Can you hear a difference in Sound between Audio Amplifiers?

[cpp]

My new ATI 3005 hasn't even arrived but I have it on good authority that it will be dark chocolaty.
It cannot possibly have air, not with its price tag.
Heft, it has

- Rich

Rich, remember bend your knees , bend your knees it should weigh all of the 126 lbs.... enjoy the amp, I like mine

 

[fmw]

What about "smoother" or "sweeter" or more "chocolaty".

Well, maybe chocolaty is OK. At least that is food.

 

[AcuDefTechGuy]

My new ATI 3005 hasn't even arrived but I have it on good authority that it will be dark chocolaty.
It cannot possibly have air, not with its price tag.
Heft, it has

- Rich

And all four of my ATI amps will be mint dark chocolaty with HANDLES.

 

[fmw]

Rich, remember bend your knees , bend your knees it should weigh all of the 126 lbs.... enjoy the amp, I like mine

Agreed. That looks like brute!

 

[AcuDefTechGuy]

Rich, remember bend your knees , bend your knees it should weigh all of the 126 lbs.... enjoy the amp, I like mine

I hope he took weight training class like I did back when I was in high school.

Hurting your back could be seriously irreversible.

 

[PENG]

I do think amps sound different, and to some extent that is a mystery to me.

I have just swapped out the A/B amps in our town home for current dumpers I have just made ready (Quad 405 IIs). The sound is definitely a little smoother and more relaxed. To me the current dumping amps produce the least fatiguing sound of any designs I know of.

I do buy in to this kind of reports, because of the words "think, mystery, a little and more.." It makes it more probably, and may be credible especially coming from you who do occasionally make highly assertive and almost seemingly intended to be authoritative (no pun intended).

Now I feel better knowing that even a critic/connoisseur like you feel that is a mystery to some extent. One time, armed with my favorite CDs that I was very familiar with, I went to audition the B&W802D. The rep used a Musical Fidelity with only 150 to 200 WPC I guess, as I don't remember exactly. They sounded really good in that 16X25 ft room especially the violin solo part. He then said, just wait, you haven't heard nothing yet, and brought out a 85 lbs Bryston 14B SST (900WX2 4 ohms), hook it up and told us to be prepared for that night and day difference. Well, we (wasn't alone at the time) heard absolutely no difference that we could be sure of, both sounded great, but obviously the sales rep did. Mind you it was a sighted test, volume match by ears only, and time in between the swap had to be more than 5 minutes.

 

[PENG]

I hope he took weight training class like I did back when I was in high school.

Hurting your back could be seriously irreversible.

That's one big reason why I would not consider multichannel power amps for HT and stick with my toy like MM8003 for the surrounds. 140WPC provides all the headroom I need for my surrounds.

 

[AcuDefTechGuy]

That's one big reason why I would not consider multichannel power amps for HT and stick with my toy like MM8003 for the surrounds. 140WPC provides all the headroom I need for my surrounds.

Surrounds definitely don't need more than that.

 

[ski2xblack]

TLS uses Quad current dumping amps, which have class A output characteristics. The difference between class A and class A/B is very subtle, perhaps imperceptible under some (many?) conditions, but it is real, not illusory. Even the literature from Harmon, which seems to be the gold standard for primary sources around here, makes that claim. Curiously, I don't see folks throwing Harmon under the bus, but the good Doc, who has probably forgotten more than many of us will ever know about audio reproduction, gets ridiculed?

Perhaps the thread has run it's course.

 

[RichB]

Rich, remember bend your knees , bend your knees it should weigh all of the 126 lbs.... enjoy the amp, I like mine

Will do. It is actually easy to lift it into my rack with two people.
The trick is getting out of the box. A third person helps with that.

And all four of my ATI amps will be mint dark chocolaty with HANDLES.

Damn it, I wanted dark chocolate or milk, definitely not mint !

I hope he took weight training class like I did back when I was in high school.

Hurting your back could be seriously irreversible.

I found that out the hard way when I fell on a sailboat.
One hand had a rope the other had a drink. I blamed the rope

- Rich

 

[PENG]

TLS uses Quad current dumping amps, which have class A output characteristics. The difference between class A and class A/B is very subtle, perhaps imperceptible under some (many?) conditions, but it is real, not illusory. Even the literature from Harmon, which seems to be the gold standard for primary sources around here, makes that claim. Curiously, I don't see folks throwing Harmon under the bus, but the good Doc, who has probably forgotten more than many of us will ever know about audio reproduction, gets ridiculed?

Perhaps the thread has run it's course.

I believe that there is a subtle but audible difference between class A and class A/B under some conditions and I believe TSLGuy did hear that difference. I meant that in my post.

 

[RichB]

I just want and re-read the Audioholics article "The Sound of Audio Amplifiers: Can you hear a difference between Amps".
It is great. The biggest take away for me comparing good amsp operating within there limits was the impedance statements by Julian Hirsch.

I had to throw my shirt away after the torching I took from postulating that might be a reason for the differences that some HTM reviewer found between the Parasound A5 and Outlaw 7900 (ATI 3000 clone).

Here is the quote from Julian Hirsch concerning his measurements:

Some pre-amp/power amplifier/speaker systems combined in such a way as to produce a very slightly rising or drooping frequency response across the entire 20-20 kHz audible spectrum. It could be a combination of the way the pre-amp and power amp combined on an input/output impedance basis, it could be because of the way a particular amp behaved with the specific load presented by that specific make/model of speaker, but there were system combinations where the frequency response showed a variation across the band.

For what it is worth, I found the specs on these amps to be comparable:

Output Devices per channel: A5:8, ATI3000: 12
Power Supply per channel: A5:440va, ATI3000: 450va (gestimate)
Capacitance per channel: A5:32,800 uv, ATI3000: 36,000 uv

Both amps have very high slew and damping factors.

If these amps were to sound slightly different, then I think I will go with Julian on this one.
I wonder if .5 DB on the upper end is in fact "air".

- Rich

 

[twylight]

I certainly cant tell...but I sure can tell the difference between bare wall, absorption, or diffusion at first reflection.

 

[Steve81]

The difference between class A and class A/B is very subtle, perhaps imperceptible under some (many?) conditions, but it is real, not illusory.

One take from Rod Elliott: Class-A Amplifiers explained

In the light of this, it is a wonder that any Class-AB (conventional) power amplifiers sound any good at all. Historically, it is exactly the problems I have highlighted here which created the term "transistor sound" (used in a derogatory sense of course) when transistor or "solid state" amplifiers first appeared. Despite anything you may read, these problems are caused by the physical and electrical characteristics of transistors, and have never gone away. New devices are far more linear than those of the 60s and 70s, but they are not perfect. Operation at higher quiescent currents (i.e. more into the Class-AB region) will reduce the non-linearity at crossover, but it can never be eliminated altogether - at least not with any devices currently available.

It is fair to say that although the problem cannot be eliminated, the effects can be reduced to such an extent that many amplifiers have almost unmeasurably small levels of crossover distortion. It is not at all uncommon that to be able to see the distortion residual (after the fundamental has been removed with a distortion analyser), it is necessary to use a digital oscilloscope that can apply averaging. The distortion is buried below the amplifier noise floor, and is not visible without the averaging feature. In tests I have performed, listening to the residual noise + distortion reveals that the distortion component (in isolation) is barely audible over the system noise - itself normally below audibility with typical loudspeakers.

So, it is entirely possible to design an amplifier whose distortion at any level below clipping is virtually unmeasurable. Marginally higher levels are commonplace, and it is thought by many that the typical distortion level in most well designed power amplifiers is inaudible under most listening conditions. There are (of course) others who deny this - either because they have done proper comparisons under controlled conditions, because they have hearing that is far more acute than most of us, or because they have been told that they must be able to hear the difference - if they can't, they must have 'tin ears'. Nothing like a bit of peer group pressure to influence one's perceptions.

Perhaps the thread has run it's course.

I'm personally waiting for the good Doc's reply

 

[ski2xblack]

I agree with what Elliot wrote, he's on the money. But he's talking about overcoming crossover distortion in A/B amps. The Quads are a different animal, with no crossover distortion to begin with, nor the circuit complications used to combat it. The Quad's self-correcting, feed-forward current-dumping circuit is certainly quite different than garden variety A/B amp.

I think I may need to partake in a controlled ABX test comparing Gene's Pass Labs, TLS' favored Quads, and a plain jane A/B amp, as I may be completely misguided. Throw a Crown XLS DriveCore 1500 in the test for good measure.

 

[Irvrobinson]

I agree with what Elliot wrote, he's on the money. But he's talking about overcoming crossover distortion in A/B amps. The Quads are a different animal, with no crossover distortion to begin with, nor the circuit complications used to combat it. The Quad's self-correcting, feed-forward current-dumping circuit is certainly quite different than garden variety A/B amp.

I think I may need to partake in a controlled ABX test comparing Gene's Pass Labs, TLS' favored Quads, and a plain jane A/B amp, as I may be completely misguided. Throw a Crown XLS DriveCore 1500 in the test for good measure.

For those with a technical bent, here's a link to an article from 1975, where Peter Walker himself explains the current dumping topology: http://www.meridian-audio.info/public/pjw_ww_dec75[3370].pdf

 

[jinjuku]

Don't forget Crowns Class I. 3000 watts and no cross over distortion. I haven't seen the like out of any audiophile boutique company.

 

[RichB]

Don't forget Crowns Class I. 3000 watts and no cross over distortion. I haven't seen the like out of any audiophile boutique company.

These are interesting.
If they had a 5 channel version in a better looking case, I would have looked seriously at them.

- Rich

 

[jinjuku]

These are interesting.
If they had a 5 channel version in a better looking case, I would have looked seriously at them.

- Rich

I don't think you would look to spend what the I-Tech HD's cost. Five channels would set you back $13-20K

 

[RichB]

I don't think you would look to spend what the I-Tech HD's cost. Five channels would set you back $13-20K

Got that right

- Rich