SOTA Pyxi Initial Impressions

[mprince]

So, I left things on but walked away for a bit. Right now the phone is turned on and I have it sitting right under my tonearm for the last 10 minutes or so to amplify its impact - so far no noises from my speakers. So, I'm not 100% on the phone as the culprit yet. When I got the Pyxi last week I went a day or two with no issues, then this noise cropped up on Monday. Looks like I may be back to last week's state right now. I am going to put the Pyxi back where it's "permanent" home was, a few inches from my tube pre buried in the back of my rack, play music and let it sit idle a bit, and see if that changes anything.

I still think there is something environmental at play here (and something I really have little control over outside of the experiments of the last few days) that is causing this issue. Some of the things I have been turning on and off to test are useful for troubleshooting, but they are not real world fixes.

So, to answer Wyn's question, I'm not sure what the next step is. I am gone for the next few weeks between travel and a bunch of medical stuff when I return, so realistically tomorrow is the last time I can dig into this until mid-September. The last time I went through this, I was determined to "fix" it, fought it for a year and wound up with a head amp that I could not return and could not sell with a clear conscience because of the issues I had using it. I don't want to land in the same place with the Pyxi, and now being fairly certain the fault does not lie with the Pyxi, a path forward trying to "fix" my system or electrical/RF environment to work with it seems a bit cloudy to me.

 

[wyn palmer]

So, I left things on but walked away for a bit. Right now the phone is turned on and I have it sitting right under my tonearm for the last 10 minutes or so to amplify its impact - so far no noises from my speakers. So, I'm not 100% on the phone as the culprit yet. When I got the Pyxi last week I went a day or two with no issues, then this noise cropped up on Monday. Looks like I may be back to last week's state right now. I am going to put the Pyxi back where it's "permanent" home was, a few inches from my tube pre buried in the back of my rack, play music and let it sit idle a bit, and see if that changes anything.

I still think there is something environmental at play here (and something I really have little control over outside of the experiments of the last few days) that is causing this issue. Some of the things I have been turning on and off to test are useful for troubleshooting, but they are not real world fixes.

So, to answer Wyn's question, I'm not sure what the next step is. I am gone for the next few weeks between travel and a bunch of medical stuff when I return, so realistically tomorrow is the last time I can dig into this until mid-September. The last time I went through this, I was determined to "fix" it, fought it for a year and wound up with a head amp that I could not return and could not sell with a clear conscience because of the issues I had using it. I don't want to land in the same place with the Pyxi, and now being fairly certain the fault does not lie with the Pyxi, a path forward trying to "fix" my system or electrical/RF environment to work with it seems a bit cloudy to me.

Well, it was not a coincidence that I suggested the cell phone, and if that is manageable then all should be set. If you would like to keep the Pyxi if it was in its noiseless state then keep it, and if future issues arise as far as the noise is concerned I'll take responsibility for refunding you the $300 and shipping for sending it back to either me or SoTa.
Well, assuming I don't die in the meantime.

 

[mprince]

Well, it was not a coincidence that I suggested the cell phone, and if that is manageable then all should be set. If you would like to keep the Pyxi if it was in its noiseless state then keep it, and if future issues arise as far as the noise is concerned I'll take responsibility for refunding you the $300 and shipping for sending it back to either me or SoTa.
Well, assuming I don't die in the meantime.

Wow, that is quite a great offer Wyn in addition to all of the other help you've given me this week. Let me continue to use it tomorrow in "normal" use case and see if it stays noiseless and I'll try to make a keep/return decision tomorrow. I may PM you tomorrow if you are available as I might have some ideas about repositioning some gear in my rack to hopefully mitigate potential interference between components.

 

[Mr Boochie]

So, I left things on but walked away for a bit. Right now the phone is turned on and I have it sitting right under my tonearm for the last 10 minutes or so to amplify its impact - so far no noises from my speakers. So, I'm not 100% on the phone as the culprit yet. When I got the Pyxi last week I went a day or two with no issues, then this noise cropped up on Monday. Looks like I may be back to last week's state right now. I am going to put the Pyxi back where it's "permanent" home was, a few inches from my tube pre buried in the back of my rack, play music and let it sit idle a bit, and see if that changes anything.

Any possibility of street work being done? Say, by the electric company?

Just shooting spit wads at the wall.

It's good you have a noiseless backup.

Thanks!

 

[wyn palmer]

Wow, that is quite a great offer Wyn in addition to all of the other help you've given me this week. Let me continue to use it tomorrow in "normal" use case and see if it stays noiseless and I'll try to make a keep/return decision tomorrow. I may PM you tomorrow if you are available as I might have some ideas about repositioning some gear in my rack to hopefully mitigate potential interference between components.

That sounds fine. Hey, although SoTa pays me nothing for this or anything else (my requirement) I still feel an obligation, so I will help in whatever way I can.

 

[mprince]

Any possibility of street work being done? Say, by the electric company?

Just shooting spit wads at the wall.

It's good you have a noiseless backup.

Thanks!

Nothing I'm aware of. These noise issues have haunted my system for ~5 years, but appreciate the spitballing (don't stop). I think we are down to having our arms around where the noise is coming from (and its not the Pyxi), eradicating the source will be the challenge that makes me crazy haha

 

[Nashou66]

You mentioned you changed cables for this most recent test. I wonder if the original cables you used were part of the issue?

Athanasios

 

[mprince]

You mentioned you changed cables for this most recent test. I wonder if the original cables you used were part of the issue?

Athanasios

I thought that too, I have the original cables back in as I put the Pyxi back where it was and just used the Morrow cable that was there from the Rothwell setup. Another thing to keep an eye on, but once I decide on a final location for the Pyxi, I think I have enough Mogami cable and Neutrik/Rean ends to make the right length cable between the Pyxi and preamp. Then all of the cables in the system will be identical construction-wise ( I like short cable paths and orderly runs).

I've messed with this a bunch this week and my head is still spinning from Wyn's last post...

 

[wyn palmer]

Possibly. The RF rejection of cables varies tremendously. You need pretty good, grounded shielding on the wires to work well. Essentially the input should look like an instrumentation amp with shielding connected to ground at the termination and complete (and thick) coverage provided to avoid leakage.

 

[Nashou66]

I also noticed in your equipment list you have and Adcom GFA-545 as your amp. When I first built the Wyn preamp I discovered that i needed at least 2 feet of distance from my Adcom GFA-535 otherwise i had a nasty hum. In this last test where there was no noise was the Pyxi further from the amp than in its first location when it did have noise?

Just more to think about.

 

[mprince]

I also noticed in your equipment list you have and Adcom GFA-545 as your amp. When I first built the Wyn preamp I discovered that i needed at least 2 feet of distance from my Adcom GFA-535 otherwise i had a nasty hum. In this last test where there was no noise was the Pyxi further from the amp than in its first location when it did have noise?

Just more to think about.

Perhaps 6 inches farther away, not too much further than normal which is probably close to 2 feet (2 shelves of separation with the Pyxi further back as well)

 

[mkane]

Wires/interconnects in close proximity to one another should cross @ 90° and not run parallel to each other.

 

[Mr Boochie]

Wires/interconnects in close proximity to one another should cross @ 90° and not run parallel to each other.

I arrange the interconnects by turning the phono and system pre-amp on to moderate to loud levels. Put on headphones and start moving the cables around one-by-one, until I get the lowest noise. Temporarily tape them into place using masking tape. Then, loosely tying them with twist ties to supports or one another --- once everything is sorted out. Twist ties allow changes, if you should need to move anything, later.

Yes, cable placement makes a difference, with low-level inputs.

 

[T68]

Maybe off topic or not. But if my smartphone gets closer than two feet of my Little bear T10 tube phono preamp all kinds of noises can start happening.

So cell phones definitely interferes with audio gear.

 

[mprince]

Another question from above addressed - interconnects. I made up a set of RCA cables this morning to use from the Pyxi to my preamp - Mogami 2534 microphone cable with Rean (Neutrik) ends. Cable has 4 conductors (which get paired together to make 2 conductors) and a nice copper shield layer, which is twisted with the ground conductor and soldered to the RCA shield in one end. Also double checked all routing - everything is neat with minimal crossing of cables, no parallel paths for those concerned about this.

It's been a while since I made a set of interconnects, forgot how satisfying that is...

 

[Mr Boochie]

Another question from above addressed - interconnects. I made up a set of RCA cables this morning to use from the Pyxi to my preamp - Mogami 2534 microphone cable with Rean (Neutrik) ends. Cable has 4 conductors (which get paired together to make 2 conductors) and a nice copper shield layer, which is twisted with the ground conductor and soldered to the RCA shield on both ends. Also double checked all routing - everything is neat with minimal crossing of cables, no parallel paths for those concerned about this.

It's been a while since I made a set of interconnects, forgot how satisfying that is...

Mogami mic cables are very, very nice items.

 

[RickB]

Another question from above addressed - interconnects. I made up a set of RCA cables this morning to use from the Pyxi to my preamp - Mogami 2534 microphone cable with Rean (Neutrik) ends. Cable has 4 conductors (which get paired together to make 2 conductors) and a nice copper shield layer, which is twisted with the ground conductor and soldered to the RCA shield on both ends. Also double checked all routing - everything is neat with minimal crossing of cables, no parallel paths for those concerned about this.

It's been a while since I made a set of interconnects, forgot how satisfying that is...

Have you floated one end of the braided shields and compared its noise rejection capability then?
That's pretty much SOP for single ended cables with dual internal conductors and a shield.
I think the theory is that grounding the shield on both ends just adds to the capacitance of the cord. and can still act as an antenna,
while the one end grounded method allows the shield to actually shield...direction, i.e., what end is connected to what device is also a consideration

 

[wyn palmer]

Have you floated one end of the braided shields and compared its noise rejection capability then?
That's pretty much SOP for single ended cables with dual internal conductors and a shield.
I think the theory is that grounding the shield on both ends just adds to the capacitance of the cord. and can still act as an antenna,
while the one end grounded method allows the shield to actually shield...direction, i.e., what end is connected to what device is also a consideration

Correct. Hence my comment "You need pretty good, grounded shielding on the wires to work well. Essentially the input should look like an instrumentation amp with shielding connected to ground at the termination and complete (and thick) coverage provided to avoid leakage."
Perhaps I should have added the word ONLY between connected and to.

 

[mprince]

Have you floated one end of the braided shields and compared its noise rejection capability then?
That's pretty much SOP for single ended cables with dual internal conductors and a shield.
I think the theory is that grounding the shield on both ends just adds to the capacitance of the cord. and can still act as an antenna,
while the one end grounded method allows the shield to actually shield...direction, i.e., what end is connected to what device is also a consideration

Yes, should have said that in previous post (thanks for that), these are directional in that the cable shield is connected only on the source end, the target end has only the conductor attached to connector shield.

 

[Nashou66]

Yes, should have said that is previous post (thanks for that), these are directional in that the cable shield is connected only on the source end, the target end has only the conductor attached to connector shield.

This is where I have had different results. One end of the shield only connected I got more hum than both ends connected to GDN . But this might have been a one off case. I need to be more data collection oriented while doing these tests, i.e., keep better notes of what I am doing, something I admit I lack discipline in.

Also I have read a few places where many in the "profession" say for phono cable the shield should be GND'd at both ends as a mandatory practice. But I guess its what works in your system.

I will revisit my cables construction at some point in the near future .

Nashou