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The unit is normally shipped with the button in the line-level or “in” position. However, before each use it is a
good idea to check for the proper position of the switch, as it could be toggled inadvertently during transport or
set-up.
Due to the 30 dB of extra gain that this switch provides, DO NOT leave it in the “out” position for line-level input
signal use! This could result in input-stage clipping of the Impulse
®
12D and cause unnecessary distortion.
DISCONNECTING AC POWER TO THE IMPULSE
®
12D
We recommend that the Power switch (3) be used to turn the unit off first, and then the AC power cord can be
removed. This minimizes stress to the power amplifiers and the transducers from turn-off transients. The power
switch has an arc suppression capacitor to help during turn-off and tends to make a clean disconnect from
the AC power, while the power cord IEC connector can make intermittent contact before finally becoming fully
disconnected, e.g., as when wiggling the cord.
TROUBLESHOOTING
No Output at All
First, make sure the unit has AC power and is turned ON. Make sure the various LED’s on the inputs of the power
amp module are illuminated (11 and 12 will always be illuminated either red or green).
If not, make certain the ON/OFF switch (3) is in the ON position and check the IEC power cord connection (2) by
ensuring it is fully engaged and seated. Make certain the AC line cord is plugged into a working AC outlet.
Finally, check the circuit breaker (1). (See the Rear Panel: circuit breaker section for safety instructions.)
Once assured your unit is getting AC power, check that the Impulse
®
12D is getting a signal. Temporarily
disconnect the cable running to its inputs and connect it to some other device capable of reproducing the signal
(i.e., a power amp and speaker). If this produces a signal, make sure that all Gain controls being used have been
turned up to a satisfactory level (one-third to halfway).
If the Impulse
®
12D has been subjected to direct sunlight or excessive heat, the built-in thermal protection may
have been triggered. If so, turn off the Impulse
®
12D and let it cool for a sufficient amount of time.
If there is still no output, contact your authorized Peavey dealer or the Peavey International Service Center.
HUM OR BUzz
If the Impulse
®
12D is producing a hum or buzz, the problem could be AC outlet related. Try plugging the
Impulse
®
12D into a different AC outlet. If a different circuit (breaker) is used for the mixer and for the Impulse
®
12D, it can sometimes cause hum problems. Unless it is not practical, it is best to use the same wall outlet
(breaker) to supply power to both the mixer and the powered speaker.
Ensure that shielded cables have been used to route the signal to the Impulse
®
12D's inputs. If speaker cables
with 1/4” plugs are used as input cables instead of shielded cables, they will be prone to hum or buzz.
Hum may be ground loop related. It may be helpful to lift the shield ground on a balanced cable at the Impulse
®
12D end by only using the ground lift switch (4). Check any input changes carefully by first turning down the
gain control(s) (13,14) before plugging and unplugging cables, or lifting the shield ground at the speaker end by
using the Ground Lift switch (4).
Check to make sure light dimmers are not on the same circuit as the Impulse
®
12D, the mixer or any source
devices. If light dimmers are used, it may be necessary to turn them full ON or full OFF to eliminate or reduce hum.
This is a typical AC wiring/light dimmer interference problem, not a design flaw of the Impulse
®
12D.
The third wire (ground plug) on the AC plug should NEVER be removed or broken off, as this is a potential safety
hazard.
DISTORTED OR FUzzy SOUND
First, ensure the mixer (signal source) is not clipping or being over driven. Make sure the gain control(s) (13,14)
on the Impulse
®
12D have not been set too low. Check that the input plugs are fully seated in the input jacks
(7) and (8) on the rear panel of the Impulse
®
12D. Ensure that the proper MIC/LINE switch setting is being
used (5,6) for line-level signals, and that a power amp has not been plugged into one of the input jacks of
