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Topping PA5 Review (Amplifier)

D

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Odd that you’d have issue with two separate units.
They replaced the power brick too I assume?

Hop you don't mind a suggestion ... Try a completely different amplifier... If you've still got the noise it is being fed to your amplifier by something upstream.
 

wlgreg

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Hop you don't mind a suggestion ... Try a completely different amplifier... If you've still got the noise it is being fed to your amplifier by something upstream.
I did swap out with my backup rig (Pi4+Hifiberry DAC+Hifiberry amp). No problems whatsoever with that combo. Static is only present when PA5 is in use.
 

JeffGB

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My PA5 has been running perfectly for a couple of months but, after confirming data sheets on the TPA3251, I decided to lower the voltage from 38v to 32v. The chip is spec'd as 12v-36v and then the "absolute maximum" is rated at 38v. I want longevity because the amplifier is just THAT good that I don't want it to die prematurely. I have an Aiyima a07 as well, so I changed it's power supply connector to the Topping one and hooked it up. It seems to run perfectly with the 32v and is cooler. I don't need any more power so it's a win win for me. I can replace the PA5's power supply's connector with one compatible with the Aiyima because the Aiyima a07 is using the TPA3255 chip which is rated at 51v absolute maximum. Time will tell if the lower voltage will result in better reliability.
 

antcollinet

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Yes, but only at the input connector.... It's done in pro-audio quite a bit.
Basically the input is an opamp set up as a differential input with single ended output.

Like this....

View attachment 200347

Grounding the cold signal (Pin 2) just forces it to revert to single ended behaviour.

Or is this amp "fully balanced", input to output?
According to tests done (earlier in thread), that is not the case. If you drive it unbalanced, you only drive one side of the BTL amp.


EDIT LATER : That is not what the tests show at all, now I've actually looked at them. See my post later in the thread post number 4256 here:

 
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D

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According to tests done (earlier in thread), that is not the case. If you drive it unbalanced, you only drive one side of the BTL amp.
Awww .... I just knew it was too good to be true.
Thanks guys .... I appreciate your responses.
 
D

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I did swap out with my backup rig (Pi4+Hifiberry DAC+Hifiberry amp). No problems whatsoever with that combo. Static is only present when PA5 is in use.
In that case I would be forced to conclude there is a problem with the PA5 ... @JeffGB may have it figured out. The TPA3251 spec sheet recommends 36 volts. Has anyone checked the voltage rating on the bulk capacitors?
 
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IPunchCholla

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According to tests done (earlier in thread), that is not the case. If you drive it unbalanced, you only drive one side of the BTL amp.
I read that, but don’t understand amplifier topology enough to understand the issue. I have been feeding my PA5 an SE signal for months now and have no issues with it. Given that, is there a reason to upgrade the DAC/Preamp?
 

Toku

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I read that, but don’t understand amplifier topology enough to understand the issue. I have been feeding my PA5 an SE signal for months now and have no issues with it. Given that, is there a reason to upgrade the DAC/Preamp?
The same question has been asked many times, but the PA5 cannot be used with an unbalanced connection.
PA5 has adopted the BTL style circuit system which uses two amplifiers in the opposite phase in one channel. The input circuit is designed exclusively for balanced connections. If unbalanced connection is made to this amplifier circuit, the signal will be input to only one amplifier and the other amplifier will not function.
If you are a user who thinks it is OK if the sound comes out of the speaker and you can hear the music, you can use it. However, if you use it like that, the measurement data of amirm becomes meaningless. Besides, there is no point in using the expensive PA5.
 
D

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I read that, but don’t understand amplifier topology enough to understand the issue. I have been feeding my PA5 an SE signal for months now and have no issues with it. Given that, is there a reason to upgrade the DAC/Preamp?
The topology isn't that complex... basically they have 2 complete power amplifiers for each channel. If they drive them out of phase (one going negative while the other goes positive) they can at least double the output power. BUT if you shut one of the two in each BTL (Bridge Tied Load) down not only do you lose power you get terrible distortion because one side of the speaker is not being properly controlled.

Balanced audio is better ... when it's done right.

The good news is that you can get relatively inexpensive converters to take the single ended RCA signal and "phase split" it for the balanced connection.
 

IPunchCholla

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Ok. But are we sure that is the topology or the consequences? Because I am not getting terrible distortion. Or maybe I don't understand what that is. REW shows THD at <1% for everything except deep sub bass and around 150-250hz where it approaches 10%.

Subjectively, my speakers sound crisp and clean. Even my sound engineer friend said they sounded great to him. These are speakers I paid $300 for 30 years ago. This setup certainly sounds better (cleaner and fuller) than my APA150 feeding an Elac Debut 2.0. It is also not noticeably distorted compared to my headphones listening to the same signal but via the pre/headphone amp.

Anyway, any recommendations for the converter? I had been planning on getting a Schiit SYS and Magnius and selling of my L30, but the Magnius is out of stock for another 6 weeks or so.

Edited for spelling
 
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D

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Ok. But are we sure that is the topology or the consequences? Because I am not getting terrible distortion. Or maybe I don't understand what that is. REW shows THD at <1% for everything except deep sub bass and around 150-250hz where it approaches 10%.

Subjectively, my speakers sound crisp and clean. Even my sound engineer friend said they sounded great to him. These are speakers I paid $300 for 30 years ago. This setup certainly sounds better (cleaner and fuller) than my APA150 feeding an Elac Debut 2.0. It is also not noticeably distorted compared to my headphones listening to the same signal but via the pre/headphone amp.

Anyway, any recommendations for the converter? I had been planning on getting a Schiit SYS and Magnius and selling of my L30, but the Magnius is out of stock for another 6 weeks or so.

Edited for spelling
That's what I'm wondering. In pro audio it's all done with cables. Surely they would have thought of that... But they're not talking about the small details in any of their documentation. That's why I asked here, myself...

You could try this converter.... the fidelity won't be perfect but for a short term it should be okay...
https://www.amazon.com/dp/B0027V760M (You will need two for stereo)
 

IPunchCholla

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That's what I'm wondering. In pro audio it's all done with cables. Surely they would have thought of that... But they're not talking about the small details in any of their documentation. That's why I asked here, myself...

You could try this converter.... the fidelity won't be perfect but for a short term it should be okay...
https://www.amazon.com/dp/B0027V760M (You will need two for stereo)
Thanks! I'll check those out. I do plan to go fully balanced, but just wondered about it since I am not getting huge audible issues. I mean my distortion level at 96dB is under 1% for everything except the bass (which is close to 5% at the worst, I misread the scale). That seems pretty close to the distortion measurements for good speakers in the reviews. And while I can hear the distortion during the 96dB tone sweep (in the bass) it isn't terrible and I don't hear it during normal playback of music (which I listen closer to 86dB). I am using LA Audio RCA to TRS cables, but that wouldn't overcome the differential audio issue, since it is essentially just having the ground function as both the ground and one half the audio input. Probably the issue would show up pretty quick if I listened louder/had a bigger space to fill.
 

IPunchCholla

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Bummer. I like the sound with one of the sources I have connected single-ended with TRS adapters to the PA5.
If you like the sound, is it an issue? I'm in the same boat and planned on upgrading to balanced feeds, but now I'm questioning it.
 
D

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If you like the sound, is it an issue? I'm in the same boat and planned on upgrading to balanced feeds, but now I'm questioning it.

Your results seem to belay the claim that it's not set up to work single ended.

So I guess the answer here is that we simply don't know...

The good news is that it would sound terrible before you damaged anything.
 

JeffGB

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If the PA5 is fully differential, as it appears to be (I'm not aware of anyone tracing the circuit, including the potted module), it will perform more like the TPA3251 spec sheet states for an SE connection, as opposed to BTL (the PA5) or PBTL (the 4 amplifiers bridged into a mono configuration). The results are not "terrible" distortion, but it is poorer (about .006 thd at 5w per the spec sheet) compared to (about .002 thd at 5w per the spec sheet). The power is also less, as others have explained.

The following comment is subjective, so avert your eyes if it bothers you. I have a MOTU M4 which outputs a full differential signal to the amplifier and I also have an Audient ID14 mkii which outputs a "balanced" signal, but which is only resistive balanced: ie it achieves the lack of ground loops by balancing the output with a couple of resistors, one of which connects to ground rather than the negative differential signal. I have no ground loop problems with either, but the MOTU sounds far better to me. The Audient sounds smooth but not very detailed. There is a substantial difference in the sound, which there isn't when I connect the same DAC's to a single ended amp. As I said this is just subjective but perhaps gives an indication there is more happening than just a different DAC chip. Again, the Audient is audibly very nice with the PA5 if it isn't compared directly to the MOTU so you don't need to throw out your single ended DAC if you find the sound with the PA5 to be fine.

I'm not trying to influence anyone with my comments, I'm just trying to add the information I have gained so that those making a decision have as much to go on as possible.

In my opinion, if you have a single ended DAC that you plan on keeping, you are better to go with an amp like the Aiyima a07, but if you have a balanced (fully differential) DAC or are planning to get one the PA5 is wonderful.
 

nawfal07

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Hi guys, I’ve been using my Denon AVC-X4700H as a stereo amp to power a set KEF Q350 speakers, feeding from Topping D90SE.

It does sound great but I’m wondering if it can be even better.

What is eveyone’s opinion if I swap the Denon with a Topping PA5 as the stereo amp? Would the smaller watt defeat the sound quality?

Thanks in advance. Cheers.
 
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