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Page updated: 1-Sep-2010

Stereo Mic Mounts

How do you mount two microphones for stereo 'coincident/crossed-pair' recording?

It's tempting to fix a spacer bar to a vertical mic stand to mimic the 'crossed-pair' pictures you see with the mics pointing inwards at 90 degrees to each other:-

Small diaphragm mics

But... if you look inside the grills, the actual capsules are still a long way apart, and the mics also get in each other's way by casting an audio 'shadow' in the horizontal plane.

Overlapping the mics one above the other would solve both problems, but to keep them horizontal requires an extender to raise one mic higher...
and how do you do this with large diaphragm mics?

Solution

After a lot of head-scratching, I realised that mounting the spacer bar to a horizontal fixture would allow both types of microphone to be horizontally 'coincident' with no shadows. The boom section would seem the obvious choice but this creates further problems: a hefty counterweight is reqd. especially for large diaphragm mics; it can also be cumbersome & accident-prone in confined areas. With this in mind, I came up with these arrangements:-

Small diaphragm mics    Large diaphragm mics

Details

My mic stand has a boom arm which is the same diameter as the upper telescopic tube; you may have to adapt the following if your mic stand is different.

Mic stand    Mic boom mount close-up

Remove the boom arm (not reqd.) and unscrew the boom mounting adapter from the vertical tube. Slide the adapter over the upper vertical tube and lock it in place with the small boom-locking screw. You now have a miniature boom stub (right-hand photo), i.e. a threaded socket which can be locked in the horizontal position with the large locking screw:-

Normal mount position    Rotated mount position

To attach the spacer bar to this, you'll need a suitable bolt. The central hole on my spacer bar was already tapped, which prevents a bolt from tightening properly, so you can either enlarge the hole or drill a separate one. I drilled a new hole (to the left of centre in photo)... but don't be too hasty yet; I ended up drilling more, so read on before turning it into Swiss cheese!

Standard spacer bar

The mics, cradles & cables are quite a weight, so use a serrated washer between the bar and the adapter to stop it coming loose.

Spacer    Spacer + cradles    Spacer + cradles + mics

This is where it stopped being a 5-minute job! The two mics need to be as close as possible without touching, so another hole was drilled. The distance between the holes depends on the lengths of your particular mics; you also need to allow for the mics sagging in their elastic cradles, so 'measure twice, cut once'...
...however, still not home and dry as some cradles won't fit flush to the bar unless they are at the ends:-

Cradle fitting

So you can either butcher the bar even further and cut it to the correct length, or make a new bar. If your cradles don't have this problem, you could make or buy a generic bar with slotted holes to allow different sized mics to be used.

Standard & custom spacer bars

Final Results

Large diaphragm mics using the home-made spacer bar:-

Custom spacer    Custom spacer + cradles    Large diaphragm mics closer together

Small diaphragm mics using a standard spacer bar; you didn't cut it, did you?! Rotate the bar and mic mounts at a slight angle so the mics overlap and remain horizontal:-

Small diaphragm mics - top view    Front view

Side view

These are quite sturdy arrangements as they are directly fastened to the vertical section of the mic stand; the whole mounting can still be tilted if necessary and raised/lowered if the section is telescopic. You can still attach this spacer bar to the boom arm for more versatility (vs. stability), in which case you'll need to fasten it with a nut if it doesn't have a threaded central hole.

Final Tips

  • If you're not using the boom arm to act as a counter-weight, ensure the mic assembly is lined up over one of the legs to prevent the stand toppling over.
  • Use foam blocks underneath the mic stand to reduce floor-bound vibration.
  • Releasable plastic cable ties are less messy than gaffer tape for keeping cables tidy (you can just see two in the photo).

tba

  • See Sound On Sound article for further info. on stereo mic techniques.