Daft idea?: A ribbon boundary mic.

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k brown

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I gave this idea to Dave Royer but he didn't run with it; perhaps a DIYer with give it a go.

Picture a Crown PCC, but inside the 'cage' is a slim ribbon motor (like the AT4081) lying on it's side, imbeded in a thick-ish plate (like the Neumann GFM 132) so the surface of the plate is even with the edge of the ribbon.

You'd have a (half) figure 8 boundary mic with all the unique qualities of a ribbon.
 
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emrr

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First you have to overcome susceptibility to vibration. You can’t chamber damp the rear so does it go 90 degrees for a front/back approach?
 

k brown

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The ribbon would sit at 90 degrees to the plate (as I said, lying on it's side - not it's back) just as the electret does in the PCC. The whole point is to have a figure 8 pattern above the boundary, same as the PCC is a supercardioid above the boundary.
 
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Chrisfromthepast

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k brown

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It's not pointed to sky - the null is. Just picture the pattern of the PCC, but with rear lobe same size as the front. As a stage mic, it would have even more attenuation as performers approach it, than does the PCC. Again, the ribbon is on it's edge, pattern points front-to-back. The PCC is half a supercardioid; this would be half a figure 8.

Looking at the PCC pattern, the null is at about 130 degrees; with an on-edge ribbon, the null would be at 90 degrees,
 

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k brown

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Hmm - At equal audio output levels, my ribbons don't produce anymore noise when their bodies are thumped than most of my condensers do. No commercial condenser boundary mics (that I know of) have any vibration iso on their capsules.
 

Chrisfromthepast

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Im not an expert, but I’ve never seen it done. Perhaps a cool idea!
Are you intending to use this for any particular source?
Have you tried your ribbons sitting on the ground as a reference for the kind of sound you want to achieve?
I’ve definitely heard of (but haven’t had the luxury to try) room mics or drum overheads near or on the floor.
In my world, systems engineers often use omni reference mics on or near the floor in order to get more accurate time domain information…
Thats not where the woman or man who mixes the show puts that mic though…
 
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k brown

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No particular use in mind - I just had the idea and presented it to Dave Royer at AES a few years ago; he nodded politely, but obviously no such product ever appeared. I present it here in case any folks might want to build one themselves, especially ribbon DIYers. If I did it myself, I'd make the boundary in the exact shape/dimensions of the Neumann GFM 132. Their research showed it to be the second-best shape for a boundary; the best was a specific spiral shape that was deemed too difficult to mass-produce.
 

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emrr

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I’ve about a dozen different ribbon types, all are more susceptible to footstomp vibration than any other mic type I own, 80+. FWIW.
 

abbey road d enfer

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No particular use in mind - I just had the idea and presented it to Dave Royer at AES a few years ago; he nodded politely, but obviously no such product ever appeared. I present it here in case any folks might want to build one themselves, especially ribbon DIYers. If I did it myself, I'd make the boundary in the exact shape/dimensions of the Neumann GFM 132.
Why don't you buy one of those $100 ribbon mics and experiment with it?
 
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I gave this idea to Dave Royer but he didn't run with it; perhaps a DIYer with give it a go.

Picture a Crown PCC, but inside the 'cage' is a slim ribbon motor (like the AT4081) lying on it's side, imbeded in a thick-ish plate (like the Neumann GFM 132) so the surface of the plate is even with the edge of the ribbon.

You'd have a (half) figure 8 boundary mic with all the unique qualities of a ribbon.
I would think that one of the most daunting problems to overcomes is the very practical one of suspending the ribbon. In a vertical plane it's suspended at top and bottom. Gravity plays a minimal role. Lying on its side, there would be a tendency, especially over time, for the ribbon to sag and rub against the magnet.
 

k brown

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Less likely with a short ribbon, like the Beyers?

Just as ribbon owners best be mindful of storing their mics upright, these would best be stored on-end.
 

Marik

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I would think that one of the most daunting problems to overcomes is the very practical one of suspending the ribbon. In a vertical plane it's suspended at top and bottom. Gravity plays a minimal role. Lying on its side, there would be a tendency, especially over time, for the ribbon to sag and rub against the magnet.
Really depends on the type and quality of corrugation. Property corrugated ribbons should not sag over time and do not require vertical storage.

By far the biggest problems here are totally weird pickup pattern, and (even bigger) its output and frequency response. That is, the boundary creates pressure zone, while for good output and linear response of ribbon mass controlled system we need velocity element. In such an arrangement those two completely contradict each other, as a principle of correct operation, so I’d expect at least a few dB lower output and very poor top end response.

Best, M
 

k brown

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Pressure meeting velocity messes with the pattern; an angle I hadn't considered. In the cardioid and supercardioid boundary mics, pressure meets gradient and the patterns don't change (other than being sliced in half at the boundary, obviously). Is velocity a special case in this regard?
 

ajgillette98

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I gave this idea to Dave Royer but he didn't run with it; perhaps a DIYer with give it a go.

Picture a Crown PCC, but inside the 'cage' is a slim ribbon motor (like the AT4081) lying on it's side, imbeded in a thick-ish plate (like the Neumann GFM 132) so the surface of the plate is even with the edge of the ribbon.

You'd have a (half) figure 8 boundary mic with all the unique qualities of a ribbon.
Ribbon motors don't really work well on their side.
 

k brown

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I was thinking a small short-ribbon motor like the Beyers wouldn't sag lying on their side.

Marik just said the a properly made ribbon doesn't much care what orientation it's used in.
 
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ccaudle

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Don't boundary mics operate in a region of maximum pressure variation, and no velocity variation? How is a velocity transducer going to work in a zero velocity environment? Or do I have a misunderstanding somewhere of boundary mic operation?
 

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