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I use software to help me align azimuth on cassette transfers all the time in conjunction with my ears. You can call it a "crutch" or you can call it being thorough and professional. Consider that you could theoretically calibrate a reel machine by ear, too, but I wouldn't hire anyone that didn't use a voltmeter or DAW meters. On Wed, Sep 10, 2014 at 9:01 AM, Richard L. Hess <[log in to unmask]> wrote: > I probably should clarify... > > Think of the azimuth error situation as a right triangle. > > The "perfect" azimuth is one leg that is vertical. The actual recorded > azimuth is the hypotenuse. The azimuth error is the leg which is horizontal. > > The length of the horizontal leg of the triangle can be translated into the > time delay and the phase shift between the two channels. > > When the two channels are summed, even small errors which CAN be equalized > out, grow into huge errors and cannot be recovered, so the re-timing between > stereo channels prior to summing will produce far better results than not > using it and summing the two channels will reduce the noise taken from > either channel. > > For high-quality music work, using a full-track head is superior, but for > oral history production work (especially from cassettes) there is merit to > summing the two tracks, especially because mono cassette machines are hard > to find and few (if any) were made with the quality of the top stereo > machines. > > Here is an example using a cassette: > > 15 arc minutes (1/4 of a degree) azimuth error. > > Single channel -3 dB point ~ 9 000 Hz > Summed channels -3 dB point ~ 3 400 Hz > Single channel -6 dB point ~ 12 000 Hz > Summed channels -6 dB point ~ 4 600 Hz > > Sliding the second channel in time to be in alignment with the first > provides a huge improvement in the high-frequency response. > > I contend that, if desired, losses of up to approximately 6 dB can be > equalized out as long as there is no additional boost and a rolloff after > the - 6 dB point (to avoid increasing noise). > > Cheers, > > Richard > > > > > On 2014-09-10 10:25 AM, Richard L. Hess wrote: >> >> Hi, Andrew and Tom, >> >> I am (very) slowly working towards a paper on azimuth. >> >> The full-track mono tape is, of course, the hardest to play from an >> azimuth perspective (of the common formats)--I hate to think about the >> 1-inch two-track! >> >> Transport guidance is a huge issue and I have found that the Studer A80 >> is magical in that regard--and the Studer A810, not so much. The Sony >> APR-5000 is between the two. >> >> For those of us who have taught ourselves how to adjust azimuth by ear >> (sort of the same thing as focusing a camera lens in many ways), we do >> not need crutches, but I have come to realize that using a two-track >> head for "factory workers" might be beneficial. >> >> For one project I proposed (but we chose not to implement) a wide/narrow >> head for full track mono. We batted around a few different >> configurations--including a long discussion with Greg Orton. I was >> thinking of something like 0.120 and 0.04. The nice thing is even if >> things go south, you still have a good percentage of the highs on the >> 0.04 track, albeit noisy. >> >> With that said, for oral history cassettes, I use, in addition to manual >> azimuth adjustment, the azimuth compensation feature of >> www.stereotool.com. This allows excellent channel summing for improved >> noise, assuming both channels were recorded. >> >> There is a similar feature in iZotope RX Advanced. >> >> Cheers, >> >> Richard >> > > -- > Richard L. Hess email: [log in to unmask] > Aurora, Ontario, Canada 647 479 2800 > http://www.richardhess.com/tape/contact.htm > Quality tape transfers -- even from hard-to-play tapes.