3.5mm mic's into mixer output to pc?

[bspmail]

Hi,

I recently bought a Nady RMX-6 with the intention of hooking up 6 mic headsets to it (3.5mm pc style) via adapters so that I could record dialog during a lan party and output it to another pc with audacity running on it for recording the whole thing. After hooking up the headsets I got nothing but slight noise in the pc I had it outputted to. Do I need a preamp setup before the mixer since they are 3.5mm style or will that even work? I've spent about 3 hours tonight looking for how to hook up pc mic's (3.5mm) to a mixer but I haven't seen what I'm looking for. I apologize if this is a newb question but I really have spent a fair amount of time looking for the solution to my application and can't seem to find it.

I'm hooking up the pc headsets into a 1/8" (3.5mm) to 1/4" adapter to plug into the back of the mixer for the inputs and the output is a 1/4" to 1/8" (3.5mm) adapter and then the required cable into the line-in on the recording pc but I just can't seem to get it working.

Is the preamp what I'm missing here?

Thanks in advance for any help.

[steve]

PC microphones are powered by the sound card. Plugging them directly into the Nady RMX-6 will not work as it is not designed to support PC microphones. You will either need to buy conventional microphones that will work with the Nady, or if you are good at DIY electronics I can probably sort out a suitable circuit that will allow you to use PC microphones with it.

[bspmail]

Thanks for the response. Could I run the pc mic's into a preamp and then to the NADY? Would that work?

[steve]

pc microphones need to be powered by a computer sound card.

[bspmail]

or if you are good at DIY electronics I can probably sort out a suitable circuit that will allow you to use PC microphones with it.

I'm up for trying this if you could configure something for me. I would sure appreciate it. I've got a few buddies that are good with electronics so I think I have the resources to get it put together.

[steve]

This is the basic circuit.
The capsule in the example is a Panasonic WM61A, but the circuit should work with whatever capsule is in the computer microphones.


This gives an "unbalanced" (single signal wire plus earth) output, so to connect it to an XLR plug it should be connected:
1. Ground (shield) to Ground (Shield)
2. Hot (+ or Red) to Signal (Centre core)
3. Cold (- or Blue) to Ground (connect to pin 1)

Note - make sure that "phantom power" on the Nady RMX-6 is OFF.

This circuit could be adapted to use the phantom power from the Nady RMX-6, but
1) I don't think that the Nady has phantom power on all inputs, and
2) if you get it wrong you could damage the Nady.

[bspmail]

Thanks a lot Steve.

[kozikowski]

That 10uF capacitor needs to be rated for at least the battery voltage--9V in this case. I would put a 15 volt capacitor in there. Also the (+) symbol on the capacitor needs to go toward the microphone, not the connector.

Being a compulsive engineer, I've been known to simulate the 5 volts normally coming out of the computer with six volts which I get either from two 3v coin batteries, or four AA cells mounted in a little box. See: Radio Shack.

I don't see any reason not to use the 9v battery, other than the volume of the microphone might be a little wacky.

Koz

[steve]

I don't see any reason not to use the 9v battery, other than the volume of the microphone might be a little wacky.

A lot of electret microphone capsules are rated up to about 10v, however you should ideally check the specification of the capsule that is being used. "Standard" PC microphones should be fine with 5 volts - the voltage referred to here is the voltage across the capsule, which will be less than 9v because of the (2k2) series resistor which makes part of a potential divider. Electret microphones typically have a resistance of around 1 k ohm.

[aighead]

My problem is similar to this, and I'm curious if that is still the best/only option?

I'm crazy cheap (read: I'm broke and spending ALL the money I have on this) and I've already spent like 100 bucks on this setup but here is what I have:

7 Logitech headsets, which I bought primarily for the microphones and the convenient place to stick 'em, I only plan on using 6 mics at a time, but it would be nice to have 8 inputs.

A Nady 4/8 channel mixer, which I've learned doesn't supply the necessary power to the headsets, therefore it's being (temporarily?) rendered obsolete.

A crapload of 1/8" to 1/4" adapters,

Window 7 with Audacity, though I can't imagine this part matters.

A deep ignorannce of what the diagram pictured above means, do you have to build one of those circuits for each mic? Is there somewhere I could buy a circuit like that? Is it a simple enough diagram that the folks at Radio Crack will undertand it if I make a printout? I have soldering experience and the abilty to use it if I need to.

I'm willing to send the mixer back to get something else but I need to stay within a similar budget, I'd be willing to spend up to 60 bucks, I guess.

Is there a 1/8" to USB adapter that would work still supplying the needed power to the headsets?

Am I out of luck? If I build the above circuit is it likely to be noisy? That's why I ended up getting the headsets for instead of a room mic, in the first place...

Thanks so much for any help!

I've already learned some junk I didn't previously know while browsing around for the solution to my problem, and you guys seem to know of/think of things that the people at Nady didn't...