per volt is more manageable.
> put my own secondary on top by hand,
** Perfectly doable.
The response will be flat to 50 kHz at least.
Ignore what that lying Turnip arsehole says.
He is just trying to prop up his transformer winding scam - at any cost
to the truth.
.......... Phil
Form@C
>
> "Form@C" <mi...@mixtel.co.uk
>
>
>> I will certainly be looking at torroids in some form. Even if I can't
>> get "hi-fi" quality out of them it doesn't really matter.
>
>
> ** You easily can - hard to get otherwise.
>
>
>> I'll ask around for custom winding as you suggested.
>
>
> ** Just ask that a secondary winding *equal in turns* to the primary
> one be fitted.
>
> Go for an 80 VA core size - the turns per volt is more
> manageable.
>
>
>
>> put my own secondary on top by hand,
>
>
> ** Perfectly doable.
>
Yep. Just added a 6.3 winding onto a little core to feed some heaters. As
long as they don't pot the thing... :-)
> The response will be flat to 50 kHz at least.
>
> Ignore what that lying Turnip arsehole says.
>
> He is just trying to prop up his transformer winding scam - at any
> cost
> to the truth.
>
<grin>
Thanks for the advice. I'll investigate further & see what I can come up
with.
Patrick Turner
"Form@C" wrote:
> On Sun, 18 Jan 2004 19:11:22 +1100, Patrick Turner wrote:
>
> <snip>
> >
> > For more about decent OPT design theory, turn to the RDH4, wherin there is
>
> Unfortunately I'm not likely to be able to find that easily around here.
> It *may* be available via a reference library but that's about it. I
> suspect it is probably rather advanced for me at the moment too... ;-)
OK.
People who say what you have just said can start with the basics,
and work up, so reading text books given to first year tech college
students should be where you start, as well as build your own workshop
where you can try circuits using basic R L and C.
> <snip>
> >
> > With a little refinement, and 10 minutes longer of machine time, decent
> > OPTs could be made en-masse, but demand is infinitessimally small
> >
>
> That sums up the whole problem in a nutshell. Supply & demand. If I buy
> (what appears to be) Sowter's cheapest EL34 UL p-p 6k6 a-a transformer it
> is over 124ukp +carriage. To put that into perspective, it is over half my
> total income for a 3-day week.
But how long will it take you to make what Sowter supply?
3 mths? and six failed first attempts?
I wound 3 terrible OPTs before I started to get predictable,
and the items were usable.
From what you are saying, it takes you three days to earn enough
to buy 2 Sowter trannies.
That's a pretty decent paying job you got, ain't it?
It takes me longer than 3 days to make two OPTs, and then there
is the cost of materials. And the design calculations, testing, varnishing,
etc.....
> A 110+110:9+9 mains torroid is about 17ukp
> delivered. For that difference in price I can live with a 7W limit and a
> steep bass roll-off at anything up to 200Hz! ;-) I have a pair of "guitar
> amp" transformers which are about 4k a-a IIRC (I can check, but have no
> other info). I suspect that they would be worse than mains torroids at the
> top end - and there may not be much bass either with only a 32mm
> lamination stack.
I have pointed out in other posts why a 17 ukp mains tranny would be hopeless
with a pair of 6L6.
But to understand why I said what i said means you'd ned to undertsand the
terminology,
and the simple formulas governing the design parameters.
That takes study. Don't worry, I am hopeless at
studying Latin, or the habits of gay left flippered whales.
>
>
> On the whole, I think it has been worth asking the question, even if Mr
> Allison's opinion of me has sunk somewhat... I'll not let it worry me. ;-)
Allison works on the principle that all students should be shot because they
are ignorant.
He bashes ppl into the dust, rather than lift them up with enlightenment.
But accordingly, *you* have to make an effort to understand.
Some folks have to spend years at a uni to know anything.
Keep trying, but the PC may not be your saviour this time,
and that's why teachers and colleges have not yet all been abandoned.
I think I was lucky to make something from what I read at uni
and tech college libraries, and from an array of ols books I acquired,
and from several years spent locked up in my workshop
well before I acquired a PC, and instead of watching TV, or
socialising at the pub.
>
>
> Oh - my SE 6L6 amp sounds quite pleasant now... Unfortunately, that has
> what appear to be "music centre" OPTs, probably intended for EL84s. Such
> is life...
The first watt might be total audio heaven, but what then when you want
10 watts?
Patrick Turner.
Patrick Turner
Phil Allison wrote:
> "Form@C" <mi...@mixtel.co.uk> ...
> Patrick Turner wrote:
> >>
> > >
> > > For more about decent OPT design theory, turn to the RDH4, wherin there
> is
> >
> > Unfortunately I'm not likely to be able to find that easily around here.
>
> ** That book was written in 1952.
The laws of physics have not changed since 1952,
and RDH4 remains a classic tome which is very useful to
anyone interested in tube circuit building.
Each and every sentence says so much.
>
>
> Modern, machine wound, plastic wrap insulated, low cost toroidals came
> out much more recently.
>
> The transformer game has changed - the Turneroid is yet to catch up.
>
> ................ Phil
I explained the background about toroidals and E&I trannies in enough
detail in an earlier post which perhaps you failed to comprehend.
Patrick Turner.
Patrick Turner
>
> Ignore what that lying Turnip arsehole says.
If folks ignore what I have been saying for years about audio trannies,
they will get very poor results from their efforts.
>
>
> He is just trying to prop up his transformer winding scam - at any cost
> to the truth.
I don't supply audio trannies.
I wind them, and place them in an amp, and sell the amp.
I have no intention to compete with the low end of the transformer market.
Now exactly what capablilities does Phil Allison have with regard to
manufacturing
anything?
Has he ever built a tube amp?
Has he ever designed and built any transformers?
Or does he want to remain a dunderhead who recommends
using mains trannies for tube PP hi-fi OPTs?
Answer me this Phil, If what you say about toroidal mains trannies is true,
then why have there not been a plethera of ready made available OPTs
manufactured just like mains toroids?
Its because none of the toroidal mains trannies have anywhere near enough
turns per volt for audio use.
For that one must go to Plitron.
No use going to Phil for an OPT, he ain't even got a clue how to wind a decent
one.
Patrick Turner.
Form@C
<snip>
> From what you are saying, it takes you three days to earn enough to buy 2
> Sowter trannies.
Nope - That price was *each*. They are 6 days per pair - if I don't
include for minor things like supporting the family, paying for food &
other necessities... My job isn't that brilliant! It probably works out at
about 12 months in real terms to get a pair of Sowter's EL34 babies. :-(
<snip>
>
> I have pointed out in other posts why a 17 ukp mains tranny would be
> hopeless with a pair of 6L6.
>
Yes, thank you very much,
> But to understand why I said what i said means you'd ned to undertsand
> the terminology,
> and the simple formulas governing the design parameters. That takes
> study. Don't worry, I am hopeless at studying Latin, or the habits of
> gay left flippered whales.
>
<grin> I'll certainly have a bash at the theory.
<snip>
>
>> Oh - my SE 6L6 amp sounds quite pleasant now... Unfortunately, that
>> has what appear to be "music centre" OPTs, probably intended for EL84s.
>> Such is life...
>
> The first watt might be total audio heaven, but what then when you want
> 10 watts?
>
If I get 10 out of this, then I'm probably in trouble and had better watch
for the smoke... ;-) I appreciate what you say though.
Max Holubitsky
"Form@C" wrote:
> On Mon, 19 Jan 2004 03:07:44 +1100, Patrick Turner wrote:
>
> <snip>
> > From what you are saying, it takes you three days to earn enough to buy 2
> > Sowter trannies.
>
> Nope - That price was *each*. They are 6 days per pair - if I don't
> include for minor things like supporting the family, paying for food &
> other necessities... My job isn't that brilliant! It probably works out at
> about 12 months in real terms to get a pair of Sowter's EL34 babies. :-(
Hey guys
It's fun being a low budget audiophile. There's a few ways to get low cost
OPT's.
#1. Hammond
#2 Hammond
#3 Used, from 60s receievers.
#4 Used, from old PA amplifiers
#5 Used, from other hobbiests who went half way, and gave up on a project
(WTB: OPT's for amplifier project, etc)
#6 Maplin may still sell the trannies they made for their Millenium 4-20 back
in the 90s
#7 Try to get the "made in China" transformers somehow. It's not impossible
I have heard about people using mains transformers and also 70V line
transformers to good effect, in budget projects involving EL-84s. I wonder if
EL-86's would be a good choice for mains XFMR's, due to their lower working
voltage? I bet it would be possible to do a philips push pull OTL cct with a
torroidial mains transforomer to match the output to normal speakers. Sure you
wouldn't use either of these options in a high dollar project, but if your
object is having some fun messing around with tubes, and getting a decent
sounding amplifier out of the deal, then go for it.
I don't think it's a huge jump of logic to say that if you can't afford to
spend what Sowter is asking on OPT's, you can't afford speakers that would make
it worthwhile anyways. Personally I'd put an amp together with mediocre
trannies, then spend the $$$ on good speakers, and after that go for the high
dollar transformers.
Just my $0.02
Max
Phil Allison
"Patrick Turner" <in...@turneraudio.com.au>
> >
> > Ignore what that lying Turnip arsehole says.
>
** Then the whole human race would be enormously better off.
>
>
> Or does he want to remain a dunderhead who recommends
> using mains trannies for tube PP hi-fi OPTs?
** What a fucking liar the Turneroid is.
What an unmitigated pig ignorant cunt.
>
>
> Answer me this Phil, If what you say about toroidal mains trannies is
true,
** Post under my words - you stinking, lying arsehole.
>
>
> Its because none of the toroidal mains trannies have anywhere near enough
> turns per volt for audio use.
** Massive lie - quite normal for the brain fucked Turneroid
........... Phi;
Phil Allison
"Patrick Turner" <in...@turneraudio.com.au> wrote in message
news:400AB05C...@turneraudio.com.au...
>
>
> Phil Allison wrote:
> >
> > ** That book was written in 1952.
> > Modern, machine wound, plastic wrap insulated, low cost toroidals
came
> > out much more recently.
> >
> > The transformer game has changed - the Turneroid is yet to catch
up.
> >
> > ................ Phil
>
>
> I explained the background about toroidals and E&I trannies in enough
> detail in an earlier post
** You explained NOTHING.
Since you know NOTHING.
Go drop dead.
.......... Phil
Form@C
<snip>
>
> It's fun being a low budget audiophile. There's a few ways to get low cost
> OPT's.
>
> #1. Hammond
>
> #2 Hammond
>
hmmm... Only 1 official outlet that I know of in the UK, Farnell. They
don't carry the audio range though.
> #3 Used, from 60s receievers.
>
> #4 Used, from old PA amplifiers
>
> #5 Used, from other hobbiests who went half way, and gave up on a
> project
> (WTB: OPT's for amplifier project, etc)
>
All good fun if you are in the right place at the right time! Radio
rallies are the best, but they are few & far between.
> #6 Maplin may still sell the trannies they made for their Millenium 4-20
> back in the 90s
>
They do, but don't stock them in the shops - only to order. They have
reduced the prices slightly now: about £30 each. I've found the firm that
winds them and they can do a "better" version (but still no full spec) for
£45-38 inclusive. That probably partially accounts for the reduction -
and they are probably about to discontinue them anyway!
> #7 Try to get the "made in China" transformers somehow. It's not
> impossible
>
guitar amp trannies are available if you can find places that repair them.
There are one or two smaller manufacturers around, but their products
(like the Maplin ones) are not really hi-fi, but a step up from most
guitar amps...
<snip>
>
> I don't think it's a huge jump of logic to say that if you can't afford
> to spend what Sowter is asking on OPT's, you can't afford speakers that
> would make it worthwhile anyways. Personally I'd put an amp together
> with mediocre trannies, then spend the $$$ on good speakers, and after
> that go for the high dollar transformers.
>
> Just my $0.02
>
...and worth every cent!
I pointed out somewhere that bass response wouldn't be too important with
smallish sealed boxes. They just won't go low enough to be able to hear
the distorted bass! Mechanical high-pass filtering. :-) These are supposed
to be -4dB at 85Hz. From the graph (optimist!) they are almost -20dB at
40Hz, so my chances of hearing the clipping on a 20Hz signal are pretty
low I should think.
http://www.allansonline.com/Anatomy/KEFDocuments/KEFCSeriesGallery/pages/p7.htm
if you fancy a trip down memory lane... :-)
<insert Deity here> knows what the response is now that they've been
carved up over the years... ;-)
Max Holubitsky
"Form@C" wrote:
> On Sun, 18 Jan 2004 21:07:43 +0000, Max Holubitsky wrote:
>
> <snip>
> >
> > It's fun being a low budget audiophile. There's a few ways to get low cost
> > OPT's.
> >
> > #1. Hammond
> >
> > #2 Hammond
> >
>
> hmmm... Only 1 official outlet that I know of in the UK, Farnell. They
> don't carry the audio range though.
>
Special order is possible... I have no idea about who would sell them in the UK,
perhaps someone here could help? I'm from Canada, so of course I have to recommend
a local product.
>
>
> > #3 Used, from 60s receievers.
> >
> > #4 Used, from old PA amplifiers
> >
> > #5 Used, from other hobbiests who went half way, and gave up on a
> > project
> > (WTB: OPT's for amplifier project, etc)
> >
>
> All good fun if you are in the right place at the right time! Radio
> rallies are the best, but they are few & far between.
>
Never underestimate the power of eBay ;) Or this newsgroup for that matter... Jon
Yaeger sold me a McIntosh preamp for $100... it's not in mint condition, but jeez
$100 for a McIntosh, how can you beat that! I use it as a phono preamp, pretty much
constantly!
I recently picked up a Dynaco ST-70 Series II, from the early 90s, on
rec.audio.marketplace. For $200, it comes with two broken output tubes, but it's in
good physical condition. Now there's 2 output transformers, a power transformer -
in fact an entire amplifier for less than what you would pay for one Sowter
transformer. I intend to use it in the living room, with a Rotel SS preamp, where
my old RCA theatre amps would seem a little bit too rugged. I must say that this
was a pure impulse buy, but it just goes to show that good deals can be had, and
all you have to do is keep your eyes open, and jump on a bargain as soon as you see
it.
>
> > #6 Maplin may still sell the trannies they made for their Millenium 4-20
> > back in the 90s
> >
>
> They do, but don't stock them in the shops - only to order. They have
> reduced the prices slightly now: about £30 each. I've found the firm that
> winds them and they can do a "better" version (but still no full spec) for
> £45-38 inclusive. That probably partially accounts for the reduction -
> and they are probably about to discontinue them anyway!
Nothing's wrong with mail order, and a little waiting. Sowter would make you wait,
anyhow. The 4-20 was no overachiever, but the specs looked good enough.
>
> > #7 Try to get the "made in China" transformers somehow. It's not
> > impossible
> >
>
> guitar amp trannies are available if you can find places that repair them.
> There are one or two smaller manufacturers around, but their products
> (like the Maplin ones) are not really hi-fi, but a step up from most
> guitar amps...
>
I've never tried any of those options... except in guitar amps. One half assed sub
the radio guys use, is to replace an output transformer in an AA5 with a 117:6.3 V
filament transformer.
> <snip>
> >
> > I don't think it's a huge jump of logic to say that if you can't afford
> > to spend what Sowter is asking on OPT's, you can't afford speakers that
> > would make it worthwhile anyways. Personally I'd put an amp together
> > with mediocre trannies, then spend the $$$ on good speakers, and after
> > that go for the high dollar transformers.
> >
> > Just my $0.02
> >
>
> ...and worth every cent!
>
Thanks!
>
> I pointed out somewhere that bass response wouldn't be too important with
> smallish sealed boxes. They just won't go low enough to be able to hear
> the distorted bass! Mechanical high-pass filtering. :-) These are supposed
> to be -4dB at 85Hz. From the graph (optimist!) they are almost -20dB at
> 40Hz, so my chances of hearing the clipping on a 20Hz signal are pretty
> low I should think.
>
Building a high pass filter into the amplifier may also be a good idea, just to
avoid letting the distortion occur in the output tranny, as its higher harmonics
will be clearly audible, despite the fundamentals being filtered out.
>
> http://www.allansonline.com/Anatomy/KEFDocuments/KEFCSeriesGallery/pages/p7.htm
> if you fancy a trip down memory lane... :-)
> <insert Deity here> knows what the response is now that they've been
> carved up over the years... ;-)
>
Look neat... I haven't got much experience with KEF's, aside from some reference
series from the late 80s. Those were some killer sounding speakers, driven by a
Carver 200wpc power amp... not my system though, but my grandfather's hi-fi... I
still use it when I visit.
Patrick Turner
Max Holubitsky wrote:
> "Form@C" wrote:
>
> > On Mon, 19 Jan 2004 03:07:44 +1100, Patrick Turner wrote:
> >
> > <snip>
> > > From what you are saying, it takes you three days to earn enough to buy 2
> > > Sowter trannies.
> >
> > Nope - That price was *each*. They are 6 days per pair - if I don't
> > include for minor things like supporting the family, paying for food &
> > other necessities... My job isn't that brilliant! It probably works out at
> > about 12 months in real terms to get a pair of Sowter's EL34 babies. :-(
>
> Hey guys
>
> It's fun being a low budget audiophile. There's a few ways to get low cost
> OPT's.
>
> #1. Hammond
>
> #2 Hammond
>
> #3 Used, from 60s receievers.
>
> #4 Used, from old PA amplifiers
>
> #5 Used, from other hobbiests who went half way, and gave up on a project
> (WTB: OPT's for amplifier project, etc)
>
> #6 Maplin may still sell the trannies they made for their Millenium 4-20 back
> in the 90s
>
> #7 Try to get the "made in China" transformers somehow. It's not impossible
Gee, I dunno what sort of audiophile I might be, but you just mentioned
7 unacceptable options for me.
And No 8, using mains toroidals is a worser option than 1-7.
>
>
> I have heard about people using mains transformers and also 70V line
> transformers to good effect, in budget projects involving EL-84s. I wonder if
> EL-86's would be a good choice for mains XFMR's, due to their lower working
> voltage?
Nope.
> I bet it would be possible to do a philips push pull OTL cct with a
> torroidial mains transforomer to match the output to normal speakers. Sure you
> wouldn't use either of these options in a high dollar project, but if your
> object is having some fun messing around with tubes, and getting a decent
> sounding amplifier out of the deal, then go for it.
I suggested an SE design using paralleled tubes might just
work with a toroidal with a 240 primary, using a parafeed arrangement.
A second 240v winding wound over the top of the existing 240v P and
Sec would just give enough P turns to allow B to be low enough for audio.
If the tubes are 6AS7 triodes, Vo might be only 100v,
indeed B would then be OK.
Circlotron is also a good PP option.
>
>
> I don't think it's a huge jump of logic to say that if you can't afford to
> spend what Sowter is asking on OPT's, you can't afford speakers that would make
> it worthwhile anyways. Personally I'd put an amp together with mediocre
> trannies, then spend the $$$ on good speakers, and after that go for the high
> dollar transformers.
I am peeved at the folks whose net worth is $500,000, say a house, car,
and all their gear, and an expensive wife, but when it come to their real passion,
audio,
they try to wheedle out of spending anything.
They think nothing of spending $300 to get a plumber to
unblock a toilet in an hour, or paying thousands on orthodontics for the daughter's
smile,
or 10k on a kitchen for the missus,
but whinge for 6 mths about transformer costs, and end up
making one compromise after another.
Patrick Turner.
>
>
> Just my $0.02
>
> Max
Max Holubitsky
Patrick Turner wrote:
Pat, what's wrong with Hammond? And also, what's wrong with the transformers from, say,
a Sansui 1000A? We're not talking ultra-fi here, but an amplifier built around either
of those options is going to measure okay, and provide enjoyment to whoever built it.
The Maplin 4-20, while again not in the ultra high fidelity category still provided
what many people considered acceptable performance. Also, what's wrong with option #5?
I've seen lots of people selling used transformers over the years... I would have no
problem using an old pair of Arcosound units, Hammond, or even Stancor.
Please keep in mind these options are *presented for people on a budget, who want to
make a tube amplifier*, and not for someone with an unlimited budget. Given an
unlimited budget, I'd buy the most expensive potted Japanese transformers money could
buy and call it a day!
I have logged many thousands of hours on a pair of Hammonds I bought in 1994, and
although they're currently out of service, I got much satisfaction out of the
amplifiers I built around them. In 1994, as a 16 year old I had to scrape together a
large bit of my savings to pay for the transformers (mind you, they've gone way up in
price since then) According to you I should have not got them, and given up on audio?
How arrogant!
>
> >
> >
> > I have heard about people using mains transformers and also 70V line
> > transformers to good effect, in budget projects involving EL-84s. I wonder if
> > EL-86's would be a good choice for mains XFMR's, due to their lower working
> > voltage?
>
> Nope.
>
Why not? EL-86s have a lower working voltage, and need a lower impedance output
transformer, so they'll not saturate the transformer as quickly as an EL84, etc would.
>
> > I bet it would be possible to do a philips push pull OTL cct with a
> > torroidial mains transforomer to match the output to normal speakers. Sure you
> > wouldn't use either of these options in a high dollar project, but if your
> > object is having some fun messing around with tubes, and getting a decent
> > sounding amplifier out of the deal, then go for it.
>
> I suggested an SE design using paralleled tubes might just
> work with a toroidal with a 240 primary, using a parafeed arrangement.
> A second 240v winding wound over the top of the existing 240v P and
> Sec would just give enough P turns to allow B to be low enough for audio.
>
Parafeed? You may as well just get a gapped OPT and be done with it. What is the
advantage to this setup, in either dollars, or performance, over buying a pre made
gapped OPT from any reasonable supplier?
>
> If the tubes are 6AS7 triodes, Vo might be only 100v,
> indeed B would then be OK.
> Circlotron is also a good PP option.
>
Why would someone who is saving money on transformers to the point of using a mains
transformer want to build the complicated power supply arrangements required by a
circlotron? I agree with you about the 6AS7 option however, it sounds like a good one
to me.
>
> >
> >
> > I don't think it's a huge jump of logic to say that if you can't afford to
> > spend what Sowter is asking on OPT's, you can't afford speakers that would make
> > it worthwhile anyways. Personally I'd put an amp together with mediocre
> > trannies, then spend the $$$ on good speakers, and after that go for the high
> > dollar transformers.
>
> I am peeved at the folks whose net worth is $500,000, say a house, car,
> and all their gear, and an expensive wife, but when it come to their real passion,
> audio,
> they try to wheedle out of spending anything.
>
> They think nothing of spending $300 to get a plumber to
> unblock a toilet in an hour, or paying thousands on orthodontics for the daughter's
> smile,
> or 10k on a kitchen for the missus,
> but whinge for 6 mths about transformer costs, and end up
> making one compromise after another.
>
This sounds like a personal issue to me. Anyone whose real passion is audio, i.e.
members of this newsgroup, is more likely to spend a disproportionate amount of their
disposable income on audio. If they are really being cheap, then maybe their paission
lies elsewhere? Maybe family is more important to them? Maybe it's hard to justify
buying thousand dollar transformers to the wife, when there exists bills to pay? Who
are you to judge?
If on the other hand, the individual really does have a low income, why should he deny
himself the right to having some fun with tube audio equipment just because his
transformers don't meet Mr. Turner's spec?
I for one would much rather see a person spending his free time lashing together a
simple amplifier out of the cheapest bottom end Hammond products, and some used parts
salvaged from old radios and TVs, than see him throw up his arms and buy a Sony home
theatre receiver. Maybe he will learn the limitations of his modest setup, and then
move on to bigger and better things once he has the funds in place. Or, maybe he'll
decide tube equipment is not for him... if so, then so what?
Tom Schlangen
> I wonder if EL-86's would be a good choice for
> mains XFMR's, due to their lower working
> voltage?
EL86/6CW5 is a *mucho*difficult* beast to deal
with, at least in rather conventional PP circuitry.
I am no tube expert at all, but I had EL86 PP
on the breadboard during the last 1/4 year with
lots of power stage and PI stage topologies. My
notes in the scratchbook of this project are
covering more than 30 pages already by now ...
To put a long story quite short, I think EL86/6CW5
in PP (pure pentode or UL - I didn't try pseudo
triode) is very discriminating regarding the iron,
when it comes to "measure _AND_ sound right".
Sonically, I failed completely when using the
seemingly very suitable iron of a highly regarded
small German company.
Technically, I had lots of trouble to get some
standard Hammond iron to work decently with EL86.
Don't use EL86/6CW5 in PP mode unless you have
*lots* of time to spare to fiddle with seamingly
"little side problems" like really suitable iron,
or PI stages which have to deliver quite some
voltage swing while only having ~200 volts
of B+ available ...
> I don't think it's a huge jump of logic to say
> that if you can't afford to spend what Sowter
> is asking on OPT's, you can't afford speakers
> what would make it worthwhile anyways.
At least regarding my situation, your assumption is
wrong. I _have_ very good (and quite expensive
to me) speakers to test my DIY projects with,
but I am not willing to spend Sowter iron prices
"for a try to see/hear/learn what happens" amp
type project.
Eventually I got it sounding and measuring right
(compared to a commercial German 70's design,
Klein & Hummel VS70, I am lucky to have at hand
to run measurements and and sound test against),
but at the moment I am right on the edge of dropping
this EL86 PP project completely in favour of much
"simpler" and better sounding tube/iron combinations.
So, I suggest to avoid EL86/6CW5 PP op, unless
you have much time to spent to get it right.
Tom
--
The first rule of magick is simple: Don't waste your time
waving your hands and hoping, when a rock or club will do.
Tom Schlangen
>>> EL-86's would be a good choice for mains XFMR's,
>>> due to their lower working voltage?
>> Nope.
> Why not? EL-86s have a lower working voltage, and
> need a lower impedance output transformer, so they'll
> not saturate the transformer as quickly as an EL84,
> etc would.
In the context of this thread, which (partly) is
about saturation issues of toroid (PP) OPTs, you
are probably right when thinking of chosing EL86
instead of EL84 just because of the lower B+ voltage.
But that is just only one part of the story, when
EL86 is mentioned.
Please see my other article in this thread - I
found EL86 definitely is not an "easy going"
tube to deal with like, say, EL84/6BQ5.
But, to stay with the intention of what you
ment, there surely are lots of other "high
current, low B+" type tubes which one could
have a try with regarding "not intended for
audio usage" toroid OPTs. Especially pass
regulator tubes like 6AS7 and the EL504/EL509
family come to mind. Maybe even those 6C33C
monsters :-)
Tom
P.S.: I am slowly working my DIY way to replace
a Velleman K4000 (double EL34 PP / ch) in my
living room with a DIY'd amp. The Velleman
K4000 (and its successor K4040) uses toroid
core OPTs of not-known-to-me origin. The circuit
and the OPTs surely deliver tons of sheer power,
but I suspect that just these OPTs are the (sonical)
reason, why I am working to replace this amp
by a DIY one, since the rest of the K4000 circuit
doesn't explain why I dislike the K4000 this
much sonically compared in double blind tests
(not only by myself) to several of my first DIY
amps. But I know too less about tube amp technology
to surely point at the K4000 OPT toroids to say
"that's the reason why".
--
Okay, maybe i am paranoid. But that doesn't mean
they are not out to get me. - unknown
Jon Yaeger
To your point, Max, I've heard that Sansui transformers were often Tamuras
and that one fellow claimed he measured the bandwidth on the 1000A iron and
that it was better than the Dyna ST70 OPTs.
I'm not far from completing a Sansui 1000A rebuild (for a photo see
www.yaegeraudio.com) and I'll soon be able to confirm or dispute that claim.
If you can't afford good OPT iron, you might try an OTL - I'm also building
a variation on Bruce Rosenblitz's 25W/channel amp using EL509s. I bought
custom power supply iron from Plitron to save on space and probably expense
. . . I'll have a few photos of that project eventually.
I really miss Fred Nachbaur and his hobbyist ethic - to try to use almost
anything and everything (especially "budget" parts) to try to make a purse
out of a pig's ear . . . Best of all was his helpful attitude and
inobtrusive manner. I'm sure he's had a few brilliant successes along the
way. Many folks here could learn a lot from Fred.
From what I've read and heard there are problems with 6AS7s such as bad
matching between sections; the tendency of some brands to flash over (with
the possibility of further catastrophe). I bought a mess of them but
decided to abandon the project. I guess I'll use them for PS regulation . .
.
- Jon
Form@C
<snip>
>
> From what I've read and heard there are problems with 6AS7s such as bad
> matching between sections; the tendency of some brands to flash over (with
> the possibility of further catastrophe). I bought a mess of them but
> decided to abandon the project. I guess I'll use them for PS regulation .
> . .
>
I read something about poor matching somewhere. I think it was a p-p amp
using one or two. The designer put a balance pot to the cathodes IIRC to
help correct it. I've considered trying one with a mains transformer
opt.... (Oh No! Not THAT again!!! - Shut up Mick!)
Max Holubitsky
Jon Yaeger wrote:
> A couple of opinions to add to the soup . . .
>
> To your point, Max, I've heard that Sansui transformers were often Tamuras
> and that one fellow claimed he measured the bandwidth on the 1000A iron and
> that it was better than the Dyna ST70 OPTs.
>
I've heard this from a few people too - with that sort of iron I suspect that your
rebuild is going to sound as good as it looks, which is pretty nice!
>
> I'm not far from completing a Sansui 1000A rebuild (for a photo see
> www.yaegeraudio.com) and I'll soon be able to confirm or dispute that claim.
>
> If you can't afford good OPT iron, you might try an OTL - I'm also building
> a variation on Bruce Rosenblitz's 25W/channel amp using EL509s. I bought
> custom power supply iron from Plitron to save on space and probably expense
> . . . I'll have a few photos of that project eventually.
>
OTL amplifiers may have their advantages, but is cost savings really one of them?
Once you add together the price of all the tubes, the huge transformers, filter
capacitors, sockets, etc. and then replacement tubes and power consuption, I'm
willing to bet that one could buy a decent quality output transformer. An OTL
amplifier is the proverbial combination space heater/boat anchor, as well as being
the only form of tube amplifier which is flat practically down to DC. All the same
it sounds like a really cool project, and I am interested in finding out how it
works out for you.
>
> I really miss Fred Nachbaur and his hobbyist ethic - to try to use almost
> anything and everything (especially "budget" parts) to try to make a purse
> out of a pig's ear . . . Best of all was his helpful attitude and
> inobtrusive manner. I'm sure he's had a few brilliant successes along the
> way. Many folks here could learn a lot from Fred.
>
I agree with you completely. Fred's approach kept the fun aspect in the hobby, which
is really the reason why I'm interested in it.
>
> From what I've read and heard there are problems with 6AS7s such as bad
> matching between sections; the tendency of some brands to flash over (with
> the possibility of further catastrophe). I bought a mess of them but
> decided to abandon the project. I guess I'll use them for PS regulation . .
>
I've read that the Russian 6AS7's are supposedly good. The Atma-Sphere amplifiers
have used them for many years, so I think that despite all negativity about them,
6AS7's are not half bad.
I have also seen them used in a World Audio Design SET amplifier from the early 90s,
using a single tube for both channels. I think it was rated at something like 4wpc,
and was built for quite a few years. I don't know how long the tubes lasted in them,
but the amplifier was on the market for quite a while.
Russ Sadd, who used to post here regularly, also built an amp based on the 6AS7. I
think it worked well for him as well, so I wouldn't totally rule out using these in
a practical amplifier.
Patrick Turner
Max Holubitsky wrote:
Nothing wrong with Hammond et all, as long as non ultra hi-fi is all you want.
I have used rather poor quality OPTs meant for 6GW8 with
6CM5 in triode ( no way UL or b.terode is possible ).
I get a reasonable 22 watts /channel. 12 dB global FB is the max possible,
and cap loads peak the output. Sounds OK though.
>
>
> The Maplin 4-20, while again not in the ultra high fidelity category still provided
> what many people considered acceptable performance. Also, what's wrong with option #5?
Usually option 5 is onobtainium, a very rare commodity.
>
> I've seen lots of people selling used transformers over the years... I would have no
> problem using an old pair of Arcosound units, Hammond, or even Stancor.
>
> Please keep in mind these options are *presented for people on a budget, who want to
> make a tube amplifier*, and not for someone with an unlimited budget. Given an
> unlimited budget, I'd buy the most expensive potted Japanese transformers money could
> buy and call it a day!
Or learn to wind your own properly, and find that maybe the potted
japanese transformers were no big deal.....
>
> I have logged many thousands of hours on a pair of Hammonds I bought in 1994, and
> although they're currently out of service, I got much satisfaction out of the
> amplifiers I built around them. In 1994, as a 16 year old I had to scrape together a
> large bit of my savings to pay for the transformers (mind you, they've gone way up in
> price since then) According to you I should have not got them, and given up on audio?
> How arrogant!
Calm down.
People with limited means have to compensate with intelligence
and careful choice and techniques to acquire a decent system over time.
The amount of recycled OPTs I find to use with larger octal tubes is miniscule.
Nearly everyone bought 10 watt amps back in 1960, and ran sensitive speakers.
Most of theose speakers are dead, and so are the OPTs....
Probably a few good ones buried at the tip, but I ain't gonna dig em up.
I just go to my shed and wind them up.
The material for a 100 watt OPT can be got for US $70,
and the rest is just time and patience, instead of watching mindless TV shows,
or boozing at the pub, etc.
Follow what RDH says, and you can't go wrong.
The slightly better core material made now ensures what you wind will
have less distortion than the cores available in 1952.
In the old days, amateur radio folks built their own receivers, transmitters,
RF coils, and antennas.
Audio amateurs do the same but its amps, transformers, speakers, etc.....
When making the amps that I sell to ppl, I have not lost sight of idealism.
Patrick Turner.