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SPEAKE(a)R: Turn Speakers to Microphones for Fun and Profit [pdf] (2017)

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Re: SPEAKE(a)R: Turn Speakers to Microphones for Fun and Profit [pdf] (2017)

#41

Post by GlumWoodpecker »

m4lvin wrote: post #13

Okay, but how do I use this as a replacement when the mic is not working on Linux?

You can use the `hdajackretask` program in the `alsa-tools` package to retask your jacks.

https://github.com/alsa-project/alsa-tools/tree/master/hdaja...

Re: SPEAKE(a)R: Turn Speakers to Microphones for Fun and Profit [pdf] (2017)

#44

Post by Anechoic »

userbinator wrote: post #17
jpc0 wrote: post #10

A magnet in a coil operates both ways, this is non intuitive but perfectly sound. Not sure if it's mentioned in the article but microphones can be speakers too...

Not sure if it's mentioned in the article but microphones can be speakers too... Only dynamic mics, which are relatively rare and seldom encountered without an attached preamp. The vast majority of mics for PCs are condensers and electrets. Anything can be a speaker, briefly and only once, if you apply enough voltage to it...

* The vast majority of mics for PCs are condensers and electrets.*

These can be run in reverse as well, it requires CB custom electronics so it’s not something a lay person can do out of the box.

Re: SPEAKE(a)R: Turn Speakers to Microphones for Fun and Profit [pdf] (2017)

#47

Post by analog31 »

userbinator wrote: post #17
jpc0 wrote: post #10

A magnet in a coil operates both ways, this is non intuitive but perfectly sound. Not sure if it's mentioned in the article but microphones can be speakers too...

Not sure if it's mentioned in the article but microphones can be speakers too... Only dynamic mics, which are relatively rare and seldom encountered without an attached preamp. The vast majority of mics for PCs are condensers and electrets. Anything can be a speaker, briefly and only once, if you apply enough voltage to it...

I think you have this backwards. Condensers and electrets (a form of condenser with a permanent charge on one terminal) almost always have a built-in preamp. The reason is that they cannot drive a capacitive load of any magnitude, and their outputs must be buffered before being fed to any wiring.

Like another post mentioned, dynamic mics like the Shure SM58 mentioned here, can drive a cable directly or through a small built-in transformer. They're still used in live sound, though condensers have become quite common there too. Condensers still tend to have somewhat better behavior, such as signal-to-noise, than electrets.

Of course everything has to be amplified or fed to a digitizer at some point. The issue is where the preamp needs to be physically located.

Re: SPEAKE(a)R: Turn Speakers to Microphones for Fun and Profit [pdf] (2017)

#49

Post by rigonkulous »

BFV wrote: post #3

[flagged]

Its one of those extremely valuable life-changing hacks that kids who grew up in the 70's with electronics magazines as their primary source of tomfoolery knew all about .. and got into trouble for .. once or twice lets say .. during particularly heated typing classes on selectric machines of the 80's necessitating a headphone distribution mixer for sane memo-taking lessons, with a few crossed wires worth of feedback generation device introduced surreptitiously one particularly memorable summer Friday afternoon - originally intending to impress the girls of the class - not deafen them (albeit temporarily) .. but, in any case, getting the party started early, nevertheless..

(If you are going to attempt this with stereo headphones, keep the streams separated at all times!)

Re: SPEAKE(a)R: Turn Speakers to Microphones for Fun and Profit [pdf] (2017)

#50

Post by gfiorav »

VladVladikoff wrote: post #38

When I was a teenager I was friends with an extremely poor kid who literally lived on the wrong side of the tracks. He couldn’t afford a microphone and used an old pair of busted headphones to rap into as a microphone. He had recorded and produced a whole album like this with Fruity Loops on an old computer he found discarded at the side of the road.

what happened to him?
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