Toronto AES Bulletin Review Sept 2000

Large Diaphram Microphones, Ampex Atr 102 One Inch Two Track Tape Recorder

Harris Institute for the Arts was host to our June 27th triple header: discussion of large diaphragm mics, a tour of Doug McClement's new Ampex ATR two track recorder and our year end social. The evening began with a recap by Hartley Wynberg (free lance location recordist and Committee Member) of his excursions to through Europe collecting sounds for this sound effect library.

Paul Gonsalves of TGI North America took the stage to discuss his research on large diaphragm microphones. Paul, TGI's North American sales manager outline some of the microphone lines covered by TGI including large, standard, compact and miniature microphones. Paul gave us a brief history of large diaphragm microphones since 1928, siting early examples including the CMV3 (aka the "Hitler" microphone), the RCA 4AA radio microphone, and the Western Electic 47 movie microphone. Encouraged by the technical demands of the war, 1949 saw the introduction of Neumann's U47 tube mic which pushed the industry's demand for quality microphones even further. 1953 saw the introduction of B&K's (now DPA) first large diaphragm microphone. In 1960 AKG introduced their C12/24 and Neumann released their U67 to be followed up in 1967 by the now famous U87 and the U89 in 1980. In 1995 DPA (formerly B&K) introduced their 4040 series of large diaphragm microphones, to be followed up by the 4041 series this year.

Paul went on to explain that "large diaphragm" means a diaphragm of 3/4" of an inch to 1 inch in diameter. He sited some of the benefits of large diaphragm mics including: lower noise, better bass response, higher sensitivity.

Some of the disadvantages include: low SPL capability, early high frequency roll-off (a flat response beyond 8K Hz and you're doing well), highly variable polar response, and degrading sound quality overtime.

Paul went on to site the advantages of small diaphragm mics: better off axis response, higher SPL capabilities, extended high frequency response, consistent polar response.

Some of the disadvantages of small diaphragm mics include: lower sensitivity and more "self noise".

DPA also carries of miniature mics for close-miking applications, the 4060, 4061 and 4962 which are designed for concealing on the body. Actually used in the filming of "The Matrix", these three microphones are acoustically identical, but differ in sensitivity and self-noise. The 4060 has the highest sensitivity of the series the 4061 is 10 dB lower and the 4062 is the high SPL specialist capable of handling up to 154 dB before clipping. Paul used this series of micro-mics to back up his statement that certain small and medium mics can be made to exhibit certain large diaphragm microphone characteristics and you should actually experiment with and listen to the small mic before discarding it to it's large diaphragm cousin. This particular series of microphones comes with a line of acoustic modification accessories--a series of different coloured grids that you slip over the microphone to achieve the desired characteristic from a soft low end boost to a high boost, thereby making your micro-mic sound like a U87.

Paul went on to talk about the difference between diaphragms made with nickel and those made with plastic. He explained that metal allows for higher tension and the stiffer the material the higher the resonance response which results in a higher resonance frequency of approximately 8K Hz. Plastic on the other hand has lower tension with a lower resonance response of approximately 1K Hz. He went on to explain that metal is more forgiving in terms of temperature and humidity. The thermal expansion of plastic and compliance vary to a much greater degree. The more compliant diaphragm will result in an increase in sensitivity.

Next up was Doug McClement of Livewire Remote to talk about his recent acquisition, the Ampex ATR 102 one inch two track tape recorder--the "new/old" format taking the music mastering world by storm. Doug explained that there hasn't been much by way of advancement recently in the world of analogue. In the music production world (vs. post) there still remains a large proponent of the old analog and tube technology--in fact as a backlash to the whole digital revolution of the 80's, we have seen a resurgence in the demand for old tube technology by those pining for it's warmth and character. Thus the resent resurgence in the popularity of the one inch two track stereo mastering. Not to be outdone, Ampex has come out with a line of refurbished two track machines, the ATR series which are quickly becoming the mastering tool of choice for music recording.

Just off of a live remote with Canada's own k.d. lang for Much Music, we were treated to example of Doug's work. Doug set up a demo of the ATR, A/B'ing between her tracks on DAT and the ATR.

Thank you to both of our presenters: Doug McClement and Paul Gonsalves for their time. Thank you to John Harris and the folks at Harris Institute for the Arts for hosting the event. Thank you to our own Paul Reibling for organizing the event.

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