Richard, you may be already familiar with this, but a decent overview of the S-D thing, and in particular "noise modulation" - free Chap. 2 download: Basics of Sigma-Delta Modulation - Springer
You said that, in your experience, "noise modulation" is the critical difference between amps; some ethereal quality that is the defining difference, but it is not important enough to everyone else in audio to even think about. Having made the claim, you then walk away from it because it is not "interesting" to you, despite the stated significance of the mysterious property.
What, the presumption that something that is claimed to be so significant should have been investigated by now?
Really? You can't see why I said that? Really? As SY said, "the Ignore List is a powerful thing". Yep!
Abs
That Springer website is irritating to navigate ... what I did was use Google, and got http://webcache.googleusercontent.com/search?q=cache:tikStWBYetEJ:www.springer.com/cda/content/document/cda_downloaddocument/9789400713864-c2.pdf%3FSGWID%3D0-0-45-1112643-p174107874+&cd=7&hl=en&ct=clnk&gl=au , then clicked on the link at the top of the page, and was able to save the PDF.
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Nope, looks like a re-read is in order. I said that differences I had experienced seemed to be as a result of noise modulation.
Naturally enough I never said it was 'ethereal' that's your gloss.
Wrong. Others have indeed thought about it. And even done measurements.
Wrong. Again. Your malformed questions were the non-interesting things, not my relating of my experience.
No. Still contains a false premise.
Yes.
I can now, my curiosity has been assuaged. Projection is the hypothesis that fits the subsequent data.
@Frank - thanks for the heads-up, got it now
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Psssst, Richard
... don't tell anyone, , but essentially the whole book is available as a downloadable thesis, here: http://alexandria.tue.nl/extra2/691188.pdf
A bit more info about how this beast is put together ... Benchmark Media Systems, Inc. - New! Benchmark AHB2 Power Amplifier - Available September 2014
THD measurements
Instead of starting a new AHB2 thread, I am reviving this thread.
There are now some independent measurements coming in and they show some interesting differences.
First the test at Soundstagenetwork: SoundStageNetwork.com | SoundStage.com | SoundStageNetwork.com | SoundStage.com
It shows some very good results, 5ppm THD1k and 50ppm THD20k at 180W/4ohm. There are not many competitors out there that has this low distortion at any pricelevel, congrats to Benchmark!
But then there is the test at HiFi-News here: https://cdn.shopify.com/s/files/1/0...nchmark_AHB2_Reprint.pdf?10048035991299387752
It shows much higher distortion especially in a 4-ohm load under _dynamic_ conditions. I wonder why?
While Soundstagenetwork uses Audio Precision with the usual stepped sinewave measurement, Hifi-News uses a dynamic distortion measurement with the Miller Audio Research suite.
Anyone knows what the Miller dynamic distortion measurement test is? Anyone care to speculate why the results are so much worse with this test?
I can start out and speculate that this is due to the class-H tracking rails causing distortion when the signal amplitude changes quickly, and that this type of non-linearity is not revealed by the Audio Precision type measurement.
Br
OJG
Instead of starting a new AHB2 thread, I am reviving this thread.
There are now some independent measurements coming in and they show some interesting differences.
First the test at Soundstagenetwork: SoundStageNetwork.com | SoundStage.com | SoundStageNetwork.com | SoundStage.com
It shows some very good results, 5ppm THD1k and 50ppm THD20k at 180W/4ohm. There are not many competitors out there that has this low distortion at any pricelevel, congrats to Benchmark!
But then there is the test at HiFi-News here: https://cdn.shopify.com/s/files/1/0...nchmark_AHB2_Reprint.pdf?10048035991299387752
It shows much higher distortion especially in a 4-ohm load under _dynamic_ conditions. I wonder why?
While Soundstagenetwork uses Audio Precision with the usual stepped sinewave measurement, Hifi-News uses a dynamic distortion measurement with the Miller Audio Research suite.
Anyone knows what the Miller dynamic distortion measurement test is? Anyone care to speculate why the results are so much worse with this test?
I can start out and speculate that this is due to the class-H tracking rails causing distortion when the signal amplitude changes quickly, and that this type of non-linearity is not revealed by the Audio Precision type measurement.
Br
OJG
AHB2 Test Results
The AHB2 power amplifier is nearly distortion free when running under full load. It's THD is closely matched to the residual distortion in the AP2722 and AP2522 test sets. The same is true of the Miller test set. This makes it very hard to acquire accurate measurements of the amplifier. Paul Miller may be repeating his measurements soon. We believe Paul's posted results do not accurately reflect the true performance of the AHB2. The same is true of some of the measurements made by BHK Labs. It is very hard to get these measurements correct.
Benchmark's published specifications are based on measurements made with an AP555, an AP2722, an AP2522 and a R&S test system. We have reasons to believe that actual performance is better than we are currently specifying. We may update some of the specifications in the near future.
There are more independent tests in progress and these tests should confirm our own published specifications.
The AHB2 power amplifier is nearly distortion free when running under full load. It's THD is closely matched to the residual distortion in the AP2722 and AP2522 test sets. The same is true of the Miller test set. This makes it very hard to acquire accurate measurements of the amplifier. Paul Miller may be repeating his measurements soon. We believe Paul's posted results do not accurately reflect the true performance of the AHB2. The same is true of some of the measurements made by BHK Labs. It is very hard to get these measurements correct.
Benchmark's published specifications are based on measurements made with an AP555, an AP2722, an AP2522 and a R&S test system. We have reasons to believe that actual performance is better than we are currently specifying. We may update some of the specifications in the near future.
There are more independent tests in progress and these tests should confirm our own published specifications.
Hi,
I am Kim Kruse from the scandinavian online magazine nomono.dk. Prior editor at the late Danish hifi magazine "High Fidelity" with chief editor Michael Madsen.
I have now during a test period of app. 3 month got the possibility to listen to this amplifier and evaluate it in relation to other high-end amplifiers.
It is easy to discuss all the measured data at this amp and be impressed. But it is much easier to listen to it. Basically the AHB shows that there _are_ difference between amplifiers. Huge difference.
All other amplifiers sounds veiled i direct comparision. Even up to 6 times more expensive amplifiers do not have the same control, look-through experience, and natural replication of the ambience and perspective in the sound.
Try to listen to the amp, instead of trying to figure out the sound based on data.
Correct, a speakers distorts a lot more than even an AHB amplifier, but you can easily here the difference.
The sound is quite chocking good!
Good work, Benchmark!
Kr
Kim Kruse
I am Kim Kruse from the scandinavian online magazine nomono.dk. Prior editor at the late Danish hifi magazine "High Fidelity" with chief editor Michael Madsen.
I have now during a test period of app. 3 month got the possibility to listen to this amplifier and evaluate it in relation to other high-end amplifiers.
It is easy to discuss all the measured data at this amp and be impressed. But it is much easier to listen to it. Basically the AHB shows that there _are_ difference between amplifiers. Huge difference.
All other amplifiers sounds veiled i direct comparision. Even up to 6 times more expensive amplifiers do not have the same control, look-through experience, and natural replication of the ambience and perspective in the sound.
Try to listen to the amp, instead of trying to figure out the sound based on data.
Correct, a speakers distorts a lot more than even an AHB amplifier, but you can easily here the difference.
The sound is quite chocking good!
Good work, Benchmark!
Kr
Kim Kruse
so, has anyone bought one, lived with it for a while and cares to comment?
and can anyone point to internal photos; the engineer in me likes to look and appreciate the efforts that can achieve these levels of performance. kinda like looking at the old, well-built test gear from years ago.
good job, john!
mlloyd1
and can anyone point to internal photos; the engineer in me likes to look and appreciate the efforts that can achieve these levels of performance. kinda like looking at the old, well-built test gear from years ago.
good job, john!
mlloyd1
When I was looking for an amplifier as an alternative to the Halcro DM38, Pas Aleph 1.2 or Thorens TEM3200, I found this power amp by accident.
https://benchmarkmedia.com/blogs/ap...radical-approach-to-audio-power-amplificationhttps://www.stereophile.com/content/benchmark-media-systems-ahb2-power-amplifier
But I miss my favorite diagram, which show THD+N (distortion and noise) waveform with fundamental notched out.
https://www.stereophile.com/content/benchmark-media-systems-ahb2-power-amplifier-measurements
What could be the reason for non-publication of that figure ?
check out post #2 under
https://www.diyaudio.com/community/...st-possible-thd-n-really-the-best-way.367692/for diagrams in this kind of various amp models.
https://benchmarkmedia.com/blogs/ap...radical-approach-to-audio-power-amplificationhttps://www.stereophile.com/content/benchmark-media-systems-ahb2-power-amplifier
But I miss my favorite diagram, which show THD+N (distortion and noise) waveform with fundamental notched out.
https://www.stereophile.com/content/benchmark-media-systems-ahb2-power-amplifier-measurements
What could be the reason for non-publication of that figure ?
check out post #2 under
https://www.diyaudio.com/community/...st-possible-thd-n-really-the-best-way.367692/for diagrams in this kind of various amp models.