Reel to Reel tape question

It would be worth it to contact Jim at Reel Audio. I sent my Revox 215B cassette deck to him just this year. It sounded good so I thought. It sounded stellar when it came back! He cleaned, lubricated and changed out caps that needed it. Calibration was done too, Besides shipping it cost me under $400.00 

This makes no sense to me,

everything ought to be physically the same, alignment, positioning of heads and tracks, reel tables height, electronics also identical, hmmmm

Any clues from the VU meters when playing? 

Any error, wear, alignment, bias, ought to be the same for either pair of tracks, it's the same heads in same position reading them.

Maybe talk to, or write to Jim, asking him what he thinks it could be.

@dtorc depending your location, I would drop Curt Palmer an email he runs Reel to Reel Tech in Vancouver BC. Easily the best R2R tech out there, he will probably give you an answer or ideas on "fixing" if need.

Unless you have the bench gear I would advise against making any adjustments to azimuth, you need an oscope and calibration tape. 

I agree that it doesn't make sense - but it is most definitely happening. I'm Boston based, and I do have a couple of repair folks who are very capable with vintage gear. They both declined to work on the deck because they didn't have the calibration tapes. I think I will get the tapes from MRL so that isn't an issue. I don't have a lot of tapes - maybe 50 7.5 ips 4 track tapes, and a couple of 15 ips tapes - but some of them sound really good, and I occasionally stumble into another good sounding tape once in a while. In other words, it is worth investing in the calibration tapes, and having my repair folks try to see what is happening. 

I appreciate the thinking and sharing.

David

When flipped, your Revox reads Track 3+4 sit in different parts of the tape coating.The reverse  side tracks may be better aligned to your A77