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Do amplifiers really sound the same?

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sergeauckland said:
Sorry to keep harking back to Peter Walker, but in an interview with Ken Kessler reported in KK's book on Quad, PW said they never listened to music as part of the design process only test tones and other "funny noises" and then for audibility of certain effects.

When I was designing Broadcast Audio equipment, I would have been laughed out of the AES if I'd designed "by ear". By all means listen to the finished result as a sort of reality check or final "well done" to oneself, but as to listening to capacitors, (or even solder...) no.

S.
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Apologies ... I knew about the Quad design approach in the Walker era. I meant to ask if any contemporary designers didn't use subjective testing in the latter stages of refining their designs.

Nic P
 
john dolan said:
Just wondering how many of you it all sounds the same guys are over 60 and how do you think your hearing compares to a 20 year old.
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Hi I'm 61 this year.
Been listening to quality HI FI since my twenties. I like to think I know what I'm listening for.
Replaced a capacitor in my pre last night with a Wima, it was an improvement.
This is how I went about it.
Plugged my lk280 directly into my Dac.
Chose a quiet intro (classical) as there was no volume control in between.
Found that I liked what I heard so decided to try and replicate it including my pre.
Changed the only cap in the circuit for a wima and got close to the sound direct from the Dac.
It is possible to hear a cap change even when your 60+
 
Mr Pig said:
Nothing? Why do they need to listen for anything? I thought they just looked at a graph to see all was well?
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In spectral composition yes, you are pretty much assessed by that criteria. I mangled up porn soundtracks taken from the net beyond recognition in SPEAR and GRMtools and granular effects so they fit the marking criteria and aced the test.

Whacky bunch spectral composers, well you have Giacinto Scelsi and György Ligeti. Not my cuppa in that early 80s nasty computer processing sound but sampling porn movies from that era was fun. Especially removing all the clippy-clopping bits.
 
hammeredklavier said:
Well, I no longer have the Naims, so it would be wrong of me to say that. I can, however, say that any difference would be very small.
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Hang on, just a minute ago you said they were 'quite a bit' better and the Naim was 'very' hissy, relativly speaking I assume.

Now any difference is very small? Sorry dude, the credibility of your opinion just left on a bus.
 
Mr Pig said:
Hang on, just a minute ago you said they were 'quite a bit' better and the Naim was 'very' hissy, relativly speaking I assume.

Now any difference is very small? Sorry dude, the credibility of your opinion just left on a bus.
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The Naims certainly did some hissing, and the Samson doesn't. Soundwise, I think the Samson is quite a bit better than the Nait and at least as good as the the NAP150/NAP90/Flatcap2 combo. Now, bear in mind that in my current set up, there is no superfluous pre-amp between the DAC and the power amp, which is going to stack the odds in the 120a's favour - all other things being equal.
 
Mescalito said:
The difference, of course is that there is a large body of evidence from all sorts of fields showing that sighted evaluation of anything is fundamentally unreliable.
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Not doubting you for a moment, but I'd like to read some of it. Have you got any links?

One thing that makes me smile is that one side says that blind tests are fundamentally unreliable, the other says that sighted tests are fundamentally unreliable.

So does that mean that sighted tests, because they don't agree with blind tests, are unreliable? Or does it mean that blind tests, because they don't agree with sighted tests, are unreliable?

Do we have a universally accepted test we can use as a control?
 
hammeredklavier said:
The Naims certainly did some hissing, and the Samson doesn't. Soundwise, I think the Samson is quite a bit better than the Nait and at least as good as the the NAP150/NAP90/Flatcap2 combo.
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So where does 'very small' enter into it? If al amps sound the same why didn't the Nait and bigger Naim amps sound the same? For what it's worth, I think that he Nait and bigger Naim amps do sound very, very similar if not stressed.
 
Mr Pig said:
So where does 'very small' enter into it? If al amps sound the same why didn't the Nait and bigger Naim amps sound the same? For what it's worth, I think that he Nait and bigger Naim amps do sound very, very similar if not stressed.
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I mean exactly what you just said.

I don't want to go so far as to say, 'they are the same', because I no longer have the Naims to hand to make sure. It's in the same ballpark as the NAP150 power wise. There's a recording I'm fond of of Wolf's Kennst du das Land by Ann Sofie von Otter, in which the 150 would always clip vilely on one of the singer's crescendos, even at fairly moderate levels and distort horribly; the Samson doesn't, or at least certainly not at those levels. Again, I'm going on memory, but none of the Naim combos offered anything like the kind of resolution I'm hearing here - but then, Naim pre-amps apply huge amounts of gain, necessitating copious attenuation. They are rather noisy, and so you don't need to be a genius to see that the S/N ratio is going to get stuffed.

Now, if I fed the Audioengine straight into a NAP150, would there be any difference? I haven't got one here so I'll have to guess; but my guess is that there wouldn't be a great lot of difference, if any. I suspect the Samson is a little bit more powerful though.

I remember when I replaced the 150 with the Avondale M130s, the first thing that struck me, apart from the huge amount of extra power, was that the frequency balance seemed more even, and the treble sounded a bit more extended. I'm being reminded of that sound now - only without the massive grunt of the 130s, sadly.
 
sergeauckland said:
You will need a pre-amp with two identical outputs, the Power Amp under Test, an attenuator, an A-B switchbox, a dummy load and another power amp and 'speakers.

You arrange the output of the pre-amp to go to both the PAuT and switchbox, the output of the switchbox goes to the power amp and 'speakers.

The second input of the switchbox goes to the output of the PAuT feeding the dummy load, through the attenuator such that the A and B parts of the switchbox receive the same signal level, matched to 0.1dB.

Then listen to some music direct, i.e. the A path and switch to the B path in which the signal goes through the PAuT. If this is done blind, and one can't tell whether the switch is direct or going through the PAuT, then the PAuT must be transparent. The dummy load can be a simple resistor, or it can be a complex load to simulate a difficult loudspeaker, or indeed it could be a difficult loudspeaker if that is placed in a separate room such that the noise doesn't affect what is being heard in the listening room.

If when switching A-B on a wide variety of music it can't be identified which is direct and which is through the amplifier, then the PAuT must be transparent.

This test can of course be done with any component.

Quad famously did it by daisy-chaining 50 of their Quad 303s and apart from a bit more noise, which wasn't audible under the music, they were still transparent.
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This test is flawed in two ways.

Firstly, it relies on subjective listening. If you can't tell the difference, it doesn't mean someone else can't.

Secondly, you are comparing one amplifier against another, which assumes the baseline amplifier is reliably transparent under the test conditions.

I was half expecting a 'scope and some spectral analysis to be part of this transparency test, but I guess I'm heartened that even you rely on your ears to ascertain transparency.

:D
 
James said:
Secondly, you are comparing one amplifier against another, which assumes the baseline amplifier is reliably transparent under the test conditions.
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Indeed, and I suspect a lot of hi-fi amps aren't.

If two amps are transparent - and this seems to be quite achievable, at very low cost these days - then obviously they will sound the same.
 
James said:
This test is flawed in two ways.

Firstly, it relies on subjective listening. If you can't tell the difference, it doesn't mean someone else can't.

Secondly, you are comparing one amplifier against another, which assumes the baseline amplifier is reliably transparent under the test conditions.
I was half expecting a 'scope and some spectral analysis to be part of this transparency test, but I guess I'm heartened that even you rely on your ears to ascertain transparency.

:D
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No, that's not quite right. One's comparing the direct path against the other path which includes the PAuT. However, this PAuT is driving the dummy load, which can be as complex as one likes, and so is being compared with a straight piece of wire. Unless the power amplifier driving the 'speakers is badly flawed, any error due to the PAuT will be audible. If nothing's audible either way, then the PAuT must be transparent.

Of course it's subjective, insofar as it needs the descrimination of a listener. That's why it's a statistical process, although one can use it to establish one's own thresholds of audibility.

S.
 
Transparency is both absolute and relative. In the analogous world of photography, the amplifier is a camera lens. It should transfer what it sees from one side and re-create an identical image on the other side on film or sensor.

Some objectivists (Vuk will call them something else) measure transparency with the amount of pin-cushion/barrel distortion (THD), chromatic aberration (IMD), contrast (S/N, dynamic range), colour rendition (FR) throughout the range of apertures (power). The subjectivist would just use the lens and see if it takes a pleasing photograph. AFAIK, the subjective attribute of bokeh, which every photographer understands, cannot be measured just yet - but it is an artefact of the lens.

Maybe we're going around in circles with amplifier bokeh.
 
sergeauckland said:
Quad famously did it by daisy-chaining 50 of their Quad 303s and apart from a bit more noise, which wasn't audible under the music, they were still transparent.
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I rank this claim right up there with people not being able to tell the difference between Caruso and a Victrola.
 
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