Has anyone ever devised a zoom mic?
 

Wouldn't it be possible to adjust the shape and position of the transducer in a mic tube so as to vary its characteristics? Sort of an audio equivalant of a zoom lens?

There are microphones that switch capsules to achieve a variation in directionality. And many directional microphones can be made non-directional (omni-directional) by occluding the rear vents.

But audio wavelengths are so much larger than light wavelengths, even the most directional "shotgun" mic is the optical equivalent of a "normal" lens. You would end up with the optical equivalent of "fish-eye" zooming to "normal".

Yes, it's called a Calrec Soundfield Microphone of which I was priveleged to see the original designs by Ken Farrar.

I note you are Bristol CT - Ask the guys at ESPN about Calrec. Give my regards :)

Bit out-of-date info here as Calrec don't own Soundfield anymore.

Soundfield is now an independent company and their website is HERE.

For on-camera use, the SPS200 may be worth a look - but you need 4 accurate matched pre-amps and you manipulate in software.

Excellent microphones, I am playing with one myself at the moment.

Thanks for the added info and update John but my point was that Calrec (Ken Farrar) designed it - it was called the Calrec Soundfield at that time. In answer to "...has anyone made a zoom type mic."

The Soundfield has been sold via a separate company for some time now as you rightly point out.

Ken was a prolific designer and was chairman of Calrec during my tenure there. The microphone business was split off in order that the company might focus on audio consoles. Sadly Ken died some years back - real nice guy who made a significant contribution to audio.

Info for Paul of Bristol CT:

ESPN first purchased a Calrec T series audio console (analogue processing - digital assignable surface) in 1997-98. The surface technology became the fore-runner to Calrec's Alpha digital console. ESPN purchased the console after seeing ABC's Monday Night Football truck which also had a Calrec T series console (quite a ground-breaking decision by ABC's project manager at the time), then came NBC's Saturday Night Live - as to the truck business in particular, the rest is history.

I used to work at AMS Neve in the early 90's when they owned the soundfield mic, we developed a location version the ST250 but it never took off as the std 416/816 mics are what the industry prefer.

It did have the ability to zoom and matrix but I would not consider it for anything other than music or atmosphere recording as the four capsules were virtually identical to a U87 and there were no phase rejection systems used. There was a rycote available and I had the use of one for five years but never used it for anything more than buzz tracks or atmos although the Stock Aitken Waterman team also used one as a vocal mic on all their hits in the 80's.

The laws of physics take over here and the only way to artificially "zoom" or make a sound source more focussed is to remove any other sounds that are not desirable, that is how shotgun mics work and the phase cancellation tubes cancel out certain frequencies.

The soundfield fundamentaly worked on M/S matrix techniques and I think they still use them on wimbledon for the sound effects and the BBC proms, there was a room at AMS where you could hear a full soundfield demo of the last night of the proms and it was most impressive as you could get a superb 3D experience with all sorts of B&W speakers feeding the matrix to the listener, you could then use the matrix box to change the image and "zoom in" on different parts of the auditorium.

I also had a lot of discussion about a digital mic, no not a std analogue mic with converters but a true digital mic working on phase diffraction from lasers to pick up the sound wave structure and translate it into digital data. I am not sure my ideas were understood by the ex Calrec analogue team so I got me coat and concentrated on the Logic console design used in the digital film console that is now standard kit in most of the dubbing theatres in the world.

Happy days and I still keep in touch with my ex colleague Mike Reddick nearly twenty years on!

AMS acquired Calrec (1985 or there abouts I think) forming AMS-Calrec including rights to then current product and acquiring some of its individuals. I believe the Soundfield was never owned by AMS Neve initially (as it didn't exist as a company at that time).

The Soundfield appeared as an AMS-Calrec product along with the VCS console. Calrec later bought itself back and focused exclusively on broadcast with an embargo not to develop any digital product for two years.

AMS-Neve as a company was formed later after Siemens (who now owned both AMS and Neve) merged them in 1992. Clearly they still had a plan for the Soundfield at that time as Gary points out.

For the more technically inclined:

Audio Engineer's Reference Book - Google Books

Hey, I used to work right next door! Nice little town. Plus Lake Compounce is nearby :)

The soundfield was an AMS-Neve product for two years after the merger (takeover) and then we sold it off to Drawmer along with the support for the reverbs etc, Keith Ming was also at AMS when I joined in 1991 and he then left to set up Hebden Sound which was basically the other Calrec mics.

I dont recall the company ever being called AMS-Calrec and the Calrec name was returned and is still making consoles in Hebden Bridge.

AMS bought Calrec to get the expertise for console design but sold the name back shortly afterwards as we lost a lot of money making the analogue kit, Karl Lynch, John Gaunt and John Prince headed up the Logic digital design team that I was involved in from 1991-1994 I also was customer support for the AudioFile editing system headed by Dave Stollery.

Not a practical solution, but it just occurred to me that parabolic dishes designed for mics place the element at the focal point. If you move the element away from this position, then the effective beamwidth opens up. Gain would go down on axis, but would the extra 'collected' by the wider angle of acceptance make up for it - effectively providing a zoom facility?

And as well all know changing the M and S content in an M/S mic will allow you to zoom the stereo image from wide all the way down to mono, the digital consoles we designed also had an A/B wide control so you could zoom the stereo image and M/S content on an A/B signal, it was also fully automated so it was great for changing the width of soundfields in post prod!

Gary, I'm not letting you (and AMS Neve by proxy) claim any credit whatsoever for the Soundfield. So go on Gary, you know you can say:

"Ken Farrar designed the Soundfield microphone in 1978 while a director of Calrec at which time they released it as a product in its own right..." without mentioning AMS or Neve in any combination in the same sentance as the Soundfield. The date is 1978, the name is Ken Farrar, the company is Calrec.

Go on, you know you can do it ;)

I'm done :)

But much like all my work with AMS Neve it is the company that takes all the credit as they are the ones who pay the salary.

I am not denying Ken designed the soundfield but when you work for a company that is then sold to another company all your design ideas and rights go to that company!

So the Calrec soundfield became the AMS Neve soundfield that then became the Drawmer soundfield and so on!