Bought a Topping A90, exchanged it, same issue.

[selmantabet]

Hey everyone, I hope this is the right forum section for this.

This is my first post, and it's about a QC issue I encountered with the Topping A90. I was referred here from r/headphones, and they mentioned someone named JohnYang1997.

I bought the amp in December from ShenzhenAudio, and when I received it, I noticed annoying noise being audible throughout loud passages when I'm plugged into the Balanced 4-pin XLR output. The Single-ended performance, however, is outstanding and shows how the A90 is such a capable amp. Sadly, I bought this amp specifically for its performance on Balanced. The input was Balanced (from an SMSL SU-8), and I kept switching AC power sources, even moved to different city districts, to test the setup. My CTH amp's balanced output exhibited no issues, while the A90's balanced output seemed faulty. I contacted ShenzhenAudio and they were kind enough to cover my return shipping cost (that's like over $40 through the cheapest air parcel service, shipping is super expensive here), and get an exchange.

A month passed and now I have the exchanged unit, and the issue was there, albeit slightly less annoying than the last one. I'd like to hear what you guys think the issue could be. ShenzhenAudio offered me a full refund and they can apparently cover the second return shipping. Since the local post offices are closed for a national holiday, I want to hear your opinion on this.

Edit: I am aware that the CTH is not truly balanced, I tried setting the input on the A90 to RCA, and the issue persisted.

TL;DR Topping A90 noisy on Balanced output, exchanged, same issue. ShenzhenAudio has been nothing short of awesome. Topping's QC is questionable at best for me now.

 

[Veri]

I bought the amp in December from ShenzhenAudio, and when I received it, I noticed annoying noise being audible throughout loud passages when I'm plugged into the Balanced 4-pin XLR output. The Single-ended performance, however, is outstanding and shows how the A90 is such a capable amp.

Weird, especially since you're using balanced in balanced out....

What headphones are you using ?

 

[selmantabet]

Weird, especially since you're using balanced in balanced out....

What headphones are you using ?

Argon Mk3 on Balanced. Worked like a charm on other amps.

 

[JohnYang1997]

Faulty cable probably? If you feel the need you can send the unit back to us we will cover the shipping cost. But on the QC, every unit is tested on APx555 with load on 6.35 and XLR. As it's second unit, it's almost impossible for both to have the same issue.
It sounds like your cable is shorting the output causing it to clip.

 

[JustAnandaDourEyedDude]

Unclear. Some possibilities to ponder. Noise? Or distortion? Loud passages? Intersample overs/peaks? Does the noise go away if you lower SU-9 output by 3dB and raise A90 volume and/or gain level to compensate? XLR interconnect between SU-9 and A90 may be faulty. SU-9 XLR output or A90 XLR input may be incompatible. Balanced cable/XLR to Argon may be faulty. A90 could have rare QC flaw or systematic design flaw. If your two A90 have the same issue, the probability of the issue being due to a QC flaw is highly reduced as compared with design flaw. But design flaw causal probability is very low at the current time since you are the first to report such an issue, and the A90 has been out for a while now. In terms of probability, all of this points to something other than A90 being the issue. Most likely a cable problem, as @JohnYang1997 said.

Hey everyone, I hope this is the right forum section for this.

This is my first post, and it's about a QC issue I encountered with the Topping A90. I was referred here from r/headphones, and they mentioned someone named JohnYang1997.

I bought the amp in December from ShenzhenAudio, and when I received it, I noticed annoying noise being audible throughout loud passages when I'm plugged into the Balanced 4-pin XLR output. The Single-ended performance, however, is outstanding and shows how the A90 is such a capable amp. Sadly, I bought this amp specifically for its performance on Balanced. The input was Balanced (from an SMSL SU-8), and I kept switching AC power sources, even moved to different city districts, to test the setup. My CTH amp's balanced output exhibited no issues, while the A90's balanced output seemed faulty. I contacted ShenzhenAudio and they were kind enough to cover my return shipping cost (that's like over $40 through the cheapest air parcel service, shipping is super expensive here), and get an exchange.

A month passed and now I have the exchanged unit, and the issue was there, albeit slightly less annoying than the last one. I'd like to hear what you guys think the issue could be. ShenzhenAudio offered me a full refund and they can apparently cover the second return shipping. Since the local post offices are closed for a national holiday, I want to hear your opinion on this.

Edit: I am aware that the CTH is not truly balanced, I tried setting the input on the A90 to RCA, and the issue persisted.

TL;DR Topping A90 noisy on Balanced output, exchanged, same issue. ShenzhenAudio has been nothing short of awesome. Topping's QC is questionable at best for me now.

 

[Veri]

Faulty cable probably? If you feel the need you can send the unit back to us we will cover the shipping cost. But on the QC, every unit is tested on APx555 with load on 6.35 and XLR. As it's second unit, it's almost impossible for both to have the same issue.
It sounds like your cable is shorting the output causing it to clip.

This user posted on reddit too. It's only when music is playing. Weird that it happens over XLR but it most certainly the DAC, or DAC connection :

https://www.reddit.com/r/headphones/comments/lg40lp

 

[selmantabet]

This user posted on reddit too. It's only when music is playing. Weird that it happens over XLR but it most certainly the DAC, or DAC connection :

https://www.reddit.com/r/headphones/comments/lg40lp

The thing is, even when the input is RCA, it would still be audible through the A90's XLR output. Wouldn't that mean that the DAC isn't the faulty part? The CTH sounds just fine with its RCA input on both XLR (not fully balanced) and 1/4 outputs.

So this is how it's like:
XLR In -> 1/4 Out (Excellent)
XLR In -> XLR Out (Noisy)
RCA In -> 1/4 Out (Excellent)
RCA In -> XLR Out (Noisy)

 

[selmantabet]

Faulty cable probably? If you feel the need you can send the unit back to us we will cover the shipping cost. But on the QC, every unit is tested on APx555 with load on 6.35 and XLR. As it's second unit, it's almost impossible for both to have the same issue.
It sounds like your cable is shorting the output causing it to clip.

Thanks a lot for your reply. I just placed an order on a bunch of cables from Hart Audio and will be getting them in a week or so to test this.

 

[selmantabet]

Faulty cable probably? If you feel the need you can send the unit back to us we will cover the shipping cost. But on the QC, every unit is tested on APx555 with load on 6.35 and XLR. As it's second unit, it's almost impossible for both to have the same issue.
It sounds like your cable is shorting the output causing it to clip.

Although I doubt it, people kept on mentioning the possibility that the DAC could be the fault in the chain. If I absolutely had to get a new DAC (which I won't if there is no need to replace my SU-8), what output impedance the DAC should have to match well with the A90?

 

[JohnYang1997]

Although I doubt it, people kept on mentioning the possibility that the DAC could be the fault in the chain. If I absolutely had to get a new DAC (which I won't if there is no need to replace my SU-8), what output impedance the DAC should have to match well with the A90?

I don't think it's the dac. I meant the balanced cable from 4pin xlr to your headphones. Something could be happening in the plug.

 

[Veri]

The thing is, even when the input is RCA, it would still be audible through the A90's XLR output. Wouldn't that mean that the DAC isn't the faulty part?

On both the RCA and XLR output, when using RCA in? The mysterious thing to me is the noise only is there when the DAC is crunching data.
Or yeah, maybe it's the headphone cable like John says.. hmm......

Although I doubt it, people kept on mentioning the possibility that the DAC could be the fault in the chain. If I absolutely had to get a new DAC (which I won't if there is no need to replace my SU-8), what output impedance the DAC should have to match well with the A90?

The SU-8 does not have an excessive output impedance. The A90 input impedance can only be problematic with really high output impedance like older/vintage gear, phono, or oddballs like the SMSL M400. SU-8, SU-9 and any modern DAC really should work well without issue.

 

[selmantabet]

On both the RCA and XLR output, when using RCA in? The mysterious thing to me is the noise only is there when the DAC is crunching data.
Or yeah, maybe it's the headphone cable like John says.. hmm......

I've included this in an edit on an earlier post but I'll paste it here.
--
So this is how it's like:
XLR In -> 1/4 Out (Excellent)
XLR In -> XLR Out (Noisy)
RCA In -> 1/4 Out (Excellent)
RCA In -> XLR Out (Noisy)
--

 

[selmantabet]

On both the RCA and XLR output, when using RCA in? The mysterious thing to me is the noise only is there when the DAC is crunching data.
Or yeah, maybe it's the headphone cable like John says.. hmm......

I don't think it's the dac. I meant the balanced cable from 4pin xlr to your headphones. Something could be happening in the plug.

I highly appreciate all of your prompt responses. The cables I included in my cables order are Argon Balanced and HD6XX Balanced for good measure. This way I could tell if it's the Argon's Balanced port or only its cable, that is, assuming the HD6XX isn't also faulty. I will report back with updates. Thanks a lot.

 

[selmantabet]

I don't think it's the dac. I meant the balanced cable from 4pin xlr to your headphones. Something could be happening in the plug.

On both the RCA and XLR output, when using RCA in? The mysterious thing to me is the noise only is there when the DAC is crunching data.
Or yeah, maybe it's the headphone cable like John says.. hmm......


The SU-8 does not have an excessive output impedance. The A90 input impedance can only be problematic with really high output impedance like older/vintage gear, phono, or oddballs like the SMSL M400. SU-8, SU-9 and any modern DAC really should work well without issue.

I highly appreciate all of your prompt responses. The cables I included in my cables order are Argon Balanced and HD6XX Balanced for good measure. This way I could tell if it's the Argon's Balanced port or only its cable, that is, assuming the HD6XX isn't also faulty. I will report back with updates. Thanks a lot.

Just got the new cables. The issue is resolved and it is absolute perfection right now. Seems it has been the cables after all. Thanks for all your help guys <3

 

[GAGBraine]

Just got the new cables. The issue is resolved and it is absolute perfection right now. Seems it has been the cables after all. Thanks for all your help guys <3

Hello
I am facing the exact same issue with my brand new a90 connected to an AK SE200 LINE OUT balanced and feeding an Audeze LCD X through the XLR out.
Did you figure out which cable was causing the issue?
Thanks

 

[Veri]

Hello
I am facing the exact same issue with my brand new a90 connected to an AK SE200 LINE OUT balanced and feeding an Audeze LCD X through the XLR out.
Did you figure out which cable was causing the issue?
Thanks

In his case it was faulty headphone cables.

 

[Jimbob54]

Hello
I am facing the exact same issue with my brand new a90 connected to an AK SE200 LINE OUT balanced and feeding an Audeze LCD X through the XLR out.
Did you figure out which cable was causing the issue?
Thanks

Is that a 2.5mm to dual XLR from the AK? My money would be on that cable being the dodgy one . Can you get a cheap 3.5mm to RCA and run that into the a90 instead to see if the headphone cable and a90 4pin xlr isnt to blame?

 

[GAGBraine]

Just got the new cables. The issue is resolved and it is absolute perfection right now. Seems it has been the cables after all. Thanks for all your help guys <3

Hello
I am facing the exact same issue with my brand new a90 connected to an AK SE200 LINE OUT balanced and feeding an Audeze LCD X through the XLR out.
Did you figure out which cable was causing the issue?
Than

Is that a 2.5mm to dual XLR from the AK? My money would be on that cable being the dodgy one . Can you get a cheap 3.5mm to RCA and run that into the a90 instead to see if the headphone cable and a90 4pin xlr isnt to blame?

Yes it is a 2.5 to dual xlr and indeed 3.5/RCA is working perfectly. 6.35 out to headphone is also sounding weird when connecting the AK through xlr so tend to agree with you.

 

[GAGBraine]

Hello
I am facing the exact same issue with my brand new a90 connected to an AK SE200 LINE OUT balanced and feeding an Audeze LCD X through the XLR out.
Did you figure out which cable was causing the issue?
Than

Yes it is a 2.5 to dual xlr and indeed 3.5/RCA is working perfectly. 6.35 out to headphone is also sounding weird when connecting the AK through xlr so tend to agree with you.

Just received a new 2.5 to dual xlr cable. It is now working perfectly and I am enjoying the a90 touch at its best. Many thanks for your guidance