DiY Headphone w/ Mic Tester

[rday1027]

Hello all. I'm on a mission to build a small device that I can plug a set of headphones, that include a mic, into to test if the left channel audio, right channel audio, and mic to see if they are working. I'm rather new to the engineering portion of creating something like this, but have no issues building, soldering, 3D printing cases/housings, etc. If anyone has knowledge or thoughts on what would be needed, I would really appreciate some help. Thank you in advance.

Tester Requirements

1. Input from an audio source to test left and right channel audio (phone or laptop)
   1. Could be 3.5mm or USB (open to an other ideas)
2. Jack to accept the headphones that need tested, assuming a TRSS jack will be needed for this
   1. In order to test the mic I'm thinking that I should be able to speak into the mic and hear it back either in the headphones OR from a small speaker
3. Powered via 5v or 12v wall wart style plug
   1. Also open to rechargeable battery pack ideas
4. Volume knob
   1. The headphones have a built in volume control switch so not sure if a knob would be needed
5. Small speaker
   1. If not too difficult it would be nice to have a DIP switch or toggle to be able to output audio from the speaker OR to the headphones

 

[rday1027]

Providing a backstory may help understand the use case. On a regular basis I receive headphones that have a built in microphone by the hundreds.. They are 3.5mm and are primarily used for phone calls and occasionally for listening to music. Recently, there have been complaints from the people the headphones are being distributed to that the mic is not working or that the audio is not coming through the earbuds. In an effort to catch defects before distribution, I'd like to build a small device to test these headphones to make sure all elements of them are working.

 

[kemmler3D]

Welcome to ASR and I think this makes sense.

I assume this is all for the same model of headphone.

Probably the simplest pass/fail basic functionality test would be to plug the headphones in to a device and hear the mic output through the left and right drivers, this way you can verify all functionality at once.

I am not the guy, but someone on ASR could probably give you advice on how to design that circuit. I think you will need a small amp and a few circuits around it, and that's basically it...?

 

[EERecordist]

I think you may find an inexpensive field mixer, battery powered. These were popular for concert tapers where the output beyond the headphones went to a portable recording device. An example would be the Sound Devices 302. Look up 2 channel portable microphone preamp with monitoring. Zoom probably has that in current models.

 

[rday1027]

I assume this is all for the same model of headphone.

This is correct.

Probably the simplest pass/fail basic functionality test would be to plug the headphones in to a device and hear the mic output through the left and right drivers, this way you can verify all functionality at once.

Yes this would work and would be the simplest solution. I would be fine with this.

I found this on Parts Express that I thought may be a starting point.

PAM8610 2 x 10W Class D Audio Amplifier Board

PAM8610 2 x 10W Class D Audio Amplifier BoardThis board is designed around the PAM8610 integrated circuit, a 10W per channel Class D digital audio power amplifier. Class D amplification offers high power output in a miniature size. 90% efficiency ensures a high quality sound reproduction...

www.parts-express.com

I’m not sure what the 3.5mm can accept. I’m assuming its an audio only input which would t work.

 

[kemmler3D]

This is correct.


Yes this would work and would be the simplest solution. I would be fine with this.

I found this on Parts Express that I thought may be a starting point.
View attachment 496450

PAM8610 2 x 10W Class D Audio Amplifier Board

PAM8610 2 x 10W Class D Audio Amplifier BoardThis board is designed around the PAM8610 integrated circuit, a 10W per channel Class D digital audio power amplifier. Class D amplification offers high power output in a miniature size. 90% efficiency ensures a high quality sound reproduction...

www.parts-express.com

I’m not sure what the 3.5mm can accept. I’m assuming its an audio only input which would t work.

I think basically what you need is a TRRS 3.5mm connector with exposed contacts, and you need a small amp to amplify the microphone signal. You connect the microphone contact to the amp input, then you just connect that output to the input contacts on the TRRS connector.

Smarter people than me could suggest where to find this connector, where to find a suitable amp(s) and how to know it's suitable, and what other parts you might need.

I can at least say that 2x10w amp board is not what you need. Headphone input power is usually measured in milliwatts, not tens of watts. You could run full-on speakers from that!

As @EERecordist mentions, you can also do this without building anything yourself.

Use one of these: https://www.amazon.com/MillSO-Headphone-Splitter-Computer-Headset/dp/B071NDLCGC/

Get some of these if needed: https://www.amazon.com/Chadou-Adapter-6-35mm-Headphone-Connector/dp/B084VGXK45/

Any mixer with a mic input: https://www.amazon.com/Pyle-Channel-Audio-Mixer-Professional/dp/B009GU4UHY/

And then it's pretty self-explanatory from there.

This is basically what I am suggesting, but I do think it should be possible to wire it up yourself for an even simpler solution.