Pass Labs XP-17 right channel hum

[Valvola]

Hi Wayne, there is no doubt in my mind that we are dealing with a faulty transformer that has a great electro magnetic field radiation.
I considered the trafo shielding sheet from Don Audio but have no experience with this type of shielding, have you tried it?
The VPI brick is too big and could not put back the top cover.

 

[MEPER]

Could it be an idea to measure the load of the transformer?
If something had happened in the amp that causes higher current draw from transformer then the radiation from the transformer will also be higher.

 

[Valvola]

Thank you Meper, but the preamp seems ok.....

 

[ACnotDC]

I have used the shielding sheet from Don Audio in my Iron Pre SE build.
It fitted exact for used trafo and greatly reduced the hum to the level under -120dB where is no longer noticeble.

 

[6L6]

Hi 6L6, if I understand correcly even our XP-17 had hum on the right chanel that was cured moving the original toroidal trnsformer in a separate power supply?

Correct. It makes a very good benefit, well worth doing.

 

[6sX7]

Trying to track since I like to make separate PSes for signal and lower level circuits, when you say make the umbilical DC, move the rectifiers to the separate box as well?

 

[Valvola]

Yes

 

[Valvola]

Thank you very much ACnotDC, did you connect the shield to ground?

 

[Valvola]

HI 6L6, sent you mail, could you please send me the photos of the external power supply please?
How many secondaries has the power transformer?

 

[ACnotDC]

No. The shielding sheet has sharp edges and is wrapped with an isolated tape. There is no need to ground it.

 

[Valvola]

Ok, thank you, I just have purchased it (6X45 cm.)

 

[Valvola]

If I understand correctly you keep the isolation tape and wrappe it without grounding.
Do you put tape to block it?

 

[ACnotDC]

Correct. I wrapped it around the toroid with overlapping to input and Cinemags.
My build is very tight, so the shield fitted exact without any extra blocking.
But you can fix it with adhesive tape anyway.

 

[Valvola]

Thank you, as soon as the shield is fitted I will give feedback

 

[ACnotDC]

 

[Valvola]

Hi all,
finally solved the hum problem with my XP-17!
in particular I would like to thank ACnotDC for giving me the great advice of trying the Shielding Sheet from Don Audio.
I wrapped the shield oround the toroidal transformer and now my XP-17 is dead quiet.
Thank you ACnotDC!
I would like to thank even 6L6 for all the support he gave me.
From Pass Labs no response to my mail.
I have sent them a mail from their website, maybe something went wrong and they didn't recieve it.

 

[Zen Mod]

From Pass Labs no response to my mail.

Wayne is PL

The right channel is closest to the transformer and with all that gain you may get some noise.
A new transformer may fix it. An additional shield or heavy steel on top like the old VPI brick may help get some answers.

 

[Valvola]

Oh! I didn't know!
Thank you Zen Mod.
An additional shield is what I did.
As I like this phono very very much, the best I have tried till now, way better than the AR SP8 and SP10, Nagra bps, Naim phono and so on.
Maybe getting a new transformer could get things and spound even better.
Any advice?

 

[6L6]

Fantastic news! Enjoy the wonderful XP-17.

 

[ACnotDC]