This weekend's project - Spiffing up my KR-9600

w1jim

I can fix it but good...
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Well, I've been wanting to do this for a while; spiff up my Kenwood KR-9600.

For the past few weeks I've been ordering up some parts and laying things aside for the moment I get the motivation. I work from home and Friday the power went out so that stopped work. And I couldn't listen the the Kenwood so I pulled it out and swapped in my Sansui 8080. Later the power came back on, so Friday night - let the festivities begin!

My upgrades came in 3 main areas:
  1. Recapping
  2. Binding posts for the speakers
  3. Replacing the tuner op amp

The recapping was what I would consider 90% in parts and 20% in cost. I replaced basically everything except for the 4 big power supply caps (expensive) and the caps on the microphone amplifier board. I never plan on using the mike input so I didn't waste the effort on it. The PS caps I'll replace when I really have to. I also replaced the 2 - 2.2 mfd (I think) tantalum caps that were in series on the amp board input with a 1.5 mfd Dayton poly cap and on the control board I replaced 2 - 3.3 mfd tantalum with some 4.7 mfd bi-polar (crossover) caps. There are still a couple of tantalums in there but since I didn't know specifically what they did I left them alone. I have a whole bunch of 220 mfd axial style caps in "stock" that I used rather then the original radial caps. Since I was using those I made sure to have the rubber side up so I could detect any leakage in twenty years from now when I'm still rockin' out in my seventies.

The spring clips on the back do not accommodate the larger speaker wires that are commonplace today and frankly are just crappy. I had some binding posts in black and yellow and though I would have preferred red these do the job nicely. The ones I used are smaller than the common ones you see on all the new gear but do take a banana plug, forked spades and bare wire. I had to trim the base a little bit with an exacto knife to get these to sit flat. The old spring clips just snap into place, removal was, well, a snap. The new ones didn't require any changes to the holes. Larger ones would have been tougher.

EchoWars had in an old post talked about how the JRC opamp was crap so I followed his advice and replaced that one with a socket and a Burr Brown OPA2132. After I got everything (except the top) back together I played with swapping them back and forth and there is a definite difference; the BB is just so much cleaner sounding. I experimented with bypassing the input caps but could hear no difference so I left them in. I also put in some 0.1 mfd metal film bypass caps between the positive input and ground and the negative input and ground. EW recommended 0.18 mfd but I had these and figured the difference likely wouldn't be that great.

So now my KR-9600 is back online ready to rock. Yeah that beast is heavy and I have some cheap rack handles (plastic) on there so I had to be carefull
I have an extra UPS, maybe I'll hook that up for the next time the power goes out.
Priorities!
JimB
 

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Nice job, I like those speaker posts. I just finished recapping my KR9600 also , I capped everything but the tuner.I replaced the mylar caps with Panasonic Z's film caps(2%) in the control board . The Z's are used in Dolby circuits ,I wonder how they will sound, Did you have to do a re-alignment on the tuner afterward? ( Maybe I will do mine). I replaced the main filters caps last time. They were a perfect fit , it took all of 20mins .
 

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I only changed the electrolytics in the tuner section so I don't think they would effect the alignment.
I've been comparing the FM to my (highly regarded yet cheap) Sony XDRF1HD tuner and I think the Kenwood sounds better. That wasn't the case prior to the opamp and cap changes. Of course that's with the Sony going HD and the Kenwood in analog. I need to find an FM station that doesn't have HD and compare them since the Sony automatically opts for HD when available.

How much did those PS caps cost you?
JimB
 
Hi JimB--
Nice work! I recently purchased a KR-9600 that WAS in immaculate shape before UPS did me in. I've got some advice from the DIY forum on straightening the faceplate. I've been searching for other updates or upgrades for this receiver. I hope to find some LED replacements for many or all of the lamps. And eventually re-cap most of the boards. Your upgrade to the tuner IC looks very interesting. I believe I would like to try that upgrade too. Socketing the IC looks excellent. Improving the FM audio would be a desirable benefit. If you have any other recommendations please PM me or post to this thread again. Thanks. jim
 
Nice work! I decided to do similar to my B-2 this morning.

B2Recap02-1.jpg


B2Recap03.jpg


B2Recap04.jpg
 
Well, the Yamaha isn't a KR-9600 so that is a bit of thread stealing but I'll allow it in the spirit of OCD musicality :cool:.

I replaced the indicator bulbs on my Kenwood with LEDs but prefer the incandescants for the main dial and meter illumination.
Here's the link to those posts:
http://www.audiokarma.org/forums/showthread.php?t=184843&highlight=kr-9600+leds

Also the phono 1 input on mine was not working. I replaced the 2 - 2SK60a J-FETs located at the input of the phono 1 stage with lower noise and less expensive 2SK30a J-FETs which worked great.
The Phono 2 (5 mv) input is less sensitive than the Phono 1 (2.5 mv) so this was important to get working.
Regarding upgrading of the op-amp I heartily recommend it!
Now the '9600 is back in it's rightful place in my main system and I'm working on doing essentially the same upgrades to a pristine SX-1010 that I picked up. I have another SX-1010 that is not as nice (and only cosmetically restored). It will be interesteing to compare them once done.
JimB
 
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