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As I in no way shape or form (or sound) know much about sound/audio/mics, I thought I'd direct my question here. We have a show that went up yesterday, and I just realized, all of their wired mics are SM81s. And we tend to use them anytime something nice is going up.

I just realized though, these are instrumental mics. Does it make that much of a difference? They were having a lot of trouble with some of those wired mics last night. They couldn't tell if the mics had been damaged, the cable/connectors/etc. had been damaged, if the placement was wrong, or if the kids weren't speaking it the mic or projecting enough.

I was curious if an instrumental mic should ever be used for singing. Also if there are any problems I can look for with their (our) current audio set-up.


(P.S. I am still trying to get them to use over the ear or hairline wireless mic placement, as on the costume has not worked out well.


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I've used the 81's as vocal mics before. The frequency response seems relatively flat, so it'll take some work on the channel EQ to get the sound you want (the SM58, 57, e935, etc. all have a slight bump in the mids for vocals).

Is this being used for performances, as in a musical? If it is a play, and people are gonna be running around on stage, then the 81 won't be a good mic to use. Where do you have them placed on stage? Where is most of the action taking place? As with most microphones, you need to be close to them to get any good sound on a loud stage.

btw, I love your sig.


Active Member
81's do a pretty good job of picking up vocals. Don't worry about it being labeled as an "instrument mic"... if it sounds good on vocals, use it on vocals!

As far as your problems... narrow it down to the mic, the cable or the board channel by swapping pieces around to see when stuff stops working. SM-81's (for me at least) have always held up pretty well. Make sure you're sending phantom power to each mic (they need that to work). Just because a mic cable may work with another mic (like a '58 or '57) doesn't mean it will work with an 81 -- it could have a pin-1 problem, cutting out the phantom power supply to the mic. Keep swapping things around until you find where your problems are...

I'd recommend to the singers to stay a bit off of the mic (don't hug it like you would a "true" vocal mic like a '58). And make sure you have the wind-screens on them. Good luck!


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I second Dillon's suggestions. If you plan on having people in a "U" around them, they should work perfectly. I've recommended the 81's for that very purpose to the last theater I worked at.


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If the problem is happening when the mics are handled, note that there is a -10 dB pad on SM81's that is activated by spinning a small ring near the pickup end of the microphone. All the 81's I've worked with have a small piece of plastic inside the microphone that prevents that swivle from spinning without removing the microphone head, sliding the plasic out of the way, spinning the swivle, sliding the plastic back in, and screwing the head back on. If that plasic is missing, and the microphones are being handled alot the -10 dB may be cutting in and our or maybe it wont work at all if it's stuck half way inbetween the two. It'd be worth a peek to check if -10 isnt messing you up!


Also check the roll-off switch on all of them. (3 position switch around where an on/off switch would be if it had one). I used 3-sm 81s for my high school choir (whole group pickup) and use sm58s for the soloists.

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