Which power amps (or all of them) have their own sound signatures, and why, by design, or just happened to be?

[Verdinut]

What?
You think its easy to sell 100WPC amps for $3000 each?

It will probably be easy to sell to audiophools with the false info that goes with their publicity.

IMO, a serious manufacturer doesn't need to use bullshit statements to sell its products.
Cheers,

 

[mtrycrafts]

.... So Benchmark's "more typical" is misleading, I still wouldn't call it bullshit though.

Or, isn't that just not true?
They would need to check all the amps then see how many are below 1%. I could well be less typical.

 

[Verdinut]

Or, isn't that just not true?
They would need to check all the amps then see how many are below 1%. I could well be less typical.

The misleading info I was referring to has to do with the following fallacy from Benchmark:
"The AHB2 is the first amplifier to virtually eliminate crossover distortion without incurring the undesirable side effects of class-A amplification."

The fact that crossover distortion is eliminated on a Class AB amp with proper biasing in the output stage is nothing new. It has been done with Class AB amps for many years.

 

[Irvrobinson]

On their website, here is what Benchmark say about the AHB2 power amp:

"Traditional class-AB amplifiers generate crossover distortion every time the push-pull output stage crosses 0 volts. This crossover distortion can be especially problematic at low playback levels.
The AHB2 is the first amplifier to virtually eliminate crossover distortion without incurring the undesirable side effects of class-A amplification."

The fact that crossover distortion is eliminated on a Class AB amp with proper biasing in the output stage is nothing new. It has been done with Class AB amps for many years.

Why do they have to publish marketing bullshit?

Not only that, but both Peter Walker and Nelson Pass devised voltage source / current mirror strategies that virtually duplicated Class A performance but with higher efficiency.

 

[TLS Guy]

That amp is a current dumper feed forward amp. So it is using Peter Walker's invention. It states in the reviews it is 1980 technology, but actually Peter Walker's landmark paper was in 1975.

Since his patents have long expired, I have never understood why his invention has not become the most common amp design of all. To me it is absolutely a no brainer,
It is reliable, reduces part count and is resilient, resulting in long term reliability along with consistent performance.

To me this design does sound superior to other output designs, especially the ubiquitous AB amps. My favorite amps are a short list. The AR Sugden/Richard Allen class A amps from that era and the current dumpers. Those class amps were 10 watts per channel. Unusually for class A amps they were reliable. My sister has had one in continuous use for over 50 years and ir has never seen a service tech or had the case opened. They now fetch very high prices on eBay.

I did do a carefully matched double blind study between a Perreaux amp and factory Quad 405-2 200 amp mono blocks years ago and listeners picked the Quads consistently as the superior amps.

I'm convinced that Peter Walker's invention not only produces better sounding amps, but also more robust and reliable amps. In my view it should be the standard amp topology.

I have used current dumpers since the mid 70s and also tinkered with them in conjunction with Peter Walker in the early days. I use current dumping amps exclusively in my systems and feel they make a significant contribution to their superior sound.

I bet those Benchmark amps do sound very good indeed.

This is the current Quad top of the line current dumper.

 

[Swerd]

Regarding why he received a second one, he said "I requested the second one because of something I was seeing in the measurements that turned out to be my issue, not the amp's."

Benchmark intended the amps to be bridged for systems requiring more than 100 watts/ch, so they wanted them to be tested that way.

Thanks for the explanations. I hoped there was a clear reason in his review. I could not read it enough detail to find out. The reviewer's writing style left me wondering if he was brilliant but inarticulate, or if he was trying to dazzle us with bs.

My golden ear comment was just being sarcastic.

That may be the only part I clearly understood .

 

[HTfreak2004]

Your beliefs (marked in bold above) are just what you believe, and only that. They are not fact. They are certainly not fact because you believe them.

All of your statements, however, are testable. Put those beliefs to the test and find out what is actually fact.

I can readily agree with you that speakers also distort sound. It's known that speakers can have quite a lot more distortion, as much as 10% total harmonic distortion, than an amplifier. Amps typically have less than 1% THD, often less than 0.1% THD.

How much distortion has been observed or measured in wires?

You are correct when implying my beliefs are mine yet our beliefs can be based upon what was once accepted as common fact only to be later proven false.

There are many experiences in our lives that are “poorly” expressed with words that must be “experienced” in order to be understood. Afterwards you can use whatever words you choose to describe your experience.

I can offer the comparison in favour of Balanced interconnects vs unbalanced interconnects as an example of how a type of wire impacts distortion especially from external interference, eg. long cable run of balanced interconnects vs unbalanced.

We could entertain the “potential” advantages for bi-amping a speaker which may have an advantage from dedicating a signal range through separate interconnects, amps and speaker cables.

Many of us already utilize such an example with regards to bass management by separating frequencies pre amplification down two or more separate pathways (sub amp and other mains channel amp) which in turn may reduce premature distortion and lead potentially to greater clarity in sound or at least that’s how it was intended to work!

 

[mtrycrafts]

The misleading info I was referring to has to do with the following fallacy from Benchmark:
"The AHB2 is the first amplifier to virtually eliminate crossover distortion without incurring the undesirable side effects of class-A amplification."

The fact that crossover distortion is eliminated on a Class AB amp with proper biasing in the output stage is nothing new. It has been done with Class AB amps for many years.

OK. And I was responding to this
The AHB2 is conservatively rated at an output level where THD+N is < 0.0003 % instead of the more typical 1% THD+N. Power at 1% THD will be higher. " [/]

 

[killdozzer]

You all seem to be focused on that specific Benchmark, while the title question is much broader. I do think certain companies deliberately try to create the "in-house-sound-signature". However, in order for anyone of you here to even consider that, you'd first have to accept that descriptions of sound signatures are not entirely arbitrary, because trying to achieve something completely unspecific is impossible. And I do know most of you here don't accept that.

I've said that a couple of times; I don't see it as desirable and I understand that words used to describe sound are not technical terms and can be imprecise. Having said that, I do think that people recognise the same feature of sound when they label it warm, for example. I think it's just like sibilance or 2nd order harmonics distortion...

And just like watts, "warm" sells.

I know PENG proposed another explanation in another thread in which descriptions reach customers before the equipment and they already "know" what they all should expect and that's where the consensus on which equipment has which sound signature comes from. I don't think this covers the entire story because I do notice a surprising amount of consistency even among the unfamiliar equipment. Also some other cases where people get used to one sound and then mistakenly describe a neutral equipment as cold (even if said equipment was never marketed as cold, for example Marantz - I'm citing a real case).

 

[PENG]

The misleading info I was referring to has to do with the following fallacy from Benchmark:
"The AHB2 is the first amplifier to virtually eliminate crossover distortion without incurring the undesirable side effects of class-A amplification."

The fact that crossover distortion is eliminated on a Class AB amp with proper biasing in the output stage is nothing new. It has been done with Class AB amps for many years.

May be not totally eliminated in all well designed class AB amps but it should have negligible effects. Also, crossover distortions, unlike IMD, is also harmonic distortions so it should have been captured in the THD+N measurements and I think even die hard audiophiles would agree 0.08% of THD+N is low enough for normal people regardless of the harmonic spectrum.

 

[AcuDefTechGuy]

...I'm convinced that Peter Walker's invention...produces better sounding amps...

Oh, so you do believe amps have sound signatures of their own and some amps sound better than others (given the same power spec).

 

[highfigh]

Auditory Hallucinations are real.

They definitely are real. A guy in Racine, WI called 911 because he heard voices in the walls of his truck and was arrested for his 4th DUI.

https://www.jsonline.com/story/news/crime/2019/05/24/racine-county-semi-truck-driver-calls-911-hearing-voices-trailer/1231230001/

 

[highfigh]

On their website, here is what Benchmark say about the AHB2 power amp:

"Traditional class-AB amplifiers generate crossover distortion every time the push-pull output stage crosses 0 volts. This crossover distortion can be especially problematic at low playback levels.
The AHB2 is the first amplifier to virtually eliminate crossover distortion without incurring the undesirable side effects of class-A amplification."

The fact that crossover distortion is eliminated on a Class AB amp with proper biasing in the output stage is nothing new. It has been done with Class AB amps for many years.

Why do they have to publish marketing bullshit?

If the amp is Class AB, why would it have crossover distortion at low levels when it's operating as ClassA at low levels. Why would other manufacturers intentionally design their amps to run as ClassA up to higher power levels if it's so bad?

Why do they have to publish this stuff?

It's their job as marketing professionals.

 

[highfigh]

Oh, so you do believe amps have sound signatures of their own and some amps sound better than others (given the same power spec).

It's not just the power spec- it's a matter of matching the rest, too. If two amps produce the same power into a resistor, they won't necessarily be equal with speakers connected.

Then, there's the matter of "How great, or small, are the differences?".

 

[TLS Guy]

Oh, so you do believe amps have sound signatures of their own and some amps sound better than others (given the same power spec).

Absolutely I do. I have stated that here on many occasions. I agree with Peter Walker that testing an amp on a bench with a purely resistive load does not provide the totality of the information you need. Testing with extreme reactive and inductive loads is crucial. That is he only way to produce an amp that will perform well into the plethora of loads an amp will face. Apart from Maggies I can think of no real world speaker loads that are in any way comparable to a 8, 6 or 4 ohm resistor. That brings us to the next problem that amps will perform better with some speakers than others. Yes, they really do as you would expect. So amps do need to perform well and an array of varying inductive and reactive loads, and to make matters worse these loads can be inductive or reactive at different frequencies. That is the real world, so no wonder results may vary. So the key to a good amp, is not only must it do well into a resistive load, but also loads way outside that parameter. Testing an amp with a resistor is like testing a car only on a long straight flat road.

 

[M Code]

Minimizing X-over distortion is a well known task to an experienced amplifier designer.. I remember reading a Marantz white paper > 40 years ago and they called it Variable Overlap Drive..
Simple to understand, basically it the bias setting for the output devices, and is higher so they turn on sooner.. But now power consumption is increased significantly and idle current is high making the unit very hot...
However NOW the output devices are already hot and their total output voltage/current capability will be decreased when needed for a dynamic power output demand as the efficiency of the output devices is decreased by up to 50% by already being hot..

Just my $0.02...

 

[TLS Guy]

Minimizing X-over distortion is a well known task to an experienced amplifier designer.. I remember reading a Marantz white paper > 40 years ago and they called it Variable Overlap Drive..
Simple to understand, basically it the bias setting for the output devices, and is higher so they turn on sooner.. But now power consumption is increased significantly and idle current is high making the unit very hot...
However NOW the output devices are already hot and their total output voltage/current capability will be decreased when needed for a dynamic power output demand as the efficiency of the output devices is decreased by up to 50% by already being hot..

Just my $0.02...

That is the whole beauty of Peter Walker's invention. The dumpers can be heavily biased to class B. Actually the 405 and 405-2 were biased class C! The spec is set by the small and highly accurate class A Amp. These amps have class A performance and zero crossover distortion and yet run very cool with low quiescent current draw.

 

[PENG]

If the amp is Class AB, why would it have crossover distortion at low levels when it's operating as ClassA at low levels. Why would other manufacturers intentionally design their amps to run as ClassA up to higher power levels if it's so bad?

Why do they have to publish this stuff?

It's their job as marketing professionals.

We have had this debate before, some class AB amps run in A at very low level, but many run in AB at all level, such as Verdinut's QSC DCA amps.

 

[Irvrobinson]

This is the current Quad top of the line current dumper.

Interesting that you would reference a review from The Absolute Sound, although I suppose Robert Greene is their most rational reviewer. And even in a magazine known for colorful writing, he didn't say anything especially positive about how the Quad sounded versus more pedestrian Class AB amplifiers.

 

[Verdinut]

Did someone notice that this AHB2 works indeed in class AB at low to moderate output levels and uses a second voltage rail to operate in class H at high outputs?

We normally see that topology in high power pro audio amps, not on 100 watts or so amps.