Can we really hear a difference between amps? - Page 5 - Home Theater Forum and Systems - HomeTheaterShack.com

View Poll Results: Is there a noticeably audible difference between two level matched solid state amps under controlled
Yes... I believe a notable difference can be heard. 135 48.39%
No... I do not believe there is any audibly significant difference. 144 51.61%
Voters: 279. You may not vote on this poll

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post #41 of 825 Old 10-17-10, 11:02 PM
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Re: Can we really hear a difference between amps?

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LOL Sonnie, the Zipser test is my fave example of the DBT working correctly. I also agree that the gear ideally will impart no signature at all on the signal passing through it, unless it is meant to, eg EQ.

My current position, based upon many years of designing, building, modifying and servicing a lot of amplifiers of probably every type is that there should be no audible differences between well made units, operating within their specifications. If there is, the unit was not designed well or the perceived colouration intentional on the part of the designer.

As I am not much of a fetishist over brands, I simply want to know if it will perform as I need it to reliably. Many years ago however, I spent a lot of time even testing parts in the amps I designed; would brand A resistor/cap sound better than brand B in this position or that and I tried many permutations of parts as well as topologies. It was not unusual to have as many as a dozen stereo amplifiers on my floor at one time. Because I changed them in/out so often I made a standard connector arrangement for them all so it was one step to change between them. One night after many hours I'd done the last bit of testing and thought I'd made the best amp so far, left it on to soak and went to bed. Next day I listened to some music over breakfast, then went to turn off the 'best' amp to permanently solder in some parts; the music kept playing. I had mistakenly connected in my old mule amp a modest SS Rotel, not the great tube amp I thought I had been listening to for the last couple of hours before bed.

After that I did a lot of testing by close level matching and switching to test myself. Amazingly obvious differences were suddenly not something I'd bet a dollar on. To be sure it wasn't my hearing, I tested others who were sure they could tell differences between just about everything. No one picked such things as a 30yo SS Marantz integrated over a Fisher tube amp for example (I had very efficient speakers with an even Z curve so no real issues there). There were many others too, so it reinforced to me how much our visual perception and preconceived ideas play in what we think we hear.
I am glad someone has a different view than I do and says so in a very tactful manner, and I honestly after all these years can admit that maybe it was thought to sound better and now want to do more A/B blind testing with the amp I have heard the differences in. I will need to repair the amp to do so.....new project.

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post #42 of 825 Old 10-17-10, 11:39 PM
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Re: Can we really hear a difference between amps?

I think a new amp always sounds better than an old one unless the new amp is uglier than expected. But that's probably from the euphoric feeling of having the new amp.
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post #43 of 825 Old 10-18-10, 12:02 AM
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Re: Can we really hear a difference between amps?

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I think a new amp always sounds better than an old one unless the new amp is uglier than expected. But that's probably from the euphoric feeling of having the new amp.
Haha, yeah new amps r great. And the euphoric feeling cant be compared, unless to a new monitor or projector.

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post #44 of 825 Old 10-18-10, 10:59 AM
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Re: Can we really hear a difference between amps?

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There were many others too, so it reinforced to me how much our visual perception and preconceived ideas play in what we think we hear.
I think this is a big deal. This had been documented in other fields, such as visual perception, and in that field its easy to show others how perception is a big part of what we actually see. The below video illustrates the point perfectly. I'm certain the same thing happens with our ears to a degree, its just infinitely more difficult to show it so inarguably.

www.youtube.com/watch?v=Ttd0YjXF0no
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post #45 of 825 Old 10-18-10, 08:21 PM
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Re: Can we really hear a difference between amps?

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I think this is a big deal. This had been documented in other fields, such as visual perception, and in that field its easy to show others how perception is a big part of what we actually see. The below video illustrates the point perfectly. I'm certain the same thing happens with our ears to a degree, its just infinitely more difficult to show it so inarguably.

www.youtube.com/watch?v=Ttd0YjXF0no
Honestly I do think looks matters. I don't want an ugly amp no matter how good of a deal it is. At the end of the day reliability is king though. If something breaks my system is down and that sounds more terrible than the noisiest of amps.
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post #46 of 825 Old 10-18-10, 10:56 PM
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Re: Can we really hear a difference between amps?

I've been through this thread ad-nauseum over at the AVS forum, and of course it always got nasty. So without getting nasty, I will explain why people continue to hear differences between amps, yet in controlled tests there is little or no difference.

As long as modern, solid-state, linear power amplifiers are operating within their linear levels, the differences are so small that they can only be measured, and not heard. The problems and differences arise when they are overdriven. Then almost every amplifier-loudspeaker combination you can put together will respond with its own sound. In most controlled tests, levels are kept low so that there is no clipping/overdriving to hear. But if the volume were turned up, then Zipper would have heard a difference. Actually, everybody would have heard it. It takes only a small increase in the levels to drive an amp into overload. A 3 dB change in volume is barely perceptible, but is double the power, so it's a big deal to the amp.

That's it in a nutshell. As a adder, the overload characteristics of tube amps are rather different from solid state, and are ususally more gradual. This is most of what tube amp sound is about, although that's not all of it.
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post #47 of 825 Old 10-18-10, 11:01 PM
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Re: Can we really hear a difference between amps?

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I've been through this thread ad-nauseum over at the AVS forum, and of course it always got nasty. So without getting nasty, I will explain why people continue to hear differences between amps, yet in controlled tests there is little or no difference.

As long as modern, solid-state, linear power amplifiers are operating within their linear levels, the differences are so small that they can only be measured, and not heard. The problems and differences arise when they are overdriven. Then almost every amplifier-loudspeaker combination you can put together will respond with its own sound. In most controlled tests, levels are kept low so that there is no clipping/overdriving to hear. But if the volume were turned up, then Zipper would have heard a difference. Actually, everybody would have heard it. It takes only a small increase in the levels to drive an amp into overload. A 3 dB change in volume is barely perceptible, but is double the power, so it's a big deal to the amp.

That's it in a nutshell. As a adder, the overload characteristics of tube amps are rather different from solid state, and are ususally more gradual. This is most of what tube amp sound is about, although that's not all of it.
I agree some ppl have the ability to disagree in a poor manner, glad u r not one of them
Nice response also, I agree different amps can clip differently.

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post #48 of 825 Old 10-18-10, 11:56 PM
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Re: Can we really hear a difference between amps?

I have had Lexicon / Parasound / Meridian / Chord & Rotel power amps in my set ups and tbh it was only when they were pushed hard did you get to notice any changes in sound and that was distortion in some cases when pushed too hard, even some AVR amps will only differ in volume output from my experiences with them, it is more to do with the processing / preamp and DAC stages that will make the sound differ.

So I feel money is better spent elsewhere in your system ie source components and also pre-amp and processors rather than thousands on a more costlier power amp.
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post #49 of 825 Old 10-19-10, 12:28 AM
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Re: Can we really hear a difference between amps?

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As long as modern, solid-state, linear power amplifiers are operating within their linear levels, the differences are so small that they can only be measured, and not heard. The problems and differences arise when they are overdriven. Then almost every amplifier-loudspeaker combination you can put together will respond with its own sound. In most controlled tests, levels are kept low so that there is no clipping/overdriving to hear. But if the volume were turned up, then Zipper would have heard a difference. Actually, everybody would have heard it. It takes only a small increase in the levels to drive an amp into overload. A 3 dB change in volume is barely perceptible, but is double the power, so it's a big deal to the amp.
If the amp audibly overloads in normal use it's too small.

As for the audibility of short duration clipping, here is Bob Cordell's experiment. If it was audible most of the flea power tube systems could only be listened to a whisper levels.

Regarding the hypothetical of whether Zipser test was too low, email Tom Nousaine and ask. There is a 3dB rating difference between the two amplifiers.

Also regarding the point of it being only clipping behaviour that determines the audibility, I have been involved in a couple, as well as my own SBT of amps of similar power. If one were adding a sonic characteristic because of clipping, it should have been apparent, yet wasn't.

Quote:
gsmollin wrote: View Post
That's it in a nutshell. As a adder, the overload characteristics of tube amps are rather different from solid state, and are ususally more gradual. This is most of what tube amp sound is about, although that's not all of it.
Modern tube amps with NFB overload in much the same way and degree as SS amps, plus as many are cap coupled there is strong potential for blocking and slower recovery.
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post #50 of 825 Old 10-19-10, 09:20 AM
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Re: Can we really hear a difference between amps?

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gsmollin wrote:
In most controlled tests, levels are kept low so that there is no clipping/overdriving to hear. But if the volume were turned up, then Zipper would have heard a difference. Actually, everybody would have heard it. It takes only a small increase in the levels to drive an amp into overload.
Your math is certainly correct: power doubles ever 3db, but it reminds me of the old saying "I get drunk on one beer... usually about the tenth one."

I don't believe your claim that most DBT's are at a" low" volume, which is to say that, in my experience, the bulk of DBT testing is done at the preferred volume of the listener. Put simply: if you are clipping then you have too small an amp.

You are right that amps driven to failure fail differently. You are wrong in your apparent inference that reasonable volumes neccesaitate failure. A properly chosen amp-speaker pair should not hit audible distortion, nor should it clip. Clipping and THD should be non-issues in both a DBT and actual use of your amp-speaker rig. If they are issues, then you've chosen the wrong amp for your application.

Note: the above applies to music *reproduction*. In music *production* it's not uncommon to deliberately drive an amp to distortion because of a desire for the distorted noise. An electric guitar amp may be set at "10" (or "11") and the gain on the guitar set high, particularly with a tube-stage, to make a distinctive sound (BTW: this can be emulated in software as well: actually running distortion is not neccessairy)

Last edited by JerryLove; 10-19-10 at 09:52 AM.
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