audio question - multiplexing audio channels
audio question - multiplexing audio channels
(OP)
I have 8 audio channels that I would like to multiplex together (4 headsets from cell phones, 2 channels per headset (speaker/mic)). Only one cellphone will be operating at a time, so it will be more like a switch.
Would it be electrically sound if I simply connected all the outputs(earphone) together, all the inputs(mic) together, and all the grounds together? I'm thinking something like a poor man's multiplexer. This way, I don't have to build in any additional circuitry and save myself a multiplexing chip.
Only one of the cell phones will be operating at a time, so only one will output to the headphone, correct? Can anyone see any impedance or other issues with this scheme?
I suppose the right way to do this would be to use an analog multiplexer, but that has been introducing noise on the audio.
Thanks for the help and sorry if the question is not very clear,
MS
Would it be electrically sound if I simply connected all the outputs(earphone) together, all the inputs(mic) together, and all the grounds together? I'm thinking something like a poor man's multiplexer. This way, I don't have to build in any additional circuitry and save myself a multiplexing chip.
Only one of the cell phones will be operating at a time, so only one will output to the headphone, correct? Can anyone see any impedance or other issues with this scheme?
I suppose the right way to do this would be to use an analog multiplexer, but that has been introducing noise on the audio.
Thanks for the help and sorry if the question is not very clear,
MS





RE: audio question - multiplexing audio channels
RE: audio question - multiplexing audio channels
TTFN
RE: audio question - multiplexing audio channels
RE: audio question - multiplexing audio channels
RE: audio question - multiplexing audio channels
RE: audio question - multiplexing audio channels
PDF datasheet: ht
Multiplexer page:
http://w
How should I minimize the noise pickup from ground and the rest of the board? Thanks,
RE: audio question - multiplexing audio channels
Those are multiplexers.. They give you one selected channel at a time. This would mean you need to actually select each phone one at a time with strange buttons, rather than which ever phone is on just works.
RE: audio question - multiplexing audio channels
What about a TDMA signal MUX for existing USB earphone/mic combinations? someone must have invented this already, at least for 8, which I think is the number of endpoints available. But maybe USB on the go does something different.
RE: audio question - multiplexing audio channels
Does anybody know of a part number or what search terms I should be using? I need a surface mount part.
Thanks
RE: audio question - multiplexing audio channels
You did not say if you wanted this gang of 4 to be able tohear each other. It seemed like you wanted only one phone in operation, but you wanted to use their microphones and speakers. Or did you just want to use the each of the phones speakers, or did you have an individual speaker for each person using a phone?
The digitial mixer would probably use TDMA or the iso mode on USB. Each phone would have to be part of the circuit on the RF USB. The advantage is that you might not have to have any wires. If 3 of the 4 phones are turned off, then USB would simply ignore them.
RE: audio question - multiplexing audio channels
crude diagram:
===|>---
|
===|>---
|----------- COMBINED OUTPUT
===|>---
|
===|>---
-------------------- COMBINED RETURNS
I don't need the phones to hear each other. I just need to reduce the number of wires output audio is transmitted over, since only one phone will be in operation at a time.
It should be safe to tie all of the mic input lines together, since that will act as a splitter to four phones being driven by one mic.
Thanks for all the help!
RE: audio question - multiplexing audio channels
Hypothetically, you should run your single mic into individual buffers that drive each mic input separately. The input impedance of a mic input may not be that high and ganging 4 together may reduce the input load sufficiently to degrade the performance of the mic.
TTFN
RE: audio question - multiplexing audio channels
are feeding, you could simply add a resistor in series with
each source, and tie all together at the amp input.
10k works well with line-level amp inputs.
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