Another DIY parabolic microphone.

[Mike Sims]

There are a number of threads on Dvinfo about theory and use of parabolic microphones (search them). This post is about another DIY. Over the past few years I have made three. I made this one early last year and I like it because it is very light weight and easy to use in the field. I promised earlier to post info about it but have delayed until now because one of the components wasn’t readily available for several months.

The parabola is a Steve Dill twenty inches diameter with a four inch focus. Mr. Dill sells his parabolas (and his own parabolic microphone) through e-bay but they are only periodically listed (e-bay search Parabolic microphone). If he does not have a listing you can contact him and he will put up a listing for you. His e-bay user name is sdill471 (e-mail me if you need additional contact information). The price is currently $36.50 with $17.86 shipping. He usually only lists a few at a time. The current ad expires in a couple of days but he will likely re-list. (His complete microphone sells for $79.50 but I don’t know anything about it.)

The microphone in my version is a Giant Squid Audio Labs omnidirectional lav ($30). The rest is made from stiff wire, cable ties, ½ inch PVC pipe, and the handle from an old plumbing snake. The tripod mount is a piece used by cabinetmakers (I don’t know what it is called). It is a brass barrel threaded ¼-20 on the inside with wood screw threads on the outside. I threaded and epoxied it into the handle.

[Chris Soucy]

Yeah, Mike, but............

how does it perform?

Quantative tests?

Reach?

Frequency response?

Weight?


CS

[Bob Hart]

I cobbled one together many years ago using a Photax spun aluminium photoflood dish which had a damaged globeholder. I faired the bulb recepticle over with a teapot lid glued inside. This by coiincidence had the right profile curve. I trimmed off the edges so that it lay smooth and araldited it in.

I made a support pillar from telecom pipe which attached to the rim of the photoflood refelctor and mounted a handheld cardioid mic in the centre at the point of focus facing rearwards.

The sound it yielded was shrill, but very directional it was. It picked up a domestic argument inside a house some 500 metres distant. It was able to filter out ambience from either side of a diesel fishing boat about 2000 metres offshore.

I was able to mount it on the original photoflood stand. It was not a practical arrangement to use at the time, more of an experiment to see if it could be done.

I have been waiting to find a discarded satellite TV dish on a streetside chuckout but have not struck lucky so far but one of these days >>>.

[Vishal Jadhav]

Mic, can you post some of the recordings from the kit, would be interested in hearing them to find the performance

best regards
vishal

[Mike Sims]

Sorry, guys. I have always intended to post a video showing capabilities but I’ve been knocked a bit off-schedule by weather (wind and rain). I’ll have it up as soon as possible. Sorry to be a tease. I went ahead and posted about the construction because several people have heard the microphone used in my UWOL videos and asked about building one. I wanted to post while Steve Dill had a listing up so they could see what parabola I used. In the mean time, you may want to view my recent UWOL Challenge videos again. There are three layers of birds recorded with this microphone in the sound bed at the beginning of my UWOL 20 Total Darkness. In my UWOL 21 Here be Dragons the birds (but not the insects or frogs) and the alligator bellows were recorded with this microphone.

Bob- Satellite TV dishes work but they generally have a focus well above the dish surface and you need extra wind protection. Another good DIY dish is a commercial wok liner from a restaurant supply outlet. They are heavy but inexpensive, indestructible and have good sound quality.

[Vishal Jadhav]

Hey today heard the Total darkness and was impressed with the sound quality.

[Mike Sims]

Vishal- Keep in mind that it is highly edited. It is supposed to stop raining today and I will try to shoot an unedited demo for you tomorrow.

[Vishal Jadhav]

Thanks Mike,

I understand that all the audio on any of the Documentaries are edited however the edited version to have a amazing quality would entail that there was good quality recorded in the first place .
would await the raw version , i have seen the seller on Ebay and wonderin how to get the whole equipment from US to India as i dont feel the dish is foldable.

best regards
vishal

[Greg Miller]

Mike, that audio is impressive, and this looks like an interesting project.

I have one specific question. Why did you use an omni at the focal point, rather than a cardioid?

Looking at the photo, it appears that 90 degrees or more of the omni pattern is not obscured by the dish (i.e. the end of the mic where the cable exits the capsule is facing open air). Thus, there would still be a large conical area that would pick up essentially unwanted sound. I'd think that a cardioid, with its own null to the rear (i.e. facing toward the open end of the dish) would have better rejection of unwanted sounds. Did you contemplate or try a cardioid, for comparison?