Amps reviews questions: Is this a classic example of subjective vs objective measurements? Does it prove anything?

[PENG]

Subjective measurements:
Starke Sound AD4.320 Power Amplifier Review - HomeTheaterHifi.com
Starke Sound’s 4-Channel AD4.320 Amplifier Uses Proprietary Class D Tech, BIG Power | Audioholics

Objective measurements:

Sample 1
Starke Sound AD4.320 Review (Multichannel Amplifier) | Audio Science Review (ASR) Forum

Sample 2
Starke Sound AD4.320 Amp Review (Sample 2) | Audio Science Review (ASR) Forum

To me, I won't suggest this amp cannot sound very good to the ears, because it definitely could.. It just seems to show that people who often claimed that just by adding such an amp to their AVRs, their speakers immediately opened right up with more details they never heard before and much bigger sound stage even at low to moderate volume etc., might have been for reasons other than increased fidelity. Regardless, as always, such pure subjective reviews are fun to read and I do hope those reviewers would keep up the good work, though they probably should be kind enough to include some sort of a disclaimer or reminder that they are pure subjective review, ymmv.. etc..

 

[Trell]

Amir measured the power output to be far lower than specified, so there is that.

 

[Trell]

Subjective reviews of audio devices can be a hilarious read, but I do find opinions on usage and handling can be useful.

 

[highfigh]

Subjective measurements:
Starke Sound AD4.320 Power Amplifier Review - HomeTheaterHifi.com
Starke Sound’s 4-Channel AD4.320 Amplifier Uses Proprietary Class D Tech, BIG Power | Audioholics

Objective measurements:

Sample 1
Starke Sound AD4.320 Review (Multichannel Amplifier) | Audio Science Review (ASR) Forum

Sample 2
Starke Sound AD4.320 Amp Review (Sample 2) | Audio Science Review (ASR) Forum

To me, I won't suggest this amp cannot sound very good to the ears, because it definitely could.. It just seems to show that people who often claimed that just by adding such an amp to their AVRs, their speakers immediately opened right up with more details they never heard before and much bigger sound stage even at low to moderate volume etc., might have been for reasons other than increased fidelity. Regardless, as always, such pure subjective reviews are fun to read and I do hope those reviewers would keep up the good work, though they probably should be kind enough to include some sort of a disclaimer or reminder that they are pure subjective review, ymmv.. etc..

I really hope the sound was much more organic and immersive. I really do.

 

[PENG]

I really hope the sound was much more organic and immersive. I really do.

It can be, take a look of the FFTs:

May be not so much the 1st sample but the 2nd one has quite a bit of 2nd and 4th harmonics. Did they intentionally "voice" the amps?

As long as their owners don't push the amps too much though, otherwise not even the predominantly even harmonics can save the "warm/organic" sound. That thing literally "clipped" at 160 W into 4 ohms. Still only 11.2% THD+N, some people may still like the sound!!

 

[ski2xblack]

Well, it seems another example of hyperbolic marketing, complete with claims of tube amp sound. If they stoop to such tactics, no wonder their power specs are equally whimsical.

The only tube amp type performance I notice in the measurements are (1) the low order monotonic profile of the nonlinear distortion, (2) the slight response aberrations under complex loads, and (3) unconventionally low gain.

While it fails to meet specs in the power department, I sincerely doubt anyone who doesn't exceed it's limits could pick it out in a bias controlled test. It's just not bad enough to produce those chocolaty mids.

 

[snbeall]

Starke have claimed a “manufacturing defect” on a ”few units” that were fitted with improper 220 volt transformers. But of the three random samples tested - one here and now the two by ASR - all three have failed. This would imply a far higher percentage than “a few”. In fact, if anything it would imply “ALL” units are “faulty”.

Notably, none of Starke’s own manufacturer power specifications include @% distortion ratings for ANY of their amps. Why not? It’s been standard practice for years - particularly in the higher end where Starke plays. Are they knowingly misrepresenting? They have halted new unit sales and are accepting returns - from anyone who is dissatisfied. Of course these customers would have to know in the first place. But they have stopped short of an active recall. Or informing their clients. And notably, they are actively re-selling the returned units as B stock.

“Lucy, you’ve got some ’splainin to do!”

 

[Am_P]

It can be, take a look of the FFTs:

May be not so much the 1st sample but the 2nd one has quite a bit of 2nd and 4th harmonics. Did they intentionally "voice" the amps?

For instance, I experience the following phenomenon on a regular basis Mr. Peng. I may be listening to a few people talking. One voice can be appealing to me and i feel like, "ah, i can listen to this voice for quite a while"....I listen to another guy talking (just the sound of it) and all i can think in the back of my mind is "you annoying lil sht". I wish i could take a comprehensive set of measurements, make a comparison and derive a foolproof scientific explanation for this phenomenon that i experience, you know? ...determine why exactly my auditory and other supportive physiology responds this way....

 

[SithZedi]

For instance, I experience the following phenomenon on a regular basis Mr. Peng. I may be listening to a few people talking. One voice can be appealing to me and i feel like, "ah, i can listen to this voice for quite a while"....I listen to another guy talking (just the sound of it) and all i can think in the back of my mind is "you annoying lil sht". I wish i could take a comprehensive set of measurements, make a comparison and derive a foolproof scientific explanation for this phenomenon that i experience, you know? ...determine why exactly my auditory and other supportive physiology responds this way....

That's always a conundrum. Its like meeting a beautiful woman with a horrible voice. Auditory and other "supportive" physiology responds in a contradictory then overload way....Have to hit reset.

 

[snbeall]

I suspec

For instance, I experience the following phenomenon on a regular basis Mr. Peng. I may be listening to a few people talking. One voice can be appealing to me and i feel like, "ah, i can listen to this voice for quite a while"....I listen to another guy talking (just the sound of it) and all i can think in the back of my mind is "you annoying lil sht". I wish i could take a comprehensive set of measurements, make a comparison and derive a foolproof scientific explanation for this phenomenon that i experience, you know? ...determine why exactly my auditory and other supportive physiology responds this way....

I suspect it is more psychological and related to past experiences than it is to any measurable parameter. But then we’re straying far afield from the OT.

 

[ski2xblack]

I have some unresolved curiosity regarding "measures bad, sounds good" amplifiers, but my ears aren't good enough to differentiate clean watts from clean watts. I've tried.

It takes a real wooly bugger of an amp for me to notice a difference, and even then it's a bit of guesswork. E.g. the Pass ACA. Very SET like behavior on the test bench, objectively poor measurements, but crystal clear and thoroughly pleasant to the ear.

It makes me wonder if there really is something to amp topologies that inherently lack crossover distortion (the proverbial sound of one hand clapping in Pass' terms) or if I merely enjoy distortion, as the distortion is undeniable yet I do rather enjoy SE tubes and the ACA. But I wouldn't bet the mortgage on my ability to pick them apart if not wildly over driven.

 

[highfigh]

That's always a conundrum. Its like meeting a beautiful woman with a horrible voice. Auditory and other "supportive" physiology responds in a contradictory then overload way....Have to hit reset.

Like Fran Drescher, Joy Behar and Kathy Griffin?

 

[PENG]

I have some unresolved curiosity regarding "measures bad, sounds good" amplifiers, but my ears aren't good enough to differentiate clean watts from clean watts. I've tried.

It takes a real wooly bugger of an amp for me to notice a difference, and even then it's a bit of guesswork. E.g. the Pass ACA. Very SET like behavior on the test bench, objectively poor measurements, but crystal clear and thoroughly pleasant to the ear.

It makes me wonder if there really is something to amp topologies that inherently lack crossover distortion (the proverbial sound of one hand clapping in Pass' terms) or if I merely enjoy distortion, as the distortion is undeniable yet I do rather enjoy SE tubes and the ACA. But I wouldn't bet the mortgage on my ability to pick them apart if not wildly over driven.

I believe crossover distortions will, or should show up in the THD+N measurements so it should easy enough to find out if it could be one of the main factors.

RC Filter Box For Class-D Output Power and THD+N Measurement (ti.com)

Total Harmonic Distortion Plus Noise (THD+N) The typical THD+N measurement combines the effects of noise, distortion, and other undesired signals into one measurement and relates it (usually as a percentage) to the fundamental frequency. Ideally, only the fundamental test frequency of the sine-wave input is present at the output of the APA, which in practice is never the case. The THD+N measurement requires notching out the fundamental test frequency and measuring the RMS voltage (which includes unwanted harmonics and noise) across the audio band (which the AP does automatically) and then dividing that measured value by the fundamental test frequency value and expressing it as a percentage.

So if XOD is the reason, we should be able to see the evidence of it, and it presumably would be more prominent at the very low output level, and that's probably why Nelson Pass emphasize the importance of the first watt. My counter point is that at very low listening level, it would be more difficult to hear any distortions too because if the fundamental signal level is low, the XOD level would also be low relatively speaking, so imo the talk of the 1st watt being so important is also a myth, or at least a partial myth.

And, thanks for reminding me of first watt amp (indirectly). I still have to dig out my DIY kit for the F5 V3 amp, I really should get it build soon. Having been in storage for almost 4 years, I hopeful all the parts are still in one place.

 

[highfigh]

So if XOD is the reason, we should be able to see the evidence of it, and it presumably would be more prominent at the very low output level, and that's probably why Nelson Pass emphasize the importance of the first watt. My counter point is that at very low listening level, it would be more difficult to hear any distortions too because if the fundamental signal level is low, the XOD level would also be low relatively speaking, so imo the talk of the 1st watt being so important is also a myth, or at least a partial myth.

And, thanks for reminding me of first watt amp (indirectly). I still have to dig out my DIY kit for the F5 V3 amp, I really should get it build soon. Having been in storage for almost 4 years, I hopeful all the parts are still in one place.

May be a myth, but any audible distortion in the area of 1W depends on the typical listening level and I think that for audio-only, many listen at moderate levels which might be right at 1W.

I went to see the guys at a local audio shop and while one was assembling a turntable, I noticed that the music playing had great detail, so I walked through the room and listened for dispersion, frequency range, etc- the amount of detail that was audible at such a low level was excellent and I had noticed that with some other systems, but not all. Sure, the equipment was expensive, but the systems that didn't provide such detail weren't cheap. If the idea that most amps sound the same holds, it had to be the sources, speakers and rooms. I still don't accept that cables & power cords make much/any difference if they're intact and not defective so I have serious doubts about them being responsible.

 

[SithZedi]

Like Fran Drescher, Joy Behar and Kathy Griffin?

Not quite what I had in mind. This list deserves a beer goggle count: +8 Fran, but don't make her moan. Don't think there is a count for the last two. Deep coma maybe?

 

[PENG]

May be a myth, but any audible distortion in the area of 1W depends on the typical listening level and I think that for audio-only, many listen at moderate levels which might be right at 1W.

I went to see the guys at a local audio shop and while one was assembling a turntable, I noticed that the music playing had great detail, so I walked through the room and listened for dispersion, frequency range, etc- the amount of detail that was audible at such a low level was excellent and I had noticed that with some other systems, but not all. Sure, the equipment was expensive, but the systems that didn't provide such detail weren't cheap. If the idea that most amps sound the same holds, it had to be the sources, speakers and rooms. I still don't accept that cables & power cords make much/any difference if they're intact and not defective so I have serious doubts about them being responsible.

I think you might have misunderstood my point. That is, as an example, if you listen to a speaker at 87 dB from 1 meter or 75 dB from 4 meters, your amp will output only 0.25W. Now if you turn the volume down further so that you will be listening to spl of 72 dB (low enough?), your amp will then only have to output 0.125 W So I am not even using 1 W as an example but just 0.125 W !!

If the music signal is at 72 dB (from 4 meters) and say that is the average, then if the XOD is 0.1%, that is -60 dB. Assuming people find XOD really nasty even at just -60 dB, but because we are now talking about listening at a relatively low (to me that's not really low) spl of 72 dB, then the XOD will be at 72-60 = 12 dB. That would be audible for sure if the room is dead silent, but if your room has a noise floor of say 25 dB minimum within the audio band, then I would say it must be tough to hear the XOD that is at 13 dB below the noise floor.

 

[lovinthehd]

Did AH get also a second sample to test like Amir so they can follow up on the original "review"?

ps In the preview/review thread Gene mentioned recently Starke had not gotten back to them....and that there's an interesting Starke speaker review coming up.

 

[AcuDefTechGuy]

I think it proves that subjective opinions are not really reviews.

The question is, do their $8,000 amps also measure 0.02% THD+N at 1kHz and cannot output the specified power output before clipping with 11% THD+N?

 

[ryanosaur]

I think it proves that subjective opinions are not really reviews.

This.

 

[highfigh]

I think you might have misunderstood my point. That is, as an example, if you listen to a speaker at 87 dB from 1 meter or 75 dB from 4 meters, your amp will output only 0.25W. Now if you turn the volume down further so that you will be listening to spl of 72 dB (low enough?), your amp will then only have to output 0.125 W So I am not even using 1 W as an example but just 0.125 W !!

If the music signal is at 72 dB (from 4 meters) and say that is the average, then if the XOD is 0.1%, that is -60 dB. Assuming people find XOD really nasty even at just -60 dB, but because we are now talking about listening at a relatively low (to me that's not really low) spl of 72 dB, then the XOD will be at 72-60 = 12 dB. That would be audible for sure if the room is dead silent, but if your room has a noise floor of say 25 dB minimum within the audio band, then I would say it must be tough to hear the XOD that is at 13 dB below the noise floor.

I would bet that the ringing in most peoples' ears would mask that distortion at 12dB, especially if music is playing, never mind the room's ambient noise floor.