"re-coning" dynamic microphones?

Not this time as I used the core of a Shure dynamic mic as a parts mule for a dropped radio mic, but just wondering if it can be done for some worthy of repairing expensive mic in the future. Both the Shure and the one with the broken hair-fine wire of the voice-coil have a thin diaphragm glued to a rigid surround . For speaker re-coning the cone is quite substantial and heat tolerant compared to this diaphragm material and hot-air heating usually removed the supension surface from the basket, but I doubt that process is possible with a mic - anyone been here before? As part of the fitting I intend using silicon rubber rather than the more rigid rubber of the originals, any thoughts as to any effect on sound quality? I was thinking a less rigid support may give more allowance as far as not transmitting shock-loads to the mic core . Initially I was wondering about a material more like a spring would give a reverb-tank spring-lime/joy spring reverberant character but then remembered a lot of studio mics are surrounded by springs.

Reply to
N_Cook
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If you change the diaphragm, you will change the mic's sound.

Given the tight tolerances and precise work required -- and the fact it's highly unlikely you'll produce a useful microphone -- I can't see this as a project justifying any expenditure of time, unless you have absolutely nothing else whatsoever to do.

There's nothing wrong with experimenting to see what will happen -- unless the experiment has no possible theoretical or practical outcome.

This is an Edison experiment. And that is not meant as a compliment to Thomas Alva.

Reply to
William Sommerwerck

Følgende er skrevet af William Sommerwerck:

Are you referring to T.A.E is said to have tried thousands of different materials for the filament in light bulbs without thoughts of what might have been useful?

Leif

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Reply to
Leif Neland

While with microphone audio. Can anyone explain why you don't need mics with

12 or more inch diameter diaghrams to register the audio from 12 or more inch diameter loudspeakers?
Reply to
N_Cook

Well I seemed to have learnt something by burrowing in. Has anyone come across failure of a microphone from having been laid down against the heatsink of an amplifier ?

I desoldered the VC tails and then with a warmed blunted needle lifted the diaphragm from the rim, without any obvious deformation. It looks as though the VC is held to the diaphragm with a wax of some sort, ie relatively low temperature melting.

So microphone assembly construction, I assume is something like this melt a thin line of wax over the end of the former , the thickness of the former lay the VC in the hole in the magnet solder the 2 tails lay a thin layer of wax in the preformed hollow of the diaphragm , of diameter a bit larger to a bit smaller than the VC former diameter with a carefully controlled amount of DC or some sophisticated signal to the coil , to make the VC move towards the diaphragm evenly and centrally locate itself with even air gap to the magnet gap (perhaps an active system monitoring capacitance between VC and magnet body) a blast of warm air , perhaps only about 80 deg C to melt the wax , in the central area of the diaphragm keep the centralising signal present while the wax cools

I won't bother unwinding 1 turn off the VC and reassembling as it was only a basic mic to start with and I've a robbed a mic core to replace it with anyway, with just adjustment of the suspension rubber as a different size rather than that wax business

Reply to
N_Cook

That's the story. I'm not sure it's true. It might have been that Edison wanted to make himself look industrious and hard-working. Regardless, whatever the material, it had to be conductive, and reach a high enough temperature to emit light, without falling apart. There aren't that many materials. I don't know whether a common metal -- such as iron -- would have worked.

It's noteworthy that General Electric developed the sintered-tungsten filament that replaced Edison's carbon filament. GE was the first company to set up a laboratory for basic research, because it understood that a better understanding of basic science and applied technology would result in profitable products.

Edison also developed one of the first storage batteries, again after testing hundreds of possible electrode materials. I once asked someone (I don't remember who) why he didn't just drop a note to Josiah Gibbs and ask for list of likely suspects. I was told that he /did/ consult with scientists about such things.

Reply to
William Sommerwerck

I don't often deal with microphones of any sort, so not come across this before. Putting the plastic cased radio mic back together I could not work out how to screw in the double threaded fitting that the mesh globe screws onto, into the transmitter body .

4 turns to fit and putting a reverse 4 turns in the wire it still ended up pulling out the connector to the mic part. This area of the body is split seemingly to take the escutcheon for the switch , but actually that slot in the body must be for putting in a wedge, I used an ISO TO220 transitor. Open up the gap and simply axially push the aluminium threaded intermediary part , remove the wedge, and tighten just half a turn.
Reply to
N_Cook

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