Topping PA7 Plus Amplifier Review

[Vladetz]

PA 5 II and PA 5 II plus are exactly the same amps but with different power supply
The same is correct for PA7 and PA7 plus
More powerful supply gives you only a bit more headroom for loud peaks
That's all the difference
Sound quality for all PA models is indistinguishable

 

[Roland68]

Ok thanks. In practical terms, what differences in real world, audible performance would there be between the PA5 and PA5plus? When I look at the sellers website the specs for output power seem to be exactly the same, despite the larger power supply in the Plus. I'm curious if it would be worth the extra $100AU over the base model.

Both amplifiers are absolutely the same, only the power of the power supplies differs. Otherwise there are no differences.
The PA5 II had 71 watts at 4 ohms and 53 watts at 4 ohms in the test with very low noise levels. The maximum was 120 watts at 4 ohms.
The PA5 II Plus will have the same maximum power and perhaps 10 - 20 watts more in the normal power.
At the moment, depending on the country, there may be offers where the difference between the two versions is smaller.

 

[ant1973]

Buy one of the low-medium cost amplifiers, try it and decide what you think. No harm in that.

If you think it's ultimately disappointing, they are cheap enough to throw out, or give away and buy something better. All this stuff is inexpensive disposable audio.

If you're happy, you've saved a ton of money.

Part of the problem with this hobby is that you can't really be happy while there is a more expensive alternative that may give you something "better".....

I have a similar issue to the other Kef owner. Purchased a pair of Kef Reference Speakers (203/2) for a really good price recently. They are rated as follows:-

Efficiency (2.83V/1m)	89dB
Maximum output level (SPL)	113 dB

They are in a large open plan area of 11m x 4m. I sit no more than 3m away. I own a 20 year old Roksan Kandy Ka1-III. It will give me 120w at 8ohms and 185 at 4ohms. The Amp gain is 38db. I paired it with an old sonos connect amp ( so a sub-par source, and indeed a $5 DAC from my phone initially). Both sounded really good, but there is no real information about whether the amp is producing a "coloured" sound.

Managed to track down the manual with the following specs

Inputs Line Level (x5), Moving Magnet (x1), Tape (x1) Input Impedance 47 kΩ Input Sensitivity (115W) Line 470mV Outputs Speaker L & R (x1), Preamplifier (x2), Tape (x1), Headphone (x1) Output Power >120 Watts, into 8Ω both channels driven >185 Watts, into 4Ω both channels driven Power Supply 500VA Ultra Low Noise Toroidal Transformer 4 Regulated Supply Rails Damping Factor >110 (8Ω) Frequency response (-3dB), <3Hz – >100kHz Gain 38dB Overall (Pre & Power) 7dB Preamplifier 31dB Power Amplifier Harmonic Distortion <0.005% 1kHz - 8Ω Signal to Noise Ratio Line 100dBa (ref 470mV) Power Source 100V – 120V 50Hz / 60Hz 220V – 240V 50Hz / 60Hz Power Consumption Standby <25W, Full Power 2-CH 8Ω < 330 W, 4Ω <550W Dimension 432 x 380 x 90 (W x D x H) mm 432 x 380 x 102 (including feet) Weight 14 Kg

I was thinking about buying Fosi Monoblocs, Topping PA7 PLus or the Nord 502 value line. But I am not really sure I need anything more than an amp that gives me reasonable volume at 3m? I am told that listening at 89db is very loud and may cause hearing damage. This calculator suggests I only need 5w of amplification tor reach that level?

https://mehlau.net/audio/spl/

At 11m, I need 60w to generate 89db.

It seemed to me that the cheapest, cleanest amp would do the job for me with some to spare?

A greater priority would appear to be a better source, however.

Am I missing something? I don't pretend to understand the graphs and information in the same way other better informed members do and worry I am missing something. The idea of pairing speakers which cost £4000 new (£6800 for the piano black ones I have!) with an inexpensive amp feels counter-intuitive, or at least proves the efficacy of audiophile advertising on those like me who are a little ignorant....

 

[Ahmonge]

Am I missing something?

To find out how much power you need from an amplifier in your case, it's best to start from the maximum volume level you need. A simple and reasonably accurate way to do this is to buy a calibrated handheld sound level meter (there are decent ones on Amazon from 30€/35$), and measure several tracks of the type of music at the volume you usually listen to, with dBC weighting and peak metering mode. Then you use the power calculator you refer to and get the minimum power needed for the amp.

Another thing is what type and price of amplifier will give you the best sound quality.

 

[JeremyFife]

Part of the problem with this hobby is that you can't really be happy while there is a more expensive alternative that may give you something "better".....

I have a similar issue to the other Kef owner. Purchased a pair of Kef Reference Speakers (203/2) for a really good price recently. They are rated as follows:-

Efficiency (2.83V/1m)	89dB
Maximum output level (SPL)	113 dB

They are in a large open plan area of 11m x 4m. I sit no more than 3m away. I own a 20 year old Roksan Kandy Ka1-III. It will give me 120w at 8ohms and 185 at 4ohms. The Amp gain is 38db. I paired it with an old sonos connect amp ( so a sub-par source, and indeed a $5 DAC from my phone initially). Both sounded really good, but there is no real information about whether the amp is producing a "coloured" sound.

Managed to track down the manual with the following specs

Inputs Line Level (x5), Moving Magnet (x1), Tape (x1) Input Impedance 47 kΩ Input Sensitivity (115W) Line 470mV Outputs Speaker L & R (x1), Preamplifier (x2), Tape (x1), Headphone (x1) Output Power >120 Watts, into 8Ω both channels driven >185 Watts, into 4Ω both channels driven Power Supply 500VA Ultra Low Noise Toroidal Transformer 4 Regulated Supply Rails Damping Factor >110 (8Ω) Frequency response (-3dB), <3Hz – >100kHz Gain 38dB Overall (Pre & Power) 7dB Preamplifier 31dB Power Amplifier Harmonic Distortion <0.005% 1kHz - 8Ω Signal to Noise Ratio Line 100dBa (ref 470mV) Power Source 100V – 120V 50Hz / 60Hz 220V – 240V 50Hz / 60Hz Power Consumption Standby <25W, Full Power 2-CH 8Ω < 330 W, 4Ω <550W Dimension 432 x 380 x 90 (W x D x H) mm 432 x 380 x 102 (including feet) Weight 14 Kg

I was thinking about buying Fosi Monoblocs, Topping PA7 PLus or the Nord 502 value line. But I am not really sure I need anything more than an amp that gives me reasonable volume at 3m? I am told that listening at 89db is very loud and may cause hearing damage. This calculator suggests I only need 5w of amplification tor reach that level?

https://mehlau.net/audio/spl/

At 11m, I need 60w to generate 89db.

It seemed to me that the cheapest, cleanest amp would do the job for me with some to spare?

A greater priority would appear to be a better source, however.

Am I missing something? I don't pretend to understand the graphs and information in the same way other better informed members do and worry I am missing something. The idea of pairing speakers which cost £4000 new (£6800 for the piano black ones I have!) with an inexpensive amp feels counter-intuitive, or at least proves the efficacy of audiophile advertising on those like me who are a little ignorant....

Hi,
One of the joys of this site is gaining the understanding that sometimes you simply don't need to spend more money to get a better sound ... it can be counterintuitive, but that doesn't stop it from being true. The hard part is to accept that

I'm not sure about your calculator, I like https://www.crownaudio.com/en/tools/calculators#amp_power_required which suggests that 90dB SPL (loud!) at 3m with your speakers and 6dB headroom to allow for big dynamic peaks in your music (basically only really for Classical) = 45W
In other words, your existing Amp is just fine.
If your Amp is not noisy (hissing in the quiet passages, crackling in the louder passages) and the sound is not distorting then you really won't hear a difference upgrading the Amp - not a priority.

One thing to look at - that input gain is high by modern standards. Think of gain as a multiplying ratio for your input signal - plenty to read about on this site - but the practical implication is that even a more highly powered Amp will probably sound quieter because of that. Doesn't change total power, but does affect the perceived volume until you are at Max.

You can probably do better for a source though. Why not try a Wiim Pro Plus - excellent DAC and automated room correction with nice EQ to adjust if if you want to.

 

[ant1973]

Thanks - that is incredibly helpful. Cognitive bias is the bane of my life!

I now understand the gain issue. I have found it endlessly puzzling that some people talk about seldom having crank their amp up beyond 10 o'clock, whereas the sound on my own amp is somewhat "quiet". It is also affected by the DAC as well. The $5 DAC is "quieter" than the Sonos Zone player. Having listened again last night, it is tolerably clear that the input signal is the issue. I have been looking at the Wiim Ultra as I quite like the look and increased feature set and think I will start from that point.

I suppose looked at rationally, the amp's job is, put simply, to "amplify" the signal. If it does that and you don't like the sound, blame the other variables e.g. source, room, etc.

 

[aler]

You could even use it in a main system if you leave the volume set and use the DAC or a pre-amp with a remote.

Hello,
I was considering this for a main system with floorstanders, but afraid reading this, what does that mean?

 

[Roland68]

Thanks - that is incredibly helpful. Cognitive bias is the bane of my life!

I now understand the gain issue. I have found it endlessly puzzling that some people talk about seldom having crank their amp up beyond 10 o'clock, whereas the sound on my own amp is somewhat "quiet". It is also affected by the DAC as well. The $5 DAC is "quieter" than the Sonos Zone player. Having listened again last night, it is tolerably clear that the input signal is the issue. I have been looking at the Wiim Ultra as I quite like the look and increased feature set and think I will start from that point.

I suppose looked at rationally, the amp's job is, put simply, to "amplify" the signal. If it does that and you don't like the sound, blame the other variables e.g. source, room, etc.

You could also consider a Sabaj A30a.
Only a streamer with a digital output is needed, no more DAC required and enough power (2 x 200 watts at 4 ohms) is available.

 

[Eldus]

Hello,
I was considering this for a main system with floorstanders, but afraid reading this, what does that mean?

All it means is that to change the volume of the amp using the amp you have to physically adjust the volume knob on the amp. If you want to adjust the volume with a remote it has to be done before the audio gets to the amplifier. Many newer DACs come with volume remotes these days and act as pre-amps. You would then turn the knob on the amp all the way up and control the volume with the source of the audio (in this example a dedicated DAC). You can adjust the volume with the knob just fine, just not far away from the amp. Amir is just assuming that a "main system" is one where you are not in arm's reach of the amp while you would want to adjust the volume and would rather use a remote control.

 

[aler]

Okaaaay! As simple as that...
Thx!

 

[ppataki]

Has anybody tried driving 2-ohm speakers with the PA7 Plus?
Thank you

 

[Guy.Cohen]

Hi,

I wonder if there is a slew rate or rise time test for the PA7.
It is true that one can estimate by the bandwidth but still I wonder.

It might be a drawback of digital amplifiers because of their output filter (and thus also speed is load dependent).
Maybe the TPAxxxx family is good in this regards or modern implementation like Eigentakt (because of the feedback sampling location) but anyway I did not see this test (and it can't be done seriously with AP, I think).

Guy

 

[staticV3]

I wonder if there is a slew rate or rise time test for the PA7.
It is true that one can estimate by the bandwidth but still I wonder.

It might be a drawback of digital amplifiers because of their output filter (and thus also speed is load dependent).

Slew rate is sufficient for flat response to, and far beyond, the capabilities of the human ear.

Anything more is useless and irrelevant.

 

[Guy.Cohen]

Slew rate is sufficient for flat response to, and far beyond, the capabilities of the human ear.

Anything more is useless and irrelevant.

Thanks.

I don't know how much slew is enough. Most dacs are limited to 4-6V/uS. I think amplifier needs to have more than this. 30-50khz bandwidth is not going to achieve it.
All measurements done usually are static and not measuring slew induced distortions (SID).
Maybe SID were popular at the past (John Curl et al) and has no meaning.
I don't understand why not to publish by manufacturer unless it is not so good and class D amplifier are suspected in this

 

[quattro98]

Thanks.

I don't know how much slew is enough. Most dacs are limited to 4-6V/uS. I think amplifier needs to have more than this. 30-50khz bandwidth is not going to achieve it.
All measurements done usually are static and not measuring slew induced distortions (SID).
Maybe SID were popular at the past (John Curl et al) and has no meaning.
I don't understand why not to publish by manufacturer unless it is not so good and class D amplifier are suspected in this

Can take a look at this PDF on page 11 for a discussion and page 17 for a summary. TL;DR: SID is not an issue.

https://linearaudio.net/sites/linearaudio.net/files/volume1bp.pdf

This PDF has been linked in this thread on ASR:

Negative feedback bad for audio?

Hello, I bought 2 monoblocks NC400 DIY kits from hypex directly, because of the measurements here in the forum. They sound amazing and the assemly was very easy. Thanks for the great reviews! Last week I had a listening session with a guy who build high end OTL tube amps and there were many...

audiosciencereview.com

 

[Guy.Cohen]

Can take a look at this PDF on page 11 for a discussion and page 17 for a summary. TL;DR: SID is not an issue.

https://linearaudio.net/sites/linearaudio.net/files/volume1bp.pdf

This PDF has been linked in this thread on ASR:

Negative feedback bad for audio?

Hello, I bought 2 monoblocks NC400 DIY kits from hypex directly, because of the measurements here in the forum. They sound amazing and the assemly was very easy. Thanks for the great reviews! Last week I had a listening session with a guy who build high end OTL tube amps and there were many...

audiosciencereview.com

Thank you, I will read the content of the links