Exotic Amplifier Technologies

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What kinds of ideas have been used in the past to make so called "hi quality"
sounding amplifiers in stereo systems?

I'm thinking of things like the Carver amplifiers of the 80s. Are there any
odd ideas that people have tried in the past?




Re: Exotic Amplifier Technologies



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**You're kidding, right? The list is very long.

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**Carver actually used two separate and equally bad technologies to build
his lightweight products. They were:

* TRIAC controlled power supplies. This system controls the amount of energy
applied to the primary of a transformer in response to the demands of the
musical signal applied. Kinda like a light dimmer. The problem with this
technology is pretty obvious to everyone. Except Carver, apparently. Mains
energy is supplied at a 100Hz (120Hz for the US) rate. Musical transient can
occur at rates of up to 20,000Hz.
* Rail switching technology. Rail switching amps (aka: Class H, Power
Envelope, etc) have been tried and dismissed by quite a number of
manufacturers. Marantz, Yamaha, Hitachi, NAD, et al, have all tried it. All
have dismissed the technology, because the result is a poorer sound quality
than regular, non-rail switching amplifiers. The problem relates to the
enormous characteristic changes inherent to ALL active devices, as the rail
Voltage is altered. IOW: Such amplifiers perform extremely well under steady
state, sine wave conditions, but poorly under actual, real life music.

As for your question, yes. The list of odd ideas is simply enormous.


--
Trevor Wilson
www.rageaudio.com.au



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**On the contrary, the system works quite well. Just not the Carver did it.
Think about their system. Focus on the transient abilities of the Carver
system.


--
Trevor Wilson
www.rageaudio.com.au



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Trevor Wilson wrote:
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(snip)
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That must be why you see so many Marantz, Yamaha, Hitachi & NAD powered
theatre & stadium concert PA rigs, wheras the minnows of the PA world
like
Crown, QSC, BSS,LabGruppen etc have no problem with rail switching and
rail
riding technology :-)
M


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Rail switching is justified by economic considerations. Home audio amps as a
rule are too low-powered for rail switching to be cost-justified.



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**Utter, banal nonsense. NAD, Marantz, Yamaha, Carver, Hitachi and many
others have used rail switchers in home audio products, because it allows
them to inflate transient power abilities, at very low cost. The first,
highly successful, amp I saw was the NAD 2200 power amp. It was rated at 100
Watts continuous, with 400 Watt transient ability. So successful was it,
that it spawned a line of smaller and larger amps from NAD. Of course, it
sounded like crap and had a bad reputation for destroying speakers, but it
looked great on paper and the reviewers fell over themselves to rave about
it. Consequently, customers fell over themselves to buy them. NAD later
dispensed with the technology, after losing significant sales to competitive
products (which didn't use rail switching technology).


--
Trevor Wilson
www.rageaudio.com.au


--
Trevor Wilson
www.rageaudio.com.au



Re: Exotic Amplifier Technologies


On Thu, 08 Dec 2005 22:00:12 GMT, "Trevor Wilson"

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A question, Trevor. If the reviewers praised the product, and
customers bought it en masse, how did NAD lose "significant sales to
competitive products"? It sounds as though you were the only one who
noticed it sounded like crap.

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**You need to understand how the retail world operates. In reality, the
number of people who actually listen to products, before purchase, is
incredibly tiny. Almost all purchase based on the following:

* A glitzy brochure.
* A well written and glowing review.
* A nice front panel.
* Fancy features.
* Word of mouth.

I would estimate that the number of people who actually do a good, hard
listen to a product, BEFORE purchase, at around 0.1%. Or less. Bribery in
the audio business is pretty much ingrained (though not in Australia,
AFAIK). Reviews are bought and sold in the US and the UK. Before you ask: I
have dealt with US, UK and Australian reviewers. No Australian reviewer has
asked for 'consideration' for a review. SOME US and UK based reviewers have
spelt out, in no uncertain terms, how much a good review will cost. I cannot
say if that is a function of the publication, or just corrupt reviewers.
Either way, I don't trust any of them. Except Scot Markwell. He seemed to be
honest and straightforward.

NAD had (justifiably) acquired an excellent reputation for budget, 'high
end' sound quality (my favourite was the brilliant 3120). Albeit, with
rather dodgy constrution and suspect component choice, thanks to the
manufacturing company - Fullet. Sometime around 1984-5 NAD moved production
away from Fullet and released the NAD 2200 power amp. As an NAD dealer, at
the time, I ordered them for my store. I was immediately struck by three
things, when I listened to the amp:

* It's spectacular amount of power, for such a modest price. It was a very
potent package. (A point which should not be underestimated)
* It's pretty decent build quality, compared to previous NAD products.
* It's extremely average sound quality, compared to earlier, less powerful
NAD products.

Based on the above, it is easy to see how, with a good review, the NAD 2200
would gather significant sales. After all, few people actually took the time
to listen to the thing. The market place is a funny thing. Like most things,
there is a time lag, between cause and effect. Yamaha, for instance, built
very good amplifiers, back in the 1970s. Quality plummetted in the 1980s,
but their sales continued rising, during the 1980s, due to the high quality
of their products produced a decade earlier. Marantz is another company
which built very good products in the 1960s and pretty decent products
during the 1970s. Late in the 1970s, my boss at Marantz called me into the
office. He explained that Marantz was about to embark on a new style of
constrution called 'value engineering'. This sounded exciting. The reality
was somewat different. Products produced by Marantz in the late 1970s were
very poorly constructed, using cheaper parts, than the equipment I was
accounstmed to. Nevertheless, sales increased. Largely due to the previously
excellent reputation and the more contemporary styled front panels. IOW:
Outside they looked great, inside was crap.

[ASIDE]: I sold a 2200 to a client who was using a pair of KEF 104.2
speakers. Although I had sold lots of KEF 104.2 speakers, I had only sold
one 2200/104.2 combination. Some time later, the customer brought back the
KEFs complaing that they had no HF. They didn't. Both (ferro-fluid cooled)
tweeters were fried. This was unheard of. The KEF 104.2 tweeters are very
tough. I sent them back to the distributors (Fred A Falk) for under warranty
repair. They rejected the warranty claim, suggesting that the amplifier was
at fault. I replied that the amplifier was an NAD 2200 (which Falk also
imported). Silence. "OK, we'll repair them free of charge." Apparently, the
NAD 2200 has/had an appalling reputation for destroying tweeters. Here's my
theory:

Customer turns amplifier up to the point of clipping (400 Watts). Then
allows the amp to run for a period of time at high levels. The Power
Envelope circuits have a time/energy circuit, which prevent damge (to the
amp), which shuts off the high Voltage supply, after a period of time. Thus,
instead of mild clipping, the amplifier reverts to massive clipping, thus
allowing huge levels of high order harmonics to destroy HF drivers. The
listener, whose ears are suffereing from continuous high level audio, cannot
hear the massive clipping and the tweeters are destroyed.

 It sounds as though you were the only one who
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**I very much doubt that. I am pretty certain other people actually listened
to the stuff too.


--
Trevor Wilson
www.rageaudio.com.au



Re: Exotic Amplifier Technologies


On Fri, 09 Dec 2005 01:32:46 GMT, "Trevor Wilson"

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Thanks for this comprehensive reply, Trevor. I love all this
background stuff. I'm not at all sure you answered the apparent
inconsistency I pointed out in your original post (how a company can
lose "significant sales to competitive products" when people are
buying their product as before); indeed I think you supported the
opposite viewpoint, that a company can ride on the back of its former
glory for a long time thanks to people not bothering to listen before
purchase. It's also interesting that you modified "sounded like crap"
to "extremely average sound quality". Given the vagaries of component
matching, I can well imagine very average sound quality passing muster
with most non-enthusiasts, whereas "crap" one would expect to be
discovered as such relatively quickly. I do still feel that you have a
tendency to hyperbole that undermines your credibility and sometimes
causes friction; given the extent of your experience and knowledge I'd
rather you curbed that and gave us the less extreme version of your
opinions in the future (just a thought). I still don't buy it that NAD
went downhill during the 90s due to some obscure design flaw in their
products ("PE"). They did probably lose some ground with the
relatively uninspiring 302/304--312/314 amp line, but then quickly
made up for that with the 320/340 line, on up to the current 320BEE.

Not sure I understand your anecdote of the NAD2200. "Customer turns
amplifier up to the point of clipping (400 Watts)." Why would anyone
in their right mind do that? And why would anyone who did, not deserve
whatever they got? "The listener, whose ears are suffering from
continuous high level audio, cannot hear the massive clipping and the
tweeters are destroyed." Indeed, along with the listener's and most of
the neighbours ears as well, I'd imagine. I don't see that NAD can be
in any way to blame for idiotic users--I certainly wouldn't have fixed
their speakers under warranty. I would have given them a good
dressing-down, but after all that they probably wouldn't have heard
me.

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**My pleasure.

 I love all this
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**Not really. There is a time lag between when people finally work out that
a company has gone 'off the rails' (and most do).

 It's also interesting that you modified "sounded like crap"
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**Mea culpa. I am guilty of hyperbole every now and again.

 Given the vagaries of component
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**Good point. I guess what I was attempting to get it is that NAD was
building genuine 'budget high end' products, before the introduction of
their Power Envelope stuff.

 I do still feel that you have a
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**Er, yes and no. I am perfectly consistent with my comments. I don't see
that damaging credibility at all. If I were to start selling (say) SET amps,
then THAT would damage my credibility.

 given the extent of your experience and knowledge I'd
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**Fair point. I may just consider that as a reasonable idea.

 I still don't buy it that NAD
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**And yet, they've ceased building PE technology into their products. If it
was such a brilliant idea, they'd keep doing it.

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**Not all listeners are sane.

 And why would anyone who did, not deserve
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**We al listen at different levels. Many times I've had to leave the room
during a demo, because the music was too loud for my tastes.


 "The listener, whose ears are suffering from
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**You missed the point. KEF 104.2 tweeters almost never failed during
warranty. The only time they did, was when connected to a NAD 220 amplifier.
The problem is that gross clipping can occur without warning, with the 2200.
Regular amps provide warning of distress, before gross clipping occurs.


--
Trevor Wilson
www.rageaudio.com.au




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On Sun, 11 Dec 2005 04:28:00 GMT, "Trevor Wilson"


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I can think of several reasons why not. All technology moves on. They
may simply have found a better way of achieving the same end, or
decided such minor power boosting was superfluous. The question is, if
PE amps sounded so bad and NAD discovered this, why did they not
discover it during the design stages? Also, why has no one but you
ever suggested PE amps sound bad? And why do they continue to enjoy
such a fine reputation with vintage gear enthusiasts who are usually
very knowing about these things (check Ebay prices). And why did the
PE amp I had sound so good (pretty much on a par with the much later,
and much celebrated, Rotel 931 Mk11. I was able to directly compare
them over several weeks).

You should know that there's a secret prize for answering these
questions satisfactorily. :-)

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**Not necessarily. GOOD technology remains.

 They
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**NAD do not achieve the same end, using different technology. They are now
using the same technology they were using prior to the introduction of PE
topology. And further: The "Minor power boosting" was hardly minor. The NAD
2200 amplifier was capable of FOUR TIMES the power on transients.

 The question is, if
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**Not necessarily. NAD just lost it's way. They forgot their roots.

 Also, why has no one but you
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**I'm not the only one. The people who chose products like Rotel instead of
NAD voted with their wallets.

 And why do they continue to enjoy
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**See previous discussion about PERCEIVED quality. Also see my previous
comments about the large amount of transient power, vs. Dollars and
packaging size.

 And why did the
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**What speakers did you use?

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**After you tell me what speakers you used, I should be able to answer your
question.


--
Trevor Wilson
www.rageaudio.com.au



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On Mon, 12 Dec 2005 05:32:17 GMT, "Trevor Wilson"


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Oh Trevor, you are forgetful. Why would I listen to speakers when I
can listen through my trusty Sennheiser HD 595s?

And yes, I know you're now going to say, "Oh well, all bets are off as
amps aren't made to drive headphones." Whatever, I'm convinced
headphones are the great leveller as they remove the power factor and
the inevitable reactive load. I've been listening to amps through
headphones now for 30 years and getting similar results to what others
report using speakers. The only complication is when an amp uses a
separate HP amp, but almost none of them do save the odd NAD pre-amp.

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**Precisely! I already knew the answer to my question.

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**Nope. Amps ARE made to drive headphones. The trouble is there are a wide
variety of schemes to accomplish this. They do so, with varying degrees of
quality. In some cases, the output stage (for speakers) has absolutely
nothing to do with the headphone circuits.


 Whatever, I'm convinced
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**Your assumption is faulty. You don't mention which NAD amp you owned, so I
can't tell you how the headphone outputs are configured. I can, however,
tell you that the Rotel RA931-II uses a series resistor of 330 Ohms for the
headphones. If the NAD uses a lower value resistor, or, even better, a
dedicated headphone amplifier, the difference in sound quality could be
substantial. Moreover, your logic is flawed. Although headphones, generally,
will expose minute differences in source and amplification more readily than
most loudspeakers, their impedance curve is more benign than most speakers.
As such, they will place relatively minor demands on amplifiers.
Additionally, I presume you are comparing similarly priced amplifiers?

 I've been listening to amps through
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**Not so. Many decent quality amps use a headphone amp. Which is EXACTLY the
kind of amp you should be using. In your situation, a power amp stage is
wasted. You would be better off using a dedicated headphone amplifier, or a
preamp which has adequate drive for headphones.


--
Trevor Wilson
www.rageaudio.com.au



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going to say, "Oh well, all bets are off as
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**Nope. Amps ARE made to drive headphones. The trouble is there are a wide
variety of schemes to accomplish this. They do so, with varying degrees of
quality. In some cases, the output stage (for speakers) has absolutely
nothing to do with the headphone circuits.


 Whatever, I'm convinced
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**Your assumption is faulty. You don't mention which NAD amp you owned, so I
can't tell you how the headphone outputs are configured. I can, however,
tell you that the Rotel RA931-II uses a series resistor of 330 Ohms for the
headphones. If the NAD uses a lower value resistor, or, even better, a
dedicated headphone amplifier, the difference in sound quality could be
substantial. Moreover, your logic is flawed. Although headphones, generally,
will expose minute differences in source and amplification more readily than
most loudspeakers, their impedance curve is more benign than most speakers.
As such, they will place relatively minor demands on amplifiers.
Additionally, I presume you are comparing similarly priced amplifiers?

 I've been listening to amps through
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**Not so. Many decent quality amps use a headphone amp. Which is EXACTLY the
kind of amp you should be using. In your situation, a power amp stage is
wasted. You would be better off using a dedicated headphone amplifier, or a
preamp which has adequate drive for headphones.


--
Trevor Wilson
www.rageaudio.com.au


We've slightly trimmed the long signature. Click to see the full one.
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**Take your complaint up with the original poster. Further, if you would
care to elucidate what the fuck "audiophoolery" (WRT this particular part of
the thread) is, I'd be happy to discuss whatever you want in more technical
detail, if you wish. Not one word I wrote is incorrect, WRT headphones and
amplifiers.


--
Trevor Wilson
www.rageaudio.com.au




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On Mon, 12 Dec 2005 19:44:28 GMT, "Trevor Wilson"

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Sneaky, Trevor. We'll have to watch you.

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In very few cases, certainly where budget products are concerned.
Inevitably it's much easier--and quite satisfactory--to run the
headphone socket from the output via a resistor. Where there's a
separate HP amp involved, as in say NAD's 160 pre-amp, the
manufacturer usually crows about it.

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NAD 7225PE receiver.

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I know. I changed it to a higher value as it didn't allow enough
movement of the volume control. I detected no change in sound quality
afterwards.

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Which relates to what I said about a non-reactive load. Thus taking
the vagaries of speaker load out of the equation.

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Exactly; that's the point I'm making. Where the same amp will react
differently to different speakers...well, you get what I mean.

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Yep. All  >$500.

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Disagree. I've listened to several HP amps. I have one now. None of
them sound half as good as my Marantz PM8200. Yes, I know there's a
lot of power wastage and I regret that, but ultimately it's the sound
that matters. Whatever may apply in theory, if one's ears tell a
different story.....



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**Not so sneaky, really.

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**True.

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**True.

 Where there's a
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**Nope, but sometimes they do.

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**I have no service manual for that model.

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**Uh huh.

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**Except that speakers are precisely what most users want from their
amplifiers.

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**I did not say that ALL headphone amplifiers are equal, nor are they
necessarily superior to the amplifier in your Marantz.


--
Trevor Wilson
www.rageaudio.com.au



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***You are still cross posting and you cant blame the OP!!

Brian Goldsmith.



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**You're not getting much smarter, are you?

IF you have a problem with crossposting (or top posting, or whatever you
imagine is a problem), then take it up with the original poster.


--
Trevor Wilson
www.rageaudio.com.au



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