Kenwood Basic C1 Preamplifier Restoration/Upgrade

Discussion in 'Kenwood-Trio/Kensonic-Accuphase' started by Leestereo, Aug 14, 2014.

  1. Anti_Skate

    Anti_Skate AK Subscriber Subscriber

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    Somewhere in Mid Michigan
    Karl vd Berg likes this.

     

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  2. Karl vd Berg

    Karl vd Berg Super Member

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    Thank you, Anti_Skate! :thumbsup:

    Just notice that the left channel in the unit here was fuzzy, too
     
  3. Karl vd Berg

    Karl vd Berg Super Member

    Messages:
    1,959
    Problem solved. I bought the one you mentioned here...

    And, for the record of a missing part number for the stock relay in the service manual, here's a pic of it.

    [​IMG]
     
  4. vsat88

    vsat88 Like my Bluetooth ?

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    Went ahead and placed an order with Mouser today for two relays, four 18V diodes, four 14V relays and should get them next week. Gonna open the C 2 back up and put those in and save the rest for the C 1, wish me luck. The C 2 sounds pretty damn good as is but I want to finish it completely out. This is a kickass thread.
     
  5. haukie31

    haukie31 New Member

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  6. haukie31

    haukie31 New Member

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    Hi i am new here , i live in milwaukee wi.(franklin) and would like to know if you could recommend someone i could trust to upgrade my kenwood c1-Thanks
     

     

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  7. vsat88

    vsat88 Like my Bluetooth ?

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    Leestereo I would trust if I did not do the work myself. I do not know if he takes these in but best I recall he does. Send him a PM and see. Welcome to AK haukie !
     
  8. Broesel02

    Broesel02 New Member

    Messages:
    42
    Location:
    Siegburg, Germany
    Hello,
    Leestereo did make a great Job here, very big thanks for that
    I have rebuild a Kenwood Basic M1 so i can recommend to replace the snubber condensers (C42 & C41)with PP Types . My OPA selection was:
    IC1, Fono: OPA 2604
    Flat Amp: OPA 2604
    Tone Amp: LME 49720NA

    Richard
     
  9. vsat88

    vsat88 Like my Bluetooth ?

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    Richard, glad to see you post here. This thread has helped me many times as well. Are you saying to replace C 41 and C42 with polypropylene instead of the ceramic 0.01uF caps ?
     
  10. Broesel02

    Broesel02 New Member

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    42
    Location:
    Siegburg, Germany
    Yes, no ceramics in my amps is :)

    Richard
     
  11. vsat88

    vsat88 Like my Bluetooth ?

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    Sounds good. I am done with my C2, not doing anything more with it however my C1 is not done yet. I have not ordered all of the parts for it yet..soon.
     

     

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  12. Karl vd Berg

    Karl vd Berg Super Member

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    Hi,

    I'd like to know if ANY small ceramic cap of, say, 22pF, 33pF or 100pF can be replaced by NP0/C0G ones...

    Thanks a lot.
     
  13. rjsalvi

    rjsalvi Well-Known Member

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    Location:
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    The short answer is, yes, since this is an audio forum. There are a couple/few "classes" of ceramic caps and NP0/C0G are the most stable (materials used in their construction afford this). They make great op-amp bypass caps!
     
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  14. Karl vd Berg

    Karl vd Berg Super Member

    Messages:
    1,959
    Thank you, rjsalvi :thumbsup:

    I saw Leestereo replacing a few ceramic caps for NP0/C0G ones at first page - here - and I thought that it could be done for every ceramic cap. But saw other restorations (Japanese amp8 restorer does it often) where those green Mylar caps were also replaced by other type of film capacitor, like in the pic below (sorry for that).

    [​IMG]
     
  15. rjsalvi

    rjsalvi Well-Known Member

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    519
    Location:
    San Diego, CA
    The small "puff" (pF) ceramics are most often not in series with the signal path, so you'll yield negligible sonic gain with replacements. Having said that, every component in a circuit will eventually drift -- some faster than others -- and replacing them with new parts ensures system integrity and brings it back to spec for another extended period of time. As far as mylar caps and differences between cap dialectrics, there are measurable differences: dialectric absorption, dissipation factor, leakage, ESR, etc ... but depending upon where the cap is in the circuit, will define its effect on the circuit. Measurable differences point to polypropylene as having a more favorable dialectric for capacitive properties than mylar. Will it change the sound? Think of an amp/receiver in the aggregate with its subsystems affecting the whole. Upgrading mylar caps to polypropylene is but one change and may, or may not, make much of a sonic difference in and of itself. But if you're changing electrolytics, resistors, film caps, ceramic caps, diodes, etc, you'll hear a change and measure one as well. It's the measurable change we hear. Lower distortions from modern parts, channel equilibrium from tighter tolerance parts, a different sonic signature from different materials in the parts, e.g., metal film vs carbon film resistors, etc. And some parts make more of a difference than others if for no other reason than they drift sooner...electrolytic caps.

    I personally don't care about a "signature" sound in a piece of gear, especially if that signature is borne out of distortions. If I refurb a piece of vintage gear, I'm more interested in performance and longevity -- cuz it's a real PITA to tear these dinosaurs apart -- and a shotgun approach to parts replacement seems to negate the need to periodically revisit where I'd been. That aside, there are far more knowledgeable individuals in this group whose opinions may differ from mine and they carry a lot of weight based on their experience. So, fwiw... :)
     
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  16. Karl vd Berg

    Karl vd Berg Super Member

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    Many MANY thanks, rjsalvi!
     

     

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  17. rjsalvi

    rjsalvi Well-Known Member

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  18. vsat88

    vsat88 Like my Bluetooth ?

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    That link to the Japanese restorer amp8 is awesome. I could look at that for hours ! Thanks for that. Bookmarked...
     
    Last edited: Apr 19, 2017
  19. vsat88

    vsat88 Like my Bluetooth ?

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    That link to the Japanese restorer amp8 is awesome. I could look at that for hours ! Thanks for that. Bookmarked...
    Sorry for the double post. I was not allowed to delete this one..edit only.
     
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  20. Karl vd Berg

    Karl vd Berg Super Member

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    Vsat88, I like that amp8 site, too. I liked seeing what he did on a couple of SY-88 preamps...
    http://amp8.com/tr-amp/toshiba/toshiba.htm

    By the way, I "upgraded" the power supply caps C43 and C44 (2200uF/35V) in my Basic C1 unit: I had Nippon Chemicon KMF series, but comparing to other preamp, I didn't like the way it was sounding. Probably the KMF's don't fit well in some PSU's. So, I decided to try two Panasonic caps of same capacitance I had around and the difference is huge. Will go on trying other caps using Panasonic, Nichicon, Vishay, etc, that are really good electrolytic caps.
     
    Last edited: Apr 19, 2017

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