...Questions about KA-9100 in preamp only duty...

Discussion in 'Kenwood-Trio/Kensonic-Accuphase' started by YoPacific, Dec 2, 2014.

  1. YoPacific

    YoPacific Member

    Messages:
    60
    Location:
    St Pete, FL The STP
    Going to be powering some Polk SDA 1As. As the 9100 is not a Common Ground amp, I will be using a Kenwood Basic M1D to drive the Polks.

    I have 3 questions:

    1. As the seperate switch has never been used, should I clean and lube 1st before flipping to seperate mode? Any special process?

    2. Would using the 9100 as a pre only possibly get me around some of the L channel drop out I now have? It typically requires a yearly cleaning and then the drop out starts again.....

    3. Does the 9100 stack up againt the C1 or C2 for pre amp performance.......
     

     

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  2. SicMan

    SicMan Fire up those speakers Subscriber

    Messages:
    2,974
    Location:
    Wolcott - CT. USA
    well I'm sticking my neck out here but ....

    1.) seeing this switch hasn't been used in years crud does built up on these and I've worked a boatload of these units. It would be a good idea to clean this switch with 100% DeOxit. The back panel should be lowered and the shield removed. Easier access to the switch.
    NOTE: you can set up the unit and hook up speakers and try the the switch, at lower volumes (just in case) if it seems to work OK .. a cleaning will help out for future problems.
    2.) My experience with the pre-amp if in very good working condition has been great, I used one for several years with zero probs. and the reviews long ago praised the phono and pre section of this unit.
    3.) I have a C2 right now, sold the 9100 after fixing. But The pre stands up to alot of top preamps, I like the 9100, if you are not super critical as far as control. It has plenty. I can't hear the difference ..concert/motorcycle ears from the 70's ... What???

    I have 12 of these right now in various stages and people love this Integrated Amp. It may not be the top of the top .. but it is a healthy contender when up to snuff.

    OK .. let the comments begin . ... :scratch2: Merry Christmas :music:

    I'll have a few 9100's and a 9150 in Barter Town soon.

    John M
     
  3. YoPacific

    YoPacific Member

    Messages:
    60
    Location:
    St Pete, FL The STP
    Thanks John, glad you replied as I respect your opinion. The switch has been cleaned, it might be worth a soft test. I'm quite partial to my 9100. it was my 1st piece of vintage gear. It sits below my KT-8300 in a Kenwood rack that came outa the box for the 1st time in 2012.

    It's time for her to get re-capped and upgrades throughout.......can you make some suggestions for this job (yourself/EchoWars/ect). Looking for someone who has plenty of experience with "my baby"

    Regards....Keith
     
  4. igiveup

    igiveup Member

    Messages:
    86
    Location:
    Kansas City
    Some folks find the 9100 hard to work on but I have found them easy enough as long as you just really tear the chassis down.

    Easy to recap the amp boards, little more work to recap the rear power supply board. I think I would skip re capping the pre amp board if you have good sound already, That's where it gets tougher. But still doable.

    Maybe the 2 priorities would be to recap the swap a few parts in the power supply and also install a multi turn resistor in the DC off set circuit. The caps in the power amp boards have seen some heat too. You may have to give the switches and the pots a triple dose of Deoxit over time. The rear pre amp switch is a real common but fixable issue.

    I have found the darlington packs to be extremely rugged.
     
  5. YoPacific

    YoPacific Member

    Messages:
    60
    Location:
    St Pete, FL The STP
    The 9100 is now in pre-duty taking power from a Kenwood Basic M1D that was new in box until last week.....(damn I love a find like that)

    I'm pleased to say that L channel drop off has gone away with the 9100 in pre duty.....at least this buys me some time. M1D had some balls powering Polk SDA 1As
     
  6. igiveup

    igiveup Member

    Messages:
    86
    Location:
    Kansas City
    How do the amps compare, the 9100 internal amp vs the M1D?
     

     

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  7. YoPacific

    YoPacific Member

    Messages:
    60
    Location:
    St Pete, FL The STP
    Since the 9100 is dual mono design its not built as a common ground amplifier. Because of that I couldn't use it with my Polk SDA 1A's as they require a common ground amp. So to answer your question the 9100 never got an audition on the SDA's.

    I'd imagine they'd be very very close......
     
  8. JoshHendi

    JoshHendi vintage audio student Subscriber

    YoPacific...

    So you were getting some L channel drop out, and using the 9100 as a preamp only fixed the dropout?

    I have one experiencing random R channel dropout, but when I am using it as a poweramp, I have no problems, hence the issue pointing to the preamp section.

    Curious if you ever found where your issue lied? Multiple thorough cleanings have yet to yield me a solution. Guess its about time to inspect the preamp board of solder/connection issues. And these preamp boards are a PITA to work on?
     
  9. SicMan

    SicMan Fire up those speakers Subscriber

    Messages:
    2,974
    Location:
    Wolcott - CT. USA
    check that seperate switch on the back also ...

    John M
     
  10. 50nstillhifi

    50nstillhifi Super Member

    Messages:
    1,112
    Location:
    Carolinas
    9100... drop out?

    I am about to "drop out" from using my KA 9100, it has a similar issue except its the right channel.

    Its posed some challenges where listening gets good and then you hear a fading of the volume.. but I have found that pressing and releasing the filter buttons have restored the channel loss. Not sure why this is.. :scratch2:

    Last year, I ventured to go through the inards, change the right channel components in an attempt to repair the signal path. Although I felt good about having a working amp after the effort, it did not fix the issue:nono:.

    So... I am content for now using the filter buttons to clear things up, it usually lasts for some time. I am however shopping for a newer technology (21st Century) amplifier.. and given the investment, do relent to pressing my filter buttons until I get the grand+ I may end up spending.

    However given my 9100 will be some 40 years old soon... I think its time to move on and upgrade.

    I am sure there is a permanent solution to the "drop out"... But I gather it may remain elusive as the other posters have found out.

    Oh well, still working for now :thmbsp:... Well 50-50 that is :yes:
     
  11. JoshHendi

    JoshHendi vintage audio student Subscriber

    Even at it's age, the KA-9100 is an amazing amp! You would have to spend quite the pretty penny to match its sonic abilities with a modern amp, IMO

    I would take the money you would spend on a new amp and instead get yours restored. The one I own has had your issue, I cleaned it multiple times with deoxit (especially the push button filters) and also removed the normal/separate switch cap and soldered the 'separate' wires together to make the separate option permanent.

    Between those two actions, my right channel drop outs have vanished, and she is singing as good as ever!

    I have quite a few Sansui TOTLs (au717, au9900, au9500) and the Kenwood is right there! Im glad I am not forced to choose between them
     

     

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  12. 50nstillhifi

    50nstillhifi Super Member

    Messages:
    1,112
    Location:
    Carolinas
    Thanks!

    I will consider a rebuild and perhaps going back in and "deoxit-ing" those filter buttons and related connectors..

    Perhaps I can get my right channel back completely.. :yes:!

    I do prefer keeping my 9100 in continued service.
     
  13. JesseS

    JesseS New Member

    Messages:
    4
    I've had left channel drop-out on my KA-9100 - a professional cleaning solved it again! Every few years it needs a tune-up that way... That said, I've read elsewhere that the amp IS a common ground, with both grounds to the chassis. True? I'll grab a pair of Polk SDA-CRS speakers soon and want to use them safely. I don't have a meter to check... Thanks!
     
  14. kydog

    kydog AK Subscriber Subscriber

    Those dang filter switches !!= Channel dropout along with the seperate pre/ amp switch in the rear. Deoxit 100 solved the problem. ( I also included the volume pot). It really cleared up after actually using the separate section for awhile ( Either as a pre vs power amp) Passing a signal through it every now & than may be a good idea ?
     
  15. rjsalvi

    rjsalvi Well-Known Member

    Messages:
    600
    Location:
    San Diego, CA
    Whenever I sell a restored unit, I instruct the buyer to turn all the knobs and flip all the switches a few times every few months, with the unit powered down. It's a small thing, but it works and makes me look good when stuff keeps working. :thumbsup:
     
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  16. Grenadeslio

    Grenadeslio Super Member

    Messages:
    3,303
    Exercising the controls :thumbsup:

    Currently running my KA7300 as a pre into a Belles I

    20181028_171129.jpg
     
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