Somewhere, which I'm trying to find ATM, I found a site detailing how to make a long-range rifle type microphone. which basically consisted of 36 pieces of 20mm PVC conduit, in 1" increments from 1" to 36", arranged in a round bundle. I think it was referred to as a gatling mike, but can't find the site at present. The tubing is easy enough to remember, but there was some sort of feed arrangement at the end which I can't remember, into a standard mike.
If I can find it, I'll post the link.
Snag with this sort of arrangement - which is standard rifle mic - is that you lose gain. May not matter for reasonable distances, but if trying to pick up quiet sounds from a long way off, a parabola is a better bet since it adds gain.
You haven't quoted anything of what I said - you're actually responding to Alex's posting. Not such a big deal in this instance but it's not hard to envisage cases where it could lead to serious misunderstandings.
Dave Plowman said
But the fact remains that for many years they were pretty well the only option available and some extremely good recordings, particularly of birdsong, have been made with them.
These days I own a number of rifle mics made by Sennheiser, AKG and Neumann, but there are occasions when I still wish that I had kept my old Grampian parab to try under unusual circumstances.
I owned a Grampian one and then when I joined the BBC in the 1960's I noticed them at Kendal Avenue and also at Ealing. They were certainly in KA until the late 1070s.
Admittedly KA also favoured much bigger parabs converted from 4 foot ( metal ) radar dishes which were lined with Sorbo rubber foam on the reverse, to deaden any ringing.
The size of a parab governs the lowest frequency which it offers gain. The amount of gain is governed by the size and the geometry. Anything from 2 feet upwards will work well on birdsong and similar sounds which have minimal low to mid frequency content. The bass response will be that of the microphone used to pick up the sound.
As the wanted sound is being magnified by the parab, there will be less need to boost the gain of the microphone, so the lower gain will also mean that unwanted sound ( most likely traffic noise ) will be at a lower level in the first place and there will be less of a need to filter it.
Gary Cavie refers to a Gatlin mic made from varying lengths of tubing.
I wouldn't bother with 1" tubing. Imagine the diameter of a bundle of
36x 1" tubes and then imagine how you might couple a microphone to them.Many years ago I used to use a commercial microphone of that type. It was made by Electrovoice and was about 7 feet long ( it broke into two parts for less inconvenient travel than would otherwise have been the case ). From memory, I would guess that the tubes were thin walled brass of about 1/4" diameter. The whole thing had to be mounted on a sturdy U shaped yoke in order to operate it.
To call it an unwieldy microphone is to be polite about it and I was glad to see it pass, although it retained it's directionality to a much lower frequency than rifle mics of the time did.
I well remember a trial of that mic in TV Theatre. Something that could pick up - say - tap dancing, while keeping well out of shot, would have been useful. But it just didn't work. It required so much gain to get any useful level that the end result was noisy. And so much bass cut that it sounded like a telephone, because without that it was omni-directional at high bass frequencies.
The first practical rifle mic IMHO was the Sennheiser 805. Which provided the gain makeup through clever internal electronics.
That's a thought. How about a lot of signal processing and a phased array of about 20 microphones.. :-)
In view of my early career background, radar design engineer, that was something I considered some time ago. However basic signal/noise considerations soon had me thinking about parabolas and the following image
Dave Plowman said
provided
It all depends on what you call practical.
Before the 805, there was quite a reasonable gun mic made by Labor ( sp ? ). It was another lobar design ( very similar to the 805 ) with the slots protected by a grille that stuck upwards. The microphone itself was dynamic within a tear-drop shaped metal housing and it needed a fair bit of gain, but high gain, low noise pre-amps were already standard in BBC OB mixers used at the time.
However what made it less than useful was the lack of an efficient windscreen. Rifle mics are amazingly susceptible to wind noise, while an omni mic in a parab will be considerably less affected. Wind susceptibility is largely proportional to how directional the microphone is.
The 805 was certainly an improvement, but what really made the difference was the Rycote windshield, which seemed to appear at about the same time. It transformed a better product into something that was vastly better. Other refinements to windshields followed later with socks and then hairy windshields, each development making a significant improvement.
However to get back to what the OP asked, making a parab is possible by either adapting and improvising, or by manufacturing from scratch. Building a rifle mic is very unlikely to succeed.
As far as DIY solutions for recording distant birdsong go, I can't think of a better approach than to make a parab of 2-3 feet diameter and to position a reasonably good microphone at it's focus.
We used to check the alignment of the focus by placing a small battery operated doorbell at a typical target distance and then moving the microphone position in and out until you hear the maximum volume with the parab pointed at it. Pan it off and you'll discover just how directional it is.
Gawd, you must be as old as me. ;-)
Think we had one in the entire TV Centre/Lime Grove/Riverside/TV Theatre complex - and it was of no use for quality stuff. For boom use in the studios where you were 'pushed out' rather further than normal - or where you needed more separation than the then normal 4033, it would be an AKG C28, or KM 54. Both just a decent cardiod.
Yes. Of course my early experience was studios, rather than OBs. And of course in those days, absolute quality wasn't *quite* the same as today.
Yup. Although we used 805s in the studios totally naked. ;-)
Yup again.
It depends on how far the OP (and mic) needs to be from the source. Something we haven't been told.
Yup again. High quality monitoring of the mic output is vital in every case. Listen to what the mic is giving you. Something which is lacking in today's cheap TV.;-(
Possibly - but age is merely a number. Still working hard and playing harder than ever.
For as long as I can remember it's been a source of amusement how studio people tried out rifle mics and declared that they're of little use. Invariably they overlook the fact that they're testing them indoors and that reflections from studio walls and sets will reduce the effectiveness of any microphone relying on phase cancellation.
When we use rifle mics outside, they're seldom in a truly reflection-free environment, but they usually work vastly better than when indoors. We have for years used them indoors and out, so are well aware of when they work and when other solutions are preferable.
It's only in the last 10-15 years or so, since studio people started doing location inserts for drama, that they've started rediscovering stuff that film and OB types have known for decades.
One of those things being that you get better results using a rifle mic outside and a cardioid or hyper cardioid indoors.
The other important thing being that when outside of a studio, windshielding is crucially important. A foam windshield will only over very limited protection in nothing more than fairly calm conditions. The secret in strong wind is to use a microphone that's no more directional than it needs to be and to use a windshield with a large amount of free space between the microphone and the outer windshield. Oddly enough, putting a foam windshield on a microphone which is within a basket windshield is likely to make things worse as it reduces the volume of free air within the windshield ( according to Neumann - and they do make the finest microphones ).
A friend of mine wanted to spend up to =A3200 on a gun microphone for use with his video camera. I persuaded him to buy a proper Rycote windshield for a little over =A3100 and a cheap but good directional microphone for well under =A350. He is absolutely thrilled with the results he gets and he his recordings are vastly more useable than others who use a much more expensive big-name microphone with a dreadful foam windshield.
If you'd put a question mark after that I'd say nearly. ;-)
While this is true, the Labor was a poor sounding mic regardless. Like most MC designs used at any distance. There's a good reason condenser mics are the norm now for high quality stuff - apart from possibly some hand mics or high sound pressure use.
But with different priorities. The quality requirements for an FX mic outdoors may be rather different than for a speech or vocal mic indoors.
Really? ;-) I personally discovered - as did my colleagues - that applying studio principles with some modifications worked equally as well for location drama. It's sometimes useful just to have a goal in mind and achieve it in your own way rather than taking accepted practices as the only way...
I prefer to stick to the same mic wherever possible. Means the quality doesn't change. And that still, to me, means a 416.
Apart from anything else you can hear the difference in quality if you leave the foam windshield in place inside a Rycoat. Of course you may have to supervise a lazy pole op to make sure he *does* remove it when changing. Similarly not to just assume you need a furry over it outdoors.
Horses for courses, again.
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