Can you use studio mics for live sound?

A tale of woe from a Audio Masterclass visitor...

Recently I did a show with a small combo, 3 musicians, 2 acoustic guitars (2 vocal mic's and 1 bass).

The guitars didn't have internal pickup systems, so I had to use normal mic's.

I'm not a professional sound engineer, but through my work I have access to a big stock of microphones, so I chose to use Neumann U89's [it's like a small U87 - RP] both for guitars and vocals. However we experienced massive problems with feedback, and couldn't get enough volume, so people had big trouble hearing us. The feedback mainly came from the guitar mics. The room was long with tilted walls (the ceiling of a barn), and there were around 60 people in it.

Now I'm wondering - did I overuse the U89's? Would I have been better off with SM57s or similar for the guitars, or was it just a hopeless task I set myself up to?

Oh and by the way - I set the Neumanns to Hypercardioid, with rolloff at 60 Hz, and they did face the right way :-)

All the best.
Lars

The human brain has a wonderful capacity for learning. Touch something hot just once and you'll remember never to do it again.

Using a studio mic for PA comes into the same category of experience. The long-term Audio Masterclass memory has almost blanked out an incident where a Neumann KM84 (forerunner of the KM184) was used as a vocal mic. More spectacular feedback has rarely been witnessed. Fortunately a trusty Shure SM58 was at hand.

I personally have frequently used studio mics for sound reinforcement, but apart from that one incident, never for rock 'n' roll level PA.

In theory, a high-quality studio capacitor microphone should have a very flat frequency response, which in itself should help protect against feedback. There isn't anything in the sensitivity of a capacitor mic that should make a difference, because that is compensated for in the gain setting of the preamp.

In the short-term then the recommendation would be to use standard road-tested mics for live sound. If it works for other people then it will work for you.

But to be honest, we don't have an answer for this question yet.

Does anyone have any theories on why studio mics don't work out for live sound? Or perhaps you've found a way of making them work?

Either way, we would like to know...