Topping PA5 II Stereo Amplifier Review

[bboris77]

Really, the problem with your amplifier "Could have taken my speaker out had I not intervened in time." ?
sorry for your trouble. my PA5 II is working faultlessly

Good for you. Just don't leave it powered on when you are not around would be my advice. I am done with Topping.

 

[DVinylfan]

I never leave anything electrical powered on when I'm not around, why would I?

 

[Sokel]

Good for you. Just don't leave it powered on when you are not around would be my advice. I am done with Topping.
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Everyone of us who values its gear should have an alter with a DMM on it and pray to it 3 times a day.
I will never get tired of saying it, gear should be measured right out of the box, while cold and while hot.

Rinse and repeat from time to time, frequently.

 

[Ahmonge]

What is disappointing is that the amp did not go in any kind of protect mode once the DC voltage went haywire.

Yes, it is. DC protection must be in place and shut down a defective unit.

 

[bboris77]

I never leave anything electrical powered on when I'm not around, why would I?

I agree in principle and don't really want to fight with you. I turn off high-power devices like amplifiers at the end of the day as well, but forgot to last night.

My beef is with the fact that this amplifier does not have any kind of protection circuitry that senses an obvious fault condition which can damage anything connected to it. That, and the fact that went poof within a day. Reputable companies burn in their equipment for a few days on racks before sending them to consumers to avoid this "early failure" phenomenon.

 

[DVinylfan]

I agree in principle and don't really want to fight with you. I turn off high-power devices like amplifiers at the end of the day as well, but forgot to last night.

My beef is with the fact that this amplifier does not have any kind of protection circuitry that senses an obvious fault condition which can damage anything connected to it. That, and the fact that went poof within a day. Reputable companies burn in their equipment for a few days on racks before sending them to consumers to avoid this "early failure" phenomenon.

just return it to Topping or Ur 3rd party seller and you're golden

 

[levimax]

The upper limit of what is acceptable according to the spec sheet is 60mV and the speaker starts getting damaged at 500mV from my limited research on the subject.

Sorry to hear about your issue. To me 60 mV seems very high. For DIY class AB amps I have built I assumed 20 mV was the upper limit and they were always lower than that. All the recent amps I have built have a DC servo on the output so have 0 mV of offset. For a supposedly SOTA amp I am surprised they have any DC offset. I am starting to wonder if compromises to reliability and protection circuitry are being made in pursuit of higher SINAD.

 

[Sokel]

Clearly a defective unit. Measured mine; no input signal, volume set to normal listening level: 12 mV (right channel) and 44 mV (left channel). Same figures after two hours listening to it.

With no sources connected to it 44mV is a bit on the high side, it should be much lower.
Ideally 0mV or single digit one when talking about a really good design.

 

[Ahmonge]

With no sources connected to it 44mV is a bit on the high side, it should be much lower.
Ideally 0mV or single digit one when talking about a really good design.

It would be interesting if other PA5 II owners measure DC output and share their results with all of us. And even better if they also measure other audio amplifiers.

 

[Sokel]

It would be interesting if other PA5 II owners measure DC output and share their results with all of us. And even better if they also measure other audio amplifiers.

A thread about it would be fun.
With pictures too, like @bboris77 's post or at speaker's terminals for an end-to-end view!

 

[bboris77]

A thread about it would be fun.
With pictures too, like @bboris77 's post or at speaker's terminals for an end-to-end view!

I’m kind of hoping you are sarcastic. I really didn’t want to make everyone with a speaker amp paranoid, but it may not be a bad idea to check stuff periodically. It’s the only way manufacturers will get serious about this.

Most class A/B amps I’ve tested are anywhere between 0-15mV. Most importantly, they don’t fluctuate madly. I know this DC offset can drift a bit over a long period of time, but not drastically.

A related question - does anyone know whether there are any under $300 class D speaker amps that have a functioning protection mechanism that kicks in if DC offset on the output gets above a certain level? I believe almost all class A/B receivers and integrated amplifiers have this basic safety feature. Some class D amps advertise DC offset detection and protection on their inputs but are silent on speakers outputs.

 

[Sokel]

I’m kind of hoping you are sarcastic. I really didn’t want to make everyone with a speaker amp paranoid, but it may not be a bad idea to check stuff periodically. It’s the only way manufacturers will get serious about this.

Most class A/B amps I’ve tested are anywhere between 0-15mV. Most importantly, they don’t fluctuate madly. I know this DC offset can drift a bit over a long period of time, but not drastically.

A related question - does anyone know whether there are any under $300 class D speaker amps that have a functioning protection mechanism that kicks in if DC offset on the output gets above a certain level? I believe almost all class A/B receivers and integrated amplifiers have this basic safety feature. Some class D amps advertise DC offset detection and protection on their inputs but are silent on speakers outputs.

My only reasoning is to protect the fellow members and if such thread come up maybe some will benefit, no more.
I just checked myself the 4 channels of my amps (icepower 1200as2 and 300a2) and they are within 1.5mVDC and 3.5mVDC so your post was a good service for peace of mind.

 

[Maxon]

A related question - does anyone know whether there are any under $300 class D speaker amps that have a functioning protection mechanism that kicks in if DC offset on the output gets above a certain level? I believe almost all class A/B receivers and integrated amplifiers have this basic safety feature. Some class D amps advertise DC offset detection and protection on their inputs but are silent on speakers outputs.

The TDA3255 has overheating protection (thermal protection) and output short circuit protection (short circuit protection). In more detail:Overheating protection (thermal protection):The TDA3255 chip is equipped with built-in thermal protection. If the temperature of the chip exceeds the permissible limit, it will automatically shut down to prevent damage. After cooling down, the chip turns on again.Short circuit protection (short circuit protection):The TDA3255 also has an output short circuit protection. If the output of the chip is short-circuited to ground or to the power supply, the short-circuit protection disables the output stage to prevent damage to the chip.These protective measures significantly increase the reliability and durability of the TDA3255 when working with acoustic systems.

 

[Fabsen]

Have this AMP for almost 1.5 years and distortion used to be 1.2% at 3400hz but as of now it is at 7% (REW measurements with UMIK). This is only for the right channel.
I checked and it is not the Speaker, nor any Cable. That is quite some degradation. Is this normal or is my unit broken?

 

[Roland68]

Have this AMP for almost 1.5 years and distortion used to be 1.2% at 3400hz but as of now it is at 7% (REW measurements with UMIK). This is only for the right channel.
I checked and it is not the Speaker, nor any Cable. That is quite some degradation. Is this normal or is my unit broken?

Did you also swap the speaker cables and RCA/XLR cables for left and right, i.e., together/at the same time?
And then measured again?

 

[Bleib]

I haven't noticed any audible change with my TP RA3
I also have PA5 II plus but it's not connected atm

 

[Fabsen]

Did you also swap the speaker cables and RCA/XLR cables for left and right, i.e., together/at the same time?
And then measured again?

One change at a time and played one channel at a time. It is easily audible then and I could identify that it is indeed the Amp. Could it be related to the 53 Watt at 8 Ohm? Maybe I am pushing beyond that, but then again, why would it only happen to the right channel

 

[Sokel]

Have this AMP for almost 1.5 years and distortion used to be 1.2% at 3400hz but as of now it is at 7% (REW measurements with UMIK). This is only for the right channel.
I checked and it is not the Speaker, nor any Cable. That is quite some degradation. Is this normal or is my unit broken?

1.2% was already high normally at 3kHz-4kHz.
At what level do you test it and with what kind of speakers (small, larger,etc)

7% is a reason to put it away before do any damage.

 

[Fabsen]

Ohh, thanks for the advice! But I do not have any other Amp around
For Testing, I leveled it to 75dB, so in my case ~60% (50% = vertical up) of the Power Amps knob. (I have a PreAmp Gain of -6.3 in EAPO (from what I understood in the Windows thread)). I use Ascend Sierra 1 V2 as Speakers. I will do more testing later

 

[Sokel]

Ohh, thanks for the advice! But I do not have any other Amp around
For Testing, I leveled it to 75dB, so in my case ~60% (50% = vertical up) of the Power Amps knob. (I have a PreAmp Gain of -6.3 in EAPO (from what I understood in the Windows thread)). I use Ascend Sierra 1 V2 as Speakers. I will do more testing later

Have a look at the distortion at Amir's test at 86dB:

I would suggest you do some near field testing, even the previous 1.2% is way too high up there.
Could be the amp,could be a whole system error, etc.

7% though seems something clearly broken.