NVA Amps
adie
Geoff Mackenzie
"adie" <ad...@oh-shit.com> wrote in message
news:xevl5b4td0ut.1t...@40tude.net...
> Does anyone have any experience of these amps?
>
Surprised nobody else has jumped in here. Nervous at advancing an opinion
in this NG - I have no technical skill in this field, just an appreciation
of audio reproduction and a decent set of ear'oles. And a large dose of
cyniscism.
And I'm not normally bitchy, but it's been a bad day....
NVA. Nene Valley Audio? Nee Tresham? Had a look/listen some time in the
eighties. Acrylic boxes with not much inside. Sold by people who said "if
you can't hear how perfect it is then you just don't understand". Why do I
think of Ivor Tiefenbrun and Jehova's Witnesses?
An analogy from something I am more familiar with - an old mate, Duggie,
describing the Pobjoy radial engine as fitted to various aircraft in the
1920's or thereabouts - "it never, ever, delivered its rated power and it
caught fire on Tuesdays". Hmmm - that was meant to be a comment abot NVA,
but just remembered my Roksan Xerces, (sp?) which at least gave warning by
running backwards for a while and it may have been Wednesdays.....
From NVA's own info at the time, I recall that the amp was absolutely
perfect, unless you used the wrong speakers. Or speaker leads. Or played
bass too loud. In any of those cases it would self-immolate, voiding your
guarantee. In other words it was totally useless in the real world.
No doubt the designer is still in his garden shed explaing how the rest of
the audio world got it wrong.
Geoff MacK
Woody
news:60rqn6F...@mid.individual.net...
Geoff
You are most welcome to this group if you continue to give us
humour/cynicism like that! Made my day.
You don't know Bill Wright in the TV newsgroups do you?
--
Woody
harrogate three at ntlworld dot com
TT
"Geoff Mackenzie" <gm...@chapterfive.org.uk> wrote in message
news:60rqn6F...@mid.individual.net...
>
Thanks Geoff that has made my day :-) Reminds me of all the stories I have
heard about Flame Linears (Phase Linears to those without a sense of
humour).
Please keep posting as your type of posts are a welcome change from the
mundane ;-)
Cheers TT
Geoff Mackenzie
"Woody" <wo...@spamblock.com> wrote in message
news:5U2qj.1447$j95...@newsfe3-win.ntli.net...
Wright - should I? The only other NG I subscribe to is
uk.rec.cars.classic. Interested to see some crossover between these
groups - good morning, Jungmeister Plowman!
Regards, Geoff MacK
Dave Plowman (News)
Geoff Mackenzie <gm...@chapterfive.org.uk> wrote:
> Thanks for the welcome, Woody, much appreciated. No, I don't know Bill
> Wright - should I? The only other NG I subscribe to is
> uk.rec.cars.classic.
Bill Write is famous for his stories - usually under 'Rigger's Diary'. He
is an aerial installer par excellance. Hangs out on uk.tech.broadcasting
mainly. Well worth a read.
> Interested to see some crossover between these
> groups - good morning, Jungmeister Plowman!
And good morning to you.
--
*Forget the Joneses, I keep us up with the Simpsons.
Dave Plowman da...@davenoise.co.uk London SW
To e-mail, change noise into sound.
Bruce Lankford
>
About fifteen years ago, there was a shop near my house which sold NVA and
quite a lot of them.
I heard a couple the amps with different speakers and they sounded quite
good to me.
The little amp (perhaps an AP20?) could not drive the ProAcs which I was
using at the time but the bigger amp was well beyond my budget.
A work colleague of mine bought the AP20, won't part with it.
Rob
In what way was it unable to drive the Proacs?
I have this (perceived) issue with Dynaudio speakers, and I've only ever
found two amplifiers that sound good - a huge valve amp (sold) and an
old Cambridge power amp (broke under the strain).
However, I've asked on this NG and been advised that any competently
designed amplifier of the past 20 years should sound identical. Not
unanimous, majority.
Rob
Serge Auckland
news:F-mdnY13J9L5FCfa...@bt.com...
Any competently designed amplifier "when used within its design parameters"
should (and will) sound identical. Some loudspeakers present a very severe
load, and consequently some otherwise competent amplifiers will be outside
their design parameters. I don't know of the specific instance of the
Dynaudio 'speakers or the Proacs, but these could well present a more severe
load than the amp was designed for.
S.
Jim Lesurf
<patchoulia...@gmail.com> wrote:
> Bruce Lankford wrote:
> > "adie" <ad...@oh-shit.com> wrote in message
> > news:xevl5b4td0ut.1t...@40tude.net...
> >> Does anyone have any experience of these amps?
> >>
> >
> > About fifteen years ago, there was a shop near my house which sold NVA
> > and quite a lot of them. I heard a couple the amps with different
> > speakers and they sounded quite good to me. The little amp (perhaps
> > an AP20?) could not drive the ProAcs which I was using at the time
> > but the bigger amp was well beyond my budget. A work colleague of mine
> > bought the AP20, won't part with it.
> >
> >
> In what way was it unable to drive the Proacs?
> I have this (perceived) issue with Dynaudio speakers, and I've only ever
> found two amplifiers that sound good - a huge valve amp (sold) and an
> old Cambridge power amp (broke under the strain).
You could perhaps give you own answer to your your own question here. :-)
> However, I've asked on this NG and been advised that any competently
> designed amplifier of the past 20 years should sound identical. Not
> unanimous, majority.
My understanding is slightly different.
That where the designer knows what they are doing, and designs the amp to
simply amplify with no audible levels of distortion, departures from flat
response, etc, and the amp is used within its output limits, etc, then
no-one has actually shown that they can hear any difference between such
amps in appropriate use/comparisons. Indeed, various controlled tests
generally show the listeners were unable to distinguish one from another in
such cases.
This is quite distinct from an amp designed with a non-flat response, a
very high output impedance, etc. Or from cases where one amp does not have
sufficient power, or limits in some other way.
Slainte,
Jim
--
Electronics http://www.st-and.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
Audio Misc http://www.audiomisc.co.uk/index.html
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Rob
I suppose the Dynaudios (Contour 1.1s and 42s) could be a severe load -
they're rated at 4 Ohms - and are beyond what most amplifiers are happy
with.
I've recently had a hifi cull and I'm in the market for a SS amplifier.
I was looking at a Denon 1500AE (to match the DVD player) and a Musical
Fidelity A5 (discounted ATM, end of range). With the notable exception
of speakers, i've always had great difficulty evaluating components in a
shop. I often think I can detect difference, but not a sense of
'better'. It's only at home over a period of time that I find something
I like. And then it breaks ;-)
Anyways, enough of my neuroses. Could you recommend a SS amplifier that
might deal with severe loads?
Thanks, Rob
Rob
> In article <F-mdnY13J9L5FCfa...@bt.com>, Rob
> <patchoulia...@gmail.com> wrote:
>> Bruce Lankford wrote:
>>> "adie" <ad...@oh-shit.com> wrote in message
>>> news:xevl5b4td0ut.1t...@40tude.net...
>>>> Does anyone have any experience of these amps?
>>>>
>>> About fifteen years ago, there was a shop near my house which sold NVA
>>> and quite a lot of them. I heard a couple the amps with different
>>> speakers and they sounded quite good to me. The little amp (perhaps
>>> an AP20?) could not drive the ProAcs which I was using at the time
>>> but the bigger amp was well beyond my budget. A work colleague of mine
>>> bought the AP20, won't part with it.
>>>
>>>
>
>> In what way was it unable to drive the Proacs?
>
>> I have this (perceived) issue with Dynaudio speakers, and I've only ever
>> found two amplifiers that sound good - a huge valve amp (sold) and an
>> old Cambridge power amp (broke under the strain).
>
> You could perhaps give you own answer to your your own question here. :-)
>
Indeed :-) Although the Cambridge amplifier really was splendid while it
worked. I'd buy another if it was still made.
Also, i'm exaggerating to make a point. Most of the time my system
sounds good using a cheap AV amplifier (£200 Cambridge something). I've
heard it better, and now that the 100W valve amplifier has gone two
things arise. The first is that I've got some money to spend (£1000).
Secondly, and in the lieu of other more important things to concentrate
on, I'd like my system to sound better.
>> However, I've asked on this NG and been advised that any competently
>> designed amplifier of the past 20 years should sound identical. Not
>> unanimous, majority.
>
> My understanding is slightly different.
>
> That where the designer knows what they are doing, and designs the amp to
> simply amplify with no audible levels of distortion, departures from flat
> response, etc, and the amp is used within its output limits, etc, then
> no-one has actually shown that they can hear any difference between such
> amps in appropriate use/comparisons. Indeed, various controlled tests
> generally show the listeners were unable to distinguish one from another in
> such cases.
>
Well, something is up, either in my mind or with the amplifier. Bass
response certainly appears to be different, depending on the amplifier,
and this is the thing that annoys me most. Also, for example, a Quad 405
is demonstrably sibilant, suggesting something is not quite flat, and
possibly the amplifier needs repair (it is quite old).
> This is quite distinct from an amp designed with a non-flat response, a
> very high output impedance, etc. Or from cases where one amp does not have
> sufficient power, or limits in some other way.
>
Which I'd like to avoid. Given (for the moment) that my AV amplifier is
not ideal, and my speakers are a tad severe, could you recommend a SS
amplifier?
Thanks, Rob
Serge Auckland
If I were in the market for a power amp, I would buy a used Krell which can
drive almost any load down to 1 ohm, and is pretty much unburstable. If
that's too expensive, then Musical Fidelity have made some pretty impressive
amps over the years, so if you can pick up the A5 at a sensible price, then
go for it.
I have also been impressed with the Behringer A500 power amp. This is
designed for PA work, but is easily good enough for domestic hi-fi, and is
designed for 4 ohm loads. Best thing is the price, under £150 brand new.
Mate this with a pre-amp of your choice, and you have superb amplification
albeit without the street-cred.
Rob
Thanks Serge. Krell is out of my price range, and I'd be concerned about
the reliability of anything old enough to cost £1000 (my limit). And
without wishing to sound fussy, they're also too big. The MF A5
certainly looks good on what little they've committed to paper. I'm
rather wary of these shiny big-watt amps, having bought a Roksan Kandy a
while back. Indescribably shrill, with (to make up for it) a phono stage
which had no bass or treble. This, the manufacturer explained, was a
compromise they'd built in. So that went back to the shop.
Behringer A500 - I bought one as a curiosity, and it'd didn't fare too
well. Clipping at volume levels noticeably below that achieved by
another (Rose Audio) 50W power amp. It is at the back of a cupboard
somewhere, so i'll give it another try. Forgotten about that!
Rob
Woody
were always designed to be able to handle complex loads - think of the
Electrostatics for a start - and are difficult to break.
As the 405 is now quite old, if it has sibilence then it may need some
of its electrolytic caps replaced, but that's about all. Many of the NAD
amps have external pre-power links that can be removed and they make a
good pre-amp with plenty of inputs.
The circuit diagram of the 405 is in its handbook if you have it,
otherwise it should be easy to Google.
If you want to get something else the Audiolab 8000A takes some beating
but it is very revealing and may show up the failings of the rest of
your kit.
Bruce Lankford
The AP 20 could not provide the listening level I required from an
inefficient speaker in my largish room. The bigger amp, an AP35, from
memory, was fine but not affordable.
My colleague has no problem with his quite efficient speakers in a smallish
room.
Serge Auckland
> For my two pen'uth, if you have a 405 get it fixed and use that. Quad were
> always designed to be able to handle complex loads - think of the
> Electrostatics for a start - and are difficult to break.
I have a great deal of respect for QUAD's engineering and designs, and the
QUAD 405 is still a very competent amplifier, with excellent longevity, but
it was never designed for extreme loads. The situation was improved with the
405II, but even that was never designed to cope with anything below 4 ohms.
Many 4-6 ohm loudspeakers have impedances that drop well below those nominal
figures, and I wouldn't choose to use the 405 or 405II for any load that
could be described as "severe". You may recall that QUAD released a
modification to parallel the two outputs, turning the 405 into a mono
amplifier capable of driving low impedance loads. This was quite succesful
at the time, but I suspect that very few 405s were ever used in this way.
>
> As the 405 is now quite old, if it has sibilence then it may need some of
> its electrolytic caps replaced, but that's about all. Many of the NAD amps
> have external pre-power links that can be removed and they make a good
> pre-amp with plenty of inputs.
I fail to understand how old electrolytics could produce sibilance.
>
> The circuit diagram of the 405 is in its handbook if you have it,
> otherwise it should be easy to Google.
>
>
> If you want to get something else the Audiolab 8000A takes some beating
> but it is very revealing and may show up the failings of the rest of your
> kit.
>
The 8000A is capable of driving tough loads, and would be a very good choice
as a used buy, but again because of the likely age, may need new
electrolytics.
S.
Jim Lesurf
<patchoulia...@gmail.com> wrote:
> Jim Lesurf wrote:
> Well, something is up, either in my mind or with the amplifier. Bass
> response certainly appears to be different, depending on the amplifier,
> and this is the thing that annoys me most.
If the amp is single rail, then the output cap may affect this in a way not
clearly shown by an 8Ohm test load.
> Also, for example, a Quad 405 is demonstrably sibilant, suggesting
> something is not quite flat, and possibly the amplifier needs repair (it
> is quite old).
The difficulty is that the Quad might be flat, and the speaker shows
sibilance when driven from it, but some other amp has a non flat response
which reduces the effect. So the root of the problem might be in the
speaker, not the amp.
Try putting a couple of 0.47 Ohm resistors in series with the speaker leads
when using the 405 and see if the sibilance evaporates.
John Williamson
>> As the 405 is now quite old, if it has sibilence then it may need some
>> of its electrolytic caps replaced, but that's about all. Many of the
>> NAD amps have external pre-power links that can be removed and they
>> make a good pre-amp with plenty of inputs.
>
> I fail to understand how old electrolytics could produce sibilance.
>
As they age, the value of electrolytics tends to drop markedly, even if
they don't fail totally open circuit, which increases the impedance more
at low frequencies than high, so the low frequencies get lost on the way
through. If they're in a feedback/ equalisation circuit, it can affect
things either way.
--
Tciao for Now!
John.
Woody
news:4f74075...@st-and.demon.co.uk...
> In article <AK6dnRi2qP9rhyba...@bt.com>, Rob
> <patchoulia...@gmail.com> wrote:
>> Jim Lesurf wrote:
>
>
>> Well, something is up, either in my mind or with the amplifier. Bass
>> response certainly appears to be different, depending on the
>> amplifier,
>> and this is the thing that annoys me most.
>
> If the amp is single rail, then the output cap may affect this in a
> way not
> clearly shown by an 8Ohm test load.
>
>> Also, for example, a Quad 405 is demonstrably sibilant, suggesting
>> something is not quite flat, and possibly the amplifier needs repair
>> (it
>> is quite old).
>
> The difficulty is that the Quad might be flat, and the speaker shows
> sibilance when driven from it, but some other amp has a non flat
> response
> which reduces the effect. So the root of the problem might be in the
> speaker, not the amp.
>
> Try putting a couple of 0.47 Ohm resistors in series with the speaker
> leads
> when using the 405 and see if the sibilance evaporates.
>
> Slainte,
>
> Jim
>
You know Jim, I remember seeing that tip decades ago - and I don't think
it was originally for the 405 - maybe the 303?
Anyway I tried it with both and I'm sure it does help - but my speakers
at that time were not a difficult load anyway (Arthur Bailey WW
Transmission Lines.)
Serge Auckland
news:rKSdnaz3Gfe...@bt.com...
That makes a certain amount of sense, but only applies to those
electrolytics used directly in the signal path for coupling, or those used
to bypass resistors, for example, emitter loads. Those electrolytics used
for power supply smoothing will only cause an increase in hum and /or an
increase in distortion as the voltage rails sag.
S.
Don Pearce
But whichever way the effect goes, it will be hitting the extreme
lows, not the highs. So whatever the result, it won't be sibilance.
d
--
Pearce Consulting
http://www.pearce.uk.com
Serge Auckland
news:47be1b8c....@news.plus.net...
I'm assuming John means that by reducing the lows, the subjective effect is
a boost in the highs, which he translates as sibilance. I find it all rather
unlikely, but I'm prepared to admit the possibility.
S.
Don Pearce
I see what you are saying, but cutting lows doesn't really sound like
boosting highs - the middles are the important bits here, and if they
stay constant relative to the highs (which they will in a low cap
scenario) the result won't sound anything like sibilance.
But people's perceptions do differ, I will admit.
Arny Krueger
IME, doing a nice job on the more extreme lows can make some overabundence
of extreme highs more tolerable.
John Williamson
if the combination of amp & speaker is already a bit shrill, turning the
gain up to get the same sound pressure could sound sibilant.
Depending on the circuit impedances, the change in capacitance in
combination with the self inductance of the electrolytic *may*
accentuate or create a resonance peak in the audio range. Unlikely, but
maybe...
David Looser
Don't forget that as an electrolytic fails it's ESR rises significantly, and
may become non-linear. Depending on it's circuit function that might result
in an increase in HF distortion.
David.
Rob
> For my two pen'uth, if you have a 405 get it fixed and use that. Quad
> were always designed to be able to handle complex loads - think of the
> Electrostatics for a start - and are difficult to break.
>
> As the 405 is now quite old, if it has sibilence then it may need some
> of its electrolytic caps replaced, but that's about all. Many of the NAD
> amps have external pre-power links that can be removed and they make a
> good pre-amp with plenty of inputs.
>
> The circuit diagram of the 405 is in its handbook if you have it,
> otherwise it should be easy to Google.
>
I gather they're not the most complicated to get serviced/repaired. It's
a case of time/energy and relative ease of punting via ebay.
>
> If you want to get something else the Audiolab 8000A takes some beating
> but it is very revealing and may show up the failings of the rest of
> your kit.
>
Indeed :-) I had a 8000A for a few years and was quite happy with it,
especially the phono amp, but that was before the Dynaudio phase. ATM,
and after some fairly brief comparisons, I've settled with an old power
amp that *seems* to do the trick, and at least relieves the urge to
spend needlessly. When and if work eases off I'll give it a more
thorough assessment, but for now it's enough just to listen to some music.
Thanks for the advice; appreciated.
Rob
Rob
Quick update - I've settled on the Behringer 500 for now, using the
Cambridge AV as a preamp. It certainly deals with the bass side very
well, but is a little harsh when pushed (which I don't do that often).
No pleasing some people :-)
I commented earlier that it seems to clip readily. In fact I only tried
it for a few days when new, and then put it in the cupboard. My comment
came from watching the LEDs, which indicated clipping. Subjectively on
listening it's not that bad, and the amp will go very loud indeed.
Rob