Handbook for Sound Engineers

Sound System Design 1315

nent farther along in the system is the most likely
culprit. Think through the block diagram at this point to
find the next suspect component. (One component that
may be a problem is the house ac power.)

When possible, patch around suspect components.
For example, a limiter can be completely removed from
the system, and the system will still operate. Thus, if a
limiter is suspect, use a patch cable to bypass it. If the
bypass operation causes the system to begin operating
again, the limiter is at fault.

When the suspect component is necessary to the
operation of the system, try to replace it with some other
equivalent component. If a loudspeaker is suspect, for
example, try switching it with a similar loudspeaker or

even a stage monitor loudspeaker temporarily in place

of a main system loudspeaker. If the mixer is suspect,

try running a CD player or MP3 player directly into the

system power amplifier to make sure that portion of the

system is still working.

34.5.5.3 DSP Troubleshooting

It’s common for an all-in-one DSP unit to host all of a

sound system’s signal processing—everything between

the mixer and the power amplifiers. A suspect all-in-one

DSP like this can’t be bypassed for troubleshooting.

Also, it’s not easy to swap it for another DSP, even if

one is available, because the second DSP must be pro-

Figure 34-79. Troubleshooting Part 1. Assumes that the problem is hum, noise, or oscillation and that block diagram flow is
from left to right. Method is to break system (disconnect) at indicated points until the faulty component is located.

Make first break

about half way

through system.

Make next break

left of first break.

Yes Make next break

right of first break.

Make next break right

of previous break

but outside of areas

previously covered.

Is the

sympton

gone?

Make next break left

of previous break

but outside of area

previously covered.

Don't

Go to 10. care! Has the faultycomponent

been found?

No

Replace or patch

around the faulty

component.

No

Yes No

Yes

Is the

sympton

gone?