advertisement


Has anyone bought a product because of a recommendation on ASR?

Steve 57 said:
…
But there good technical reasons why some amplifiers sound better than others..
It's just that those technical reasons dont come in the scope of published measurements
Click to expand...

Maybe it’s a topic for a new thread?

Would you care to expand on the technical reasons why some amplifier sound better than others?
 
S-Man said:
Maybe it’s a topic for a new thread?

Would you care to expand on the technical reasons why some amplifier sound better than others?
Click to expand...

I was at the ETF in Holland last year, I was told by many my gear was a couple of levels above the rest
And of course I was asked why.
I've been building Set amplifiers for nearly 30 years (along with solid-state and push pull valve..but SETs are my thing) When I said that virtually every circuit published will not get best out of the valves, and once understood I got quite a following.

Set amplifiers generally have no feedback and no push pull valve arangement so keep the signal intact, forget the distortion as i use them well below that level.. at the ETF it was commented how sharp and fast the music sounded, its the leading edges that makes music sound real..

Back to commercial solid state amps.. which I owned may fair share of.. there's what I'd call sticking plaster low distortion.
Both feedback and push-pull are included, push pull give more power at the expense of splitting the signal in two, and the most common used feedback, gives a route for the back emf from the loudspeakers and mix it with your input signal changing the original signal.. now that not shown up testing an amplifier with a fixed load but sure effects the sound in use
Now I'm not saying that feed back and push pull won't work perfectly if components are matched and accurately selected, but that makes for an expensive product as theres sometimes wide tolerances on components.
So in use, most push pull and feedback causes varying cancellation in the signal as well as cancelling the distortion

its also easy for a manufacturer to 'select' the item for testing

Next time your at an audio show listen how the music sounds, it's the systems with the sharp instant leading edges to notes that sound more real.

From that, rise time can be heard in the amplifier, solid state amplifiers have improved, but valves don't suffer rise time, but you can slug them with miller effect.
Again explaining the openess many hear with some valves.. its that leading edge to the sound again.
 
Steve 57 said:
I was at the ETF in Holland last year, I was told by many my gear was a couple of levels above the rest
And of course I was asked why.
I've been building Set amplifiers for nearly 30 years (along with solid-state and push pull valve..but SETs are my thing) When I said that virtually every circuit published will not get best out of the valves, and once understood I got quite a following.

Set amplifiers generally have no feedback and no push pull valve arangement so keep the signal intact, forget the distortion as i use them well below that level.. at the ETF it was commented how sharp and fast the music sounded, its the leading edges that makes music sound real..

Back to commercial solid state amps.. which I owned may fair share of.. there's what I'd call sticking plaster low distortion.
Both feedback and push-pull are included, push pull give more power at the expense of splitting the signal in two, and the most common used feedback, gives a route for the back emf from the loudspeakers and mix it with your input signal changing the original signal.. now that not shown up testing an amplifier with a fixed load but sure effects the sound in use
Now I'm not saying that feed back and push pull won't work perfectly if components are matched and accurately selected, but that makes for an expensive product as theres sometimes wide tolerances on components.
So in use, most push pull and feedback causes varying cancellation in the signal as well as cancelling the distortion

its also easy for a manufacturer to 'select' the item for testing

Next time your at an audio show listen how the music sounds, it's the systems with the sharp instant leading edges to notes that sound more real.

From that, rise time can be heard in the amplifier, solid state amplifiers have improved, but valves don't suffer rise time, but you can slug them with miller effect.
Again explaining the openess many hear with some valves.. its that leading edge to the sound again.
Click to expand...

Thanks for taking the time to post that!

I think there is an element of truth in that. Apparently, people can hear transient information that is well above the frequency of a continuous tone that can be heard. And timing information is critical to things sounding “right” IME.

OTOH, I find the sound of some fabled amplifiers pretty boring, even if they sound good in hi-fi terms. Two examples are; the JLH 10 W class A and the Pass Aleph 5. I suppose they still have feedback, even if they are sort of Single ended. I think I’ve only tried one power amp with no global feedback the Hawk A18, however, this is push-pull.

My favourite amp uses a single ended input stage and push pull CFP bipolar+FET output stage. This presents the music with the best combination of rhythm and melody of all my amps. I’m sure the high efficiency brigade would think my system doesn’t have enough leading edge “bite“, but it’s the compromise which suits me best for long term musical satisfaction with all genres and recording qualities.
 
Steve 57 said:
Both feedback and push-pull are included, push pull give more power at the expense of splitting the signal in two, and the most common used feedback, gives a route for the back emf from the loudspeakers and mix it with your input signal changing the original signal.. now that not shown up testing an amplifier with a fixed load but sure effects the sound in use
Click to expand...

Could you explain what you mean by "back EMF mixing with the (amplified) signal"?
To the best of my knowledge negative-feedback actually reduces the effects of back-EMF by increased damping but I am always willing to learn.
And Stereophile's measurements of no-feedback amplifiers using a dummy load show that the frequency response is greatly affected by the varying load produced by most speakers, although its effects can be minimised by band-passing the amplifiers (e.g. active configuration).
 
Last edited:
tuga said:
Could you explain what you mean by "back EMF mixing with the (amplified) signal"?
To the best of my knowledge negative-feedback actually reduces the effects of back-EMF by increased damping but I am always willing to learn.
And Stereophile's measurements of no-feedback amplifiers using a dummy load show that the frequency response is greatly affected by the varying load produced by most speakers, but its effects can be minimised by band-passing the amplifiers (e.g. active configuration).
Click to expand...
The amplifier feedback it taken from close to the speaker connection in most cases, the loudspeaker rarely keeps exactly up with the music signal, the back emf developed by the loudspeakers movement can nearly match the input voltage, and this is voltage is on the speaker connections too. The result is the back emf enters the feedback loop along with the amps originsl output
I'm excluding any effect the crossover may have on this signal passing back to the amplifier, but it's hardly pure in most cases, but it's amplifier/ speaker/ volume/ music related

But it's there .. you can easily measure it as I have done. And it's only small amounts, but many amplifiers are very sensitive so there's little music signal at the 1st stage of many amplifiers.
Generally it's effect is one of cancellation as the signals are mixed
 
Last edited:
Steve 57 said:
The amplifier feedback it taken from close to the speaker connection in most cases, the loudspeaker rarely keeps exactly up with the music signal, the back emf developed by the loudspeakers movement can nearly match the input voltage, and this is voltage is on the speaker connections too. The result is the back emf enters the feedback loop along with the amps originsl output
I'm excluding any effect the crossover may have on this signal passing back to the amplifier, but it's hardly pure in most cases, but it's amplifier/ speaker/ volume/ music related

But it's there .. you can easily measure it as I have done. And it's only small amounts, but many amplifiers are very sensitive so there's little music signal at the 1st stage of many amplifiers.
Generally it's effect is one of cancellation as the signals are mixed
Click to expand...

It would be great if you could share those measurements.
 
Tuga my measurements where simple..just used a high quality fluke meter.
with your extensive knowledge you should be able to work the test out ?
 
You must log in or register to reply here.


advertisement


Back
Top