3.5mm mic's into mixer output to pc?

Special Interest Groups Recording Equipment
1

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.

2

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.

3

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

4

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

5

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.

6

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.
7

Thanks a lot Steve.

8

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

9

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.

10

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…

11

While I crank through all that, I noticed that not once in that post to you tell us what the show is. What is it? I can feel the next request coming that eight people around a conference room table are intending to Skype into a conference with three other cities. You’ll need to record both sides of all the conversations.

Did I hit it?

Koz

12

<<<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. >>>

Model numbers or web page?

<<<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.>>>

Maybe temporarily inappropriate, but we’ll tell you that right after you tell us which Nady.

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

What kind, which sex, and which direction? 1/8"stereo socket to 1/4" mono plug?

http://www.radioshack.com/product/index.jsp?productId=2062462

<<<Window 7 with Audacity, though I can’t imagine this part matters. >>>

Not directly. If you’re on a large deskside machine, the mixer should plug right in. If you’re on a Windows Laptop, it typically won’t be possible to plug the mixer in without an adapter. We’ll tell you that right after you tell us all about the computer.

Koz

13

Ha! Thanks for being curious! It’s http://aighead.com/presents or aighead.com presents: whichever you prefer. For the most part it’ll be several us sitting around a table in the aighead.compound carriage house just telling lies. There is no Skyping (yet, but I’d prefer to keep it that way) and the reason for my desire of 8 channel is occasionally there will be anywhere from 2 to 7 of us sitting around, and I’d like to have an extra channel for some random noise input (synthesizer style). I’d be happy with 4 channel and a splitter or two if I knew it would work.

Ok, now on to the real info…

The headsets are these, and I’m not concerned about the headphone part at all, we’ll all be close enough to hear the conversation without having monitors to listen through, and they are light enough to not muffle any sound. http://www.logitech.com/index.cfm/webcam_communications/internet_headsets_phones/devices/268&cl=au,en

The mixer is: http://www.nady.com/mm242.html and again, I’d be fine returning this one and getting something else, again, assuming it works.

The adapters are all 1/8" female to 1/4" male and they vary, I’ve probably got enough stereo to stereo, stereo to mono, mono to stereo, and 6 mono to mono that I just bought today (mono versions of the one you linked to).

I’m using a laptop with 1/8" mic and line in inputs…

All that to say that ideally I’d like to be able to keep the headsets (though I now realize that may be unlikely) due to their inexpensiveness and I’m pretty happy with their sound. If there is inexpensive workarounds I’m certainly willing to do some work (like searching for hours trying to figure out what the heck is wrong) to get things going. Just so you know you (and this forum) are much more helpful than the Nady support folks.

Thanks again for your help!

14

Don’t go crazy until we unscramble you.

The headset information is supremely unhelpful. Do you have two plugs hanging from each headset, say one pink and one black?

You have an almost there system.

The headsets are designed to plug into a computer. The stereo earpieces get their sound from the headphone system in the computer (or iPod, or wherever). The microphone works from a five volt power system inside the computer and it delivers a very tiny mono voice signal to the sound card.

That’s the top and bottom illustrations here…

http://www.kozco.com/tech/audioconnectors/audioconnectors.html

The mixer is close but no cigar. Yes, it will mix eight high level things down to one show on one wire. What it will not do is supply the power needed by the headset microphone, but more importantly, it will not boost the microphone signal the thousand or so times needed.

<<<I’m using a laptop with 1/8" mic and line in inputs…>>>

Typical Windows laptops do not have Stereo, High Level, Line-In. Does it say you have that, or are you assuming that from the large deskside computer you used to have. Deskside machine do have both as a rule.

We need to chew on this for a little while. Any specific reason the people around the table are wearing headphones?

Koz

15

My bad, yes 2 plugs. One pink, one black.

Correct with the pictures.

Both the mic and the line in are 1/8". So, in total I have a spdif headphone jack, mic, and line in inputs, all 1/8".

There is no reason for everyone to have headphones other than them being attached to the inexpensive microphone, I wasn’t planning on plugging them in anywhere. They are there for decoration and looking cool.

Thanks again man!

16

<<<My bad, yes 2 plugs. One pink, one black.>>>

No, you’re fine, the web site declines to tell anyone about the connections. I know, I looked.


I keep getting drawn into the system I designed for one of the conference rooms at work. It came in about $200USD. Four cheap (self-powered) Radio Shack microphones [http://www.radioshack.com/product/index.jsp?productId=2102927] mounted in pressure zone configuration and evenly spaced around the table. They feed a small Peavey mixer [http://www.sweetwater.com/store/detail/PV6/] and then on to a video conference unit [http://www.lifesize.com/Products/Video/LifeSize_Room_Series/Room_220.aspx]. It worked spectacularly well and they’re considering copying it at one of the other locations, but it was mostly hand-built with custom woodworking and audio adapters. Not something you’d attempt without a good handy-person on the staff.

You can duplicate this work with a commercial sound system for only about 4 to 5 thousand dollars - US. I know. I looked.

Instead of plugging it into a conference unit, you plug it into your Mac, or large Deskside PC, or PC Laptop with USB adapter.

That’s the other part of this puzzle. You’re designing a relatively plain, multi-microphone live sound shoot. Past one microphone in a computer system, you need to add lots of external stuff like mixers and monitors and headphones (for the producer). Many people would kill to be able to plug multiple microphones straight into their laptop. Not so far. Multiple microphones take management.

A while back someone designed “Aggregate Mode” which allowed two microphones to appear in one computer. That worked until you needed to manage one microphone (make it louder) without the other. Sorry. Can’t do that.

Peavey makes the PV6 with a USB output now. That came out after I bought mine. That will plug into any type of computer.

So that’s where we are.

Koz

17

Missed one.

Yes, you can totally build a battery inserter for your existing headsets. I’ve done that multiple times using the posted wiring diagram, but you do need to park the circuits inside a metal box because you are messing with tiny, tiny voice signals and they need to be shielded.

After that, you still need to get the signals into a microphone amplifier of some sort. That’s where I use the Peavey.

Koz

18

As it stands right now, I have what amounts to be a super cheap version of what you speak of with “I keep getting drawn into the system I designed for one of the conference rooms at work”.

My version works but it also picks up my noisy, noisy recording environments, not to mention that I’m a relatively low talker, mixed with some of my buddies who are extra loud.

How difficult and expensive is the circuit method, and am I correct in assuming that I’d need a circuit for each microphone?

I’ve got a small guitar amp laying around somewhere, is that what you are talking about or is the mixer you’ve linked to also an amp? I’m again worried if I’m going to pick up immense hums, my experience removing hum has been semi-unsuccessful. Also at that point could I still use the mixer I already have?

Without knowing anything about circuitry, is this something that a relatively competant new circuiter can manage? It looks simple enough, but I don’t know what any of it means…

Seriously, I can’t thank you enough for your understanding and putting up with my ignorance.

19

<<<My version works but it also picks up my noisy, noisy recording environments>>>

That’s part of the fun of doing this. You can’t record any of this in a boiler factory or a bus station. That’s where the noise canceling headset microphones shine. That’s why I didn’t say the words “the headphones gotta go.” Headsets may be the only way to pull this off.

Koz

20

Here’s all the pieces you need for a single channel. The missing parts are the cable to the computer and the computer itself.
MicPowerSupply1.jpg
This is the same thing put together. This mixer will handle four microphones.
MicPowerSupply2.jpg
Here’s an explosion of the power supply.
MicPowerSupply3.jpg
Here’s a detail.
MicPowerSupply4.jpg
I used two 3 volt coin batteries to simulate the 5 volts coming from the computer. I didn’t even mount the batteries. I just pushed them into plastic sleeves and stuffed the whole thing into the case.

I believe all these items are available at Radio Shack.


Here are the overall system parts you need.

– Noise canceling microphone
– Battery for the microphone
– Microphone amplifier
– Sound mixer
– Connection to the computer for recording.

If you have a laptop computer, you’ll probably need one of the USB adapters we reviewed like the UCA 202. This mixer can be gotten with USB interface.

The headset with noise canceling mic you already have. The battery can be added with the home-made adapter. The microphone amplifier and mixer are the same box in this case. That’s a Peavey PV6 and will manage four microphones.

Connection to the computer changes with the computer. PC laptops typically need USB somewhere.

Here’s a view of the Radio Shack 3013 microphone…

http://www.radioshack.com/product/index.jsp?productId=2102927

…taped to a board for conference use. This microphone has its own battery supply built-in. Plug it into the mixer through an adapter and go…
ConfMic.jpg
Koz