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I have had some practical experience with dubbing tapes in reverse and then
reversing the digital file on the computer.  After reversing the absolute
polarity, the files were not identical by appearance, although close.  It
could be that a small azimuth error would do that.  Upon listening, the
sound was also close but not exactly the same, again possibly a very small
azimuth error causing this difference, or perhaps it was the reversed
playback thing.   In every case, on the one project I am recalling, I opted
for the forward play dub as sounding a little better than the backwards
one.

However, on really problem tapes where playback is physically difficult,
like where the tape is physically deformed--stretched on one edge, is no
longer in a straight line, that kind of thing, playing backwards can be a
good tool.  Getting good tape-to-head contact is the issue, and playing the
tape backwards changes all the stresses and the physical aspects of how the
tape is moving past the heads.  I have even had a tape that was so deformed
that just keeping it moving by the heads required "hands on"
treatment--gently holding it on place with fingers (which you can do on the
Technics 1500 series head design) while it played, making a number of
passes this way, including reverse ones, and then assembling the music bit
by bit on the computer, using only the pieces where "good passes" were
obtained (i.e., where the tape to head contact was right).  A ridiculous
way to have to do something, and anything but efficient, but it worked,
salvaging what was on an otherwise unplayable tape.

Best,
John



On Tue, Feb 9, 2016 at 1:09 AM, Corey Bailey <[log in to unmask]>
wrote:

> I need to remind everyone that I never made a backwards copy of an encoded
> (stretched) tape, regardless of the noise reduction employed. I was there
> when the "to decode or not decode" controversy was at it's height. My
> position was (and still is) to decode the original and re-encode the copy.
> Reason: If you make a copy of an encoded tape without decoding it, the copy
> will have baked in tape hiss that will ultimately not be affected by the
> noise reduction when applied for final playback. Thus, the copy will be
> nosier than if you decoded and re-encoded the copy.
>
> Cheers!
>
> Corey
> Corey Bailey Audio Engineering
> www.baileyzone.net
>
> On 2/8/2016 9:19 PM, Jeff Willens wrote:
>
>> Actually, that was the one thing I always heard you could NEVER do with
>> Dolby encoded tapes -- dub them without decoding them.
>>
>> I'm going back 15 years or so to remember this, but it is possible I did
>> not
>> decode the Dolby on some of the analog copies I made, probably for test
>> purposes. As I said, decoding backwards was not my preferred method, but
>> no
>> one seemed bothered by my concerns. I did the dubs per the request of the
>> reissue producer. If there were residual decoding artifacts, I never heard
>> them or heard about them from the others involved.
>>
>> On Mon, 8 Feb 2016 21:23:34 -0000, Ted Kendall
>> <[log in to unmask]>  wrote:
>>
>>
>>
>>> This runs counter to my own experience. Firstly, one great benefit of
>>> Dolby
>>> A was that straight copies of encoded tapes could be made without
>>> decoding,
>>> provided that the reference tones were retained on the copy, so there
>>> was no
>>> need to decode as part of the dubbing process. Secondly, to decode a
>>> Dolby A
>>> tape on reverse play is just plain wrong - the attack and decay
>>> chracteristics of the system are asymmetrical, so the decoding will be
>>> wrong, no matter how much you have finessed the other parameters.
>>>
>>>
>>>
>>>
>>> ----- Original Message -----
>>> From: "Jeff Willens"<[log in to unmask]>
>>> To:<[log in to unmask]>
>>> Sent: Monday, February 08, 2016 1:22 PM
>>> Subject: Re: [ARSCLIST] Playing reels backwards - separating myth from
>>> fact
>>>
>>>
>>> I should think the net gain depends on the type of music involved. Back
>>> at
>>> Universal, I was asked by a producer to make 1:1 analog copies of album
>>> masters played in reverse to be sent out for mastering. The thinking was
>>> exactly as you describe: sharper transients, better bass response and
>>> definition,etc. Since these were all reggae albums from the 70s and 80s,
>>> they felt it was worth the effort.
>>>
>>> In my own crude testing, I found that, aside from making sure the
>>> channels
>>> were consistent (something one can easily overlook), I also found azimuh
>>> to
>>> be the crucial factor in achieving any success, Many masters were Dolby
>>> encoded, which gave me much pause, but no one else was concerned about
>>> it (I
>>> figured decoding between the two tape machines was the least of all
>>> evils).
>>>
>>> Was there a difference? Hard to say. I believe there was a slightly
>>> better
>>> result from  reverse transfer, but nothing drastic. And definitely
>>> nothing
>>> that couldn't be got with skillful use of modern compression and EQ.
>>> =========================================================================
>>>
>>>
>>
>>
>