Mic please help!

Thread Starter

Torbek

Joined Apr 19, 2019
26
Hi folks so I acquired my son's gaming headset after the lead failed yet again. So instead of consigning to the bin, I have decided to replace the lead with a plugged lead. Anyway, everything went well, and I ended up with a headset that works quite well, exept I was not terribly happy with the microphone. Levels are rather low and while windows recognises for voice commands and do not think it is good enough for talking to poeple.

Now if you look at the picture I have posted, one thing that occurred to me straight away, was that the built-in mic, being a tiny electret type, had no power supply. I wondered if my son's ps3 controller perhaps provides a voltage?

What I am fairly sure about, is that despite telling the soundcard I have plugged in a mic, it doesn't provide a supply. This means the output must be tiny and might explain why results are not sensitive.

Soo, I knock up a standard mic circuit and plug it in...

And here lies the problem. Powered up, output is mute. Powered off and it is like I haven't done the mod. On writing this I do wonder if the mic is being saturated and I should try a higher resistor?

Any ideas would be appreciated!

Thank you!

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p.S. I just want to add circuit has been checked, the pins have got to be correct otherwise I would either get an echo sound from speakers (ground pin wrong) and no mic or mic and good sound and I have the latter.
 

Thread Starter

Torbek

Joined Apr 19, 2019
26
Thanks Keith. I wonder if the splitter (4 way socket to two 3 way plugs with mic and headphone) has mixed wires up i.e. if the bias is on the wrong pin it might be grounded. The sound input is via the motherboard. I will try plugging a standard stereo jack without the splitter and see if I can measure a voltage.

I still don't know why applying power to the circuit would mute the mic though. When the switch is off the mic works fine. It's even worse because the capacitor would block any DC volts from the soundcard if it did supply a bias!
And yes I am 100% sure as I have measured the volts when switch is on. 1.3 at mic resistor drops about 0.2v.

Another thought maybe 1v5 isn't enough!
 

Thread Starter

Torbek

Joined Apr 19, 2019
26
Right. The sound card does indeed produce the required voltage, and I can only assume that it did originally get to the mic. Now I still don't know how I am getting audio that is as clear now that I have put a blocking capacitor inbetween mic and input because now all the DC won't be getting to the mic. Weird.

I still think the mic needs boost. Could be a cheap electret I don't know... Anyway too late to mess around now. Tomorrow is another day!
 
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