Rear Panel
(25) POWER OUTPUT SWITCH
This three position switch controls an attenuator which allows the maximum output of each amplifier to be
switched between 100%, 25% and 5% of rated power. Therefore on the 100 head this would be 100W, 25W
and 5W, on the 50 combo this would be 50W, 12W and 2W and on both the 20 combo and 20MH it would
switch between 20W, 5W and 1W.
This enables the user to drive the power stage hard, therefore producing the characteristic power amp
overdrive, but without such loud volumes produced by the speaker.
On the lower settings it may be necessary to slightly increase the Resonance, Presence and/or Damping
controls for the desired tone. This is due to the change in damping factor when the speaker is driven less.
(26) SPEAKER OUTPUT(S)
Provided for connection to either the internal speaker (20 and 50 model combos) or external speaker
cabinet(s).
Load impedance is selectable via the IMPEDANCE SELECTOR (27).
(27) IMPEDANCE SELECTOR
This switch allows appropriate selection of speaker/cabinet impedance. On the 100 head, 50 combo and
20 combo a three position switch is provided to allow selection of either 16Ω, 8Ω or 4Ω speaker/cabinet
impedances. On the 20MH a two position toggle switch is provided to allow selection of either 16Ω or 8Ω
speaker/cabinet impedances.
If two enclosures of equal impedance are used, the switch should be set to half the individual value. For ex-
ample, two 16Ω enclosures necessitate an 8Ω setting, while two 8Ω enclosures would require a 4Ω setting.
Minimum speaker impedance is 4Ω on the 100 head, 50 combo and 20 combo, 8Ω on the 20MH.
(28) SPEAKER ENABLE/DEFEAT SWITCH
This effectively disconnects any speaker/cabinet connected to the SPEAKER OUTPUT(S) (#26). This
enables the user to monitor their playing using the signal from either the MSDI
output, USB output or
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headphone output (20MH only). Therefore they can play or record at much lower volume levels.
This is done safely as, instead of being loaded by the speaker, the tube power amplifier is loaded by an
internal dummy load.
(29) HEADPHONE OUTPUT (20MH only)
This is for connection to normal headphones/earphones via a stereo mini-jack allowing the user to
set the amp to the SPEAKER DISABLE position and practice silently. The signal is derived in the MSDI
™
circuit (see below), therefore is filtered for a 12" guitar speaker-like tone.
(30) MIC SIMULATED DIRECT INTERFACE - MSDI™
Peavey's exclusive MSDI
simulates the sound of a microphone placed approximately 8" from a loud-
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speaker cone, allowing the user to send an accurate, good quality signal to the mixing console without
any acoustic spill from other instruments on stage. This is a non-powered output and safe for use with
any mixing console.
(31) GROUND LIFT
Engage this switch if the mix engineer is hearing a hum in the MSDI
output. This should eliminate the
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hum by removing the ground loop.
(32) EFFECTS LOOP SEND
1/4" output jack for supplying signals to external low-level effects or signal processing equipment.