1/8 mic to 1/4 input wiring?

Question

I am trying to connect a headset with inline microphone to my computer through my NI Komplete Audio 6 audio interface. The headphones have a 1/8" TRRS male cable which I have plugged into a 1/8" male splitter. I plug the headphone splitter into a 1/4" adapter and into the headphone jack of the interface and this works fine. My problem is when I go to plug the 1/8" mic into (the same type) of 1/8 to 1/4" adapter and then into one of the interface inputs. The interface does not pick up anything no matter what I do (turning all the gains up/using inst level).

I have confirmed:

• The input to the audio interface is receiving signal (plugged a guitar with 1/4" cable and heard sound on monitor and computer).
• Microphone is working (plugged headphones into computer with direct TRRS adapter)
• Confirmed headphones are working through splitter

What could be the problem here? My only thought is that the 1/4 in jack may be wired differently than the 1/8"?

Answer 1

What could be the problem here? My only thought is that the 1/4 in jack may be wired differently than the 1/8"?

It's worse than that. They are electrically incompatible since the microphone needs "plugin power". That's not the same as "phantom power", but adapters like the Røde VXLR+ (the + is important since the VXLR without it will not provide plugin power) can be used on the XLR socket of your soundcard if you switch on the +48V phantom power. They will convert the +48V to something like +3V and the unbalanced connection to balanced. You'll still need your TRRS splitter for pretty much any adapter I know.

There are battery-powered adapters too: essentially they consist of a battery, a resistor (I have one with 1k on an AA battery, but another ballpark value from wireless receivers is 4.7k on 4V) from the battery plus to the microphone signal (on T and R) and battery minus to microphone ground (on S), and a capacitor (47µF low ESR or so) to keep the DC from getting to the 1/4" mono input.

With a soundcard, the phantom-powered adapter will be more convenient. If you use plugin-powered devices on an instrument amp, however, the XLR inputs on instrument amps rarely provide phantom power at all, and even when they so, commonly with considerably lower voltage than +48V.

Battery life of adapters with battery will be quite long (assuming you unplug the microphone between uses) since such microphones typically draw something like 0.3mA. It's just that batteries tend to run empty at inconvenient times.