McIntosh C35 recap

eedork

Super Member
Just purchased a nice, working C35 and am planning to recap it. Everything works with one exception - the volume is very sensitive. Between 1 and 5 is about all I have for usable range. Not sure what's going on there but I haven't had the cover off yet to take a closer look.

I'll be using Nichicon ES for all NP and low value signal path caps, Nichicon KL for all low leakage caps, Nichicon FG for all other signal path caps, and Nichicon PW for all other caps. This combination has worked very well for me on all of the other McIntosh and non-McIntosh units I've recapped.

Any other C35 specific issues to be aware of?

Thanks!
-Matt
 
That's my main preamp, recapped by a member here.

I am typically hanging out between maybe 3-9 on the volume level, depending upon source and how loud I want to go. I think the highest I've ever gone was maybe 15-20. So it does have a lot of gain and I'm already using the 2.5v input setting vs 0.75v setting on my Mac amp. So it's not clear to me you necessarily have a problem, but by opening it up you can probably tell whether someone's been in there and tweaked it.

If I recall, there may have been an instance or two where the service manual was wrong, but if you replace in the same polarity, same value, and low leakage for low leakage, you should be fine.

There was one on eBay that was described as "over-amped" or something to that effect - not sure if that was the one you picked up, but if so, that was a great price.

If you own a scope, maybe you want to just input a signal of a known magnitude and check whether you're getting the spec'd 20dB gain at the outputs. Look for distortion or any other anomalies.

BTW, the variable loudness is a great feature on this pre.
 
Hey captouch -

Thanks for the feedback. Yes, the one you mentioned is the one I purchased.

This is actually the second C35 I've owned - the first one was not restored and if I recall correctly I was able to use a little more of the volume. I'll know more once I get inside it.

I also love the variable loudness and wish they would bring this feature back.

-Matt
 
I own two, and I think this is a wonderful preamp.
With my Mc452, I run the volume anywhere from 1-25.
(If I am in the mood for some thunder)
I'll be recapping both of mine sometime this year.
 
What are people's thoughts on swapping out the old Signetics 5534 op-amps for new TI low-noise 5534ANP parts? Seems like a cheap and easy upgrade, especially since not all of the old Signetics were 'low-noise' variants. I've never used the TI replacements, but it looks like that's all that is available at Mouser now. In past McIntosh projects (amps primarily) I used On-Semi op-amps but those are no longer available.

-Matt
 
I can not analytically document my belief but I think the change from the stock bipolar input caps to the Nichicon ES version provides the biggest bang for your buck.
 
Thanks Chris. I was planning on recapping both input boards with ES caps - we'll see how it goes!

-Matt
 
Hey guys -

I have my cap list together and am curious to know what people think about using Wima MKS2 instead of Nichicon KL for all low leakage caps.

Unfortunately I'm having a hard time finding a leakage spec for the MKS2, but I assume it has to be better than the KL series. Any thoughts on this?

Thanks!
-Matt
 
I can not analytically document my belief but I think the change from the stock bipolar input caps to the Nichicon ES version provides the biggest bang for your buck.
Based on your observation, I just bought 100 10uF 25v. ES series caps for my C-35's, and my C-31v. :)
 
Parts are in .. should get started tonight and will post pictures as I go.

One thing I discovered is that the front panel is not easy to remove. The tone / EQ board appears to be bolted to it from behind, and I cannot figure where the fastener is. Not a big deal, since I can get to everything from the bottom anyway.

I am thinking about converting to LEDs ... Mouser no longer carries the 6.3V JKL bulbs needed for the C35.

-Matt
 
I tend to doubt there'd be any noticable sonic improvement changing out the OP amps.
If you want to try, I'd definitely put sockets in.
It'd let you AB easily.
If you have the gear I'd like to see the test results.
 
The op-amps are already socketed, so it is super easy to swap them out. I opted not to order op-amps so I'm going to skip that for now and focus on just the recap.

-Matt
 
I am thinking about converting to LEDs ... Mouser no longer carries the 6.3V JKL bulbs needed for the C35.

-Matt
What do these bulbs look like? Are they little white bi-pins or have leads? Take a look at Digi-Key. Mouser and Digi-Key are almost like twins.
 
They are JKL 7381 (6.3V) white bi-pins. All three are still working although they look quite toasty. I think I'm going to just run these until the first one dies and then replace them all. At that point there may be some better LED alternatives. Looks like I can still get 7381s from other sources, just not Mouser.

-Matt
 
A friend of mine had a C-28. Which really liked,, then he had a blow out to his lower spine crippling from the waste down, He had to heart to heart with my boss and as the FBI was tracing radical groups I got a full time escort doing sound systems for this group of meetings where they attended. They tried to throw me off and isolated sound location we used for big touring groups.. I wash thankful because they next time they got access to me my mild manner Scrawny FBI agent has the black dude in control. The gent asked his leader was which they already new. Having friends in the FBI in the 70's saved a lot grief . Any way the Boss called rep and he had one at the next at bus station over night. Bob really enjoyed the unit every day until his passing 5 years later. He Kept the C-28 and the 2100 and bought a 7200 to drive his 4 ML-1Cs.
 
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