2. amps-preamps
  3. 192478-110266

Preamp issue

I am having a problem with my preamp would like some feedback/guidance from the members of this forum.

For the past two years my system has been a WIIM Pro to PSAudio Stellar Gain DAC to Backert Labs Rhumba 1.0. preamp to Classe CT2300 amp to Harbeth SHL5 speakers, 

System worked fine and I liked the sound. But, then you get the itch. . .

I was interested in trying to an r2r DAC so I purchased a used (one year old) Denafrips Pontius II 12th DAC. Today I swapped out the PSAudio DAC, fired up the system and listened for about 5-10 minutes, then there was a POP in the speakers and the Rhumba preamp went into its mute mode. I shut everything off and restarted the components now have low frequency(100Hz?), low volume, vibrating sound coming out of both speakers. I have swapped out pieces from a second system an definitely isolated the problem to the Rhumba preamp. 

I am going to have the pream repaired. But since the Rhumba preamp failed shortly after swapping in the Denafrips DAC-

Could the Denafrips DAC have caused the preamp to fail? How? Was it just coincidence? Should I have the Denafrips tested as well or just return it and find a different r2r unit? Your input will be appreciated. Thank you in advance.

Happy Holidays

128x1282tuby

Showing 3 responses by larryi

larryi
4,154 posts
 

Measuring DC offset does not rule out an intermittent failure like a large buildup of charge that is discharged as a large pulse characterized as a “pop.”  But, I have not  heard of such pulse damaging a tube linestage.  I think Backert Labs will be best in position to say what caused the problem.

larryi
4,154 posts
 

For the DAC to be the cause, something intermittent and very strong affecting both channels would have to be the cause.  I don’t have any idea what that would be, but my guess is that this is an unlikely event.  Most likely is something wrong in the linestage power supply and the DAC switch is purely coincidental.  Coincidental failures are the most frustrating because one is thrown off track in making a diagnosis.  

larryi
4,154 posts
 

If you can, talk to manufacturers of both components.  The Backert Labs folks should be able to tell what was the likely cause of the damage to its component.  At high fi shows, their folks seem to be quite frank and forthcoming.

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