In article ,
Johnny B Good wrote:
No. The idea was to get the very best tape contact to the heads. And
miniumum weave and flutter etc. A very clever design.

Both capstans were direct drive. And I assume clever electronics to
maintain the correct tape tension.

It was a pro 1/4".

In which case, the capstan motors weren't being synchronised in the
conventional sense. The electronics must have been used to set up the
tiny (and appropriate) speed differential required to generate the
required tension in the section of tape passing the heads. Clever
electronics indeed.

Quite. So not in exact sychronisation, but a degree of offset.

I suppose such clever (or 'smart') electronics could easily include
accurately timed solenoid control of the pinch wheels to allow for the
effect of 'run up time' (no matter how brief) to eliminate the start and
stop pitch slide effect.

Whilst extremely low inertia motors can be made by making the rotor
'ironless' using a rotor made entirely from just the copper wire formed
into a moving coil shape[1] by the use of an epoxy glue, this doesn't
seem to be a good idea when you want to eliminate flutter from even the
most residual of commutation/cogging effects on the motor's angular
speed.

I have seen one in bits, but can't really remember the motor design -
except it was pancake shaped.

It was certainly ahead of its time in terms of a very stable transport.
You could lock a colour VTR to it and edit pictures exactly where needed
(within the limits of the PAL system) Which was very handy for doing dance
etc numbers to pre-recorded music with multiple passes. It was some time
before the likes of Studer caught up with the more conventional single
capstan design.

Its other trick was you could use any size of spool on either side with
zero problems.

--
*What boots up must come down *

Dave Plowman London SW
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