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Topic: new breakthroughs in audio gear DBT? (Read 5961 times) previous topic - next topic
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new breakthroughs in audio gear DBT?

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I'm not talking about the esoteric stuff that make wild claims but there is both a measurable and audible difference between a run of the mill low end AV receiver vs a state of the art Separates combo or even a flagship receiver that has better DAC's and a more robust amp section.


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You've demonstrated this how? Level-matched randomize double-blind testing with neither amp clipping?


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Yes actually I have. I've done level matched blind listening tests for trained and untrained listeners to test the audible differences between an amp with a high vs low output impedance. Both amps were not driven to clipping. The amp with the high output impedance had surprisingly more but boomier bass than the amp with the lower output impedance. Everyone preferred the latter. I've done similar between 2 different CD players (one that was a low price DVD player vs a high end dedicated CD player). Even in controlled listening tests, there are provable differences in audio gear with receivers being more obvious b/c there is more opportunity for differences (amps, DAC, power supply, etc) followed by dedicated power amps and then DACs. DACs are getting so good these days that the differences are getting harder to detect however. That said if you do a blind comparison of say an Oppo BDP-103 vs a BDP-105 analog outputs, there is a subtle improvement in the BDP-105 but it becomes a complete wash if your using the HDMI outs of both players since the AV receiver/processor now becomes the DAC.



http://www.avsforum.com/forum/91-audio-the...ml#post39226850

new breakthroughs in audio gear DBT?

Reply #1 –
What were the analog outs of the Oppo 103 and 105 playing? CDs? There's no means to synchronize the playback to the millisecond (nor level match to the tenth of a dB without introducing external gear in the path).

new breakthroughs in audio gear DBT?

Reply #2 –
Quote from: krabapple on
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I'm not talking about the esoteric stuff that make wild claims but there is both a measurable and audible difference between a run of the mill low end AV receiver vs a state of the art Separates combo or even a flagship receiver that has better DAC's and a more robust amp section.



There ain't that much difference in the distortion in the amp sections of most high end AVRs and low end AVRs if you are willing to back off on the power levels, particularly of the low end AVR.  Some lower end AVRs have shown generally lower levels of measured distortion than higher end AVRs from the same manufacturer.

Since clipping of the DACs or associated circuitry in an AVR is unlikely asite from serious design flaws, the most like remaining difference would be background hiss, which is almost always swamped out by the background noise in the media during recorded passages. So, if DellaSalla is actually hearing differences, he's auditioning gear with the media stopped or between tracks.

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You've demonstrated this how? Level-matched randomize double-blind testing with neither amp clipping?


Quote
Yes actually I have. I've done level matched blind listening tests for trained and untrained listeners to test the audible differences between an amp with a high vs low output impedance. Both amps were not driven to clipping. The amp with the high output impedance had surprisingly more but boomier bass than the amp with the lower output impedance. Everyone preferred the latter. I've done similar between 2 different CD players (one that was a low price DVD player vs a high end dedicated CD player). Even in controlled listening tests, there are provable differences in audio gear with receivers being more obvious b/c there is more opportunity for differences (amps, DAC, power supply, etc) followed by dedicated power amps and then DACs. DACs are getting so good these days that the differences are getting harder to detect however. That said if you do a blind comparison of say an Oppo BDP-103 vs a BDP-105 analog outputs, there is a subtle improvement in the BDP-105 but it becomes a complete wash if your using the HDMI outs of both players since the AV receiver/processor now becomes the DAC.


The  official denunciations of DBTs that I've read in DelllaSalla's web site suggest to me that when DellaSalla says blind, at the very best he means SBT which is to say for the tests he's running, by usual professional standards, invalid.

new breakthroughs in audio gear DBT?

Reply #3 –
Quote from: mzil on
What were the analog outs of the Oppo 103 and 105 playing? CDs? There's no means to synchronize the playback to the millisecond (nor level match to the tenth of a dB without introducing external gear in the path).


Level matchiing is not problematical if you can engineer and build the appropriate gear, which is pretty simple.

Back in the day we solved the synchronization problem by injecting an external clock into one of the digital players.

So, your comment about external gear is confirmed, but its nothing that DellaSalla shouldn't be able to muster should he feel the need.

new breakthroughs in audio gear DBT?

Reply #5 –
Quote from: krabapple on
For the amps it could be a case of this:

"The Amp/Speaker Interface: Are Your Loudspeakers Turning Your Amplifier into a Tone Control?" E. Brad Meyer, Stereo Review, June 1991, page 54


http://www.avsforum.com/forum/91-audio-the...ml#post39239122


Amplifiers that speakers turn into tone controls (i.e. amplifiers that have frequency curves that strongly depend on loudspeaker impedance curves) have high source impedances. This is relatively common with tubed power amps, and relatively rare with SS amps. One good reference would be Stereophile amplifier tests which generally present this information.  I've never seen any evidence that AVR power amps have this problem, at either end of the price spectrum.

If I read much DellaScalla, I get this impression of a dyed-in-the-wool sighted evaluator. For reviewers sighted evaluations are a sort of security blanket because it puts them, not science, in control of the review.

While DBTs are very challenging to implement when applied to speakers and rooms, not so with amplifiers and DACs. Now that we have the  ready ability to compare highly accurate recordings of amplifier outputs while they are driving real-world speaker loads, DBTs of amps can be distributed to general users by anybody who really wants to, and with the ready availability of software ABX tools such as the current Foobar2000 ABX plug in, the tests can be run by anybody who has access to a computer with a decent audio monitoring subsystem.

new breakthroughs in audio gear DBT?

Reply #6 –
Quote from: Arnold B. Krueger on
Quote from: mzil on
What were the analog outs of the Oppo 103 and 105 playing? CDs? There's no means to synchronize the playback to the millisecond (nor level match to the tenth of a dB without introducing external gear in the path).
  Level matchiing is not problematical if you can engineer and build the appropriate gear, which is pretty simple.  Back in the day we solved the synchronization problem by injecting an external clock into one of the digital players.  So, your comment about external gear is confirmed, but its nothing that DellaSalla shouldn't be able to muster should he feel the need.


I'll make you a gentlemen's bet he injected no such external clock into one of the CD players to achieve synchronization.

I also strongly suspect he didn't introduce level matching to the tenth of a dB either, however that's not part of my proposed bet, only disc synchronization is. Note, I don't plan on contacting him so we may never find the answer, however it might be considered as a friendly, long term wager and perhaps some day he will tip his hat in some post and divulge his exact methodology, at which point one of us will win. Will you take the bet?

new breakthroughs in audio gear DBT?

Reply #7 –
Quote from: Arnold B. Krueger on
Quote from: krabapple on
For the amps it could be a case of this:  "The Amp/Speaker Interface: Are Your Loudspeakers Turning Your Amplifier into a Tone Control?" E. Brad Meyer, Stereo Review, June 1991, page 54  http://www.avsforum.com/forum/91-audio-the...ml#post39239122
...I've never seen any evidence that AVR power amps have this problem, at either end of the price spectrum.


A few recent AVRs, including H/K and Pioneer, have switched to Class D amps and traditionally these are more prone to showing frequency response anomalies (possibly, but not always), arguably audible deviations, into certain loads.

Think of that class D NAD power amp the scaremongers like to trot out, for example. [I'm thinking most here know what I'm talking about. References available upon request.]

new breakthroughs in audio gear DBT?

Reply #8 –
Quote from: mzil on
Quote from: Arnold B. Krueger on
Quote from: krabapple on
For the amps it could be a case of this:  "The Amp/Speaker Interface: Are Your Loudspeakers Turning Your Amplifier into a Tone Control?" E. Brad Meyer, Stereo Review, June 1991, page 54  http://www.avsforum.com/forum/91-audio-the...ml#post39239122
...I've never seen any evidence that AVR power amps have this problem, at either end of the price spectrum.


A few recent AVRs, including H/K and Pioneer, have switched to Class D amps and traditionally these are more prone to showing frequency response anomalies (possibly, but not always), arguably audible deviations, into certain loads.


Yes. Looks like we need some more newer technology to get the switching speeds high enough that the impact of the usual LC networks in the audible range is even lower.

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Think of that class D NAD power amp the scaremongers like to trot out, for example. [I'm thinking most here know what I'm talking about. References available upon request.]


The scaremongers like to equate high price and high performance. Unfortunately, class D AVRs usually sell for a premium. Of course being scaremongers they don't exactly have to stick to the truth

new breakthroughs in audio gear DBT?

Reply #9 –
Class D amplification is also becoming increasingly common in the very cheapest of AVRs: the ones packaged with disc players and speakers/subs in all in one HTiBs, or "Home theater in a box" systems. I doubt Mr DellaSalla meant those, but who knows?

I generally avoid class D unless I can see response curves which are flatter than this $6K NAD integrated amp's, not that I think it would much matter to my old ears:



" Fig.1 NAD M2, >8 ohms speaker compensation, frequency response at 2.83V into: simulated loudspeaker load (gray), 8 ohms (left channel blue, right red), 4 ohms (left cyan, right magenta), 2 ohms (green). (2dB/vertical div.)"
-Stereophile review of NAD M2

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Regarding my other post, I guess Arny won't take me up on my bet.

new breakthroughs in audio gear DBT?

Reply #10 –
Quote from: mzil on
Regarding my other post, I guess Arny won't take me up on my bet.


I don't think that DellaSalla is interested. Positive listening test results are popular with audiophiles. Bad time synch is relatively easy to hear, even if your ears are old and tired like mine.

new breakthroughs in audio gear DBT?

Reply #11 –
Quote from: Arnold B. Krueger on
Amplifiers that speakers turn into tone controls (i.e. amplifiers that have frequency curves that strongly depend on loudspeaker impedance curves) have high source impedances. This is relatively common with tubed power amps, and relatively rare with SS amps.


Well that's what I mean. GDS seems to have found one of those rare birds. Look again at what I quoted above:

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The amp with the high output impedance had surprisingly more but boomier bass than the amp with the lower output impedance.


(I'm assuming both amps were SS)

new breakthroughs in audio gear DBT?

Reply #12 –
Quote from: krabapple on
Quote from: Arnold B. Krueger on
Amplifiers that speakers turn into tone controls (i.e. amplifiers that have frequency curves that strongly depend on loudspeaker impedance curves) have high source impedances. This is relatively common with tubed power amps, and relatively rare with SS amps.


Well that's what I mean. GDS seems to have found one of those rare birds. Look again at what I quoted above:

Quote
The amp with the high output impedance had surprisingly more but boomier bass than the amp with the lower output impedance.


(I'm assuming both amps were SS)


Not only that, but since he is talking about the bass, he's not talking about switchmode amps which are generally very good in the bass range, but have their issues, if any in the top octave.

We might agree that Gene is distracting his readers by focussing on an exception, and not the general rule.