0
\$\begingroup\$

I have two electret microphones. I would like to connect them to my computer to record stereo sound. I've checked a couple videos on YouTube and people there show they connect them "directly": signal from the first mic to the right channel and from the second mic to the left channel. Two "-" wires from two microphones are connected to the ground. Something like this:

schematic

simulate this circuit – Schematic created using CircuitLab

But also I've checked Wiki and in the scheme provided there is shown that electret microphone should be connected to some voltage source.

So, now I am a bit confused. I am not sure whether I need voltage source or not. If connection without voltage source is possible what pros and cons does it have?

So the main question is in the title: How to properly connect two electret microphones to computer to be able to record stereo sound?

UPD: Microphone datasheet

\$\endgroup\$
  • 2
    \$\begingroup\$ Add a link to the mic datasheet into your question so we know what you're talking about. \$\endgroup\$ – Transistor Nov 29 '18 at 23:33
  • 1
    \$\begingroup\$ Some electret mikes have a built-in preamp. Some don't. Which type are you talking about? As @Transistor says, add a data sheet. \$\endgroup\$ – WhatRoughBeast Nov 29 '18 at 23:42
  • \$\begingroup\$ @WhatRoughBeast I've done. Please check the link at the bottom of the post \$\endgroup\$ – danielleontiev Nov 29 '18 at 23:49
  • \$\begingroup\$ Provide a link to the Youtubes you're talking about. Unless the microphones have built-in batteries, I don't believe your diagram will work. \$\endgroup\$ – WhatRoughBeast Nov 30 '18 at 0:42
1
\$\begingroup\$

Your datasheet specifies 3VDC supply and 2200 ohm resistor. Your wiki link shows how to connect them. The capacitor is needed for removing DC from the audio. It is a few uF electrolyte or plastic insulated, for ex. 4...10uF. If you are lucky your soundcard has all those extra parts, you connect only the capsules. The driver software can have the option to turn the mic supplying DC on. You must have full spec for yor soundcard and check the polarity of the possibly existing DC.

Your datasheet gives also some tolerance. DC can be max 10V and the resistor can be bigger, even 10...15kOhm, only have such voltage that the remaining voltage for the capsule is 3V. Altough not specified, the capsule can work also with lower voltage, for ex. 1.5V But nobody quarantees it.

\$\endgroup\$
  • \$\begingroup\$ And if I my soundcard does not have DC (I am 99% sure it does not. I use 10 y.o. cheap laptop) which DC should I use? Is it possible to use two AA batteries? \$\endgroup\$ – danielleontiev Nov 30 '18 at 0:25
  • 1
    \$\begingroup\$ Check the soundcard driver user interface advanced options and at least try the simple version at first. If there's no DC output (check it with a capsule and DMM) then get 2x1,5V battery, a common 3V is ok for 2 mics and use wiki's schematic. \$\endgroup\$ – user287001 Nov 30 '18 at 0:32
  • \$\begingroup\$ does the values of resistors and capacitors should depend on smth? Which influence have it on the result? \$\endgroup\$ – danielleontiev Nov 30 '18 at 0:38
  • 1
    \$\begingroup\$ too small caps eat bass, too low resistor eat general volume, too high voltage eat your capsules. You can well have 4,5V and 3,3kOhm resistors to get full 3V supply for the capsules and reducing the signal loss. Bass attenuation can be preferable for speech clarity. \$\endgroup\$ – user287001 Nov 30 '18 at 0:43
  • \$\begingroup\$ I've just put a Jack into my microphone input and tested it with voltmeter. It shows 2.66 V \$\endgroup\$ – danielleontiev Nov 30 '18 at 0:43

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.