MC75 question

[bonsai]

I have a pair of MC75 60 Anniversary amps made in 2009. These are different from the vintage MC75 amps. They have a different tube line up.

I had read that in a MC275 a 6414 in the 12AT7 spot of the McIntosh 275 Cathode Follower tubes (V4 & V7) that the 6414 is a nice tube to run. The 6414 has slightly less gain then a 12at7. it is a bit taller and the heater pulls just a bit more current. But most circuits running 12at7 this 6414 is a good sub

I have a couple 6414 and I'm thinking of trying but I'm not sure what spot on the MC75.

The manual says

Tube Compliment
1 - 12AX7A Input and Phase Inverter
1 - 12AT7 Voltage Amplifier
1 - 12AT7 Driver
2 - KT88 Power Output

 

[bonsai]

I'm trying to identify what tube in a MC75 60 Anniv. amp is the Cathode Follower tube

Also trying to ID if a 6414/E180CC/7062 tube is a good sub for a 12at7.

Brent Jesse says:

E180CC or 7062:

Most often found in European types, typically Amperex or Philips, this tube is virtually the same as a 5965 in regard to electrical specifications. Audiophiles have been seeking it out since the price is generally lower than the premium ECC81 NOS prices currently. Like the 5965, it has slightly lower gain than the 12AT7, and has the added advantage of a 10,000 hour heater life to make it another audiophile "secret" tube. A super bargain when you find them, since they are musical and smooth to listen to, and actually sound better than many standard 12AT7 tubes. Better grab them now while the prices are still low! Be on the lookout for the rare Holland D-getter types from the late 1950s, and the even rarer "pinch waist" types with the narrow glass middle section. These are superb tubes. This tube is about a half-inch taller than the standard 12AT7, so chassis space is an important consideration.

 

[dshoaf]

There's not enough data, here, IMHO, to pass any judgements. Need to see the schematic and links to the data sheets for the various tubes.

My experience with the later Mac tube gear is that the circuit topologies will tolerate variances in gain, Mu, and other tube parameters but there are limits, of course.

I'd not be putting any of those alternatives into a circuit until I could understand what to expect. I also do not go by much of the blather out in the blog-o-sphere about tube substitutions. Exceptions include Jim McShane, among others - and they'd want to see the schematics before commenting, too.

IME, the only guidance I'd put any bets on are a well-used tube substitution handbook from the 60s from RCA, GE and the like. They understood their products better than anyone else.

On which tube is a cathode follower, likely that the 12AT7 listed as a driver will be closest to that - but all bets are off until a schematic surfaces......

Cheers,

David

 

[bonsai]

David,

I think your right thought wise.

I wonder if anyone tries to sub any tubes for the 12AX7A and 12AT7 you run on a new current MC275?

 

[MX117.MC7150]

When I had a set of the MC75 60th Anniv amps (was before the GL 12AT7/12AX7 reissues were available) was quite pleased with the JAN Philips and Sylvania small signal tubes in place of the originals. Also preferred the reissue Tung Sol 6550s to the reissue GL KT-88s. Ran the same tubes in the MC275MkV before the MC75 and was very pleased with them there, as well. Now run the 6550s in the Cary SLI-80 Sig.

 

[bonsai]

I've done some tube rolling on the 12ax7 and 12at7 small signal tubes and have some sweet sound. My favorite combo is Sonotone clear top 12ax7 and then mullard 12at7

I was more wondering if anyone tried any 12at7 similar tubes like the 5965 or 7062

For now I may have to run my JAN Philips again ;-)

 

[ron-c]

JAN 6201 is the best sub for a 12at7 or 12az7.

Thanks,
Ron-C