Do all amplifiers sound the same thread

[gtpsuper24]

I do like properly conducted DBT in audio. I know it's not as rigorous and meaningful as drug testing on patients. But it does remove human bias. I think it is unfair comparing amps when people know exactly which amp costs $300 (like Pioneer AVR) and which amps cost $20,000 (like Boulder monoblocks).

I don't think it has to be double-blinded; but a single-blinded test using that amp switcher would be cool. IOW, the person physically doing the switching knows which amp is which, but the person doing the listening/ comparing does not.

I don't think we should tell everyone, "Okay, this is the Pass Lab........this is the Emotiva........"

I think it should be, "This is amp#1.......this is amp#2......."

This is kind of what I proposed in the $2500 system thread. But I got the impression that it ruffled a few feathers and wasn't worthwhile.

Pursuing the Truth in Audio & Video, I would think trying to discover if a $50,000 mono block sounds better or not than the typical receiver or lower end $1000 monoblocks, would fall in that discussion. It seems like a touchy subject, it would just be benefical for those people researching whether or not to go separates or a beefy receiver. Like Onkyo TX-NR818 ($1000) vs Emotiva XMC-1/XPA 5 ($2300) as examples.


No big deal, I guess. I just thought it would be interesting to read about the panels thoughs on cheap receivers, cheap stereo amps vs the premium brands.

 

[jinjuku]

Assuming a perfectly resistive speaker load, low noise, low output impedance and the amplifier can maintain sufficient output voltage without power supply lag, then its very conceivable the sonic differences between two amps will be indistinguishable. Lots and LOTS of caveats for this to be the case.

All one needs is an amp that can fill in all those pot holes w/o breaking a sweat. I personally believe there are a bunch out there. I could pick 8 or 9 or 10 that I would put money on that would drive the Titus 8T's or some Quads or other ESL no problem.

All under $1000 thrown into the bargain.

 

[jinjuku]

Like Onkyo TX-NR818 ($1000) vs Emotiva XMC-1/XPA 5 ($2300) as examples.


No big deal, I guess. I just thought it would be interesting to read about the panels thoughs on cheap receivers, cheap stereo amps vs the premium brands.

With you on the receiver: 17X23X10 room and my Denon 4308ci does a great job. I was able to sell my Adcom 5503 for $50 more than I paid.

GT, where are you at in Ohio?

 

[gtpsuper24]

With you on the receiver: 17X23X10 room and my Denon 4308ci does a great job. I was able to sell my Adcom 5503 for $50 more than I paid.

GT, where are you at in Ohio?

Yep if a receiver like the Denon or another quality receiver can power speakers to reference levels or close to reference I don't see what the point of adding a separate amp would be. Like you getting rid of the Adcom. I'm just trying to understand where some come from that believe that amps add finer details, tighter bass, broader/wider soundstage ect... I

If you need more output than I agree that a more powerful amp is need. But if someone is looking to improve the finer details, tighter bass, or a better soundstage, than IMO one needs to look at room acoustics, setup, ect.. Not monoblocks or 1000watt amplifers.



I'm about and hour north of Columbus and maybe two hours south of Toledo.

 

[KEW]

No need for a Blind test as you can't determine which amp is playing like you could with speakers seeing the cones moving. It would be fun to instantly switch between amps.

I think the point of contention over blind testing is a simple matter of semantics.

In the literal sense blind means without sight.

However, when doing research involving people, a blind test is one where the subject has no way to know which condition they are experiencing. By this definition and with Gene's statement above, this would be a blind test.

A DBT (double blind test) requires that the person administering the test also be "blind" to which condition is which. This is the standard for good testing of subjective perceptions. It has been established that a blind test and a double blind test often have different results; while DBT's are repeatable. If the person who administers the test knows which condition is which he will unintentionally give off subtle cues which are subconsciously picked up by the subjects in the test.

In the case of testing one amp against another, there is no reason for the test administrator to be in the room with the subject (assuming the subject can be trusted to not investigate the wiring), so it would be easier to do an "Indirect DBT". I would propose the test administrator wire up an A/B switch and leave the room. The subject then would enter the room and establish which amp, A or B, was preferred and write it on a pad. The subject would then leave the room before the administrator saw the result. Some type if bell or simply a single knock on the wall could communicate when one party had completed their task. Repeat this 10 times. If the score was then 10 to 0 for one amp vs the other, it is done. Anything else, repeat the ten trials a second time.

Understand that I am no expert at this type of testing. There is probably a better protocol. I wanted to get specific to make the concepts clear and to throw out a discussion document for refinement (if that is a place this thread wants to go).

In case someone doesn't fully understand the need for the double blind test, simply consider that if the test administrator receives the info from the third trial and it is consistent with the result from the first two (a score of 3 to 0). He might (without awareness) raise an eyebrow or betray some subtle hint of congratulation or respect to the subject.

The next question is what does a 9 out of 10 score mean? 8 out of 10?
I don't think either would be conclusive, but repeating the entire test and scoring 9 out of 10 for the same amp as the first round would make for a significant result.

 

[Swerd]

On the question of double blind vs. single blind test… Although it is true that a tester who is not blinded may unintentionally reveal subtle clues, an honest tester can easily avoid this.

In clinical trials, the real value of double blind studies comes when patients are treated over several weeks or months and may interact with more than one doctor or nurse during their repeated visits. Although medical staff may mean well, expecting them to reveal nothing over a long period of time, and expecting that all such medical staff will operate the same way is asking too much. In such cases, a placebo-controlled double blind study is a more reliable way to avoid expectation bias than depending on honest good intentions. Of course, when a clinical trial is done at a number of different locations, all this takes on greater importance.

In a test of listener perceptions of speakers or amps that takes place on a single day, I don't see any advantage that a double blind test has over a single blind test, as long as the tester(s) is being honest.

 

[Swerd]

An electrical engineer, named Bob Cordell, who has actually designed amplifiers in the past, and who has a continued interest in audio was once interviewed.

Pjay's Interview of amp designer Bob Cordell

His words are the best information I know of to address the question of do amps have a sound?

 

[Swerd]

Salk had a very cool switcher at our GTG event that allowed you to instantaneously switch out amps and speakers all level matched via remote. I need to get me one of those. No need for a Blind test as you can't determine which amp is playing like you could with speakers seeing the cones moving. It would be fun to instantly switch between amps.

I want to be able to test sonic differences between say an Emotiva XPR-2 and a Pass Labs X350.5.

This switcher is made by Audio by Van Alstine avahifi. It isn't listed as an available product on the website, but there are at least a few of those in existence. I have no idea what it might cost. I saw one on loan that Dennis Murphy used last July at the Capital Audio Fest, and it seemed very cool.

 

[jinjuku]

An electrical engineer, named Bob Cordell, who has actually designed amplifiers in the past, and who has a continued interest in audio was once interviewed.

Pjay's Interview of amp designer Bob Cordell

His words are the best information I know of to address the question of do amps have a sound?

He has one quote that I can not agree with however:

However, it seems unlikely that one will ever make a Class-D amplifier that can sonically outperform the best-designed Class A-B amps. The newer, less expensive and more compact amplifier technologies may also help foster the migration of the power amplifiers into the cabinets of active loudspeakers.

 

[Swerd]

He has one quote that I can not agree with however:

However, it seems unlikely that one will ever make a Class-D amplifier that can sonically outperform the best-designed Class A-B amps. The newer, less expensive and more compact amplifier technologies may also help foster the migration of the power amplifiers into the cabinets of active loudspeakers.

I think that interview dates back to 2005, seven years ago, and I'm not sure what class D amps were available then. Perhaps the only thing new with audio amplifiers in recent times is the progress with class D amps.

 

[agarwalro]

Way back when I had an Axiom setup, M60, VP150, QS8, being driven by a Denon 3806, I decided to play around with a dedicated amp. I picked up a Parasound HCA 2205A on Craigslist. I ran all 5 speakers through the Parasound for some time and later biamped the M60s through it, letting the Denon handle the center and surround duty. Later still I ran the M60's full range, biamped through the Parasound in a 2.0 setup vs letting the Denon drive them.

For the life of me I could not tell the difference, and if I could, there was no assurance that it was not psycho-acoustic. I guess the Denon amp section was sufficiently robust for the Axioms.

 

[jinjuku]

I think that interview dates back to 2005, seven years ago, and I'm not sure what class D amps were available then. Perhaps the only thing new with audio amplifiers in recent times is the progress with class D amps.

And that is the reason I couldn't square his statement. He said 'Ever Make'. There is a lot of talent out there. The Crown video I posted they even talk about their current class D's doing stuff better then analog amplifiers on the market. That's 3:57 into the video. That's one bold statement to make and I'm sure the engineering team doesn't make that claim lightly.

 

[Steve81]

For the life of me I could not tell the difference, and if I could, there was no assurance that it was not psycho-acoustic. I guess the Denon amp section was sufficiently robust for the Axioms.

Or we could go with the "audiophile" explanation that your ears are made of tin or that your Axioms simply aren't resolving enough

 

[ACsGreens]

I find this very interesting and since I first read these discussions on here I have been trying to distinguish differences myself. I have not heard a huge variety of amplifiers, but have heard many residential and commercial, of many price points. A few weeks ago I was listening to some Salk speakers driven by a B.M.C S1 amp, needless to say the sound was amazing. From what my very, very amateur ears hear, minus the bmc, there is no real difference in sound quality or characteristic. I wish I had the technical background to give more to the discussion but that is not the case. I do, however, know that I hate digital amplifiers. Thanks for the great discussion!

 

[agarwalro]

Or we could go with the "audiophile" explanation that your ears are made of tin or that your Axioms simply aren't resolving enough

LOL!

It would be easy to bash the Axioms, but honestly, my 'room' has never been good enough to eliminate it as the cause. That's why I decided to downscale to a smaller but more accurate nearfield setup .

 

[Swerd]

I find this very interesting and since I first read these discussions on here I have been trying to distinguish differences myself. I have not heard a huge variety of amplifiers, but have heard many residential and commercial, of many price points. A few weeks ago I was listening to some Salk speakers driven by a B.M.C S1 amp, needless to say the sound was amazing. From what my very, very amateur ears hear, minus the bmc, there is no real difference in sound quality or characteristic. I wish I had the technical background to give more to the discussion but that is not the case. I do, however, know that I hate digital amplifiers. Thanks for the great discussion!

Which Salk speakers did you hear?

Several of the Salk speakers (Songtower, HT2-TL, and similar towers) are easy to drive with amps of 80-100 wpc, but they will sound excellent with a big powerful amp such as that BMC S1.

The HT3, however, is a difficult speaker to drive, and requires a large potent amp at least as big as that BMC S1, and probably bigger.

 

[BoredSysAdmin]

And that is the reason I couldn't square his statement. He said 'Ever Make'. There is a lot of talent out there. The Crown video I posted they even talk about their current class D's doing stuff better then analog amplifiers on the market. That's 3:57 into the video. That's one bold statement to make and I'm sure the engineering team doesn't make that claim lightly.

could you post the link again. can't find it now

 

[Irvrobinson]

I ran an experiment last week. I just got an ATI AT602, their bottom-of-the-line 60w/90w/ch (8/4 ohm rating) stereo amp for use in my simple video system. For grins, before I installed the AT602 in the cabinet I swapped out my ATI AT3005 (being used in 3002 mode) from my he-man audio system (Salon 2 speakers) and used some XLR-to-RCA adapters to insert the AT602 into the signal path. The AT602 does not have balanced inputs. I wanted to see if I could hear differences, and to be perfectly honest, I figured I would. You know, I'm such a world-renown golden ear and all.

The AT3005 uses fully differential circuitry from input to output, and 24 bipolar output transistors per channel, and has well over 450w/ch into the 4 ohm load of the Salon 2s. Also, an AT3005 used in stereo mode puts a dedicated transformer on each channel, while a normal AT3002 would get only one transformer shared between the channels, so the AT3005 would have an advantage, perhaps. While not quite a Krell or a Pass Labs, it's a pretty good amp. I use a dedicated 20 amp mains circuit wired with 12/3 for the amplifier.

I don't have a facility to switch back and forth between the amps quickly, and this isn't a DBT. I was just curious if I could hear any differences.

I used various CDs I normally use for speaker testing, that I know are quite revealing of subtle differences between speakers. One CD I bought recently that sounds different on different speakers is this Peter Erskine CD. He does a lot of of brushwork on the snare and the cymbals that is surprisingly revealing of differences between speakers, but I couldn't hear any differences between the amps. None. Damn.

I tried several CDs featuring violins and chamber orchestras played at realistic volumes, and, still, I couldn't hear any differences. Strings tend to highlight distortion and congestion. I was surprised that the AT602 sounded identical to me in this case. I expected to hear some congestion with the smaller amp. I was listening at some substantial volume levels. Hmmm.

I have two favorite CDs for testing a speaker's ability to reproduce complex arrangements, namely this Spyro Gyra CD and this Papa Doo Run Run Beach Boys tribute CD. I posted some time back that I was able to get the AT3005 to clip on the Papa Doo Run Run CD.

On these CDs the differences were easy to discern, and I have no doubt I could pass a DBT. Played at volumes driving measured 102db peaks at my listening position the AT3005 blew the AT602 away in clarity, detail at high volumes, lack of congestion, and what some people call "jump factor". Yeah, I'm confident the entire difference can be explained by the AT3005 having at least 8db more potential output than the AT602. For all of the balanced end-to-end topology advantages of the AT3005, I have to concede that within the power envelops of the two amps there's no way I could pick out differences between them. I would guess the actual noise and distortion level of the AT602 would be 3-6db worse than the AT3005, but apparently my ears have gotten too old to detect it. Maybe when I was 25.

Now, these are two Class AB amps from the same company, so this isn't a Class D versus Class A comparison, which would be more interesting. After Gene's test of the Pass Labs X350 I would like to hear one in my system, to see if I could hear a difference, because it has the cleanest 1w FFT I've ever seen, and perhaps compare it to one of the Crown amps ADTG raves about. With the ATI amps within their performance envelops, however, I have to admit defeat. I wouldn't even consider a DBT bet on them.

 

[mtrycrafts]

If my cousin thinks his $50,000 tube amp sounds better with his Focal Grande Utopia III than some Emotiva or Crown amps, I'm not going to argue with him no matter what I think because it is not worth it.

And if someone thinks his Emotiva or Crown amps sound just as good as Pass Lab, Mark Levinson, Krell, etc, there's no harm in that as well.

You are right. At times an individual reality is king.
I guess we all choose when truth matters.

 

[mtrycrafts]

+1 .... That's how I would run it. The level match Salk device would make it so much easier.

Yes, certainly would make level matching simple but switching alone is not enough as detecting differences involves achieving statistically significant data. Guessing a few coin flips correctly does not make one able to predict outcomes in a significant manner, if you know what I mean.