Topping PA5 (TPA325X) : Is a modification worth it? ?

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Amplifier dude

Amplifier dude

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Joined 2020
5th element said:
Harmonics that you cannot hear matter as it shows you a window into the amplifiers gain and feedback structure. I, for one, am very interested in seeing how class D amplifiers perform when the measurement bandwidth isn't limited to 20kHz. The reason for this is because it's what separates the wheat from the chaff.

The absolute best non switching amplifiers will show very little rise in distortion as frequency increases out to 20kHz and this is when measured with 100kHz bandwidth. Class D, on the other hand, usually falls to pieces here.

Measuring class D with 20kHz bandwidth sweeps stuff under the rug and presents things in a far more pleasing light than is actual reality.

Anyone can design an amplifier that has extremely good performance at 1kHz. This isn't a particularly interesting figure of merit when comparing high performance amplifiers. What is interesting is what happens from 1kHz to 20Khz with 100kHz bandwidth as this is where all the interesting stuff happens. This shows how the designer has tried to squeeze as much performance as possible out of the limited bandwidth of the open loop system and then the associated phase margins of the closed loop system. In other words have they done anything different to the competition.

Can we hear a lot of this? No. But that's academic when it comes to the state-of-the-art. These differences, and how they've been achieved, are what's interesting and what you should be interested in looking at. Of course you need to know why this is interesting in the first place for it to make any sense.
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So is the 18/19khz 2 tone IMD test rubbish?
 
M

mamocel

Member
Joined 2018
I do not think that the measurements between a class D amp and Ab is comparable ... Beyond 20k
The inductors and filter outputs of classD amplifiers are responsible for removing all unwanted Hamonics and the modulation carrier of the amplifier.

Or measure the amp without an output filter ...east that's my point of view ... :hohoho:
 
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KSTR

KSTR

Member
Joined 2007
DIYA member @alexcp has suggested two-tone complex with 7kHz and 13kHz which is better than 1kHz THD (obvious), 20kHz THD (less obvious) but also better than the 19k+20k twin-tone, see post https://www.diyaudio.com/community/...-with-a-sound-card.366714/page-3#post-6615692 and following.
alexcp said:
Second, one can choose a different set of frequencies for the IMD test in order to push the products of both symmetric and asymmetric distortion (i) away from the fundamental; (ii) closer to each other; and (iii) closer to the upper limit of the audio band, in order to reduce the effect of both notch filters and loop gain. For example, one can combine three sines in the test signal, as Bob Cordell did in his paper, but choose the frequencies so that the products are grouped around 20kHz rather than 1kHz. But I like the simple combination of 7kHz and 13kHz sines, which produce an even-order IMD product at 7+13=20kHz and odd-order, at 13+13-7 = 19kHz. In addition, the 3rd harmonic of 7kHz is at 21kHz.
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I for one got fully conviced.
 
TheWalkman

TheWalkman

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Joined 2013
xhitespirit said:
@inteificio
If it can help: I was able to compare a (not modified) Aiyima A04 to a recent decent mid-level ($600) Onkyo integrated amplifier (all other elements identical). I can say that the A04 was close to, but not as good as the Onkyo re listening impressions. Onkyo has better slam, better sound stage (depth) and is less harsh, while remaining quite neutral with no particular emphasis. Some kind of maturity, in particular on complex music, the A04 lacks. But price ratio is 1/10 for A04, so VVG value for money anymway. (Once the A04 modified, the Onlyo is beaten, but this is another story).

Reading TheWalkMan above who owns both, it seems there is not so much sonic differences between A04 and Topping PA5.

Then @TheWalkman
Would you please share with us more on your PA5 listening impressions, vs the 04 ? No need to conclude if any is better that the other :) Just curious about differences you could hear, if any, re frequency response, details, sound stage (height, width, depth), speed, warmth, etc.

Have fun !
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xhitespirit,

It seems like the PA5 might be a bit more detailed but both sound good to my 61 year old ears. (I'm not doing a controlled, A-B test so it's hard to say much more than that. And don't ask me to compare a nice Burgundy to an aged Russian River Pinot. I'll probably tell you I like them both in their own ways!)

I'd really like to see Amir run a review on the A04 to see how they compare on paper. I also have the A07 which he did review and the 04 sounds cleaner, louder, etc. compared to the 04 but they both sound very good to me, and it's hard for me to quantify, "a buttery presence and sound stage, blah, blah, blah."

They all sound great and at some point, I think we're chasing specs over actual sound improvement.

As I've stated over on ASR several times, for someone just getting into this hobby, especially a kid who is working hard for their money, I think you can't go wrong with either the Aiyima 04, 07 or the Topping. I would recommend spending the extra cash on better speakers. I'm running these amps into my Elac DBR 62s, which I am completely enamored with, not my JBL L65s or Elac UF5s, and you will get better sound.

Sorry if that didn't answer your question directly, but that's my take on the Topping.
 
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Amplifier dude

Amplifier dude

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Joined 2020
Since this is a DIY forum, the best value for a budget class D amp is either the Icepower 100 or 200as modules. Probably outlast all this Chinese stuff as well. Top quality parts, and designed for 24/7 operation for many years.

Get 20 people together on a group buy and they’re $68 a piece shipped for the 100AS2

https://icepower.dk/buy/as-series/100as2/
$78 for the 200AS2

https://icepower.dk/buy/as-series/200as2/
 
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X

xhitespirit

Member
Joined 2020
Thank you for you kind answer @TheWalkman.
No doubt PA5 is a fine amp. However this new TPA3251 implementation is ~$300 when A04 is $50.

I am familiar with the A04, of which we modded 2 copies, assembled in bi-amp. The overall result is a strong improvement in many areas compared to one stock A04 unit, which any ear can easily spot on. And all this for less than 300 bucks. (If interested, i suggest you look at Aiyima TPA3251 Modification Build Thread, mainly ClaudeG's posts. Most mods are easy to do with basic soldering skills).

Don't get me wrong, I'm not saying PA5 is not worth the money: actually as DIY, it seems it is still possible to do better with less. That was the bottom line of my thinking behind my question.

Enjoy music !
 
amirmaj

amirmaj

Member
Joined 2011
audiosciencereview.com
TheWalkman said:
Let me me ask this: do you think JY may be gaming your tests? By sending a PA 5 to you, directly, could the test unit be a cherry? Do you think that JY really designed this unit for overall fidelity or to be certain he aced your tests, knowing, full well, that a glowing review would spike his sales (and possibly put a new Ferrrari under his Christmas tree?)

If I need to send you my PA5 for testing to confirm that what he sent you wasn’t a one off, I’m willing to take one for the team. You know how to PM me over at ASR. It’s not that I can’t spare it for a couple of weeks.
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There is always a possibility of this but Topping once made an offer that I can buy any of the gear they have tested in the open market to confirm that they are not gaming the system. From time to time members send me addition units to test and I am happy to do that in this case. So let's organize it on ASR.

And if you were in Kimura-san's team, for sure our paths may have crossed!
 
amirmaj

amirmaj

Member
Joined 2011
audiosciencereview.com
Amplifier dude said:
This is what happens when people who have no experience designing audio gear get their hands on an audio analyzer. But I suppose his objective has been met. He is getting decent traffic.
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Why are you talking about yourself in third-parson Mike? You recently bought the Prism Audio dScope analyzer, right? You had never touched one in your life before that. Nor do you understand how to use it given the elementary mistakes you make about its measurements. I have been using an Audio Precision analyzer since company inception. Bought the first one when I was working at Sony in early 1990s. And have had three different units since then.

FYI, dScope is also way too low end to measure state of the art products I test. Many have performance far in excess of the dScope. You need Audio Precision APx555 to measure these products as I do. Alas, it costs five times the dScope so you are not likely to get your hands on one. dScope is a nice entry level unit (I used and liked it) just not suitable for this kind of work.
 
amirmaj

amirmaj

Member
Joined 2011
audiosciencereview.com
PMA said:
On my scale it is one of the most meaningful amplifier tests.
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Meaningful by whose standard? Spectrum of music has high frequencies massively dropping in level. No way dual high frequency tones ever appear in music. They are at least 40 to 50 dB down. You don't have to justify tests that you run. I do. It is trivial to run such a test on AP and I have indeed run it on occasion. The fact that I can't defend it with a straight face is why I don't run it. Here are the results for example on Benchmark AHB2:

index.php


Reduce those sidebands by 40 to 50 dB and they sink well below noise floor. So you don't learn anything from it.
 
Amplifier dude

Amplifier dude

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Joined 2020
amirmaj said:
Why are you talking about yourself in third-parson Mike? You recently bought the Prism Audio dScope analyzer, right? You had never touched one in your life before that. Nor do you understand how to use it given the elementary mistakes you make about its measurements. I have been using an Audio Precision analyzer since company inception. Bought the first one when I was working at Sony in early 1990s. And have had three different units since then.

FYI, dScope is also way too low end to measure state of the art products I test. Many have performance far in excess of the dScope. You need Audio Precision APx555 to measure these products as I do. Alas, it costs five times the dScope so you are not likely to get your hands on one. dScope is a nice entry level unit (I used and liked it) just not suitable for this kind of work.
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You must be confusing me for someone else. My analyzer can measure down to -116 THD+N, up to 100v. Good enough for any amplifier out there. With all that experience you have, you’d think you would understand why professionals use the 18/19khz IMD measurement. Sadly you haven’t made it to that part of the manual yet I guess.
 
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