I recall Bob Olhsson mentioning that reverse transfers were beneficial.

On Mon, Feb 8, 2016 at 8:22 AM, Tom Fine <[log in to unmask]> wrote:

> 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


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