SOTA Pyxi Initial Impressions
- Thread starter mprince
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wyn palmer
Addicted Member
It can be as simple as rotating the Pyxi, or the mesh/router node, or shifting the phono cables. or it may not work at all.
There is a "fix" that substantially improves the situation, but it's a board/component change in the second build and I don't know if SoTa is manually wiring it into the first build.
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wyn palmer
Addicted Member
The DIY design at home and the Acrux are essentially immune to this. it's very specific to the layout/phono socket build/wiring. You need to avoid antennas. I have a wifi socket a few feet away and it has no effect on the Pyxi, but the mesh node does.
The MM design with the FET input designs is less susceptible, not just because of the lower gain, but also because FETs are less affected than bipolars.
wyn palmer
Addicted Member
If the wifi scenario is confirmed, and the repositioning doesn't work, let SoTa know.
I've already successfully dealt with a user who had a similar problem which used up my one and only "fixed" prototype, but I believe that SoTa may have more units they can substitute, although I could be entirely wrong. They have no obligation to keep me in the loop, although, to their credit, they often do.
I've already successfully dealt with a user who had a similar problem which used up my one and only "fixed" prototype, but I believe that SoTa may have more units they can substitute, although I could be entirely wrong. They have no obligation to keep me in the loop, although, to their credit, they often do.
mprince
Super Member
Doing some troubleshooting this morning, results thus far:
- Base Case - WiFi node on, Pyxi installed in MC mode, no record playing: got the hum through right channel in less than 5 minutes.
- Disconnect WiFi node: played one album side, got audible hum through right channel shortly after side finished.
- Disconnected tonearm ground from Pyxi - persistent hum, increases when arm is touched.
- Put my SUT in circuit with Pyxi in MM mode, tonearm ground connected to SUT: played one album side, sat next to speaker when complete, did not detect any hum (waited ~10 minutes)
- Removed SUT, left Pyxi in MM mode with tonearm ground connected and played music (also reconnected WiFi node, but moved it a few feet further away from Pyxi as taking it out did not eliminate issue). Got audible hum through right channel (same as #2)
wyn palmer
Addicted Member
Hum and wifi interference are different things. The wifi will produce multiple c. 10Hz pulses, producing a burbling noise, hum will be, well, a hum- i.e. harmonics of 60Hz. Which is it? Depending on which it is the approach will differ.
It might be better if you take this offline- either email me directly or PM me on AK. That way we can go through a more complete debug.
mprince
Super Member
Will do (PM), at this point I see a return of the unit to SOTA. Any sound differences are spoiled by this noise issue, and all of this is not there with my incumbent phono stage.
As info, the SUT/MM Pyxi combo has been silent for over an hour.
Thats is whats weird, adding an SUT to the MM has less noise and hum with out. This has been mentioned to the same with the DIY version as well.
I need to try this when I get home but my MM section of the DIY has no noticeable hum unless i crank the volume full on.
Athansios
mprince
Super Member
To Wyn's point above, I may have mischaracterized my noise as hum. This is a sporadic pulse of noise that randomly comes through, it lasts less than a second. To me hum is pretty distinct and more constant. The problem I've had in troubleshooting this is that the noise is random and very short in duration, so it is hard to characterize.
Based on some of the stuff Wyn has asked me to do off-line, I am inclined to say the Pyxi is fine and the noise is being introduced to it via my tonearm wiring - this is not audible in the incumbent phono stage, possibly the SUT is acting as a filter of sorts? I don't have an educated background in this stuff, but in my experience with this SUT (5+ years) it "fixes" these noise issues regardless of what MM stage is downstream of it.
Based on some of the stuff Wyn has asked me to do off-line, I am inclined to say the Pyxi is fine and the noise is being introduced to it via my tonearm wiring - this is not audible in the incumbent phono stage, possibly the SUT is acting as a filter of sorts? I don't have an educated background in this stuff, but in my experience with this SUT (5+ years) it "fixes" these noise issues regardless of what MM stage is downstream of it.
mprince
Super Member
So, to close the loop on the past day or so...Wyn has helped me with some more troubleshooting, and we are both confident that the Pyxi is working properly. We both feel the noise is being introduced through my tonearm, which in simple terms is acting as an RF antenna. I guess the bad news with that is that I don't really have a path to fix that within the arm - when I had noise problems in the past, I shipped the arm back to Jeff Spall at Audiomods to check it, he found nothing wrong and also rewired as a precaution (because he is a great guy). I do have an email in to Christian Griego at SOTA to see if he has any guidance on anything additional I could do between the turntable and the arm to mitigate this, but I've been down this path before to an extent, and I don't really think there is any more to do there.
The good news is that my "hail mary" when I was battling noise previously was to use an SUT with a MM stage. That is how I have been successfully running the past 4 years. Wyn did confirm today that the SUT effectively blocks the RF from reaching the MM inputs, resulting in good performance. This was confirmed when I put the SUT in front of the Pyxi a few posts ago at Nashou66's suggestion. I just didn't know this was a real answer when I did it four years ago, I got lucky on my own.
So, SOTA is willing to take the Pyxi back; I hate to return a perfectly good unit, but it's not going to work in my system without an SUT, and it doesn't make sense to me to have an MC phono pre where I run it in MM mode to use MC. I've let Christian know I'd like to return it, just waiting for an RMA. I may ask him about the next iteration of the Pyxi with the updated board/improved noise rejection Wyn mentioned up the page.
If this random noise issue hadn't popped up, I could have seen the Pyxi replacing my Rothwell setup, I liked it very much. I can still recommend the Pyxi, it just didn't work completely with my system (not the first phono stage I've said this about). Looking forward to hearing about others' success with their Pyxis, and special thanks to @wyn palmer for the assist with this today!
The good news is that my "hail mary" when I was battling noise previously was to use an SUT with a MM stage. That is how I have been successfully running the past 4 years. Wyn did confirm today that the SUT effectively blocks the RF from reaching the MM inputs, resulting in good performance. This was confirmed when I put the SUT in front of the Pyxi a few posts ago at Nashou66's suggestion. I just didn't know this was a real answer when I did it four years ago, I got lucky on my own.
So, SOTA is willing to take the Pyxi back; I hate to return a perfectly good unit, but it's not going to work in my system without an SUT, and it doesn't make sense to me to have an MC phono pre where I run it in MM mode to use MC. I've let Christian know I'd like to return it, just waiting for an RMA. I may ask him about the next iteration of the Pyxi with the updated board/improved noise rejection Wyn mentioned up the page.
If this random noise issue hadn't popped up, I could have seen the Pyxi replacing my Rothwell setup, I liked it very much. I can still recommend the Pyxi, it just didn't work completely with my system (not the first phono stage I've said this about). Looking forward to hearing about others' success with their Pyxis, and special thanks to @wyn palmer for the assist with this today!
I read this thread with a lot of interest, not trying to hijack this thread. When @wyn palmer mentioned WiFi as a possible culprit I started wondering if that hasn't been my issue with phono preamps over the years. I have a PC that's within 18 inches of where my preamp sits and also about 8 feet away is a wifi access point that I use with a MagicJack & a DialGizmo for my antique phone.
It's maddening when trying to trace the source of noise.
Mike
It's maddening when trying to trace the source of noise.
Mike
mprince
Super Member
Mike - curious if you had any noise issues with the Pyxi while you had it in your system? I agree that tracking down noise, especially in the analog chain, can drive one a bit crazy.
Just out of curiosity, does your office have fluorescent lighting?
I used to get that random "beat-like" noise at certain frequencies on my shortwave receiver. After much ado, I turned off the ceiling lighting and the noise went away.
It's like the lights cycle or something, when turned on.
mprince
Super Member
Not fluorescents, but a couple LED bulbs. I did turn them off yesterday while troubleshooting, to be fair I can't remember what if any effect that had. While I still have the Pyxi I need to turn these lights off and totally shut down WiFi throughout the house (not just my office node) to see if the issue persists. Bit of a roadblock doing that right now is my daughter came up last night and is working out of my house the next few days, so she needs WiFi to work (I have no problem interrupting my work though haha). Maybe at lunchtime.Just out of curiosity, does your office have fluorescent lighting?
I used to get that random "beat-like" noise at certain frequencies on my shortwave receiver. After much ado, I turned off the ceiling lighting and the noise went away.
It's like the lights cycle or something, when turned on.
I think LED lights which I'm sure most of us have can also cause interference. I know that they can cause issues with TV reception.Just out of curiosity, does your office have fluorescent lighting?
I used to get that random "beat-like" noise at certain frequencies on my shortwave receiver. After much ado, I turned off the ceiling lighting and the noise went away.
It's like the lights cycle or something, when turned on.
Mike
I've haven't had LED problems. But, reading the OP accounts --- this sure sounds like fluorescent lights. The noise is a random switch-like pulsing tone. A couple of short ones, then a long one that last maybe 10 seconds. Random is what made it hard for me to trace down.
You don't have any fluorescent lighting in the office, anywhere? I think that the noise can be injected into the AC power line.
mprince
Super Member
This is not my noise. Mine is a "blip", a short pulse of noise that lasts less than a second. There is no pattern of multiple noises, just randomly-spaced single noise which is the same every time. I'd say the noise does not repeat in less than 10 or 20 minute intervals.