PF-20T / PF-50T Bass Guitar Amplifier
PortaFlex Series Rear Panel Features Continued...
20. IMPEDANCE SELECTOR: Use this
switch to match the output impedance
of the amp to the speaker(s) being
used (4 or 8 ohms).
For help in deciding the total impedance
of your system, consult the chart below.
21. SPEAKER OUTPUT: This mono 1/4" TS
output jack supplies speaker-level power
to the speaker cabinet. The rated power
output is 20 watts rms [PF-20T] or 50
watts rms [PF-50T] into 4 or 8 ohms.
Make sure the total speaker impedance
load is 4 ohms or greater.
Cabinet Number of Total
Impedance Cabinets Impedance
4 ohms 1 4 ohms
8 ohms 1 8 ohms
8 ohms 2 4 ohms
16 ohms 2 8 ohms
16 ohms 4 4 ohms
For example, you could connect:
2 16 ohm speakers in parallel = 8 ohms
2 8 ohm speakers in parallel = 4 ohms
Use speaker cables with 1/4" TS ends
to make the connections. Do not use
instrument cables as they may overheat.
NOTE: Unlike many tube heads which
require a load (speaker) be attached
for operation, the PF-50T / PF-20T
may be operated with or without
a speaker load attached. When using
this feature, make sure to disconnect
the speaker cable from the Speaker
Output of the head.
This is extremely useful for direct
recording or bypassing a speaker
entirely in a live setting. This is also
useful should the speaker become
disconnected during performance,
as the amplifier will not be harmed.