pogo
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No, unfortunately not. I would also be interested in the results, especially for the bridge mode of the purifis.
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Is it time for the traditional 1kHz tone test for amp power to go? (brief Amir name drop)
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valerianf
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He already does this test which has a curve at 20 hz into 4 ohms. This example from the recent Fosi mono amps.
And this with the power cube. What more do you want?
ads_cft222
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I don’t think I saw that test on the WiiM amp review…
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The power sweep at 20 hz was done on the WiiM. Not the power cube.
EERecordist
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Sure others have noted, the Audio Precision is a signal generator across frequency and level. Then it is an FFT analyzer of that stimulus through the device.
Personally I am interested in audio device transfer function across input amplitude and frequency. If you have the time you could program your Audio Precision to sweep that. Many software plugin makers do that for all the knob settings for hardware then implement that in software.
@amirm has stated, the ASR review panel is a repeatable Audio Precision test plan simply presented. Across audio engineering the source of nonlinearity beyond the standard test would be hard to find. Generally nonlinearity is when analog devices are driven to a high level. In digital, there are analog portions.
For critics and improvers, what is/are your tests, and how would you graph them? There is a whole topic in REW as an alternative to Audio Precision and there are several Audio Precision competitors you can buy and develop test plans.
Personally I am interested in audio device transfer function across input amplitude and frequency. If you have the time you could program your Audio Precision to sweep that. Many software plugin makers do that for all the knob settings for hardware then implement that in software.
@amirm has stated, the ASR review panel is a repeatable Audio Precision test plan simply presented. Across audio engineering the source of nonlinearity beyond the standard test would be hard to find. Generally nonlinearity is when analog devices are driven to a high level. In digital, there are analog portions.
For critics and improvers, what is/are your tests, and how would you graph them? There is a whole topic in REW as an alternative to Audio Precision and there are several Audio Precision competitors you can buy and develop test plans.
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As I noted above he already does a sweep in amplitude at several different frequencies. If those are good, it would be very unusual for some in between results to be out of pocket. One can see some class D amps are not as well behaved above 10 khz as below. Not many have shown lower frequency anomalies. One could ask for more frequencies to be tested, but I am failing to see what added information would be gained.
restorer-john
Grand Contributor
I am failing to understand what EERecordist is going on about.
Amplifiers are linear until they aren't. We've been running power bandwidth tests for most of a century, where the frequency extremes at which the amplifier can sustain either its rated power or -3dB (more common) power are determined. Amir is already doing the equivalent power sweeps vs THD with spot frequencies (which is more than sufficient) and with way more detail than a simpler power bandwidth test.
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As @Blumlein 88 noted, it was done for other frequencies already down to even 20 Hz.
By the way, In terms of current capability, keep in mind that reactive loads does not result in higher current at given applied voltage and ohmic values. That is, at say 30 V, 2 ohms, current is going to be 15 A regardless of the phase angle, just that at phase angle (lagging or leading) than 0 degree, the output devices will have to diasipate more heat.
The calculated lower "EPDR" ohmic value vs the actual impedance ohmic value is based on increased heat dissipation, not actual higher current, at the same applied voltage and same actual impedance (ohms).
valerianf
Addicted to Fun and Learning
As explained else where in the forum, there are at least 2 weakness for amplifier that are currently tested only at 1 khz:
1) Current capability with a low impedance load.
The power cube as used for now is only operated at 1 khz.
If an amp is successfully providing 100W at 1 khz, I want to now what is its capability at 50Hz because I got large woofers that are fully operating at this frequency.
The power cube test need to be conducted at 50Hz in addition with the test at 1Khz.
2)Load stability.
The power cube as used for now is only operated at 1 khz with the capacitive and inductive load.
For the same reason as above, we need to verify that the inductive and capacitive load are in the range of a woofer characteristics (i.e. 8" woofer) and we need to conduct the test a 50Hz.
Standardized test at 1 Khz are useful but nor sufficient to characterize a good amplifier.
If the amplifier is class D, then we need to add additional tests in the high frequency range where are located the usual weakness.
1) Current capability with a low impedance load.
The power cube as used for now is only operated at 1 khz.
If an amp is successfully providing 100W at 1 khz, I want to now what is its capability at 50Hz because I got large woofers that are fully operating at this frequency.
The power cube test need to be conducted at 50Hz in addition with the test at 1Khz.
2)Load stability.
The power cube as used for now is only operated at 1 khz with the capacitive and inductive load.
For the same reason as above, we need to verify that the inductive and capacitive load are in the range of a woofer characteristics (i.e. 8" woofer) and we need to conduct the test a 50Hz.
Standardized test at 1 Khz are useful but nor sufficient to characterize a good amplifier.
If the amplifier is class D, then we need to add additional tests in the high frequency range where are located the usual weakness.
Rhubarb
Member
I’m curious when the last time was that everybody calibrated their humor sweep meters, and complex load sarcasm inductors. Is there an averaged threshold of audibility level for drollery? I think there may be some high frequency deficits : )
This is pure satire or I’m missing the plot? 
Unless he says otherwise, this video of his deviated from satire that was the core of others.
Rhubarb
Member
Are you asking whether I take it that his statements about measuring are satire? (I do not think they are satire) Or are you meaning my post? (I was being silly,This is pure satire or I’m missing the plot?
I hope I understood you correctly!
[Edit: one strikout and *]
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No. I was referring to the Video not your post specifically. My apologies for being unclear. This guy has done a lot of satirical videos and I suspect that this is more of the same. He likes to push his act as close to real as he can to see how many he can fool/trick. My money is on this is just another version of his First Run Copper video work. I did think your post was funny.
I do believe that this is just an elaborate joke at Audiophiles and reviewers who don’t know what they are talking about but talk anyway. Just going from his past work. He does work hard to appear like he really means what he says. A lot of people fell for his First Run Copper advertisements.
Rhubarb
Member
Aha, thank you, Adam.
I have so little grasp of the technical side that any insider “audiophile testing humor” would be waaay over my head, and — embarrassingly — I had not even considered that possibilty, ooba.
Hooboy — life has been a little too “interesting” lately . . . I think I need to watch a few epidodes of Three’s Company or Gilligan’s Island . . .
Definitely S|A deserves the 1st Inaugural Andy Kaufman Audio Journalism Award.
Go have a read through this thread and you should see what I’m talking about.
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He also has more Audio related Satire on his YouTube channel:
While you may be right to call it "weakness", the positive thing is, also "in the forum", both 1) and 2) have been addressed to a large extent by Amir's recent addition of the reactive load tests, that in my opinion is an improved version of the so called power cube test, and the current capability with a low impedance load has been addressed for a long time based on Amir's also standard variable load, down to 20 Hz, that's 50 Hz below your requirement test. Again, all of such tests can obviously be further improved, no argument there, and as @pogo pointed out, we don't know the duration of those tests, @amirm told us once (I asked him) about the duration of his sweep test, he gave the answer so I think in time he will tell us more about the duration for the reactive load test as well. Duration obviously matter for load tests results that have implications on thermal issues, perhaps less so on stability issues I guess..., though the two could be related somewhat too, as too much heat could/might also result in stability.
So, your 1) and 2) identified weakness, while true to a point, based on the fact that all those tests could be improved, ASR does provide us with helpful information, that few, if any other reviewers have done.
I would like to take the opportunity to thank @amirm again for being so willing to listen to his forum members and incorporated more and more tests, and for now I just hope he would say more about the test durations for the various load tests. In principle, we already know those sweep test are likely not of fixed duration out of necessity, but in such cases, may be for future tests that are load dependent and heat related (e.g. output stage dissipation), he would provide some sort of a range, like between X ms to Y s so we can have a idea.
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