Kenwood Basic C2 Preamplifier Restoration/Upgrade

Discussion in 'Kenwood-Trio/Kensonic-Accuphase' started by vsat88, Apr 20, 2017.

  1. vsat88

    vsat88 Like my Bluetooth ?

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    Myself and a few others have been posting in a C1 thread and we wanted to break away from doing so by starting a thread about the C2 Kenwood Basic Preamplifier so the information would be easy to find if others needed it. We were going to detail the upgrades and restoration to this unit a bit at the time. . I would like to thank @Leestereo for starting the C1 thread that this thread was named after. You will find a plethora of fine information and facts about both units here :
    http://www.audiokarma.org/forums/in...c-c1-preamplifier-restoration-upgrade.609337/
    More to come..Thanks for watching !
     
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  2. Karl vd Berg

    Karl vd Berg Super Member

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    Nice! :thumbsup:

    The C2 is a complete and nice preamp. Having seen quickly the schematic, it has nice/really good components in it, so how do you describe the sound of your unit?
     
  3. vsat88

    vsat88 Like my Bluetooth ?

    Messages:
    432
    Location:
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    Mine sounds like you explained on your C1 before the upgrades. "turning the volume up high and there was no bass and weak sound" I cant really say it sounds bad. I do not know exactly how to explain it except kind of as you said, weak and little bass. and I have to turn the volume up too far to it to go louder. Its clear as a bell but for a dOUK aUDIO 40.00 tube 12V preamp to sound better than the C2, that is just not right. I have tried everything I can think of. Upgraded the Op amps, a complete capacitor shotgun, diodes swapped with the 16V fast recovery ones, cleaned every switch, every pot. It all works perfectly. It just does not sound as nice as I think it should. I will have to say that I do not use any loudness treble or bass controls. I run every bit of my equipment that way. To me if I have to use that then something is not right to start with. I am using a matching Basic M2 amp as well. Both gain controls are all the way up on the amp..I may just sell it and buy a American made preamp as I have a B&K ST-202+ Amp and my speakers are Polk Audio SDA-SRS 's so, maybe go all Americian made equipment ??
     
  4. jheu02

    jheu02 AK Subscriber Subscriber

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    vsat88 and Karl vd Berg like this.
  5. vsat88

    vsat88 Like my Bluetooth ?

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    Location:
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    Thank you John. I want to say this as well. I had completely forgotten that you had posted all of your restore. In fact after reading it again I found that in the past I had referenced it more than once during parts of my upgrade. I had thought there was more information here at AK in regard to the C2 but had read so much in the past that I had forgotten where. I am at a temporary stopping point now as far as work go's on the C2 due to illness in the family. I will get back here as soon as I can to document more. Thanks for adding the crosslink !
     
    Last edited: Apr 24, 2017 at 11:11 PM
  6. 24Vboost

    24Vboost Active Member

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    268
    Location:
    Alberta
    Hi guys.

    I am new here and just caught the tail end of the resto on the C1, I just bought this preamp yesterday and hope that pre is okay. By reading your post vsta88 is the turning up the volume to get any sound have to do with the 5V pre output? I actually do not know what that means only the my old Yamaha CX600u had 8.5V so I am thinking if a preamp has that voltage higher you would not have to crank it as much...

    The bass for the pre does it suck then? I was hoping for fine a replacement for my Yamaha I mistakenly sold as it ran my Nikko Alpha II nicely. The 'db' is higher on the Kenwood too and I was hoping the sound grade would be a bit better...but I am here to learn from the pros...

    If there is a rebuild you guys suggest to upgrade the C1 may I ask where I would find that thread and may I ask for permission to copy the contents and save (the original author as I do not wish to start any issues on copyrights etc...)!

    Thanks guys nice to meet you virtually!
     
  7. jheu02

    jheu02 AK Subscriber Subscriber

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    Look here.
     
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  8. 24Vboost

    24Vboost Active Member

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    268
    Location:
    Alberta
    Thanks I saw this but forgot where to find it...guess just type it in!!!!!
     
  9. vsat88

    vsat88 Like my Bluetooth ?

    Messages:
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    Location:
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    What John said ^^
    And no, the bass does not suck on either the C1 or C2. They are both fine amplifiers. I just want more of a good thing I guess : )
     
  10. Broesel02

    Broesel02 New Member

    Messages:
    35
    Location:
    Siegburg, Germany
    The Kenwood Basic C2 is a very fine Preamp. Moreover, it is easy to fix it up. I have made many of them


    img1.JPG


    and don’t forget to clean up the switches

    IMG_0959.JPG

    Richard
     
  11. Ross6860

    Ross6860 AK Subscriber Subscriber

    Messages:
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    Location:
    Ohio
    Just got a Basic C1 from a fellow AK'r with a Basic M1a amplifier.

    I also have had a a Basic C2 pre-amp for a while.

    I don't find them lacking. I just started playing with the C1/M1a combo tonight. Volume on 2 got me the "can you turn that down a bit" request from the second floor.

    Depending on source material and volume, I do have to run the loudness at 2 and the bass at +1. But this is running through Infinity RS5b, which are pretty hot on the high-end and mid-range, especially at low to mid volume levels. They are also not a real easy speaker to drive, not bad, but they do like a bit of clean power. Start cranking the volume and the bass starts to come in. Different speakers will probably respond differently. Running a pair of Klipsch or Large Advents (or two pair of Large Advents:)) should be a piece of cake.

    Dollar-for-dollar it's hard to beat these "budget" pre-amps.

    I may send them out for a complete overhaul at some point, but for now they appear to run just fine. I guess I do prefer the Apt Holman, but it was quite a bit more expensive.
     

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