Cheap Home Brew Mic Stand Design Quest ... (um ... er ... did I mention CHEAP?)

[MicMaven]

I purchased a Samson GTrack USB microphone for next to nothing on eBay, and immediately swapped its puny 16mm capsule for an inexpensive 25mm capsule also acquired on eBay. I made my own capsule saddle from a grey PVC plumbing connector. (See attached photos) The replacement capsule is a substantial improvement. I will use the microphone with computer speech recognition software which thrives on clean, articulate, flat, speech input.

So far, so good, right?

The microphone did not come with a stand mount, and the Samson SP04 shock mount would cost more than I paid for the microphone. Being a handy and cheap ham radio operator, I quickly cut and assembled a home-brew mic stand using bits of scrap lumber. The body/shell has a .44" (11.33 mm) lip at its lowest point surrounding the USB connector. The microphone sits nicely in a 1.5" (380 mm) hole, held in place by its own weight. (See attached photo.)

BUT ... (well, shoot, it seems there is ALWAYS a BUT ...)

The wooden stand is unduly microphonic and introduces deleterious reverberations and ambient sound.​

THE No-Holds Barred CHALLENGE -

Design a better home-brewed stand which does not add to the mix. It must be easy and cheap to make and assemble. It must employ easily and affordably acquired materials. It can be stand-alone, or be part of a larger system, e.g., something mounted on or added to an existing standard metal desk stand or other object. Did I mention it must be simple and cheap? (Ham operators are notoriously frugal ... a polite substitute for CHEAP.) Finally, it must also look reasonably good on the desk with my other audio and radio equipment. (I may be cheap, but I like nice things.) It can be an entirely new design, or a worthy modification of my original wooden stand, provided it attenuates its microphonic proclivities. BONUS POINTS if it ends up four or five inches taller, but that is not a specific requirement.​

Any traction?

Surely we can devise an easy, simple, low cost something I can make in the workshop that does not adversely alter the sound. The microphone sounds pretty good with the replacement capsule. The speech recognition engine likes it. (Note: the recognition program does not work with line-in devices, so this microphone solves a problem providing clear audio input to the software application.)

Thank you for considering my conundrum. James - K8JHR

 

[Khron]

Add a layer of foam (or foam rubber) around the hole in the wood, for the mic to "float" on? Perhaps enlarge the hole and add a layer of that in there too, so the connector "neck" doesn't make direct contact either?

 

[rock soderstrom]

The main problem with the current solution is that the tabletop acts as a membrane, i.e. a receiver for structure-borne sound, and transmits this unhindered to the microphone.

This must be interrupted or heavily damped. The remedy of choice is to mechanically decouple the microphone from its environment by suspending it freely in an elastic suspension.

Here we see traditional solutions that can be used as a model:


Same idea...

Thus, a simple solution for mechanical decoupling would be, for example, to suspend the microphone in elastic bands/springs from the ceiling of the room, if local flexibility is not required.

If mobility is required, then you need an appropriate stand or tripod.

 

[MicMaven]

Good Day! Thanks for the prompt replies!

Mr. Khron: Right on. Last evening I tried exactly what you suggest. I made a "gasket" out of squishy packing foam and other materials, and pads made of felt, rubber and other materials a) between the microphone and the stand (as you suggest, and b) between stand and desk. It sounded best standing on two layers of egg-carton acoustic foam. Surprisingly, it was quite stable standing on the foam, notwithstanding it is somewhat squishy. Equally surprising, it sounded better mounted on the wooden stand atop the foam, than sitting on the foam by itself without the stand. Go figure.

Mr. Solderstrom (your screen name sounds like a character in a Flintstones episode ...)
I get the point about suspending the microphone and decoupling it from the desk, although it is not particularly practicable. I imagine dangling on big rubber bands or bungee cords suspended from an arm attached to storage cabinets on the wall above the desk.

All good. I appreciate the different approaches.

While experimenting with different materials, I realized it is less a matter of microphony, and more a matter of ambient sound and optimal microphone placement. I effectively resolved the problem by moving the mic closer and mounting it on a second, better made, less microphonic stand. The attached photo depicts the current arrangement. I added a rubber pad to the bottom of the base, and a padded ring (gasket) around the mic base, as Mr. Kron suggests. Ultimately, a lesson in improved stand design and optimal mic placement.

Thanks for weighing in and looking over my shoulder. Happy trails to you. James / K8JHR

 

[Paul W]

I would think that a relatively tall, narrow and massy stand on a spongy base would act like an inverted pendulum to isolate the mic from horizontal motions... the bottom of the stand may move left and right but the top will move much less, and that effect will be bigger the taller the stand is and the more the mass is concentrated near the top. I'd guess that the taller the stand is, the smaller the angle it goes through as the base vibrates left and right (or fore and aft) under it, and the less the CG of the mic will move at all.

I would also think that for vertical vibration, the taller the foam section, the better. So instead of having a half inch of foam and 8 inches of wood, it'd be better to have 8 inches of foam under a half inch of wood.
Presumably that's the idea with tall spider mounts. The more pendulous you can make the suspension, the less horizontal motion is transmitted, and the mic just rocks slightly. And the longer the vertical bungies, the more vertical motion can be absorbed by the elasticity before reaching the mic.

I assume that acoustics people have written dissertations on this sort of thing. Does anybody know of an accessible treatment for non-engineers, using smallish words?