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McIntosh MC225 questions

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These amps are my favorite. I have two in monobloc mode. A C-41 is the pre, Tannoy DC3 speakers, and Ridge Street audio cabling. Sources: a VPI TT, & a MacMini to Ultra Fi USB DAC (a very satisfying combination especially with ripped CDs into AIFF).

I have some questions for experienced users:

Tubes:

Other than the 7591 power tubes (I'm using matched EHs right now), from your audio point of view which/what other of the amplifier tubes reveal a significant difference when tube-rolled: the two phase inverter tubes: the 12au7's?; the one voltage amplifer tube: the 12AX7?; the two drive amplifer tubes: the 12BH7s? I have NOS RCA blackplates in there mostly (as I recall).

If in your experience some or all made a difference, what in your experience in your system was that difference and what tubes did you settle on?

I've changed the fuses (HiFi Tuning), ok but nothing to get excited about; changed the power cables (cryoparts IEC adapters) to IEC Kubala-Sosna Fasicinations (significant difference in clarity and dynamics over-all); and updated (Terry DeWick) the caps, etc. as per his recommendations.

Generally, this system is the soul-satisfying system!

Thanks for your points of view,

:) listening,

Ed

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istanbulu
apachef1
164 posts
 
I also have two Mc225's in mono mode. For tube rolling the 12ax7 is the most noticeable change from tube to tube. The 12au7 less significant but you will notice. I did not notice a change with the 12bh7's but I did not try to roll from grey plate to black plate. I think you would hear differences between the two.

I've rolled 1950's long plate mullard 12ax7 with 1960's bugle boys and smooth plate tele's and I seem to like the teles. But they all have their strong points and make for some interesting listening experiences. You really get to know you equipment
istanbulu OP
291 posts
 
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Hi Apachef1... what was it you noticed or preferred about the smooth plate tele 12ax7?

:) listening,

Ed
apachef1
164 posts
 
More life like vocals and 3d sound staging. The amperex and mullard were stronger in the bass and more of a forward midrange presentation. Tele's has much smoother highs. These are very small differences and will only be noticed if you have very revealing speakers.
I put tele's 12au7 and 12ax7 in for my tube rolling. i think once you are happy with a certain 12ax7 replace the 12au7 tubes with that same brand and plate constuction. it will enhance the sound a little more.
Mixing the brands gets interesting and it all becomes a matter of what you like. I do find myself changing it up every six months or so but always seem to go back to the tele smooth plates
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