> > > Message: 1 > Date: Thu, 3 Feb 2011 11:59:36 -0000 > From: "Steve Higgs" <[email protected]> > Subject: Re: [Sursound] Calrec CM4050 Surround Microphone SN: 502 - > update > To: <[email protected]> > Message-ID: <005b01cbc399$d92b3050$0200a8c0@OFFICE> > Content-Type: text/plain; format=flowed; charset="iso-8859-1"; > reply-type=original > > 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?
Steve, I think that in 1979 it was a MKIII. As I recall it was John Rushby Smith in command, so you might try asking him if he is still around. I was there at several of the broadcasts, mainly providing moral as well as technical support to Bob Harrison, who on a number of these occasions put his job on the line in his advocacy for the SFM and Ambisonics. 1978 was probably a MKII, but I will have to dig out my old diaries to check. > 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. No factory processing was supplied for a MKII, the first control box was for the MKIII. That is why we built our own. The MKI and MKII were part of a research project at the university; we were making it up as we went along, so there was no 'factory' processing available. > > 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. Absolutely. If you stand centre stage at the RAH and just make a single handclap you can hear all the problems. I think the particular problem with recording with the SFM there is that, if you put it in the normal 'stereo' position, behind and above the conductor, the recording sounds like you are floating in space, especially played back periphonically, this is partly because of the lack of early (floor!) reflections. Musically it balances ok, apart from perhaps too much brass. But then, that often happens.... rgds, Geoffrey _______________________________________________ Sursound mailing list [email protected] https://mail.music.vt.edu/mailman/listinfo/sursound
