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I will carve out some time later this week to run full-track and 2-track tapes forward and backward and we can compare the audio. I'll put raw transfer audio up, so you can analize and process as you see fit. I have to find some appropriate full-track material, probably will use session audio from TV commercial soundtracks, made at A&R Studios in the 70s. For 2-track, I'll use an old Mercury 1956 duped stereo jazz tape, probably Max Roach so we can look at how percussive and trumpet wavefronts behave. I have to change some things around in the studio setup to do the Quad tapes, so I'll hold off on that until all the tapes arrive. For that project, I also have to get over to my locker and get my two Dolby B playback units, because some of the tapes (not those I was wondering about running backwards) are Dolby B encoded. -- Tom Fine ----- Original Message ----- From: "Corey Bailey" <[log in to unmask]> To: <[log in to unmask]> Sent: Monday, February 08, 2016 12:39 AM Subject: Re: [ARSCLIST] Playing reels backwards - separating myth from fact > Hi Richard, > > Yes, this was the analog era and only MONO or 2Tr masters were involved. The 1970's-1980's, in > fact, and many people on this list probably bought vinyl that was produced form one of those > backwards copies. > > Other "out of the box" thinking at the time led to disabling the erase head for first-pass on > virgin tape to help the signal-to-noise ratio. This was accomplished by switching the erase > voltage to a dummy head so that the load remained the same on the erase amp. Even tried this with > 2" multitrack recording with improved S/N results but then, the mixer du-jour would forget to turn > on the erase head when needed and record sound-on-sound for a punch-in so, the multitrack > innovation was abandoned. > > Cheers, > > Corey > > On 2/7/2016 12:43 PM, Richard L. Hess wrote: >> Hi, Corey, >> >> Very interesting. >> >> Just to be crystal clear, you were making analog to analog copies. Absolute polarity in that case >> is a non-issue as there are, in effect, two polarity reversals. The first one when you play the >> original tape backwards and the second when you play the backwards-recorded tape forwards (in >> essence backwards again). >> >> Obviously, one needs to flip the polarity in the digital domain as the file reversal should not >> include a polarity reversal, although if the function were designed for this purpose it COULD do >> both in one pass, but I don't think any do. >> >> Your results are in keeping with what I have heard for analog copies and I think since we are >> concatenating two complete passes through the analog tape chain that there is more of a reason to >> say this is good for analog copies than for digital copies. >> >> I really hope Tom (or someone) does some listening tests. I've done my share recently with the >> Satin software NR decoder. >> >> Cheers, >> >> Richard >> >> >> On 2/7/2016 3:03 PM, Corey Bailey wrote: >>> I used to routinely transfer 2 track music masters backwards. The >>> results were noticeably better than a transfer made forwards. The tapes >>> were non-Dolby encoded (I was never a fan of noise reduction for music >>> recording). Azimuth is absolutely critical. It has to be spot on as well >>> as the playback EQ calibration. This process was always done on the same >>> machine that recorded the master tape. Azimuth and playback EQ are >>> calibrated with the tape playing forward and then the tones are played >>> in reverse, recorded and observed. If there is any difference in the >>> recorded level of the source tones on the reverse copy, then the >>> playback alignment has to be re-checked and the culprit is usually >>> azimuth. I always adjust azimuth with a dual trace scope and overlap the >>> channels to insure absolute phase although there are a few ways to >>> calibrate azimuth and get it right. When it comes to the absolute >>> polarity of the copy, it was never an issue because the phase >>> relationship remains the same if all is adjusted properly, even though >>> absolute phase is reversed. Did many A-B listening tests with everyone >>> concerned and an overwhelming majority preferred the backwards transfer. >>> Those who weren't sure could usually not tell the difference. Then, of >>> course, there were those nervous producers who were afraid of anything >>> outside the box. >>> >>> I have never tried this with 1/4 track or 4 channel formats and Richard >>> Hess makes a valid point about the difference in 4 channel heads vs. 1/4 >>> track. I did try the process on a 2" 24 track tape and the results were >>> not great and I have to reason that it was an azimuth issue because >>> multi-track heads are never perfect. The 2" transfer was tried on an >>> AMPEX MM1200 which are fixed azimuth machines. >>> >>> Cheers! >>> >>> Corey >>> Corey Bailey Audio Engineering >>> www.baileyzone.net >>> >>> > >