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Is there a noticeably audible difference between two level matched solid state amps under controlled

  • Yes... I believe a notable difference can be heard.

    Votes: 136 48.6%
  • No... I do not believe there is any audibly significant difference.

    Votes: 144 51.4%

  • Total voters
    280
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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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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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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.

 

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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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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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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 :T
Nice response also, I agree different amps can clip differently.
 

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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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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.

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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gsmollin said:
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)
 

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I believe some of the confusion in this area is in partly due to people thinking "system" when others are speaking of a discrete component called a power amplifier. Jerry is correct saying that two amps that have the ability to produce a similar amount of output power are going to sound the same. And if there is distortion then the amp/system is undersized or set up wrong.

The caveats within the power amp are, as mentioned by others, is there enough capacitive storage in the power supply to cover low end demands. But that gets right back to Jerry's comment that if it is not underpowered then it will not distort.

So based upon designing amps, using amps, listening to untold number of amps I can conclude that equally powered amps are going to sound equal assuming that there is no distortion due to the amp design. That means that the THD or measureable distortion is within acceptable limits. One way to think of it is that a power amp takes a signal, sine wave or music, and simply takes it from a one volt wave to one that is much larger in size. The amp simply multiplies what comes in and sends out an "exact" match but much taller. If both amps do this without coloring (adding unwanted EQ) or clipping then they will sound the same. As one person said, the amp is a commodity. Some are built with better components and last longer. A pure power amp is such a basic simple design that there is not much difference between them. There are different "types" of circuits used to make power amps but they really are a commodity now meaning that all decent amps do the same thing.

So in an A/B situation swapping only the amp there would not be any audible difference as demonstrated by all the examples given in this thread.

If one is to start thinking of systems and EQ and impedance and matching then there is not enough time or forum space to compare them.
 

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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.
I agree with you recruit that pre-pro's make a much bigger difference in SQ than a well designed amp.

Any amp that Does Not Harm the signal should sound the same.
 

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The trouble is, all amps harm the signal. I think this is why there is a difference between so many amps. The difference may not be huge or it may be pronounced, but I think amps sound different.
 

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The trouble is, all amps harm the signal. I think this is why there is a difference between so many amps. The difference may not be huge or it may be pronounced, but I think amps sound different.
This is true. All amps distort soun and the distortion efffect is not likely to be uniform. Amps have a published spec regarding how much distortion they create. For most any amp worth discussing, it is less than .1%. That is far below human hearing.
 

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The trouble is, all amps harm the signal. I think this is why there is a difference between so many amps. The difference may not be huge or it may be pronounced, but I think amps sound different.
That's true, I should have said Does the Least Harm
 

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Thanks for the replies to my post about amplifier overload. Overloading an amplifier is not a simple matter. The load is a complex electromechanical device, the source material can contain pathological signals, and amplifiers almost all have self-protection circuits that distort the signal when they are tripped.

I have a number of speaker impedance curves, and at least one premium brand 8-Ohm speaker has a dip to less than 3 Ohms at the crossover between woofer and midrange, at about 400 Hz. Connect that speaker to an amplifier not rated below 6-Ohms, and send a signal with a strong 400 Hz component, and the system will suddenly distort. This can be heard, but one will have a hard time pinning it down, because the amplifier has to be hit with the bad combination. Nevertheless, if and when this sort of thing happens, the careful listener will hear "A difference in the amplifier". It's not that simple, but it is also true that an amplifier change may break up the bad combination and the new amplifier will "sound different". I know a lot about this incident because it happened to me, and I tracked down the sources of the problems. I would say that the speakers were more to blame than the amp, but everyone knows that if you change the speakers your system will sound different, and they are probably right. With the amplifier it's not so straightforward, and gives rise to threads like this.
 

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Do you also think that all DACs sound alike as well? I just wonder where the line is drawn in this question??
I think there is a lot more feeling that processor make a fair bit of difference in a setup, and I for one lean that way. I agree, starting a thread on that subject would be very interesting.
 
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