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SOTA Pyxi Phono Stage Review

Rate this phono stage:

  • 1. Poor (headless panther)

    Votes: 10 8.4%
  • 2. Not terrible (postman panther)

    Votes: 24 20.2%
  • 3. Fine (happy panther)

    Votes: 66 55.5%
  • 4. Great (golfing panther)

    Votes: 19 16.0%

  • Total voters
    119

restorer-john

Grand Contributor
Joined
Mar 1, 2018
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Gold Coast, Queensland, Australia
No, both MC and MM cartridges are seismic type which basically means they start working accurately once the frequency gets high enough for the stator part of the cartridge, which is the bit in the headshell, is close enough to stationary with respect to the stylus, which happens from around 2x the natural frequency of the mass on the suspension.
At very low frequency the cartridge body and headshell move with the stylus - which is just as well otherwise it wouldn’t be able to track the record of course. As the frequency goes up towards resonance the same excitation is moving the headshell much more than the stylus then at resonance there is a 180 degree phase shift and the cartridge body amplitude starts to reduce until at around twice the natural frequency the headshell becomes acceptably close to static relative to the stylus and the system starts accurately transducing the signal.

Of course if the frequencies around resonance are not excited much it may not be a serious problem but fundamentally those low frequencies are spurious in amplitude and phase and good engineering practice is to simply filter them out. Then it doesn’t matter if they are excited or not to the downstream electronics.

Most important post ever in relation to vinyl playback, the issues and limitations with accurate LF reproduction.
 

wynpalmer

Active Member
Technical Expert
Joined
Dec 14, 2018
Messages
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214
I bought one of these Pyxi's and it has a terrible ground loop issue that I can't get rid of.

A direct swap with a Pro-Ject S3B I have in comparison has no issues.

I sent SOTA an email and waiting on their response. If I can't fix it, I'll be sending it back.
Well, you are the amongst the few in what, 400+ units that use this approach.
You'd probably be better off communicating with me directly to explore the issue, as ultimately that's what SoTa will do, and if it can't be resolved then return the unit. Let SoTa know that you are doing this.
If you don't mind, the easiest way to contact me is at Audiokarma- PM me @wynpalmer. As far as I'm aware all other issues have been resolved.
 
Last edited:

jjmanda

Member
Joined
Aug 5, 2020
Messages
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119
Well, you are the amongst the few in what, 400+ units that use this approach.
You'd probably be better off communicating with me directly to explore the issue, as ultimately that's what SoTa will do, and if it can't be resolved then return the unit. Let SoTa know that you are doing this.
If you don't mind, the easiest way to contact me is at Audiokarma- PM me @wynpalmer. As far as I'm aware all other issues have been resolved.
Thanks for your response. Wish that other companies that frequent this site would take a more proactive approach like this.

SOTA has not yet responded to me so I'll reach out to you if I don't get anything back from them in the next day or so.

I've known of SOTA since like around 1980 or so. So hopefully the product and service still lives up to their reputation.
 

wynpalmer

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Dec 14, 2018
Messages
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Thanks for your response. Wish that other companies that frequent this site would take a more proactive approach like this.

SOTA has not yet responded to me so I'll reach out to you if I don't get anything back from them in the next day or so.

I've known of SOTA since like around 1980 or so. So hopefully the product and service still lives up to their reputation.
It does, service is generally excellent, but they're just a tad busy at the moment- lots of irons in the fire don't you know.
Whether you hear from them or not you should start a conversation with me, as that's more or less how it works with any of the more "difficult" situations.
They have had a problem with some of the wall wart transformers- apparently the manufacturer's QC isn't as good as would be hoped for- but they check for that and any other issues that have popped up in manufacturing.
I have a set of questions that I can pose to you and that will start the debug off on the right foot, but that needs to be taken off line.
 

jjmanda

Member
Joined
Aug 5, 2020
Messages
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119
Did you find a fix?
Yes, there is a fix, but I will be working with SOTA and Mr. Wyn Palmer on an exchange of my unit for another with a fix.

To their credit, both Mr. Wyn Palmer and SOTA are very proactive with this. It's good to see this type customer service still exist :)
 

wynpalmer

Active Member
Technical Expert
Joined
Dec 14, 2018
Messages
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Still no ground problems...
Oddly enough, jjmanda and I are the only two to have experienced, or at least reported, the issue. The fix will be incorporated permanently into the board of future builds and I have a modded unit. The issue was discovered post release.
 
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pedrob

Active Member
Joined
Oct 1, 2020
Messages
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45
No. The external thing is just an AC transformer. The rectifier and filtering is inside and that is what needs improving. I understand they are working on a "lower noise" version so maybe that is what they are addressing.
DC in would be a better solution.
 

wynpalmer

Active Member
Technical Expert
Joined
Dec 14, 2018
Messages
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DC in would be a better solution.
No it would not, unless a DC-DC conversion is done to generate the +/-15v rails, or +/-18 or so volts are supplied- as was the case with the Acrux, and that requires a separate case and umbilical. I think the low voltage ac source works well for low current circuits- as was shown in the Pyxi.
What is your objection?
 
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