Topping PA5 Review (Amplifier)

[Hemini]

Has anyone tried powering a He6 of any variant off the Pa5? @JohnYang1997

 

[Toku]

Hi all,
can I use a RCA to TS (unbalanced) cable? Can it damage the amp?

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. 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 compare this operation to the wheels of a car, it is like running with two of the four wheels removed. Not only is it not possible to demonstrate its original performance at all, but it is also not good for the operation of the amplifier.

 

[nsfgp]

Hi all,
can I use a RCA to TS (unbalanced) cable? Can it damage the amp?

EDIT: Just to answer your questions: #1 Yes. #2 No. It has been done and works as shown in the video.
(Not trying to answer the question of if you should do it. As it is obvious this is not the recommended way to use a balanced input. )

 

[Toku]

It has been done and works.

Sound will be produced even with such a connection. However, the distortion increases and the output power is reduced to less than half. The operation of the amplifier is similar to SE, and the ground is half the value of the power supply voltage. There is no point in using PA5 with this.
You shouldn't do it unless you have no knowledge of electronic circuits and just want to make a sound.

 

[Eldus]

Sound will be produced even with such a connection. However, the distortion increases and the output power is reduced to less than half. The operation of the amplifier is similar to SE, and the ground is half the value of the power supply voltage. There is no point in using PA5 with this.
You shouldn't do it unless you have no knowledge of electronic circuits and just want to make a sound

So, it is safe, when turning off before plugging/unplugging cables and such, just reduced performance of the amp producing a lower quality sound?

 

[AudioArchitech]

If you're planning on using RCA’s, you're better off with something like SMSL AO200 or DA9…

 

[Gianni]

I'm temporarily using an unbalanced DAC with the PA5, awaiting the release (and @amirm review) of the Topping DX5

 

[BoredErica]

Sound will be produced even with such a connection. However, the distortion increases and the output power is reduced to less than half. The operation of the amplifier is similar to SE, and the ground is half the value of the power supply voltage. There is no point in using PA5 with this.
You shouldn't do it unless you have no knowledge of electronic circuits and just want to make a sound.

I'm temporarily using an unbalanced DAC with the PA5, awaiting the release (and @amirm review) of the Topping DX5

Exactly what Gianni said. I did the same thing when I had to wait for balanced dac to come in. I wanted to make sure pa5 was not defective while I waited. Pa5 always had more power than I needed, and unbalanced was no exception. It worked fine and beats not being able to use my speakers until dac came in.

Had I been more stubborn in getting Motu Ultralite mk5, 3 months in I'd still have no speakers to use with no eta if I was unwilling to temporarily use unbalanced.

Sometimes life events or supply shortages force us to work with things we didn't intend to originally, even if only temporarily.

 

[DualTriode]

Hello All,

I just purchased a silver one of these to test drive with the APx555.

This amplifier will take over tweeter duties driving JBL D2 compression drivers in a tri-amp system.

If things work out 3 of these things will take the place of the large bulky Crown amplifiers that I am using.

Thanks DT

 

[Eldus]

Hello All,

I just purchased a silver one of these to test drive with the APx555.

This amplifier will take over tweeter duties driving JBL D2 compression drivers in a tri-amp system.

If things work out 3 of these things will take the place of the large bulky Crown amplifiers that I am using.

Thanks DT

With all of this RCA to TS adapter talk you should test the distortion and power with a standard 2v RCA feed and 2.6v RCA signal.

 

[DualTriode]

With all of this RCA to TS adapter talk you should test the distortion and power with a standard 2v RCA feed and 2.6v RCA signal.

Hello,

All of this RCA to TS adapter conversation is “crazy talk”.

Internally this amplifier is two amplifiers in bridge mode. Using single end input is cutting off one leg and dragging the other.

Thanks DT

 

[genfreeciv]

So, odd question. Until/if I purchase a proper crossover DSP unit would wiring my active sub (Dayton SUB1200) this way be harmful?

Sometimes I want to play music with the sub off but speakers on to not bother the bedroom below mine.

View attachment 193216

A few posts later it is said that PA5 should not make such connections with a subwoofer.
This is not the case, however, for some subwoofers.
For example, in the case of SVS SB-1000 Pro subwoofer, the speaker level black (-) terminals are isolated from each other and from the amp chassis, so that you can safely use PA5 with a SB-1000 Pro with speaker level connections as you described .
For the same reason, a SB-1000 Pro can be used with no problem with speaker-level connections with a Class D amplifier whose black terminal output is always about 10 V higher than the chassis.

 

[antcollinet]

A few posts later it is said that PA5 should not make such connections with a subwoofer.
This is not the case, however, for some subwoofers.
For example, in the case of SVS SB-1000 Pro subwoofer, the speaker level black (-) terminals are isolated from each other and from the amp chassis, so that you can safely use PA5 with a SB-1000 Pro with speaker level connections as you described .
For the same reason, a SB-1000 Pro can be used with no problem with speaker-level connections with a Class D amplifier whose black terminal output is always about 10 V higher than the chassis.

Do you have a reference for that - I couldn't find anything on the SVS website.

 

[genfreeciv]

Do you have a reference for that - I couldn't find anything on the SVS website.

I checked the insulation of my SB-1000 Pro terminal blocks with a digital multimeter.
I also e-mailed SVS directly and confirmed the isolation of the speaker level inputs of the SB-1000 Pro and that there is no problem even if I connect a BTL output directly to the SB-1000 Pro.
I also sent the spec sheet of PA5 just to be sure, and received a reply that there is no problem with the speaker level connections.

 

[pjug]

A few posts later it is said that PA5 should not make such connections with a subwoofer.
This is not the case, however, for some subwoofers.
For example, in the case of SVS SB-1000 Pro subwoofer, the speaker level black (-) terminals are isolated from each other and from the amp chassis, so that you can safely use PA5 with a SB-1000 Pro with speaker level connections as you described .
For the same reason, a SB-1000 Pro can be used with no problem with speaker-level connections with a Class D amplifier whose black terminal output is always about 10 V higher than the chassis.

I don't know if it matters but the voltage would typically be about half the power supply voltage, so a lot more than 10V in this case.

 

[genfreeciv]

I don't know if it matters but the voltage would typically be about half the power supply voltage, so a lot more than 10V in this case.

Yes, but since it is OK with the PA5 BTL outputs, I think it does not matter if it could raise up to +20 V or more.

 

[daniboun]

Hi Amigos,

Just finished to mount the New Active PFC PSU A-DP 400. By testing it I made a great discovery, in any case it is observable at home!

I first set the A-DP 400 @ 40V / 10A, The PA5 simply refused to switch on, like it was going into protected mode
Then I gradually lowered the voltage, and @ 36V it starts ) This makes me say that the PA5 has a protection tuned by topping to avoid tweaking its nominal voltage.... I reproduced the scenario several times and I can therefore confirm this test with a multimeter measurement.

Now concerning the sound, I'm in the test phase and I'm going to listen to it with my Playlist at different volume levels, to see which of the two PSUs sounds better. As reminder :

Connex SMPS 300RS LLC @ 36V / 8,3A VS A-DP 400 Active PFC @ 36V / 11A

The Connex SMPS300RS use state of the art, very efficient LLC Series Resonant Converter Topology. Due to the soft-switched topology used, the SMPS300RS has very low EMI noise and also has a very low ripple.
The A-DP 400 has an active PFC controller for an high efficiency, PF value greater than 0.98, and its Output ripple is less than 150mV.

I mounted both PSUs with a DC blocker and good quality cables.

 

[gamerpaddy]

I first set the A-DP 400 @ 40V / 10A, The PA5 simply refused to switch on, like it was going into protected mode

That is because the PA5 uses a TPS5430 Step-down IC which is only rated up to 36Volts.

40V Absolute maximum with following note:

Approachingthe absolute maximum rating for the VIN pin may cause the voltage on the PH pin to exceed the absolute maximum rating.

lucky one that you didnt damage it, they usually fail with a short. Vin on Vdd would blow up the tpa3255 or worse, the potted secret topping module.

EDIT:
it seems that its the TPA3251 not tpa3255!
its max. recommended voltage is 38V, absolute max 50v. so its allready running full steam
i wonder what happens when you solder in a tpa3255, its pin compatible it seems.

 

[daniboun]

That is because the PA5 uses a TPS5430 Step-down IC which is only rated up to 36Volts.

40V Absolute maximum with following note:

lucky one that you didnt damage it, they usually fail with a short. Vin on Vdd would blow up the tpa3255 or worse, the potted secret topping module.

Thanks, )

So we are all lucky in this case) since the stock brick power supply is given @ 38V / 4A... fortunately : the multimeter measurements show 35V and it oscillates in passing.... (34V - 35V)

 

[gamerpaddy]

Either your Multimeter is faulty or your Power supply, maybe you also got some noise getting into your test leads somewhere. the psu isnt grounded, ac leakage is normal and can mess up your results.

i tested mine.

(!! some of it could be from my setup and equipment, im sitting on budget stuff. !!)
equipment used: Unit-T UT61E, Siglent SDS1204X-E, EastTester ET5420 Electronic Load, probes set to 10x. dodgy and long wiring all over the bench.

No load:
37.96V
pretty stable over a timespan of 14 seconds (2V/div)

Noise wasnt too bad either
20Mhz BW limit, 17mV at a few hundred hz.

FFT up to 200khz, ive seen worse.

Constant 4A Load:
Voltage was 37.67V,
also quite stable i dont saw any movement over 14sec (again 2V/div due to my offset range wasnt big enough on 1V/div setting)

noise and ripple increased. roughly 40mV at inner part. looks extreme but keep in mind this is a very low level signal.

And where is all that HF crap coming from? right, the SMPS switching frequency.
its at ~155khz with a bandwidth of 20khz.

the PSU got a little warm after a few minutes under 4A load, nothing to worry about. most notebook psu's doing much worse.