10. Channel Select
A four-position Channel Select rotary control is provided to access the three channels when the footswitch is not connected or available.
11. Loop Assign
A five-position Loop Assign switch is provided to assign the effects loop to any or all of the channels or select FTSW to trigger the loop on and off with the Mark V footswitch.
12. External Switching Jacks
Four 1/4" external switching phono jacks are provided for remote control of the Mark V channels, EQ and Solo control from a master switcher.
13. Effects Loop
The effects loop is fitted with a hard bypass feature that removes a whole tube (two stages) and all associated circuitry from the signal path for the purist who insists on the most direct path to tone in the studio.
14. Reverb Controls
Individual reverb controls for each channel allow you to set the desired mix of the rich all-tube reverb effect for each channel without compromise.
15. Pentode/Triode Switch
A pentode/triode mini toggle switch allows you to choose the wiring configuration on the middle pair of power tubes in Channel 3 only. Pentode produces a bolder, tighter voice that has a more pronounced midrange curve and is excellent for adding percussive authority to lower gain single note solo sounds. Triode softens the attack and scoops the mids a bit more to create a more liquid, legato feel that really shines for high gain styles and faster playing.
16. Switchable Rectifiers
Channels 1 and 2 are fitted with individual mini toggles that allow you to choose between the tight, bold higher-headroom response of silicon diodes or the saggier, sweeter low-output looseness of tubes in the 45-watt power setting only. The 90-watt setting automatically selects the silicon diodes and the 10-watt setting requires the tube rectifier to operate safely.
17. Speaker Outputs
Two 8- and 4-ohm speaker outputs are provided and with these jacks almost any speaker cabinet combination can be accommodated.
18. Tuner Output
A 1/4" tuner output is provided and a silent tuning feature has been incorporated so you can tune the instrument onstage without bothering the band or audience.
19. Slave Output/Slave Level Control
A slave output and slave level control allows you to capture the full sound of the Mark V, both preamp and power section, for a feed to processing racks and/or additional power amps for big venue applications.
20. Footswitch Jack
The footswitch jack is conveniently located on the right side of the rear panel and accepts a 8-pin male DIN cable.
21. Cooling Fan
The cooling fan is fitted with an on/off switch to allow silent running in the studio or late night practicing in the lower wattage settings.
22. Bias Select
A bias select switch is included that allows you to run EL34s in place of the stock compliment of 6L6s. The EL34 style tubes will produce a brighter, skinnier sound that will clip with an enhanced harmonic content. The 6L6s will likely perform better for a wide range of sounds.


Channel 1 contains the lowest gain sounds of the three channels and can be thought of as the Rhythm or Clean channel.

Toggle up: tight, skinny CLEAN. Toggle center: a warm, rich FAT clean sound with added lower fundamental. Toggle down: higher gain TWEED. Bold switch: adds punch and cut starting in the high mids to help you stand out in a dense mix and give you an increase in headroom.

Channel 2 is the transitional channel between the low-gain sounds of Channel 1 and the high-gain fury of Channel 3.
Toggle up: stripped, British-inspired EDGE. Toggle center: a thicker, throatier CRUNCH. Toggle down: the iconic high-gain voice of the MARK I. Thick switch: affects the Mark I mode only to add extra gain in the mids for added single note focus.

Channel 3 goes on from there to encompass the best of the Mark Series Overdrive sounds.
Toggle up: the classic voice of the MK II C+. Toggle center: a dose of thick midrange gain combined with a rounding out of the upper harmonic peak of the MARK IV. Toggle down: a full-gain assault that cuts through any mix on the EXTREME setting. Bright Switch: affects all three modes in Channel 3.