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:
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
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:
- Recapping
- Binding posts for the speakers
- 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