On 2015-03-10 12:14 PM, DAVID BURNHAM wrote:
> When I talked about phase reversal when a track is played backwards, it has nothing to do with azimuth, I'm talking specifically about the polarity of the audio, which will be inverted whether the azimuth is correct or not.
Thanks for clarifying, David
I was attempting to address several different concepts.
- If made on well-slit tape on the same machine at roughly the same
time, and assuming that both tracks of your premium repro head have
precisely the same azimuth, the azimuth error coming off the forward and
backward passes will be the same. Therefore adjusting for one will
automatically adjust for the other.
- For any tape that I would do this with, there will not be tones for
precise azimuth alignment and none of the stereo tools will help as
there is only one track (unless you have a split head like the Nakamichi
Dragon's inner track heads) so you cannot compare. Therefore we are
relying on peaking high-frequency energy from the program content as the
sole means of adjusting azimuth. While that gets it close it is not as
good as using tones.
- I concur with Tom Fine and others, I pick what tapes I do this with.
I would not do high quality, music that way, but high quality music was
never supposed to be recorded in a bidirectional manner and quarter
track was not a high quality music format. However, there are always
exceptions to the rule. I do not reduce my charges because these tapes
also often require more post processing and other fussiness so I can
afford to do some if I capture in one pass.
- If you do a reverse transfer the audio will require a polarity
reversal in the software to match the forward channel.
- There is no absolute polarity reference on a tape, so one cannot know
which of the two tracks is correct. It is a toss up as to which is
correct. You might do as well listening to see which sounds more in
polarity and switch the other one. Or viewing the waveform is sometimes
instructive (positive peaks are usually higher than negative peaks)
Richard L. Hess email: [log in to unmask]
Aurora, Ontario, Canada 647 479 2800
Quality tape transfers -- even from hard-to-play tapes.