Soundman OKMII repair

I’ve had my Soundman OKMII binaural microphones for over ten years, and they are my favourite mics for urban field recordings. DACS is the UK supplier.

Soundman OKMII binaural microphones
Soundman OKMII binaural microphones

They don’t really work in wind, and they aren’t the quietest, but they are as stealthy as you can get, looking just like earbuds. A decade ago you still looked a little bit of a geek using them and monitoring on a recorder, but nowadays most people are looking at their smartphones, rather than the lamp-post/road they are about to encounter. On the off-chance that they do look up, they will assume you are just another human trying to escape the real world for the virtual one inside your phone, which happens to be a field recorder.

I was going for a general recce on the Somerset levels, looking for interesting sounds. I heard a lot of birds congregating in some trees, and started the OKMII. There was a lovely little flurry of about 100 starlings flying overhead at about 2 and 4 secs against a background of other starlings gathering in the trees

The OKMII isn’t really a birding mic, but it picked up some of the essence of these guys

and then I encountered this ghastly full-scale 0dBFS noise on the left

a bad contact on the left channel. After 10 years these mics don’t owe me anything, but I figured it’s worth a look if a fix is possible. Skinning the foam earpads shows this

OKMII Two plastic shells melted together
OKMII Two plastic shells melted together

It’s possible to separate these with a craft knife along the obvious seam, concentrating on the melted bits. The microphone is glued to the shell with a hole, try and keep this together to expose the contacts on the rear of the capsule.

OKMII innards
OKMII innards

Unsoldering the capsule to free the cable, I could then measure continuity, which was intermittent and ratty to earth

Poor continuity was not surprising when the shield came off like this

This had failed at the kink where the cable leads out, so it could be pared back and trimmed

cable pared back about 0.5cm and trimmed

and then resoldered to the capsule with the same polarity as before.After that, reassemble the two halves, and remelt the polypropylene shells with a soldering iron along the original lines

Fortunately the cable isn’t the litz on kevlar sort of wire headphone cable is usually made of, but I guess the downside is the cable fails after many years of use. There’s a greenish verdigris on the lapped shield, but not on the centre conductor. The right answer is probably to get Soundman to replace the cable, but this should give me a few more years…

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