From: moose@guppy.tds.kth.se ((]ke Nordin))
Newsgroups: rec.audio.pro
Subject: Re: Sound reinforcement questions
Date: 7 Sep 92 19:32:07 GMT
Reply-To: moose@guppy.tds.kth.se ((]ke Nordin))
Organization: Royal Institute of Technology, Stockholm, Sweden

In article <1992Sep4.141808.20794@uc.msc.edu>, dpm@msc.edu 
(David P. Mottaz) writes:
|> What is the best mic placement for mic'ing up a guitar amp(a combo
|> with one 12" speaker).  I have a Shure SM-57 to handle the chore.
|> This is for live performances.  I have heard several opinions about
|> this and usually its backed up with "well I always heard...".  What
|> are the differences in sound from having the mic aimed at the middle
|> of the speaker about a foot away vs having the the mic close to the
|> edge of the cone vs laying the mic in the back cavity of the amp vs...

Its impossible to tell one single ''best'' placement, but there are 
some clues to what you get from different placements. The main issue 
to be concerned about is what you want it to sound like. The sound 
of a particular guitar and amplifier combination is determined by 
many items, the "sound" of the speaker driver used in the combo amp 
is one major source of that sound. 

Those hi-efficiency drivers often used are very "rich" in resonances, 
the resonances being due to (deliberate) instabilities in the cone. 
The radiated power of the resonances is much higher near the rim of 
the driver than at the center, near the (stabilizing) coil former. 
Thus, you get the "fatter" sound near the rim. The sound of a mike 
in the back cavity might be fun to someone, but i suspect that it 
is far from the "normal" sound in front.

It is actually the same case as when you try to close up, say, a cello.
The sound differs a lot depending on where you put the mike. One trick 
with a cello is to back off some distance to get "the whole picture", 
but that's usually not possible on a rock stage. I used to hang a SM57 
down the grid of the combo with the capsule midway between center and 
rim. It has always seemed to be a reasonable (and compact 8^) compromise 
to me, if that grid just doesn't rattle too much.

|> Another area of concern;  We have never been able to get a very good
|> sound from the kick drum.  It's a huge Tama.  It has a lot of initial
|> attack "thwap" but it lacks serious "boom".  This is acoustically(sp?)
|> and it(of course) doesn't get any better amplified.  He uses a felt
|> beater.  I don't know what else is needed to diagnose this one.  Any
|> ideas?  The drummer for some unknown reason is reluctant to analyze
|> this so I am fishing around for solutions.

There were some good comments on the tuning of the kick drum, but 
the drummer himself seems to be happy with the sound. He may well 
have a point there, because "serious boom" often means less "punch". 
As noted earlier, the duty of the kick drum is not all that deep 
bass. 

I would suggest that, together with accessing the rear of the beated 
skin with a mike, you try to boost the low-mids (some 80-150 Hz) 
somewhat. Then add a touch of reverb, and possibly a dose 
of compression (if the drummer's kicks aren't all that steady 8^). 
A pillow on the bottom inside the drum might also aid the distinction 
in the sound from the mike.

By the way, does he kick around in a little sound box, or are you 
playing in one of those unused cellar bomb shelters? The sound 
from a mike inside a kick drum should have considerably more 
"serious boom" than what you hear standing in the sound box.

|>         "Decouple the expertise from the procedural"

It's this groups essence: you mike it and we tell you how 8^)

________________________________________________________________________
\oAke Nordin                                  Internet: moose@tds.kth.se
Dept. of Telecom and Computer Systems (TDS)   Telephone: +46 8 790 78 99
The Royal Institute of Technology (KTH)       Telefax  : +46 8  24 77 84
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