Cavalli-Kan Kumisa III help? CK2III

  1. amb
    Your voltages look fine. The pop noise you hear is probably not from the amp. It's either an external interference (cell phone, refrigerator, motors, etc), or from the source. Does the pop noise still occur with the volume control turned all the way off?

    I suggest casing up the amp and see if it helps.
     
  2. Henmyr
    Quote:

    Originally Posted by amb /img/forum/go_quote.gif
    Your voltages look fine. The pop noise you hear is probably not from the amp. It's either an external interference (cell phone, refrigerator, motors, etc), or from the source. Does the pop noise still occur with the volume control turned all the way off?

    I suggest casing up the amp and see if it helps.




    I've now cased my CK2III in a wooden enclosure (no lid at the moment, still searching for the perfect one) and all wire pairs are twisted together.. The "pop" still happens and it is there even when the volume is zero, doesn't seem to be volume dependent.

    Just now I heard a "pop" and at the same time I heard the refrigerator fan stop. Exactly at the same time. Might have been a coincidence though, or my amp really is affected. Other times I do not hear anything specific.

    There is no "pop" when I use Gamma2 > phones or Gamma2 > CTH > phones, why is it only the CK2III which is affected, if it's something external?

    Is there a way to make it less sensitive if it IS external interference?

    Thank you very much for all your help during this very long but exciting process[​IMG]
     
  3. nightanole
    do a search for gainclone or 3886 emi rfi. There was alot of depopping stuff to get rid of spikes from the lights and fridge since they are normally unregulated.
     
  4. tamu
    I just ordered the parts and the board. I have a question about the opamp though: I have an ad8066 which is a "fet input" and an opa2111. Can I use the opa or should I use the 8066?
     
    thanks
     
  5. amb
    AD8066 can't operate with +/-15V rails (the max is +/-12V).  It also has too much bandwidth for this application.
    OPA2111 is most likely ok, but I've not tried it.
     
  6. tamu
    Himm. yep its 24v max.
    thanks for the info.
    Finally I found a use for my opa2111am.:)
     
     
     
     
  7. Henmyr
    It seems that my popping sound is increased as the quiescent current increase. I turned the trimpots down a lot, and the popping sound is much less. As the amplifier heats up, some popping start to appear.
     
    Is there something special in the design of the CK2III which makes it more sensitive to external power spikes? No other headphone gear I've used have "popped".
     
  8. amb


    Quote:

    No.
     
  9. tamu
    Hi everyone
     
    so I finished building the ck2III today and been listening to it for the last hour.
     
    I however have a bit more than 1mv dc offset. its 1.5 and 3mv for channels. I know it still is in the "acceptable" range but what do you guys think?
     
    I used a 30va trafo. Also I had some issues with my insulated rca plugs. they werent actually insulated and I went through 6 fuses until I found what was wrong. teflon tape solved that problem.
     
    thanks
     
  10. amb


    Quote:

    What are you using for the DC servo opamp?
     
  11. tamu
    opa2134pa.
     
  12. tamu
    I checked it again and everything is normal. Dc offset fixed itself magically!
     
  13. Giordano
    Hi,
     
    I was looking for a general CK2III thread, but could not really found. I hope some CK2III builder will see it.
     
    I have recently finished, boxed my CK2III (see http://www.head-fi.org/forum/thread/85561/post-pics-of-your-builds/7620#post_7163137 ) , I'm quite satisfied with the result now, but still have one (or two) issue :
    - the warmup takes about an hour. This is too long for me. I have an OTL SE tube based headphone amplifier (the CK2III is quite close), but I need another one to move around the house when I have some time to listen to music. A solution could be to have it on always, but I do not like it. I know it is not much, but I do not feel good keeping it on for a day for one hour listening.
    - I had to play with the C7 C16. I have built it first with polyester. The stereo, the transparency, was excellent, but the high part was too hard, made me tired. Then I have changed to different capacitors and all was different compromise. With some, the stereo collapse. No I have a "bennic" cap, I do not know the material. It sounds the best so far, has excellent stereo and transparency, but the high is a bit too hard now. What cap do you suggest ?
     
    Headphone is a sennheiser HD565 ovation, but I need to buy a decent closed. I'm searching my way to listen to music without disturbing the family. Music : everything, 40% classical, 30% pop like Roger Waters, 30% jazz and others.
     
    Thanks,
     
    JG
     
  14. nightanole
    An hour warm up?  I had mine setup with the heatsink being the case and i didnt have more then 20min before stabilization.  I would try changing your bias pots (R19 and R43) for increased current and use bigger heatsinks(i used the case) or air cool the outputs.  I also bonded all my bjt's together with jb weld.  This adds more thermal mas and equal heating.  jb weld is non conductive (you can use it for an electronics potting) so you can go nutts.
    c7/c16 shouldnt change anything since this is a dc coupled amp, its just there for stability.
     If anything you could try messing with c8c9/c17c18 or even omitting them all together.
     
  15. amb
     
    Quote:
     
    There is one.  A whole sub-forum, in fact.
     

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