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.



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
Richard L. Hess                   email: [log in to unmask]
Aurora, Ontario, Canada                             647 479 2800
Quality tape transfers -- even from hard-to-play tapes.