Can you hear a difference in Sound between Audio Amplifiers?

[RichB]

I have compared a Sunfire 7400 to an Outlaw 7500 with my Revel Salons.
The Outlaw had more impact, better bass control, and instruments remained distinct.

I have found that both amps sounded much better plugged directly into my 20 amp circuit than they did plugged into the Furman Elite 14 PFI amplifier plug.
I returned that product

Generally, I think Home Theater Mag and Some outfit named Audioholics do amplifier reviews that I have some confidence in.
At least there are some measurements at HTM.

I looked for an Outlaw 7500, 7700, ATI2000, or ATI3000 review here but could not find one.
What's up with that?

Looking into 250 to 300 WPC amps, I was going to get an Outlaw 7900 but came across this review at Home Theater comparing the A5 and the 7900:

The A 51 really came into its own with multichannel musical sources. The Model 7900 does an amazing job with just about any content, but the A 51 definitely had a more musical nature with its detailed top end. High-volume playback of John Mayer’s Where the Light Is live concert Blu-ray was a great showpiece for the A 51. It was less fatiguing than with the Model 7900, and the instruments had a richer sound with better definition. The comparison wasn’t night and day, but it was noticeable.

Either this is subjectivism or there is another explanation.
I doubt the amplification is going to account for this.
What about the input impedance match to the P7 preamp.
The Outlaw has an input impedance of >10K whereas the A5 has an input impedance of 96K ohms. Could this be the source of the difference in sound quality?

Audioholics says this about the A5:

The amplification sections of the A 21 and A 51 were equally as impressive as the other portions of Parsound's design. All of the transistors are discrete as opposed to integrated circuits. The input stage uses matched pairs of JFETs and the driver stage uses matched pairs of MOSFETs which tends to give a less harsh and colored resulting sound. These two stages give the amplifier its sonic signature while the output stage gives the amplifier its high current capabilities. Parasound also implement bipolar transistors in the output stage since such a design typically results in very rugged high current capability.

Should the input stage be part of this shootout.
If this does matter, then you want a Preamp that has low output impedance to be a good test with all amps.

- Rich

 

[fmw]

I think this pretty well sums up the situation for many reviewers. They dare not conduct such tests, because many of their readers will imagine that the reviewers have flawed hearing rather than showing that the two things really are audibly indistinguishable. Most people have a far greater interest in their livelihood and their reputations than they have in the truth.

Of course, many people who write reviews are not capable of competently performing a proper double blind test anyway, so they obviously will never do such tests.

Well said, Pyrrho. Amplifiers without audible distortion will sound the same if they aren't clipping. There are amps with audible distortion and they do sound different but there aren't many. We conducted exhaustive bias controlled tests about a dozen years ago. One amp - a single ended triode - had a sound different from the others. Harmonic distortion was more than 6% and the the amp didn't respond very readily to frequencies above 10Khz. Most competently designed and made amps will sound the same despite what career oriented reviewers and placebo filled amateurs will say. Been there done that.

 

[Irvrobinson]

Either this is subjectivism or there is another explanation.
I doubt the amplification is going to account for this.
What about the input impedance match to the P7 preamp.
The Outlaw has an input impedance of >10K whereas the A5 has an input impedance of 96K ohms. Could this be the source of the difference in sound quality?

It is very unlikely that the input impedance of the amps caused the perceived difference in musicality. More likely their opinion is just complete crap - they are the same company that publishes Stereophile.

 

[3db]

I have compared a Sunfire 7400 to an Outlaw 7500 with my Revel Salons.
The Outlaw had more impact, better bass control, and instruments remained distinct.

I have found that both amps sounded much better plugged directly into my 20 amp circuit than they did plugged into the Furman Elite 14 PFI amplifier plug.
I returned that product

Generally, I think Home Theater Mag and Some outfit named Audioholics do amplifier reviews that I have some confidence in.
At least there are some measurements at HTM.

I looked for an Outlaw 7500, 7700, ATI2000, or ATI3000 review here but could not find one.
What's up with that?

Looking into 250 to 300 WPC amps, I was going to get an Outlaw 7900 but came across this review at Home Theater comparing the A5 and the 7900:



Either this is subjectivism or there is another explanation.
I doubt the amplification is going to account for this.
What about the input impedance match to the P7 preamp.
The Outlaw has an input impedance of >10K whereas the A5 has an input impedance of 96K ohms. Could this be the source of the difference in sound quality?

Audioholics says this about the A5:



Should the input stage be part of this shootout.
If this does matter, then you want a Preamp that has low output impedance to be a good test with all amps.

- Rich

Wow, more subjective opinions confused as fact.

 

[Steve81]

Wow, more subjective opinions confused as fact.

You do understand that these comments were asked for in the OP, right?

The question is, can and have you heard differences in audio amplifiers. Please share your experiences here.

 

[cpp]

I unplugged my pre-amp and speakers from both of my amps (tubes and SS) and turned on the power and listened, and wait for it, the results were, I could not hear anything so they do in fact sound the same

 

[RichB]

Wow, more subjective opinions confused as fact.

Is that a fact or an opinion?

In fact, what is the difference between an "opinion" and a "subject opinion"?

- Rich

 

[3db]

Is that a fact or an opinion?

In fact, what is the difference between an "opinion" and a "subject opinion"?

- Rich

A single blind listening test would go along way to add some credability to an opinion.

 

[mtrycrafts]

I have compared a Sunfire 7400 to an Outlaw 7500 with my Revel Salons.
...
- Rich

Maybe you could inform us how you conducted the comparisons?

 

[RichB]

A single blind listening test would go along way to add some credability to an opinion.

A bit of courtesy would help the credibility of yours.

I had another Oppo beta tester present.
I trust judgment as well.
BTW, selecting an Outlaw over a Sunfire is not the obvious opinion taken by those who are swayed by bright and shiny things.

I asked sensible questions about input impedance.
I prefer doing that than insisting that the reviewers are either corrupt, morons, or completely incapable of making dispassionate assessments.

I approach these problems as first experiencing a difference and then looking for the cause.
If you already know all of the answers, what is your purpose here?


- Rich

 

[RichB]

Maybe you could inform us how you conducted the comparisons?

This is a bit of a story.</SPAN>

Sunfire 7400 and Outlaw M2200</SPAN>
My brother in law (****) had a 2 channel system with some 3-way B&W’s, a Pioneer Elite SC-27, and an Oppo BDP-83. He is cost conscious, so I recommended upgrading to a BDP-15 and connecting it to a couple of Outlaw M2200 mono-blocks. </SPAN>

It was a huge improvement and I was very impressed with the sound. So I invited another Oppo Beta tester to my house (Geoff). **** brought his M2200 mono-blocks and Geoff brought some Focal bookshelf speakers (the model before they added the beryllium tweeters).</SPAN>
My system was Oppo-BDP 105 (all processing defeated) connected via the 7.1 outputs to the Marantz AV8801 (Pure Direct Mode, all video processing disabled) connected to the Sunfire via XLR.</SPAN>

We began listening to some CD of mine and then some that Geoff brought. He brought Lady GaGa as a bass test (not my thing). We had it cranked and the gain levels between the Sunfire 7400 were comparable. I switched over to the Mono-blocks using my XLR connections.</SPAN>

The difference was dramatic. The Sunfire was harsh where the M2200 were producing excellent bass a clearer presentation. I kept turning up the volume to try to get the point where they became harsh but it did not happened.</SPAN>

We listened for a while, and I asked Geoff: Which amp would you like to use with Focals. He selected the M2200. BTW, I was very impressed with the Focals.
</SPAN>As the result of that, I bought a used Outlaw 7500 (ATI2007 clone).</SPAN>


Outlaw 7500 and the Sunfire 7400
</SPAN>
When I first plugged in the Outlaw to replace the Sunfire, I found the sound was also a bit harsh and flat. This bothered me greatly. The next day, I also discovered transformer hum coming from the Outlaw and from the Panamax 5400 power conditioner that it was plugged into. This could be heard a few feet away. So I unplugged the Outlaw from the Panamax and plugged it directly into the wall.
</SPAN>
The sound opened up and the dynamics were much improved. I liked the sound but the hum was still present. Then, I plugged the Panamax into a different circuit. The Outlaw was not completely quiet.</SPAN>
So, I concluded not only does the Panamax suck because it current limits or otherwise pollutes the power going to the amp (via its dedicated amplifier output), but it also pollutes the power of anything plugged into the same circuit.
</SPAN>
At this point, my Sunfire was up for sale, but I wondered if I just bought a new amp because the Panamax is a POS. I was alone and did a quick check of the swapping the XLR outs from the preamp between the Sunfire. This was a more difficult comparison because Outlaw has 6DB more gain.
I played “Sinner Man” from The Thomas Crown Affair sound track. At the end of the song the symbols crash, and I could not quite get the same sound from the Sunfire.
</SPAN>
I also played some other music at 100 DB that I am very familiar with and I felt the Sunfire was not a clear at those levels. Since I was felt the Outlaw was a better amp, I am happy with how it all turned out.</SPAN>

- Rich</SPAN>

 

[3db]

A bit of courtesy would help the credibility of yours.

I had another Oppo beta tester present.
I trust judgment as well.
BTW, selecting an Outlaw over a Sunfire is not the obvious opinion taken by those who are swayed by bright and shiny things.

I asked sensible questions about input impedance.
I prefer doing that than insisting that the reviewers are either corrupt, morons, or completely incapable of making dispassionate assessments.

I approach these problems as first experiencing a difference and then looking for the cause.
If you already know all of the answers, what is your purpose here?


- Rich

I've been tainted from reading far too many "professional" reviews, especially cable/interconnect reviews where the cables cost more than a new car and the reviewers have stated that the cables clear up "PRAT" and make the music more danceable... As an Electrical Engineer, I'm very suspect of these reviews. I admit to taking your opinion out of context and I do apologize for that part. It could very well be that your Revels stress the amps out enough to hear differences. Then again, I would like to see your testing methods. Were levels matched etc... But as a whole, unless the tests are blind listening tests, I have problems with sighted reviews because one cannot isolate the sense of hearing with the other senses. They all have influence on what is perceived to what sounds better.

 

[RichB]

I've been tainted from reading far too many "professional" reviews, especially cable/interconnect reviews where the cables cost more than a new car and the reviewers have stated that the cables clear up "PRAT" and make the music more danceable... As an Electrical Engineer, I'm very suspect of these reviews. I admit to taking your opinion out of context and I do apologize for that part. It could very well be that your Revels stress the amps out enough to hear differences. Then again, I would like to see your testing methods. Were levels matched etc... But as a whole, unless the tests are blind listening tests, I have problems with sighted reviews because one cannot isolate the sense of hearing with the other senses. They all have influence on what is perceived to what sounds better.

No problem.
I am 100% agreement with you.

You can read what I did above.
I never intended to test anything really. Just having fun with this hobby that I enjoy. When I heard something that I did not expect, that is when it got interesting.

Much of the difference turned out to be the god awful power conditioner polluting the world. I even tried a newer Furman Elite 15 PFI and that was just as bad. I have concluded that, at least with the two amps that I have tried, plug them directly into the 20 amp circuit and all is well.
At volume, I felt that the Outlaw was clearer and a bit better.
Perhaps faster. That might be a difference between Class-H and A/B.

In the end, I upgraded or cross-graded and I am pleased.
I am in the hunt for either an ATI3005 for a bit more power.
I like the sound of Outlaw so the ATI is either the same or better.

- Rich

 

[English210]

I just replaced a 150wpc Yamaha (I thought is was 125, but looked it up, and it's 150), with an Odyssey 150wpc. MAJOR difference. I've had my speakers for 25 years, and used some test material I'm very familiar with, and heard bass out of my speakers that I've never heard from them before, and it was more musical. I did have an expectation of hearing an improvement, hoping it would be a little less harsh at high volumes, tone done the highs some. There was some of that, it is better, but the major difference is in the bass. I couldn't turn the volume up as high as I used to try to get with the old amp. Not a scientific conclusion, no, and I may get dismissed for not doing a double blind, etc, etc, but say what you will, there is a difference that is far more noticeable than I hoped, and in a different frequency range.

 

[mtrycrafts]

Maybe you could inform us how you conducted the comparisons?

I guess now one has to be careful what question is asked as you might receive some bad rep points.

 

[mtrycrafts]

Thanks for your reply. But I didn't see any real controls applied for the comparison. Oh, I think I have heard of Geoff.

 

[RichB]

Thanks for your reply. But I didn't see any real controls applied for the comparison. Oh, I think I have heard of Geoff.

Well, the thread is "Can you hear a difference in Sound between Audio Amplifiers?".

Are experiences under certain conditions unsuitable for this thread?

- Rich

 

[M Code]

Very strange...
Users commenting about How amplifiers sound different, yet there has been no mention about having the listener's hearing tested before doing the actual comparison...
Below is an interesting quote from Sean Olive, who is President-Elect at the Audio Engineering Society and Director, Acoustic Research, Harman International...

"We have a calibrated audiometer and we test and screen all of our listening panel members to make sure they have no significant (> 20 HL) hearing loss. We do this because Floyd Toole showed data that listeners with hearing loss give less reliable ratings.... Sadly many of these listeners were sound engineers. Hearing loss is an occupation hazard in the audio industry so many of the listeners who should be qualified to judge sound actually are not"...

Both Dr.Floyd Toole and Dr.Sean Olive are well respected experts in evaluating the sonic differences in loudspeakers and electronics. And have written many AES presentations for Blind Listening Tests..


Just my $0.02..

 

[RichB]

I am new here but I am having are hard time understanding the culture.
This is a thread begins with a poll.

You spend some effort explaining your experiences and folks want to know if you can prove that you are blind but not deaf.

Interesting

- Rich

 

[cpp]

I've been tainted from reading far too many "professional" reviews, especially cable/interconnect reviews where the cables cost more than a new car and the reviewers have stated that the cables clear up "PRAT" and make the music more danceable... As an Electrical Engineer, I'm very suspect of these reviews. I admit to taking your opinion out of context and I do apologize for that part. It could very well be that your Revels stress the amps out enough to hear differences. Then again, I would like to see your testing methods. Were levels matched etc... But as a whole, unless the tests are blind listening tests, I have problems with sighted reviews because one cannot isolate the sense of hearing with the other senses. They all have influence on what is perceived to what sounds better.

So true, I think it has to do with marketing with reviewers assisting the advertising market with "positives' vs NO negative reviews on cables and what gets me is when a person spends $1000.00 of dollars plus on speaker cable and interconnects when their system including speakers doesn't exceed $500.00 thinking there is a miracle in them there cables.