Noise issues with Sparkos Labs SS2590 Pro on Audiophonics HPA-DM750ET

[Morinor]

Hello to ASR community. I want to share an issue that maybe an engineer could give his view.
I have recently bought an Audiophonics HPA-DM750ET and two Sparkos Labs SS2590 Pro. Upon receiving and installing the OPAMPs, I got some noises and one OPAMP seemed to not be stable (blue light on buffer stage was flashing). I first followed the RMA process to Audiophonics as the OPAMPs were not send properly into the packaging and the OPAMP in question also didn't had any feet protector resulting into a little feet bending. They response was that nothing was wrong when they receive it, but they send another anyway.
When I received it, first I thought that something was still wrong with that. Somehow it worked for me but it seems under certain conditions. It should either have no XLR connected or I should have attached the XLRs on my preamp (Aune S17 Pro) as a few days later I discovered that with hanging XLR or a direct connection with my Eversolo DMP-A8 (without playing music) produced crackling issues on both channels, flashing led on one of the channel or even a completely channel shut of. Connecting again directly the preamp the issue is gone.
I tried even on a friend that had a power conditioner and filter with a more premium power cable and I got the same issue. The situation was improved when I attached his more premium XLR by not having crackling noises, but still having some low level hum.
Another indication was that somehow touching the amplifier chassis seemed to change the character of the noises, but not eliminating them or reducing them substantially. I checked the ground inside and I have noticed that the ground is connected directly on the chassis and nothing else seemed to be connected with that. Power supply also do not seem to be connected with ground.
Stock OPA1656IDR do not have any kind of those issues.
Does any have any clue were it could be attributed? I am suspecting something with the grounding, especially with that of XLR cable. It is strange though how the OPAMP rolling would have any relation with that. In case of having a faulty OPAMP (3 at the same time?), wouldn't been expected to have issue all the time and not having working cases (amp connected directly with a preamp)?

 

[RandomEar]

Hello to ASR community. I want to share an issue that maybe an engineer could give his view.
I have recently bought an Audiophonics HPA-DM750ET and two Sparkos Labs SS2590 Pro. Upon receiving and installing the OPAMPs, I got some noises and one OPAMP seemed to not be stable (blue light on buffer stage was flashing). I first followed the RMA process to Audiophonics as the OPAMPs were not send properly into the packaging and the OPAMP in question also didn't had any feet protector resulting into a little feet bending. They response was that nothing was wrong when they receive it, but they send another anyway.
When I received it, first I thought that something was still wrong with that. Somehow it worked for me but it seems under certain conditions. It should either have no XLR connected or I should have attached the XLRs on my preamp (Aune S17 Pro) as a few days later I discovered that with hanging XLR or a direct connection with my Eversolo DMP-A8 (without playing music) produced crackling issues on both channels, flashing led on one of the channel or even a completely channel shut of. Connecting again directly the preamp the issue is gone.
I tried even on a friend that had a power conditioner and filter with a more premium power cable and I got the same issue. The situation was improved when I attached his more premium XLR by not having crackling noises, but still having some low level hum.

It is not quite clear to me under which circumstances you have crackle and noises. Is it only when the Eversolo is directly connected to the Audiophonics? Either way, this sounds like a classic ground loop combined with a an XLR cable with bad shielding which picks up some EMI. XLR is normally quite resistant to ground loops, but it's not totally immune. There could also be some DC component coming from the Eversole, which gets properly rejected by the Aune S17 but not by the Audiophonics.

Troubleshooting steps:

• Replace the XLR cable with a good quality professional one (don't buy snake oil for hundreds of dollars, some decent Cordial or Monoprice Star Quad will be fine)
• Measure the DC component at the Eversolo XLR output with a multimeter
• Check that the mains outlets in your music room are properly wired and grounded (there are cheap-ish devices like this, if you want to test it in a fool proof way)
• Connect the Eversolo and the Audiophonics to the same mains outlet/power strip and test for noise
• Connect the Eversolo and the Audiophonics to mains outlets in different rooms / on different circuits and test for noise

Also, "premium power cables" are 100% snake oil. Power conditioners are 90% snake oil, with very few exceptions. Don't waste your money on those.

Another indication was that somehow touching the amplifier chassis seemed to change the character of the noises, but not eliminating them or reducing them substantially. I checked the ground inside and I have noticed that the ground is connected directly on the chassis and nothing else seemed to be connected with that. Power supply also do not seem to be connected with ground.

This all sounds correct and also points to a ground loop problem. Please don't alter the safety ground or cabling inside the amp unless you really know what you're doing. Otherwise, doing so can be extremely dangerous!

Stock OPA1656IDR do not have any kind of those issues.
Does any have any clue were it could be attributed? I am suspecting something with the grounding, especially with that of XLR cable. It is strange though how the OPAMP rolling would have any relation with that. In case of having a faulty OPAMP (3 at the same time?), wouldn't been expected to have issue all the time and not having working cases (amp connected directly with a preamp)?

That's really strange. Maybe the ground plane routing on the Sparkos is just bad? Is it possible you installed them "the wrong way around", or are they non-directional? If not, please do not just flip them around, it could fry the chips. Just check if this could be a problem

On the plus side, the simplest solution would be to install the OPA1656 and send the Sparkos back to Audiophonics for a refund. There will be no audible difference between the op amps anyway.

 

[Morinor]

It is not quite clear to me under which circumstances you have crackle and noises. Is it only when the Eversolo is directly connected to the Audiophonics? Either way, this sounds like a classic ground loop combined with a an XLR cable with bad shielding which picks up some EMI. XLR is normally quite resistant to ground loops, but it's not totally immune. There could also be some DC component coming from the Eversole, which gets properly rejected by the Aune S17 but not by the Audiophonics.

Troubleshooting steps:

• Replace the XLR cable with a good quality professional one (don't buy snake oil for hundreds of dollars, some decent Cordial or Monoprice Star Quad will be fine)
• Measure the DC component at the Eversolo XLR output with a multimeter
• Check that the mains outlets in your music room are properly wired and grounded (there are cheap-ish devices like this, if you want to test it in a fool proof way)
• Connect the Eversolo and the Audiophonics to the same mains outlet/power strip and test for noise
• Connect the Eversolo and the Audiophonics to mains outlets in different rooms / on different circuits and test for noise

Also, "premium power cables" are 100% snake oil. Power conditioners are 90% snake oil, with very few exceptions. Don't waste your money on those.


This all sounds correct and also points to a ground loop problem. Please don't alter the safety ground or cabling inside the amp unless you really know what you're doing. Otherwise, doing so can be extremely dangerous!


That's really strange. Maybe the ground plane routing on the Sparkos is just bad? Is it possible you installed them "the wrong way around", or are they non-directional? If not, please do not just flip them around, it could fry the chips. Just check if this could be a problem

On the plus side, the simplest solution would be to install the OPA1656 and send the Sparkos back to Audiophonics for a refund. There will be no audible difference between the op amps anyway.

All devices are on the same inexpensive power strip. Using the "isolated" power conditioner didn't help and I think it is not a problem there as I have issue when I connect XLR without anything attached. I tried the conditioner because maybe in this case something could happen. It is strange though that the same happened on another house. I will check with a multimeter that I have, if there is something on the ground.
The XLR replacement also was weird to me that gave some difference. I am using custom made Mogami W2534 with Neutrik plugs as I am all these years. Maybe I could try a used Audioquest Mankenzie that claims it has extra isolation/noise dissipation and uses separate conductor from the shielding.
About the Eversolo, maybe it somehow closes the connectivity as it didn't play a sound. I could give a try if playing music solves also the issue.

I am waiting also Audiophonics response after my new finding as they should expect to have that OPAMP used on their amplifiers. Their buffer stages devilish have a square marking exactly the size of Sparkos.

 

[RandomEar]

OK. If you connect just the XLR cable to the Audiophonics with nothing connected to the second end of the XLR, you're effectively attaching an antenna to the amp. It makes sense that this picks up EMI from the room like for example from LED lights or switching PSUs. That in itself is not concerning.

But if there is noise or hum with any other device connected to the amp, like the Eversolo, it is likely a ground loop.

 

[Morinor]

I am still investigating the issue. Yeah it seems that there is issue as noise is induced in the system through XLR working as antennas. It shouldn't be an issue though when connected to a source like Eversolo or in some cases even Topping E70. I have tried different cables. A pair of Audioquest XLR Mackenzie turned the issue more to a clear noise being less frightening for the speakers. The issue almost was solved with a pair of Sommercable having Neutrik EMC cables. Then the noise was roughly heard when going near the speaker. Having looked what those plugs do I find strange that not all cables do not have them.

What concerns me though are two things on the amplifier, if the XLR pin 1 is indeed not connected with the signal circuit and about a strange single cable connecting directly the ground plane of two buffer stages:

Does anybody find it logically to make such kind of connection? Audiophonics told me that it is expected and on other images that I have saw not having it is that the engineer didn't make proper assembly.