Topping PA5 Review (Amplifier)

[DanielT]

There's a cohort of people that don't believe phase variances are audible or significant.

Absolute phase then you can hear difference but not relative phase shift, differences because it is masked by reflections in the listening room and becomes inaudible? Or?

Edit.
Forgot that this exists. Interesting:

 

[maty]

It is very easy to detect the phase impact on the tweeter using rePhase, at least in my second and cheap audio system (KEF Q100 5.25" coaxial modded and tweaked by me).

 

[KSTR]

@maty,
Which kind of phase changes exactly? Please give details.
Care to take part in a forum ABX I might do to verify your claim?

 

[voodooless]

It's hard to tell what impact phase has had because it's not the only variable that has changed. Once it is the only variable, all bets are off it's unlikely anyone could detect a minor phase difference coming from amps with different bandwidths and roll-offs.

It's far more likely that the perceived difference is from the change in gain than anything else.

 

[KSTR]

It's far more likely that the perceived difference is from the change in gain than anything else.

This (when not level-matched), and from changed distortion and noise patterns.

 

[pma]

I'm one of them wrt to amps at any rate, assuming non-pathological situations.

We both know that there is a direct relation between amplitude response and phase response of the physically practicable systems and this relation is the Hilbert transform. Thus, in case we have amplitude response deviation that is proven to be audible, then we necessarily have phase response that is audible and this phase response would be calculated by Hilbert transform from amplitude response. So, we cannot say that the phase response is inaudible .

 

[maty]

I emulated the Hypex phase, and it was really easy. If only 10º to 20 kHz is more difficult, that is the logical thing. With good acoustic recording and large dynamic range.

I did not do ABX, I have been saying for a long time that something happens to foobar2000 with ABX.

With JRiver MC the sound is clearly better and it is much easier for me to detect differences.

 

[KSTR]

Good catch, Pavel (unterstood you're tongue in cheek smilie).

As phase changes kick in much earlier than amplitude changes, we still have significant changes in phase (10deg++) eben with amplitude differences below thresholds, at the corners of the audio band. Think 10Hz highpasses and 40Khz lowpasses

 

[pma]

I have been saying for a long time that something happens to foobar2000 with ABX.

.... and this is something you have never proven. In fact, foobar2000 ABX yields bit-perfect output and the problem would be elsewhere.

 

[pjug]

That’s interesting that you say it’s not a normal run of the mill chip we can swap to do this. Well lots more head scratching on this then, but armchair reverse engineering costs nothing, so nothing lost.

It is really hard to believe it is not one of the TI parts. The connections seem consistent with the TI. He didn't say it wasn't, just that drop in replacement won't give normal function. Is it possible that the circuit requires individual tuning for each amplifier IC to give optimum performance? I wouldn't think so, but I wonder.

I am just curious. I hope nobody copies the design.

 

[bravomail]

This happened to a TPA3255 implemented following the TI Reference design as to LC filter and snubber. It only blew up when I ran at about 125w for over 30 seconds without a load. This was a stress test on a 300w load resistor. The channel without the resistor blew up. I don’t think it would have blown up at 75w. The LC filter is designed assuming a particular load to damp the oscillations. I suppose catch diodes had they been implemented would have e prevented this.

did TI Ref design include catch diodes?

 

[ClassicGuy]

Well John, filling a patent on something that was already on the market is like... wasting a bit of ink at most, let alone trying to enforce it... I would take it as a tribute
Congrats btw, i wish you sell zillions of these.

Patent law may not apply the same way in China.

Also, even in the US, when a company obtains a patent to an already existing technology, it can still cause significant disruption and inconveniences to other vendors. You can look up the MailBlocks case.

 

[xrk971]

did TI Ref design include catch diodes?

No

 

[Holmz]

…, differences because it is masked by reflections in the listening room and becomes inaudible?
…

Does that assume that people do not hear the direct path, and that they only get the ensemble of everything arriving at once?

 

[restorer-john]

assuming non-pathological situations

What would be pathological to you?

 

[NTK]

Quoting Douglas Self:

The Dan Rather Approved Douglas Self Site

 

[AudioArchitech]

Has anyone received their PA5 and done any subjective listening comparisons yet?

 

[bahamot]

Has anyone received their PA5 and done any subjective listening comparisons yet?

Toku posted it on couple pages before:

Regarding the sound quality that is most worrisome, I compared it with PA3s, AO200, A20a, and AIYIMA A07/A04, but PA5 produces a different dimension of sound from these amplifiers.
The energy of the mid-low range, the transparency of the high range, and the resolution are improved. It sounds like an upgraded version of the highly acclaimed MA12070 chip amp. The first thing I felt when I heard the sound of PA5 was the size of the sound stage. When you hear this sound, you are satisfied with the price of PA5. However, how you feel the sound varies from person to person, so please understand it for reference only.

 

[Toku]

Has anyone received their PA5 and done any subjective listening comparisons yet?

Amazon in Japan has a detailed usage report.

Amazon.co.jp: TOPPING PA5 Full Balance Power Amplifier 140W x 2 TRS x 2 Input Speaker Terminal Output, Class D Power Amplifier HiFi Amplifier Black : Electronics

Amazon.co.jp: TOPPING PA5 Full Balance Power Amplifier 140W x 2 TRS x 2 Input Speaker Terminal Output, Class D Power Amplifier HiFi Amplifier Black : Electronics

www.amazon.co.jp

 

[DanielT]

Does that assume that people do not hear the direct path, and that they only get the ensemble of everything arriving at once?

What Amir mentions in the video I linked to is the "phase soup" that takes place in a normal listening room, due to all the reflections in the listening room. Thus, in practice, we can not hear the phase differences.Works the same way with headphones.However, we can detect direction due to the location of our ears, the direction from which the sound is coming. But that's another matter.

Then a little OT:
Time, time dealy also plays a role but it is also another matter.Then on to the directivity, frequency response and distortion so well it is as far as I know the only parameters that determine how something sounds.Unfortunately, I can not develop it more than that due to lack of knowledge, but this is basically basic acoustics. Basic course 1A for an acoustician and acoustician should be plentiful at ASR. They can certainly help and sort out in more detail how this with sound and how we humans work.