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RE: Should we send a "representative" to Magnepan?

But you didn't have to adjust within an angstrom by tapping with a screwdriver. :-)

We did routinely send waveform monitors, vectorscopes, and oscilloscopes to Tektronix for recalibration. And spent a lot of time calibrating stuff in house as well, not just the scopes but monitors.

Quad VTR head assemblies were designed to be swapped rapidly when tip projection was too low or a head broke or went out of quadrature. This happened pretty frequently because the head wheel rotated at 14,400 RPM and it could certainly happen during a session, they weren't generally reliable enough to get to the 200 hours or even close. Each machine had to be aligned and checked by a technician in the morning, and adjusted by the tape operator when a new tape was mounted. The routine alignment process typically took about 15 minutes, a soup to nuts alignment much longer. Even when functioning properly, tape interchange was a problem because of changes in track geometry as the head wore. For that reason, masters were recorded with a head that was halfway through its life for maximum compatibility. And you still couldn't count on it working.

All of this was necessary because when the first VTR's were introduced, there was no time base correction so they had to be able to produce a broadcast quality signal mechanically. Amazingly enough, before the development of digital editing, they would splice the videotapes by developing the tracks with an iron oxide solution and cutting and reassembling them under a microscope! The process was so touchy that an old timer who had been around then told me that when a spliced tape played successfully, everyone would cheer.

When color was introduced, limited electronic time base correction made it possible to directly record color subcarrier. VTR's, like 3/4" or 1/2", didn't have the low time base error of a quad, so they had to heterodyne the subcarrier, making them unsuitable for broadcast use. But when digital time base correctors were developed, it was possible to upgrade 1" industrial machines to full broadcast quality, and they replaced the old quads. The 1" machines were much smaller, more reliable, and easier to maintain, though they still required a skilled engineering staff.

But I know a lot more about that crap than making speakers, so the speaker questions will have to go to Wendell. :-)

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