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MC 240 Tubes - Suggestions?

Karmices

Karmices

AK Super Member
Subscriber
I have a nice MC 240 with mostly original tubes, which some are starting to test a bit weak. I know in the near future I'm going to replace the tubes, so what would you replace all the tubes with? Buy a tube kit of Genalex or Mullard etc.. from the bay or go with new tubes or?? This is used sparingly on a secondary system so I don't want to go crazy with really expensive stuff, but $300.00ish for a full set would be an ideal price range +/- a little $$
 
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I would go NOS...I purchased a New Set of JJ's for my MC240 which I wanted to sell but the tubes were lousy and at least two were bad when I installed them. Just My 2cents
 
New production Russian TUNG-SOL 6L6-G is a cool looking "big bottle" (shouldered) 6L6GC - assuming you don't have a tube cage. (The TUNG-SOL 6L6-G are tall.) This is what I have installed in my MC240. Might not fit your budget.

A great value in 6L6GC is the Soviet military surplus 6P3S-E. I just put a quad in my Scott 296. I also run a pair of 6P3S-E in an SEP amp. A matched quad of 6P3S-E is available on eBay from a USA seller for $70. I just bought a quad - No problems with eBay transaction.

12AX7: In my MC240 I like Genalex Gold Lion 12AX7 / ECC83 / B759 gold pin (Russia). (Not the cheaper short-plate Chinese tubes.) Vintage Telefunken can be good.

12AU7: In my MC240 I use Genalex Gold Lion ECC82/B749 gold pin (Russia)

12BH7: In my MC240 I use a vintage RCA
 
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I picked up my MC240 about 27 years ago. It had RCAs, Amperex, GEs, Telefunkuns, etc., as the small tubes, but only 3 RCA 5881 grey plate power tubes. I immediately put in 4 new Sovteks 6L6WGC/5881s. Just recently, I decided to buy a single RCA 5881 and pulled the Sovteks, reuniting the amp with the hermit RCAs. The difference is quite noticeable - more airy sound, better imaging, etc.
 
Karmices said:
I have a nice MC 240 with mostly original tubes, which some are starting to test a bit weak. I know in the near future I'm going to replace the tubes, so what would you replace all the tubes with? Buy a tube kit of Genalex or Mullard etc.. from the bay or go with new tubes or?? This is used sparingly on a secondary system so I don't want to go crazy with really expensive stuff, but $300.00ish for a full set would be an ideal price range +/- a little $$
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to fit your budget, I would buy a new quad set of Tungsol KT66s for the outputs from a dealer or ebay seller, and look for used / NOS US made input tubes. There are tons of 12AU7s out there, and less but still common 12BH7s. The 12AX7 on the front end you could look for a good GE or RCA.
 
KT66 tubes pull a bit more filament current than the 6L6GC tubes will. Will the PT care? Who knows in the long run but when I asked Jim McShane about it he advised that it probably wasn't a great idea.
Using KT66 tubes will load the 6V PT output by an additional 1.2A, a not insignificant amount. On my MC40 monoblocks it added 0.6A to the PT draw.
After checking with Jim I decided that the 6L6GC tubes were just fine. I have no interest in trying to source a replacement PT if one should fail.
Just something to keep in mind. McIntosh did not recommend using them either. I have never seen anything in there literature that said they were fine to use in either of these models.

BillWojo
 
I've had about a dozen MC240s. I always used NOS GE or RCAs for the outputs. They're still plentiful ... At least last time I looked.
 
When I had my MC240 I liked the Sovtek KT66s I had installed. They aren't really KT66s (just big bottle 6L6GCs) but they worked well and looked the part. I had trouble getting real KT66s working with my amp so abandoned the idea. I don't think they make the Sovteks anymore though...might find some randomly on a site though or a bay sale.
 
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