How many version of MC30 were there? Difference in R13

[Seamaster]

I am in the process restoring a pair of MC30 with upgraded caps and resisters that are inspired by Jeff Day's Bolog and Mr. Yazaki's real sound theory. While I am research for parts, I ran into two different version of MC30 schematics, one is calling for 1k 0.5W resister at R13 position and the other is using 2.2K 0.5W resister. Which is what or correct? How can I tell the difference or there is no difference between MC30s? Thanks for help!!

 

[tuberadios69]

The schematic dated 5-15-56 for MC-30's with serial numbers 15329 and above show 2.2k, 1/2 watt for R13. The Sams Photofact from April 1955 (4-55), Set #275, Folder #9, shows 1meg, 1/2 watt for R13. There may be additional schematics for later dates as McIntosh did tend to make small changes as production lasted many years.

 

[ybeauvais]

There were as many as seven versions of the MC30 circuit. And part numbers are not the same in Sams as they are in the various versions of Mcintosh schematics. R13 in Sams in one part, R13 in Mc schematic is another part, even for amps of the same generation/version. let alone with different amps. Forget the parts #s, focus on the parts' value and mostly look at your amp!

 

[Seamaster]

Thank you tuberadio69 and Mr. Ybeauvais for the advise, I guess I need to focus on the parts' value instead schematics. BTW, Mr. Ybeauvais, this is for a different pair of MC30, not the pair I bought from you, yours is nicely done I would leave them as they are, cheers.

Griffin