Ampeg Portaflex Series - Rear Panel Features - Continued; Impedance Selector; Speaker Output

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PF-20T / PF-50T Bass Guitar Amplifier
Rear Panel Features - Continued
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20. IMPEDANCE SELECTOR: Use this
switch to match the output impedance
of the amp to the speaker(s) being used
(4 or 8 Ω).
For help in deciding the total
impedance of your system, consult the
following table.
Cabinet
Impedance
Number of
Cabinets
Total
Impedance
2 Ω 1 2 Ω
4 Ω 1 4 Ω
4 Ω 2 2 Ω
8 Ω 2 4 Ω
8 Ω 4 2 Ω
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 Ω.
Make sure the total speaker impedance
load is 4 Ω or greater. For example, you
could connect:
• Two 16 Ω speakers in parallel = 8 Ω
• Two 8 Ω speakers in parallel = 4 Ω
Use (non-shielded) speaker
cables with 1/4" TS ends to
make the connections. Do not use
(shielded) 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.
This is extremely useful for direct
recording, or for bypassing a speaker
entirely in a live setting. This is also
useful should the speaker become
disconnected during performance, as
the amplier will not be harmed.