14. (FAN): The temperature controlled, variable
speed fan draws cool air into the amplifier and
forces heat out through the exhaust vents (also
on the rear panel, between the speaker jacks
and the power amp in jack). Do not obstruct
the fan or vent hole openings.
15. (FUSE): The fuse helps protect the unit
from damage due to overload conditions. If the
fuse fails, replace it only with the same size and
type. If the fuse fails repeatedly, check the line
voltage or contact an Ampeg Service Center.
16. AC LINE IN: Firmly insert the supplied AC
power cord into this socket until it is fully seated.
This grounded power cord is to be plugged into
a grounded power outlet, wired to current elec-
tric codes and compatible with voltage, power,
and frequency requirements stated on the rear
panel. Do no attempt to defeat the safety
ground connection.
17. SPEAKERS: The 1/4” jacks offer a con-
venient method of connecting to speaker cabi-
nets using cables terminated with 1/4” plugs.
However, when using the amplifier at or near its
full output power, using the Speakon
®
jack is
recommended. (Pin 1+ = hot, pin 1- = return.)
NOTE: When connecting multiple speaker
cabinets to the amplifier, keep the overall
impedance at or above 4 ohms. The following
chart shows the total impedance load when
connecting speaker cabinets in parallel:
cabinet # of # of
impedance cabs impedance
8 ohms 2 4 ohms
16 ohms 2 8 ohms
16 ohms 4 4 ohms
18. POWER AMP IN: This mono jack allows
you to feed the preamp output of another ampli-
fier to the input of the SVT450H’s internal power
amp. This bypasses the preamp circuitry of the
SVT450H.
19. PREAMP OUT: A post-EQ signal from this
jack may be sent to the house mixing board,
recording console, or an external amplifier.
20. EFFECTS RETURN: Use this jack to con-
nect the output signal from an external effect to
the amplifier by means of a shielded signal
cable.
21. EFFECTS SEND: Use this jack to send a
signal to the input of an external effect by
means of a shielded signal cable.
22. -20dB/0dB: This switch, when depressed,
attenuates the signal at the Bal. Out jack (#24)
by 20dB.
23. POST/PRE: This switch, when depressed,
sends a post-EQ signal to the Bal. Out jack
(#24). When this switch in the out position, the
signal at the Bal. Out jack (#24) is pre-EQ.
24. BAL. OUT: This XLR connector provides a
balanced preamp output signal for connecting
to the house mixing board, a recording console,
or an external amplifier with balanced inputs.
The signal at this jack can be set to be pre or
post EQ by means of the Post/Pre switch (#23).
The level of the signal can be adjusted for mic
or line type inputs by means of the -20dB/0dB
switch (#22).
SVT450H Bass Amplifier
