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Re: Frank and Richard

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!

Richard Links
Berkeley, CA


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