AIYIMA A07 TPA3255 Amplifier Measurements and Review - LM4562 (and OPA2134) option

[Svend P]

But it feels right...

ASR might not be the right place for you. But just read the first post of this thread, and you'll know

Message to golden-eared audiophiles posting at ASR for the first time...

Hello friend. Hey, listen...we know how it is. Believe me, most of us have been there too. You've spent years toiling in the muck of audiophilia. You read ALL the reviews. You watched ALL the youtube videos. You visited ALL the other forums where everything always makes a difference. You...

www.audiosciencereview.com

 

[chasmo57]

"XYZ might not be the right place for you"


Sorry, I thought this was a forum for sharing audio. At least it led me to a better amplifier (even if I'm not allowed to say it sounds better- wait... what's the point of hifi again?) sorry, I got confused

AIYIMA A07 TPA3255 Amplifier Measurements and Review - LM4562 (and OPA2134) option

AIYIMA A07 TPA3255 Amplifier Measurements LM4562 option I received my A07 yesterday, on January 6, 2021, shipped from Italy. Purchased at Amazon.de and as stated on their website, it arrived without a power supply. I am testing the A07 with 2 different power supplies. One of them is a linear...

audiosciencereview.com

Remember- if all amplifiers sound alike, what's the point of even discussing it? Dogma.
thanks,

 

[Svend P]

Sorry, I thought this was a forum for sharing audio.

It isn't. It is a science forum. If you can't back your flowery prose of audio improvements up with measurements or blind testing they have no value, since your perceived improvements most likely are just the cause of biases.

 

[chasmo57]

Two words:
"Listening Impressions"
These appeared in the very first posts of this thread.

AIYIMA A07 TPA3255 Amplifier Measurements and Review - LM4562 (and OPA2134) option

AIYIMA A07 TPA3255 Amplifier Measurements LM4562 option I received my A07 yesterday, on January 6, 2021, shipped from Italy. Purchased at Amazon.de and as stated on their website, it arrived without a power supply. I am testing the A07 with 2 different power supplies. One of them is a linear...

audiosciencereview.com

Well EXCUUUUSE ME! My perceived improvements are a direct result of making a change based on the OP's recommendations. He did the measurements, didn't he? So,
May I still stay to read others' listening Impressions even if i have to keep mine 2 myself-
(or should I go & vote 4 the incumbent)? I'm sure there are other participants here who like to share and are less dogmatic. I think I'll keep on reading.I live in a free country (USA)
Apologies to PMA & the moderator!
Signing off!

 

[Svend P]

May I still stay to read others' listening Impressions

If you can find them, sure, but they are of no value.

Note how there are none when Amirm tests electronics. Wonder why? (hint: they are indistinguishable from each other)
You clearly haven't read anything on this forum before posting. Maybe read the room better next time?

Master Audio Review Index

www.audiosciencereview.com

 

[375HP2482]

First I listened with 5532's, then switched to the amp with the LM4562's. I switched back and forth several times and at one point lost track of which amp was modded(covers in place).

Uh, yeah...

 

[chasmo57]

Try being kind (or at least respectful) and give a senior citizen a benefit of the doubt...
The two amps were pretty close to the casual listen; however, I have been doing comparative listening sessions since the late 1970's
Remember Audio Critic Peter Aczel and J. Gordon Holt? - I do. Two ways of looking(listening) to the same thing.
Lesson learned- 3 subjects to avoid in polite conversation:
1. Politics
2. Religion
3. Hifi sound
Thanks

 

[375HP2482]

Here's the thing: This forum is dedicated primarily to scientifically-verifiable (objective, if you will) factors. Yes, we have a lot of "I prefer this over that" talk, which is normal. On the other hand, one will encounter objections when posting a scientifically-unsupported preference or opinion as fact.

 

[chasmo57]

Thank you, 375HP... for the respectful and informative response.
I will also try and respect this community and avoid potentially controversial posts in the future. I believe I can still learn from the culture here. Also
I know what I know, but it's still my opinion (and you know what they say about opinions)

 

[chasmo57]

Questions regarding measured improvements in SINAD of the Aiyima A07, stock opamps vs LM4562 & OPA2134 (w/good DC supply)
If the SINAD was ~83 w/ ne5534, was ~86 w/ LM4562,
and was ~88 w/ OPA2134,
how shall we (officially) describe these differences and shouldn't there be a difference in quality based upon the data?
Respectfully,
-the new guy

 

[Zek]

It is a science forum.

Can you briefly explain what is scientifically on this forum (I don't count on technical measurements, which are perfectly OK).

 

[375HP2482]

Questions regarding measured improvements in SINAD of the Aiyima A07, stock opamps vs LM4562 & OPA2134 (w/good DC supply)
If the SINAD was ~83 w/ ne5534, was ~86 w/ LM4562,
and was ~88 w/ OPA2134,
how shall we (officially) describe these differences and shouldn't there be a difference in quality based upon the data?
Respectfully,
-the new guy

Some of those measurements were made, unfortunately, with different power supplies as well as different opamps, making conclusions difficult. For example, most of the differences noted in PMA's measurements with different opamps can be traced to the different amounts of AC power supply artifacts (50/100 Hz), which are components of SINAD.

Other measurement differences can contribute, such as the lack of bandlimiting (< 20 kHz), or A-weighting (which discounts AC supply effects). A-weighting can be somewhat useful, as AC line artifacts are difficult to hear using modern loudspeakers of modest bass sensitivities, combined with our hearing's fading sensitivity at low frequencies/levels. The noise component we should focus on is the broadband noise ("hiss") in the higher frequencies that, though low, is usually audible at closer distances.

 

[chasmo57]

"Some of those measurements were made, unfortunately, with different power supplies as well as different opamps, making conclusions difficult..."

I'm trying really hard to conform, while visiting ASR, to the "No subjective, be objective" requirements here. Where might I find some useful objective measurements around which I can try to wrap my brain, as it were? I was so excited when I found this forum

Has anyone here done valid, scientific (standardized) measurements on one of the Aiyima basic amps, comparing SINAD readings using one power supply and substituting a different op amp for stock?

And why aren't we calling out those who are not following rigorous scientific methodology?

Sorry, I thought I sensed some hypocrisy after getting flamed.

I'm truly grateful for any clarification. Thanks

 

[Svend P]

SINAD has to be really bad for anyone to detect a difference. Even though you might be able to measure a difference, it is not always possible to hear it.

Audibility thresholds of amp and DAC measurements

Introduction A recurring theme on ASR is whether or not the various measured qualities of the devices are audible. In this post, I'll present some clear and visual thresholds for when those imperfections can be considered a potentially audible concern. I will not explain the basics of amp/DAC...

www.audiosciencereview.com

 

[chasmo57]

So, what?
Maybe I'm missing something, but doesn't a measurement need to be standardized?
I read that A.P. considers these measurements to be
"Figures of Merit".
Show me the merit!

 

[antcollinet]

"Some of those measurements were made, unfortunately, with different power supplies as well as different opamps, making conclusions difficult..."

I'm trying really hard to conform, while visiting ASR, to the "No subjective, be objective" requirements here. Where might I find some useful objective measurements around which I can try to wrap my brain, as it were? I was so excited when I found this forum

Has anyone here done valid, scientific (standardized) measurements on one of the Aiyima basic amps, comparing SINAD readings using one power supply and substituting a different op amp for stock?

And why aren't we calling out those who are not following rigorous scientific methodology?

Sorry, I thought I sensed some hypocrisy after getting flamed.

I'm truly grateful for any clarification. Thanks

Here you will find a hypothesis for the absollute limits of audibility of various measuremnents. Most people can’t get close to even the lenient limits shown here, and with real music, the limits will be lower still.

Audibility thresholds of amp and DAC measurements

Introduction A recurring theme on ASR is whether or not the various measured qualities of the devices are audible. In this post, I'll present some clear and visual thresholds for when those imperfections can be considered a potentially audible concern. I will not explain the basics of amp/DAC...

www.audiosciencereview.com

Here is a place you can test your own ability to hear distortion with real music. Most who try this test can’t do better than about -45dB. With speakers, even less (with speakers I struggle to hear -25dB distortion)

Listening Test

www.klippel.de

Now imagine how difficult it is to hear the difference between -80dB and anything lower than that, when you can’t hear the distortion at -45dB.

 

[antcollinet]

"Some of those measurements were made, unfortunately, with different power supplies as well as different opamps, making conclusions difficult..."

I'm trying really hard to conform, while visiting ASR, to the "No subjective, be objective" requirements here. Where might I find some useful objective measurements around which I can try to wrap my brain, as it were? I was so excited when I found this forum

Has anyone here done valid, scientific (standardized) measurements on one of the Aiyima basic amps, comparing SINAD readings using one power supply and substituting a different op amp for stock?

And why aren't we calling out those who are not following rigorous scientific methodology?

Sorry, I thought I sensed some hypocrisy after getting flamed.

I'm truly grateful for any clarification. Thanks

See here for some equivalent measurements. Differences are tiny - or if large, get much worse when swapping from stock.

Fosi Audio V3 op-amp rolling, has anyone tried it? Snake oil? Or are there actual differences?

A plastic cup holds water. A glass looks better, has better specs in certain areas... but still it just needs to hold water, which it does fine be it crystal, Ikea glass or plastic. And sometimes the "worse" component, a plastic cup, is just what was specified for the job and lasts longer and...

www.audiosciencereview.com

 

[375HP2482]

"Some of those measurements were made, unfortunately, with different power supplies as well as different opamps, making conclusions difficult..."

I'm trying really hard to conform, while visiting ASR, to the "No subjective, be objective" requirements here. Where might I find some useful objective measurements around which I can try to wrap my brain, as it were? I was so excited when I found this forum

Has anyone here done valid, scientific (standardized) measurements on one of the Aiyima basic amps, comparing SINAD readings using one power supply and substituting a different op amp for stock?

Look no further than the first two "Spectrum magnitude" measurements on the first page of this thread. Reading the text indicates that the stock NE5532 measured 1.5 dB noisier than the LM4562. However, looking at the low-frequency spectrum of the two measurements shows, again, that the AC supply artifacts at 50/150 Hz are likely responsible for most of that difference. That post attributes the difference to superior power-supply rejection of the LM4562, which is inaudible for the reasons previously stated. Most likely the difference in the audible "hiss" component of SINAD is much less than 1.5 dB.

It's worthwhile to emphasize that, not only is the broadband noise component virtually the same between the two opamps, the absolute level for both is so low that you have to place your ear right up to the tweeter in the absence of signal to detect it, with the unit's actual harmonic distortion components well below that level -- and, in any event, would be masked by the test tone's fundamental frequency.

 

[chasmo57]

Thank you for the constructive responses and the useful resource links.
Now I feel welcomed (if a bit overwhelmed-ball in my court)
Have a great weekend guys!

 

[375HP2482]

Thank you for the constructive responses and the useful resource links.
Now I feel welcomed (if a bit overwhelmed-ball in my court)
Have a great weekend guys!

Welcome to ASR.

Your skepticism and curiousity are valuable traits in a scientific environment. Remember: "Always a skeptic, never a cynic."