-=> Quoting Bonnie Goodwin to Cameron Hall <=-
Hi Bonnie,
 CH> before someone hits a fader to tone it down to kill any feedback.
 BG> :-)
 BG> Right.. Also I installed a  peak limiter that was set below that
 BG> clipping point so that it would be idiot proof.
 
Great idea!
 BG> Very true. When drivers are hit with a amplifier that is clipping,
 BG> that clipping causes the peaks to square off, creating massive
 BG> increases in the high frequency energy, and is often the cause of
 BG> popping tweeters, and in the bass side of a biamped system, the woofers
 BG> can't dissipate the energy as sound.
 
A woofer bottoming is more noticable then heat, and with heat it just
quits.  At least with bottoming, ya can turn it down. :-)  Besides, the
extra WHACK from the bottoming tends to "colour" the sound unduly. 
 BG> Two ways. The first was that the response of the bass bins fell off
 BG> sharply before that frequency, as it was designed and wired for an
 BG> optional sub woofer system (for the electronic "pipe" organ) and the
OK, so the sub filtering did it.
 BG> 1/3 octave had a low cut off trim (UREI forgot the model number). The
 BG> bass was so potent, that it was decided not to add the subs.
For most church work, yes, the low end isn't needed as most usage is
vocal with the organ as accompanyment unless other instruments are
brought in.  And in some cases, a person will bring in a tape to
accompany them.  Was provision made in the install to allow cassette or
VHS HiFi dubs of the services and output for those needing wireless
amplifecation for the hearing impaired?  I volunteered at a church for a
while do that kind of stuff.  Great way to see the services and get some
of your hobby in too. :-)  They also had 4 wireless mics as well.  For
the most part, those worked not to bad, but they had their limitations.
 BG> carte blanche in the design and equipment selection, which in the
 BG> sound contracting biz is difficult to find a job like this, working
Yeah, ya got that right. :-)
 BG> directivity 20*40 horns, 4 per side, with the two clusters meeting
 BG> right at the center isle. Move to the seats on one side, and the sound
 BG> moved to that cluster, move to the other side seats and the sound
 BG> shifted to the other cluster. Visually, in the front seats, the sound
Excellent!  Like that.
 BG> didn't quite match the visual location exactly, but this was minimized
 BG> in the rest of the house. The balcony was fed with ceiling 8" speakers
 BG> time delayed to allow the house system to be heard first, then adding
Interesting idea.
 BG> This configuration was used to have precise control over the sound so
 BG> that the direct sound only hit the seating areas, with very little
 BG> hitting walls and other surfaces to excite the reverb field, which
Reverb was a problem, but one trick was to increase the gain and notch
out the feedback frequencies.  This I feel only works with fixed mics. 
Once a person becomes mobile, the whole "image" changes.
 BG> turned out to be a little deader than was originally projected, giving
That will change with audience "loading" and will change slightly with
the season depending on whether coats come in or not, and how popular a
particular sermen is.  I read in Audio years ago an excellent article on
Silva Hall in I think PA that was heavily electronically amplified and
had curtains that could be raised/lowered to fine-tune the ambience.
 BG> a very high direct to reverb ratio and high intelligability. After all,
 BG> getting across the word of God is what church sound is all about
 BG> (besides the show biz aspects).
Exactly!
 BG> Quite often, sound systems are designed by one person, the consultant,
Or even worse, when a retailer makes the desicion... :-(
 BG> who specifies the gear to be used, a sound contractor wins the bid,
 BG> who then tries to figure out how the hell to give the specified sound
 BG> system for that rediculously low bid, what corners can be cut to get
 BG> there, and who has to make what that consultant design work perfectly,
 BG> no matter how badly that consultant blew the design, and that happens
Hmmm...  Sounds awlfully familiar.
 BG> more often than not it seems. Or like what happened once when the
 BG> architect moved the speaker cluster behind the microphones on a church
 BG> I designed with out consulting me, and we won the bid to install it.
 BG> Talk about a major hassle during that installation. We had to
 BG> substitute hypercardiod mics to get anywhere near sufficient gain..
In our case, they put the cluster RIGHT ABOVE THE PULPIT.  Then used the
8" satalites to do the parimiter.  The main mics weren't the problem
(cardoids) but the onmni wireless ones.  Snap crackle and feedback and
gain riding.
 BG> Just try to get an architect to take blame for anything!
Hmmm... :-)
 BG> I could go on and on about some of the weird designs and problems I've
 BG> had to deal with over the years in
 BG> installed sound.
I'm quite sure.  Thinking back to some of the Audio classic articles,
two others come to mind for echo discussion.  One detailed the ears
frequency response and how it changes from the angle that sound enters
the ear and how the brain uses that info to tell direction.
And the equipment profiles, especially the ones from Lipra Labs. :-) :-)
See ya, Cameron Hall
cameron.hall@bluebeam.gryn.org | ad121@freenet.hamilton.on.ca
Blue Beam BBS | 905 662 5784 | Stoney Creek Ontario Canada | v34 vFC FAX
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