[QuadList] New Octaplex recorder design

[Don Norwood]

I ran this by Ted and he thought it was appropriate for the quad list, so 
here's some info that may be interesting to the group.

Tim Stoffel and I have exchanged a good bit of info over the years about 
octaplex recorders.  For those of you not familiar with these, they are 
transverse recorders with 8 heads, allowing two simultaneous recordings on a 
single tape.  Some years ago, I even found us some octaplex heads for an RCA 
machine.  All of what we have seen to this point has been based on an 
8-headed design on a single drum.  Now, I have something new to report.

I just got a manual dated Feb '63 for an Ampex AN/ALH-4.  It is an air-borne 
or portable machine, dual channel, but instead of 8 heads on one drum, it 
has two "standard" quad heads sandwiched together!  It will record a single 
channel at 12.5 ips for an hour or run in two-channel mode at 25 ips for a 
half-hour. Response is 10 Hz to 4 mHz, 30 db S/N.   It has two auxilliary 
channels, one of which is available with a multiplexer to record three audio 
channels.

The manual is quite large, so I have a good bit of studying to do, but 
several things besides the head design jump out at first glance.  Because it 
is designed to operate in a variety of temperatures,  there are several 
different systems used to maintain a constant temperature inside the 
recorder.  The transport cover seals and there is air circulated within the 
unit and passed thru a heat-exchanger area where outside air is used for 
cooling when needed.  For low temperatures, there is a case heater to bring 
the entire machine up to 65 degrees C, but also a heated roller on the 
supply side of the tape to bring the tape to a predetermined temperature, 
and the female head guide is also temperature controlled!

Another cute feature is the head-hour meter which is part of the head 
assembly.  I've attached a pic of the transport so you can see what the 
beast looks like.  It looks like some of the mechanical design definitely 
carried forward to the VR-3000.

Enjoy!

Don
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