XP-10 problem

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Gyuri

Gyuri

Member
Joined 2003
My friend recommended to someone a Pass Labs system a few years ago.
It consists two XA-100 monoblock and a XP-10 preamp.
They ask me if I can help?
Of course I will if I can.
For this I obviously need help, as well.

So there is a problem:
XP-10 occasionally shows some channel imbalances.
Main problem, right channel was quieter than left channel, at volume setting above 21.
As my friend tried it, for several times setting volume lover and higher, the degree of error was slightly reduced.
At the same time, there is a crackling sound from the right channel.
It has gone, if volume settled down and up for several times.
Especially if there some of the relays clicking.
(of course I don't know, which one.)

So the problem is summarized:
Channel imbalances in level and occasional crackling sound.
It depends on the volume setting, and changing at around volume setting 21.
It is independent from input channel.

Serial number is:
21118
Its revision number is:
XP10R2, from 2009

I really would like to help, but I need some hints.

Perhaps wizard assistant has some good idea. :)
(To send it back to US not an option.)

Thank you in advance,

Gyuri
 
Gyuri

Gyuri

Member
Joined 2003
I think that can be anything.
Cold solder joint, a dying relay, bad contact in one of the sockets.
I really do not know, I have not even seen this amp, I rely on the narrative.
But I'm pretty sure if that's a common mistake, Wayne knows what's going on.
 
C

ColinA

Member
Joined 2005
From the instructions.
"The electronic volume control allows greater than 70 dB range and is
driven by a micro-controller that reads the optical encoder serving as a
front panel volume control. In this manner tracking of the volume of the
two balanced channels is possible with accuracy unavailable on any ordinary
volume control, assuring precise level steps and high common mode
rejection in balanced circuits.
Wayne Colburn’s exceptional volume control in conjunction with the
fluorescent display gives the user ability to replicate volume levels with
absolute accuracy in steps of roughly 1 dB."
 
Gyuri

Gyuri

Member
Joined 2003
BTW, my friend says it is a quite good preamp, he likes it more, than his Promitheus Audio Signature TVC: (If it plays normal, at the moment.)
Signature TVC
He has a Pass Labs XA-30.5, a pair of Focal JMLAB Vega, A MSB Platinum Link DAC and that TVC, some good sounding cables.
He is not a DIY chap, but his system is a quite good sounding one.
It is a pleasure for me, if I listen to it.
And I quite pleased, when I come home, and listen to my DIY system, and I do not get a weeping crap, I can listen to it wit joy.
 
wrenchone

wrenchone

Member
Joined 2004
Ok, moderately proletarian low-level contact material that might be undone by a bit of schmutz over the years. If you could get the cover off, a piece of clean paper might be abrasive enough to restore pristine conductivity.

Edit - probably not an issue with the mercury reed relays, but they are orientation-sensitive, and anathema to the ROHS types...
 
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