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There were like 3 models of the c20 style wise and I got this one back in 1991 and I traded it for an apt holman ss preamp..The plastic glass on the front was bad and I had taken it apart hoping that audio classics would come up with a repro glass or plexi glass but they never did..There is a guy in Germany that was making some and now he doesnt..Can anyone tell me is that the correct type end cap for the c20? It seems it is but Im not sure where I have those end caps but I think these are it..You can see it standing up on top of the preamp..Any other info would help to as Im restoring it now.
Follow Ups:
I figured you guys would get a kick out of that preamp..Its not quite as bad as it looks and the only reason Im attempting it is that reason and it has a tube rectifier..No I know it will never the highly upgraded citaiton one I have but then I dont think any preamp matches those but you guys are right in that I hope I can find the pieces..I had all the pieces when I got it other than the glass that was a mess.The middle strip you can get from a hobby shop and this was told to me my Terry dewick..They can cut you a piece of gold colored stripping for a couple bucks.The knobs cleaned up pretty nice and Im going to paint the transformer next..
This is my own preamp so thats another reason I can attemp this and Im sure it will be time consuming.I see the c20s are selling for more now than they used to but I dont know how good they sound when upgraded.Again thanks guys because I was worried I didnt have the right strips and the other metal bracket I have.
Hi, Mike (and Frank):Looks like you have a challenging little project on your hands, my friend, so best wishes to you in that regard!
For years and years, folks have complained about those flimsy end caps. The same was true for the C-11.
Incidentally, if you properly update the caps and check the resistors on your C-20, it should wind up sounding decent.
One thing that I am unable to confirm is whether or not McIntosh chose to use some of those "printed circuit modular" circuits for RIAA and other applications in the C-20. I know for a fact that they were featured in both the C-11 and C-22. At the old McIntosh Laboratories Clinics, folks like Dave Evans (now deceased) and Dave O'Brien (our hero!) discussed the failure rate for some of those yellowish wafer-like modules in the C-11 and C-22 preamps and that was over TWENTY YEARS AGO! McIntosh Labs ran out of replacements in the late seventies, I believe. Their failure often manifests itself in measurable distortion on phono, which often was the case when thesee units were subjected to bench testing at these dealer-sponsored McIntosh Performance Clinics.
Of course, it is possible to cobble up perf-board replacements with discrete components if you have the time and are so inclined.
In comparison, the classic Marantz 7 tube preamp, which was a "kissin' cousin" (circuit-wise) to the C-11 and C-22 preamps, did NOT include such modules and had a chance to peform reasonably well over time.
Very few, if any, of these vintage preamps can perform within spec unless the majority of small coupling caps are replaced and resistors checked, not to mention updating the power supplies in such units, particularly ones featuring old Selenium rectifiers, which your C-20 does not apparently include.
If you are a clever person, you might try fabricating a lucite front panel replacement for your C-20, but try to obtain a good photo of an existing one to start with. In any event, you might wind up with a decent piece afterall!
I once fabricated an entire lower metal piece for a C-11 and used architectural transfer lettering for the nomenclature. I also fabricated genuine walnut side end caps, since none were available at that time. That unit went to a collector in northern Italy over twenty years ago without any complaints!
I had my C20 for more than 30 years when I sold it last year. In fact, It still had a couple of stickers on it from the two McIntosh clinics I took it to in the late 60's/early 70's. {Guess that tells you I'm an old fart}I gave it a good hard look before I sold it. I took mine over the Peter Lederer (ex Bozak engineer) who runs Soundsmith. They went through it and pronounced that it met all the original factory specs. My ears told me otherwise. I added up the costs for all the caps I'd need to replace, and the resistors that had drifted out of spec, and compared it to what the carraige trade was paying these days for C20's... Just not worth it to me to restore compared to what someone else would pay for it in "original" condition.
My hat's off to Mikey!!
I had a C20 up until last year (had it since 1968). Those stupid end caps kept falling off their pins until I added a little goop. Also, the chroming on the plastic isn't very durable, so they look tacky pretty fast. Not my favorite cosmetic feature of the amp.So yeah, I recognize the end cap, from picking it up off the floor for 30 years!
I'm not convinced that preamp is worth much of your effort, Mike. I doubt it will ever sound as nice as your Citation 1's.
Hi, Michael:Wow, that certainly is one sorry looking C-20.
Did you also manage to save the escutcheon pieces which hold the glass and accommodate the end caps? If not, I want to wish you good luck in finding those sorts of pieces.
However, the end cap sitting on the top looks correct to me and I believe that the same style end cap fits all three variants of the C-20 preamp. They might also possibly be inter-changeable with the early MR-65 FM tuner--which is a mere guess on my part.
I assume that you have tried to contact McIntosh Labs to ask about replacemetn dial glass? If not, try this number for tech assistance: (888) 979-3737, though I have not dialed that number in a few years.
One version of the C-20 front panel was made of one piece of glass with a metal strip mounted on it, separating the top row of knobs and the bottom one. Another one (I believe) did not have the horizontal separation brass bar and the last one might have had glass on the top and metal below.
That is only a guess on my part.
Happy reassembly!
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