This adapter lets you use in-ear headphones or headset with electret mic and a 3.5mm TRRS phono connector, with a theatrical/broadcast comms panel or beltpack with 4-pin male XLR headset connector.

It is confirmed to work with Riedel Bolero and Artist panels/beltpacks, provided that they are in auto or electret mic mode. It should work just fine with any other comms pack that supports providing 5V mic bias.

Important Notes

If the comms device only supports dynamic mic headsets, this adapter will not work for microphone! It will however still work for the (mono) headphone side.

This adapter only supports in-ear or particularly high-sensitivity on-ear headsets, as it relies on transformer isolation of the headphones. Unfortunately this means it is not recommended for use with any over-ear headphones! The sound will be quiet and distorted.

Instructions

Insert the 3.5mm headphones plug of your headset into the H2X adapter prior to connecting the H2X to the comms beltpack or base station. This is necessary for microphone and headset type detection to work correctly.

In the case that you hear feedback or ringing, try unplugging and replugging the H2X adapter, or turn off and on the comms device. Next, check the microphone mode the device is set on. Most modern comms gear supports auto-detection of dynamic and electret microphone headsets, but if you are having issues, please try manually selecting Electret (Condenser) Microphone type.

You will likely need to turn down the master headset volume on the comms device, as in-ear headphones are much more sensitive than over-ear comms headsets. On Bolero, this can be achieved by briefly pressing the Menu button, then scrolling one of the two encoder wheels.

Any buttons on the 3.5mm headset have no function, as comms stations don't support controls on 4-pin headset connector.

Design

I designed H2X as I was sick of sharing uncomfortable and unhygienic comms headsets at work in a theatre, but Bluetooth is not always supported for comms headset connection.

I discovered that due to the difference in circuit design of broadcast headset (separate mic and mono speaker) and phone headset (shared ground between mic and stereo speakers), directly wiring up an adapter did not work, but caused horrific feedback on the mic input.

This adapter includes a tiny high-quality 1:1 isolation transformer on the speaker side, to maintain the isolation between speaker and mic circuits and appear like a regular electret-mic comms headset. This means it is completely passive and does not require any additional power.

After prototyping as a dongle, the design was miniaturised to fit entirely within the high-quality Neutrik XLR-FXX connector shell.

I've used it on several productions, and users have found it reliable and a huge relief when comms headsets are uncomfortable. Microphone quality of course depends entirely on the headphones used, but was never an issue.

May take 3-5 business days to ship products.