I have a pre with a remote.
A lot of people here say the KC rack series preamps are junk and holding back the rest of the system. I couldn’t find someone with one and discussed why it was bad. I wondered if everyone was just repeating what someone else said.
I was curious so I’ve been on the look out for one in my price range.
I found a KC-208 but it was a bit above my budget ($40).
I finally found a KC-209 for half that.
First thing was to get my VISO remote to work (code 30038). Seems to control power, mute and volume. And the Xfinity remote XR11 works too (code 30027).
Hooked it up to my lab setup (basic M1, Infinity RS, Sony CDP-102). I really like this power amp and the CDP seems to keep going and going…
Enable CD Direct on pre.
Sounds fine.
Studying the schematic there are 4 10 uF/35, 2 uPC4570C opamps and 3 resistors (470R, 1K, 47R) in line level signal path for each channel. This does not include the phono section.
Taking a page out of our beloved C1 restore, I replaced the 10uF/35 electrolytics with MUSE bi-polar of the same value. If you have deep pockets, 10uF/50 WIMA MKS would work too (and might sound better).
The uPC4570C-A opamps seem to be ok (15 MHz and 7 V/uS) and I left them in. Searched AK and DIYaudio and didn’t find an agreement on good replacements. The KC-209 does have +-15v supplies.
Change 3 resistors with metal films. Replaced the 47R with 33R metal films (had them for my C2 restore).
I was going to beef up PS caps C70, C71 from 2200/35 to 6800/35 but space seems tight. The 2200 caps are probably fine and 2200uF is used in the C1 restore but I had the 6800 in my spare parts. Here is one link where someone thought the 6800uF PS caps helped.
Or I can put in some UHV 2200/35 I have. These should fit better. Right now, I left in the originals.
Replace C74, C75 100/16v with 100/35 FG. 16V caps on a 15v power supply isn’t much margin.
And replace the jumper eaten up by the cap assembly glue near C70, C71.
If you are still curious, here are the caps I changed
C56,C57,C62,C63,C157,C158,C166,C167 to bi-polar MUSE 10/35v
C74,C75 100/35 FG.
Resistors to metal film (RNF series)
R52,R53 47R → 33R
R3,R4 1K (on Volume board)
R46,R47 470R
one jumper wire
Not really sure what I will do with the kc-209. I'd like to pull the C2 and put this in the main system and listen to it. I have a balance pot for the C2 I'd like to try. it isn't easy pulling gear out of the my cabinet so I may not get to it. I don't expect this to replace the C2 or my other preamps but i think there might be hope for this lowly KC.
A lot of people here say the KC rack series preamps are junk and holding back the rest of the system. I couldn’t find someone with one and discussed why it was bad. I wondered if everyone was just repeating what someone else said.
I was curious so I’ve been on the look out for one in my price range.
I found a KC-208 but it was a bit above my budget ($40).
I finally found a KC-209 for half that.
First thing was to get my VISO remote to work (code 30038). Seems to control power, mute and volume. And the Xfinity remote XR11 works too (code 30027).
Hooked it up to my lab setup (basic M1, Infinity RS, Sony CDP-102). I really like this power amp and the CDP seems to keep going and going…
Enable CD Direct on pre.
Sounds fine.
Studying the schematic there are 4 10 uF/35, 2 uPC4570C opamps and 3 resistors (470R, 1K, 47R) in line level signal path for each channel. This does not include the phono section.
Taking a page out of our beloved C1 restore, I replaced the 10uF/35 electrolytics with MUSE bi-polar of the same value. If you have deep pockets, 10uF/50 WIMA MKS would work too (and might sound better).
The uPC4570C-A opamps seem to be ok (15 MHz and 7 V/uS) and I left them in. Searched AK and DIYaudio and didn’t find an agreement on good replacements. The KC-209 does have +-15v supplies.
Change 3 resistors with metal films. Replaced the 47R with 33R metal films (had them for my C2 restore).
I was going to beef up PS caps C70, C71 from 2200/35 to 6800/35 but space seems tight. The 2200 caps are probably fine and 2200uF is used in the C1 restore but I had the 6800 in my spare parts. Here is one link where someone thought the 6800uF PS caps helped.
Or I can put in some UHV 2200/35 I have. These should fit better. Right now, I left in the originals.
Replace C74, C75 100/16v with 100/35 FG. 16V caps on a 15v power supply isn’t much margin.
And replace the jumper eaten up by the cap assembly glue near C70, C71.
If you are still curious, here are the caps I changed
C56,C57,C62,C63,C157,C158,C166,C167 to bi-polar MUSE 10/35v
C74,C75 100/35 FG.
Resistors to metal film (RNF series)
R52,R53 47R → 33R
R3,R4 1K (on Volume board)
R46,R47 470R
one jumper wire
Not really sure what I will do with the kc-209. I'd like to pull the C2 and put this in the main system and listen to it. I have a balance pot for the C2 I'd like to try. it isn't easy pulling gear out of the my cabinet so I may not get to it. I don't expect this to replace the C2 or my other preamps but i think there might be hope for this lowly KC.
.