Need McIntosh help - new to McIntosh

[monty]

Regarding Berner's site, I emailed him for the 240 manual since it said "for sponsor's only" and he sent me a copy via e-mail. So try that.

Now, for my equipment: I've been playing with it all day and I can't seem to locate the problem exactly. I know it's not my speakers; I hooked them up to another system, and they sound good. With the c-20/240 set up, the left channel is lower than the right channel, and I have to pan to the left in the stereo input on the 240. The left channel seems to have more bass trouble, but they both have it to some extent. I've been playing Glenn Gould's Goldberg Variations, and when turned fairly loudly (but far from ridiculously loud) it sounds like something is rattling in the speakers when the music gets bassy. This is more prominent on the left, but happens to some extent in the right too. I've been playing with the controls, but unless I have the bass turned way up on the c-20, I don't get much bass at all. For someone with a similar setup, where do you keep your bass, treble and audio comp controls? Just as a general guideline. I'd like to see how it sounds when set at positions that you find generally acceptable. Either way, what does bass rumble like this suggest? Could it be a weak tube, or am in a lot of trouble here? Thanks in advance

 

[monty]

Terry:
to more specifically reply to your suggestions, I switched the inputs but the results are inconclusive. Generally, the left speaker is lower than the right. When I switched the inputs, it channels were more or less equal, suggesting that maybe both the 240 and c-20 are having problems? But the bass rumble is the real problem, and both channels have this problem to an extent; when correctly wired, the left channel has it worse, but when inverted, they both have it about the same. I wish I could be more specific, but it's hard to pin down exactly.

 

[dewickt]

Here is Monty's C20, a virgin one that works perfectly now, .02% thd and flat 20 to 20,000 hZ at 3V output, will be on it's way home soon.

 

[CarlV]

I'd say monty will be happy to see it home and working as it
should finally.

Carl

 

[dewickt]

MC240 is complete, both will go to FedEx Monday morning, Monty should have them by the end of the week. Expect to see a report on what he thinks of the sounds ........
MC240 - <.1% THD at 40W Left and right channels, and a healthy 54 watts before clipping with less than .5% THD, the winged C 6L6GC's do a respectable job.

 

[monty]

I can't wait to get it back...thanks so much. I'll be sure to report...

 

[ronflugelguy]

So, what were the problems with the two units???Tubes or more??

 

[dewickt]

No unusual or odd problems, they had the type of problems that I see often.
C20 has a tired volume pot, good cleaning and lubrication should preserve it for many years, to correct for the unbalance in the sections caused by age I use a ground side trim resistor on one of the sections, this was used on the late production C20's by the factory to match the channels due to varience in the sectins of the four section volume control.
The MC240 was running over 100 V low on the B+, caused by bad capacitors in the voltage doubler, replaced them and output came up to 20 and 30Watts, tired original output tubes. A set of new winged "C" 6L6GC's brought it up to 54W before clipping with .5%THD, and a very good .1%THD at 40W, well under the factory .5% spec..
Both have all original capacitors in the signal path yielding a very smooth musical sound that McIntosh is famous for.

 

[monty]

Well, I've got my c-20 and 240 back and they work perfectly. I know Terry is well-regarded around here anyway, but I just thought I'd let everyone know that he fixed the problem, did it quickly and the bill was much lower than expected. I definitely recommend his services.

Now the only problem I have is deciding what to play on this system--it sounds so good, it's hard to choose.

 

[Rich Andrews]

Time to play it all starting with the old favorites you haven't heard in a while.