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Tubes for Mcintosh MR71

I've got a McIntosh MR71 tuner that I’ve done some tube rolling on but I have not been very pleased with the results. What I think are new tubes are resulting in increased background noise and poorer selectivity. I don’t have a tube tester so I can’t check tubes to confirm they are “new”. I am about to get the tuner aligned and want to use the best tubes I can since my understanding is the tubes effect the alignment (with the obvious exception of the audio tubes). Has anyone found what they think are the best tubes for use in this tuner?
pmotz
fatparrot
1,314 posts
 
What are you using for your "new tubes" and where did you get them from?
pmotz OP
412 posts
 
The guy who will be doing the alignment does not have a tube tester so having him test is not an option. With respect to the tubes I was trying here’s what I’ve got:
12AT7 – Telefunken and RCA
6BN4A – RCA, GE, and Zenith
6AU6A – IEC (Japan) and RCA
6CS6 – Zenith
6BN8 – RCA
6U8 – Raytheon
12AU7 – Telefunken, GE, Sylvania
These all came from a ham swap, so no real guarantee they are new. The tubes that have been in the unit since I got it several years ago are McIntosh, mostly rebranded RCA.
s23chang
620 posts
 
Try some Amperex 6BL8, Mullard M8162 ( 12AT7 ), Amperex 7316 ( 12AU7 ) and Amperex 6U8. For 6AU6A, stick with GE or RCA.

I still own MR-71 and have sent back to Richard Modifferi ( ex-Mac chief engineer ) for the upgrade mod. The gain is much better and very quiet overall. The mod also increased the lower frequency response. YOu should really consider to send it to Richard. Regular tune and repair is $350 via audioclassics. Don't let anyone else touch you tuner other than a Mac person. I learned from the hardway and got rip off and made worst sound...
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