BRIDGE MODE APPLICATION
OF THREE LOUDSPEAKER CLUSTER - Page 2
I can show you how to get +6 dB more performance out of this
system with no more financial investment, while having the
system configured to prevent anyone from changing the calibration
of the Near and Far Field gain structure. The secret to this
application is to operate the CS-800X in bridge mode. Connect
the Far Field HDH-244T across the two red binding posts of
each channel, i.e., in normal bridge mode operation. Then you
would connect one of the Near Field HDH-244T's, across the
A channels' red and black binding posts. Next, the second Near
Field HDH-244T would be connected across the B channels' red
and black binding post, however (note) the second Near Field
HDH-244T, connected to the B channel output, would have the
loudspeaker leads reversed. This is very important, since the
B channel is out of phase with the A channel, you don't want
the second Near Field speaker to be out of phase, so reversing
the loudspeaker leads will maintain the proper polarity. In
this application I would recommend reversing the loudspeaker
leads at the speaker itself.
This would prevent someone from noticing the different color
wires on the A & B channels' red and black banana posts, and
then they might be tempted to change them a round, thinking
that they are "correcting" someone else's error.
In this application with CS-800X, the Far Field HDH-244T would
automatically have +6 dB more gain that the Near Field HDH-244T
loudspeakers. When the Far Field loudspeaker received 800 Watts
from the power amplifier, each of the Near Field speakers would
receive 200 Watts. I have shown you a way in this application
to obtain +6 dB more performance in both the Near and Far Field,
with no more investment in dollars. Typically, you would have
had to quadruple the number of loudspeakers to obtain +6 dB
more system performance.
The CS-800X can operate bridge mode into a four-ohm load. It
can operate in stereo down to two ohms on each channel. In
the above application we are connecting a single eight ohm
loudspeaker across the two red binding posts of channels A & B,
and then an additional eight ohm speaker is connected to channel
A, and another to channel B. As far as the amplifier is concerned,
it's as if we had a four ohm load hooked up in bridge mode.
Don't try to make this application anymore complicated than
it already is. Many times when I have explained this approach
to someone, they immediately try to figure out how to utilize
even more loudspeakers in the same application. In some rooms,
such as a pie shaped auditorium or church, where the farthest
distance can be to the left and right rear corners, the same
three loudspeakers can be employed in a different configuration.
That is, the center loudspeaker is flown upside down with more
of a downward angle, while the two outside speakers are flown
right side up with less of a downward angle. The center speaker
is now covering the Near Field, so it requires the -6 dB of
attenuation, and the two outside loudspeakers are now playing
to the Far Field, so they do not need the -6 dB reduction in
gain. With this type of array, there is no way to employ the
above outlined application.
Here is one more application that can work however with the
CS-X amplifiers. Perhaps we are in a room that is long and
narrow, and yet we still need both Near and Far Field coverage
without increasing the horizontal coverage angle. We can fly
the two loudspeakers one above the other and configure the
top (Far Field) speaker in the above bridge mode application,
and then the bottom (Near Field) speaker can be connected across
the A channels' red and black banana posts. This will work
the same way as the first three-speaker array, i.e., the Near
Field speaker will have the proper gain reduction (-6 dB).
I believe we covered a lot of ground in this article. If you
thoroughly understand the operation of power amplifier in bridge
mode, you may want to undertake some of the outlined applications.
If you are still a little cloudy on how bridge mode works,
I would advise you not to try the above applications.
After I thought up this approach several months ago, I explained
my proposed application to Jack Sondermeyer, Peavey Electronics'
director of analog engineering. Since Jack is the engineer
that actually designed the Peavey CS-X series of amplifiers,
I knew that he would be able to spot any flaws in my thinking
regarding this application. After I explained this method to
Jack he laughed a little, and I said, "On no, don't tell me
there is a fly in the ointment?" Jack laughed once again, and
said that he was laughing because it was a great idea, he couldn't
believe that he hadn't thought of it.
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