2. amps-preamps
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Do all tube preamps leak DC?

 I want to pair an Audible Illusions L1 tube preamp with a Job 225 amp. Although both pieces have high gain, the gain can be reduced manually via two gain controls on the L1 preamp coupled with a master volume control. But here is my concern, the Job 225 amplifier has a Direct Coupled circuit that could potentially pass damaging DC leakage on to the speakers. So the question remains, do all tube preamps pass DC to one degree or another, specifically the Audible Illusions tube preamp?
phd
phd OP
1,330 posts
 
Hi Keith, I believe you are correct about Ralph & would agree that he is very knowledgeable. It is nice to know that we have people like him to provide reliable info on most given subjects (questions) but you are also in the "A" Class, an asset to the audio community and a hell of a good guy to boot.
audiolabyrinth's avatar
audiolabyrinth
4,555 posts
 
Paul,  have you taken the hood off the Audible illusions l1 preamplifier to visually check if you have coupling capacitors located next to the tubes?, and check the condition of the capacitors?, also,  I would ask Ralph here how to check if the specifications are up to par on the coupling capacitors even if they pass the visual inspection,  sometimes capacitors dry out,  or are just to old,  if all this passes,  I believe you have no worries of DC,  however,  if the capacitors fail any of the mentioned here,  I would replace before proceeding,  cheers. 
phd OP
1,330 posts
 
Keith yes, although this particular Audible Illusions L1 is factory refurbished, I removed the top cover after I received it to inspect the tubes. There are two large caps near the output and four smaller Panasonic caps next to those. According to the manual the four dip switches are there to turn off the four smaller Panasonic cap only leaving those two bigger caps remaining in the signal path. At this point I feel very confident based on what I have read here on this thread, that I don't need to be concerned about DC and would like to thank all those that participated!
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