REAR PANEL FUNCTIONS
REAR PANEL, LEFT TO RIGHT
1. GROUND
SWITCH – Select position which yields quietest operation. With a properly wired AC outlet and
factory supplied AC cord, this switch will not produce a noticeable difference.
2. AC MAINS INPUT –
Connect to a grounded outlet in accordance with the voltage and frequency
specified on the rear panel of your amplifier.
Use only the factory supplied cord set or a UL approved equivalent type.
3. MAINS
FUSE – Protects the amplifier from electrical faults. Replace only with type and rating specified
on the rear panel of your amplifier.
4. DC
FUSE – Protects the power supply and output transformer from electrical faults. Replace only with
type and rating specified on the rear panel of your amplifier.
Warning! Replace only with same fuse type and rating.
5. POWER AMP MODE: Class AB/Class A – Class AB operates power tubes in fixed bias mode for full
power for crisp highs and deep low end. Class A operated power tubes in Cathode Bias mode for full
slightly reduced output (30 Watts in Class A/NORMAL Mode) and softer highs and lows.
6. POWER AMP MODE: ENHANCE/NORMAL/AUTO – ENHANCE operates power amplifier from a Silicon
Rectifier for crisp tone and increased power amp dynamics. NORMAL operates power amplifier from a
Tube Rectifier for smoother tone and increased power amp compression and distortion. This is
accompanied by a slight reduction in output power to about 40 watts. AUTO ties the MODE SWITCH to
the front panel or foot-controlled channel switching function. In this mode NORMAL operates on the RED
channel and ENHANCE operates on the GREEN channel.
7. IMPEDANCE
SELECT - 4, 8 or 16 ohms. Example: Two 8 Ohm cabs = 4 Ohms, two 16 Ohm cabs = 8
Ohms.
8. SPEAKER
OUTPUT – Parallel wired jacks. Impedance switch setting should equal total of all cabinet
impedances plugged into both jacks. “Use First” jack must be plugged in for output to operate.
9. LINE
LEVEL - Power amp line level control.
10. LINE OUT - Power amp line out jack.
11. FOOTSWITCH – Connector for footswitch controller.
12. EQ IN/OUT SWITCH – Manual Bypass switch for Graphic EQ. Must be in OUT position for footswitch
function to operate.
13. EFFECTS - Activates F/X Loop. Also activated by footswitch jack.
14. EFFECTS RETURN - Overall level adjusted by Hi/Low switch, then feeds to EFFECTS LEVEL. Also
serves as power amp input.
15. SERIES/PARALLELSWITCH – Sets loop for Series or Parallel operation. See FAQs at www.vhtamp.com
foe a complete explanation about Series and Parallel loop operation.
16. EFFECTS LEVELSWITCH - Sets overall send and return level (LOW = -10dB, HI = 0dB).
17. EFFECTS SEND - Send level set by preamp volumes. Also serves as preamp output for recording and
slaving.
