Dear Iluminati
An rathey practical posting and update as to my investigations into this
mic, - it does work, with only a slight modification as to a safe chassis
earth to the mains PSU.
Some more clarification as to its construction. The mic head appears to be
just as it left the factory,
The head cable is remade - now 10meters .
The mains PSU is tested and working, it does contain 4 FET/transistor
amplifiers - or is that filters. A set of tweaks inside (with amps/filters
on a Vero board construction and another 4 multi-turn tweaks accessible from
external. So provision for fine tuning - set-up. The polarising voltage
measures 52V off load.
The pair of joined diecast boxes are untested. A mains cable is provided to
the bottom box marked 'amplifiers', which also has mono jack inputs for the
signals from the above filter?/PSU.
The top box with I believe PBF's notes written on masking tape contain 2
Vero boards mounted on edge connectors, the bottom board has 4 daughter
boards with 2 x 8 pin OP amps, the top board has no components - just some
wire links (a simple programmer?).
No passive processing.
My investigations lead me to Richard Elen's article 'Ambisonics - a BBC
Soundfield Experiance', from Studio Sound/Sound International from Oct 1979,
just 3 years after I joined the BBC. Paragraph 14 is when I started to see
daylight. Antony Askew is I'm afraid no longer with us, an I am at the
moment out of contact with Bob Harrison. I strongly suspect that this mic
and collection of boxes is the prototype MK2 evaluated at the RAH at the
Proms in 1979. Jeff Barton might you remember? As other readers of this list
I am very interested as to what was the (if any) processing provided for the
MK1, why did Reading University at some time and trouble construct this
control/processing kit, and what was the post microphone processing kit
supplied (factory) with a MK2.
It is amazing how things 'come around. I have been closely connected with
the surround mic set-up at the proms for HD TV for the last 6-7 years to
provide the required 5.1 output - Just the TV output, while all mics are
available to both Radio and TV the surround TV (BBC2) output is mixed
entirely separately to the Radio output. Unfortunately a Soundfield is not
used. A MK5 was again evaluated during the 2009 season and was not found to
be satisfactory. Any microphone has got to be 'in the right place' and
remote control of it's parameters cannot totally make up for positioning for
the highest quality recordings, (I'm sure this can be argued, especially
with the very recent advent of digitally processed microphones such as the
Schoeps Super CMIT). The RAH is a very - well unique if not difficult place
to record, and perform as a soloist, essentially a lack of early
reflections - and then the echo. The Proms BBC coverage from the RAH have
their own problems with so many consecutive (incessant?) concerts,
rehearsals and very limited (if any) rerigging hall time.
My own training (and now problem) was to record things as they sounded, Some
choirs have, I'm sure, been very disappointed with my recordings - it
doesn't sound as they think they sound!
Steve Higgs
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