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
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.

2tuby's avatar
2tuby OP
35 posts
 

Paulcreed-

Was not near my system when it popped.

Where did you run your winter ground line?

2tuby's avatar
2tuby OP
35 posts
 

Silverfoxvtx1800, et.al.-

 

I purchased the Denafrips DAC from a USAudiomart seller. When I contacted him about the problem he Iimmediately offered to refund the purchase price.
I started this discussion because I liked the DAC and really did not know if the DAC caused the problem of if the preamp just died. I purchased the DAC on 12/24 and felt it was unfair of me to not make a decision today. In that time I have used the Denafrips DAC in two configurations in my system and have had no issues. I have also been influenced by all of you who responded.
To my ears I prefer the sound of the Denafrips to the PSAudio so I have decided to keep the Denafrips preamp. I have contacted the seller (thank you) and will contact Backert Labs and move on from there.

To all who responded to my post, I thank you.

2tuby

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