Mixed driver tube for Mcintosh MC275


I just wonder if anybody know which sections of Mcintosh MC275's driver tube are most crucial? Is it all sections of equipment are the same in terms of the importance of the driver tubes. Another thing, is it using a tube that has a sonic trait that is different than another like combining a thinner more detailed tube like a Telefunken can actually work very well with a warmer tube like a Mullard?
yewhlock
Tzh21y
You can find schematic of MC275 re-issue in http://farm5.static.flickr.com/4037/4204605299_bdfa12827f_b.jpg. You can study from the schematic that V1 is not in the signal path.
Okay, after viewing the schematic, it is clear that V1 is not in the signal path. Then what am I hearing? Voodoo? I am obviously crazy! Now I am convinced as to not buy anymore tweeks because my hearing is somewhat flawed.

I thought I noticed a more full sound with the other tubes I used. This is crazy. I am going to put my one pair of balanced cables back into the amp and see what I hear. I did ask the tech and he did say it was in the signal path and would have an effect on the sound. I felt I was pretty clear on how I asked the question. My mind is obviously playing games with me. This is a very informative thread. Maybe I will try different balanced cables and see what happens. There I go again, tweeking.
Tzh21y --

1.) I don't think there is anything at all wrong with your hearing! I'm 68 and I KNOW my hearing isn't what it used to be (to say the LEAST!!) however my ability to LISTEN is better than ever ;--) I wish I could go over your system with you in person, because I know I could find out what is keeping balanced operation from sounding completely marvelous and far superior to single-ended.

2.) My long experience talking with McIntosh technical people (even those at the top) has been 'highly unsatisfactory' to be diplomatic about it ;--) You would have better luck talking with one of the engineers; at least they understand English, but they are harder to reach. See if you can get hold of Ron Evans, V.P. Engineering.

I have a couple of system specific comments:

1.) JPS interconnects are OK (as in: decent)
2.) Everything "Cardas" sucks! Way too much capacitance (especially for your Merlins) and terrible time-alignment. There may be a couple pieces of equipment on the planet that one could connect with Cardas cables, but nothing I'd want to own! ;--))
3.) I'd be interested in knowing what kinds of (good) tubes you own for the amp, and -- I almost forgot -- what (if any) tube changes you've made to the C220?

Neil
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I have the Cardas on the CD player. I am listening ( auditioning) to JPS superconductor 3 cables connected to the turntable. I can see how some can be critical of them. I have NOS Telefunkens in the C220, all Telefunkens in the 12ax7 position in the amp, GE 12at7's and Tung Sol 6550 in the 275.

I am going to plug the XLR's back in try that V1 thing again. If it still sounds different,
Tzh21y -- If you like the JPS product, you should stick with them, perhaps throughout your system for synergy. I just don't like (almost) any of Cardas' products because of their high capacitance (especially of their speaker cables) and the excessive time smear of their interconnects -- all due to all that "Golden Section" multistranding ;--)

Did your MC275 come with 6550 tubes? And what vintage Tung Sols are they? I ask because you might want to try a quad of KT88's which are more powerful and some say more accurate. I haven't tried 6550's in my amp, so I haven't compared the two. The best price/performance current KT88's are the SED's (yes, I've listened to them and tested them ;--) You can get a matched quad here for about $170 http://www.conusaudio.com The other tubes you are using are OK for now pretty much, except if you are using the C220 phono section, I would recommend tubing that part with 5751's -- either Sylvania or RCA triple-mica blackplates for ultra-quiet, great dynamics, and smooth top-to-bottom frequency response.

In order of bang for buck:
1. KT88 power tubes $170
2. JPS speaker cables (??)
3. Sylvania blackplate 6201's (12AT7's) $150/quad
4. JPS for the other cables (??)
5. RCA or Sylvania TMBP 5751's (12AX7's) for the phono section. $140 or $200 per pair respectively.
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