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MC275 IV - E180CC/7026 vs 12AT7

H

Hubb

New Member
My MC275 IV has seen it's fair share of rolling and right now is outfitted with Gold Lion reissue KT88's, a 1959 Amperex large halo 12AX7 in V1, 1960's Tung Sol long grey plate 12AX7's in V2 and V5 and Mullard CV4024's in V3, V4, V6 and V7. A couple of tube vendors extol the virtues of E180CC/7026's (or American 6414's) as subs for the 12AT7's. One vendor going all the way to claiming once you try them you may never go back to standard 12AT7's again. They are lower mu (47 vs 60) so its kinda like subbing a 5751 for a 12AX7. One vendor suggested that this was only needed in V4 and V7 since they are the cathode followers and V3 and V6 are the driver tubes. My question is is the second suggestion valid. Can I leave two 12AT7's in and sub two E180CC's/7026's for the other two. If so, which gives the better return/reliability - using 7026's in driver positions V3 and V6 or in Cathode follower positions V4 and V7? Or is it better to use either E180CC/7026's or 12AT7's in all four positions? I know it will be up to me to determine if the E180cc/7026's are "better" than 12AT7's but answers to my questions will greatly help me determine a path of rolling.:music:
 
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incorrect tube number

I'm sorry about the inaccuracy of my tube identification in this thread - that should be E180CC/7062. Thank you for any feedback
 
Have not tried them myself but, have read very good things about them. Their gain is lower than a 12AT7. I doubt that would make much difference. You can find them priced around $15 and up. It is a sleeper tube that audiophiles want to keep a secret so prices don't go up. I say go for it. I am going to.

I am currently running Siemens ECC801s with remarkable results in the sound. My power tubes are reissue Gold Lions and the other signal tubes are Telefunken ECC83/12AX7 smooth plates. Another good 12AT7 tube is the RCA black plate. I am running them in my C2200.
 
MC275 IV - E180CC/7062 vs 12AT7

Thanks WGRR. I received a reply on another site from the same sort of post. Gentlemen informed me that, like you said and I already knew, the mu is lower in a 7062 vs 12AT7. But also, and he seemed more concerned about this, the plate resistance is lower and the plate curves indicate higher 2nd harmonic distortion. I am getting a pair on Tuesday and will post my results. I know that Mac amp circuits are very forgiving and tolerant of minor variances in tubes one plops in. We will see what we see. I'll let you know how it goes. I too am enjoying some RCA black plates. A pair of 5751's and a pair of 5814's populate the phono section of my Rogue 99.
 
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