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
paulcreed
564 posts
 

Hi, did you touch the Pontus when the pop happened, I think there is something in the way the Pontus is wired that static hits it, mostly in the winter time. I had the same problem, there was a definite pop and it originated from the Pontus.

 

I read others have experienced this also. I jumped up and shut down the amp and some of the system shut down on its own. I’ve never seen anything like this before.

 

I ended up running a ground to touch if I was going to touch the Pontus.I don’t use the ground in warmer weather, sounds crazy but that’s what I did. The Pontus is gone now but a nice dac for the money.

 

I also posted on Audiogon what the hell that pop was, good luck with your search. I would contact Denafrips and ask about static and the ground. 

silverfoxvtx1800
181 posts
 

Be sure and let us know what happens no matter how long it takes…

silverfoxvtx1800
181 posts
 

Reading about your problem made me think back to my problems with tube gear. I had a Primaluna EVO 400 amp and preamp and it would pop,  blow fuses, tubes would short out at random times….always a problem until I went cold turkey and sold all of it…now with no amp or preamp I went with Pass Labs preamp and amp, solid state…no problems now for 6 months….and I have the Denafrips Venus 12th anniversary, at first the WIIM pro as a streamer until I upgraded…I am a firm believer in getting the preamp and amp from the same manufacturer….maybe get a Classe preamp,to match your amp…

pdspiegel
22 posts
 

2Tuby, you did the test right.  There is no DC offset voltage on the Denafrips outputs so that is NOT the source of the problem.  At least that is ruled out.

larryi
4,048 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.

More to discover