The Audio & Design Recording boxes that Geoff Barton designed were
intended as (analogue) outboard units that could be patched into a
conventional mixing console to generate (mainly) first-order (all there
was) Ambisonic B-Format.
The Pan-Rotate unit included eight 360-degree controls, each with a
radius vector (distance from centre) control with a switched position
for maximum radius vector. In addition there was a B-Format Converter
which allowed console panpots to be used to pan across a quadrant, using
four groups and an aux send.
Finally, a Transcoder unit generating 2-channel UHJ only could be fed
with stereo signals for front and rear stages with a stage width control
on each.
The units are described in these articles:
http://ambisonic.net/branwell_arb.html
http://ambisonic.net/ambimix.html
I'm afraid I don't have circuit diagrams but Geoff presumably has.
--R
On 16-Feb-20 15:18, Peter Carbines wrote:
On 16/02/2020 12:19, Augustine Leudar wrote:
I'm mainly interested in purely analog devices in this thread
The small team I was involved in during the 1970s built a 4-input
proof-of-concept Ambisonic mixer. We were interested in developing a
mixer to produce B-format from multitrack recordings, creating an
artificial soundfield.
It had 360-degree panning ability and radius-vector control on each.
Two input channels used sine-cosine 360 degree potentiometers derived
from scrapped electronics, probably radar consoles. Because we were
unfunded and basically running on 'pocket money', the budget didn't
allow for 4 sine-cosine pots so we designed and built two switchable
pan-pots, initially 30-degree but planned for an eventual 15 degrees. ...
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