FEATURES

This tube amp features three gain structure options, extensive tone control network, 40-70 watts of (clean) output power, series effects loop with level options, selectable level boost at foot switch control with a front panel knob to set desired boost.

Tuned "POWERSUCK" switch for great tone even at small clubs.

BJF designed custom-made huge transformer, best audio components and careful fine-tuning with wonderful hand work by Bukka M. are some of the secrets behind this amp.

The real beauty is in the amp circuit that is a piece of art.

Lot of special tuned circuits where the placement of components and length of wires makes a difference in tone.
Mad Professor has FOUR ways to control the critical treble response:

FOCUS switch has two options with slight treble boost, then there is
TONE BALANCE that you can adjust treble with, the
TREBLE control of course adjust certain Treble frequency and the
PRESENCE controls another Treble frequency.

You will find the optimal Treble response with any guitar and cabinet using these controls.

Second is the Distortion even the clean tone you hear on a guitar amp has distortion. You hear it as shimmer, sparkle, twang etc. To hear a totally clean guitar tone plug to your home stereo and enjoy (or try some of the early silverface Fender by CBS engineers).

You can get distortion from each input (NORMAL, ABNORMAL at tube setting and ABNORMAL at FET setting).
You can footswitch between the TUBE and FET setting when you are plugged into ABNORMAL input and the TUBE/FET switch is turned to FET position.

You can have distortion from Preamp or from Power-amp, you can have it at lower volume levels with the special POWERSUCK switch.

There are lot of different distorted tones from this amp: "clean", sweet, crunchy, fat, "On the edge", singing, dynamic, with powertube saturation or without.. You can tailor the distortion so that treble distorts earlier than the low-end etc....

The amp is LOUD but has also great tone at club-levels thanks to special BJF design "POWERSUCK" option.

Front panel controls

NORMAL INPUT used for clean sounds to light overdrive
ABNORMAL INPUT used for overdrive sounds
FET-TUBE SWITCH selects the type of distortion obtained from Abnormal input - where the FET option lets the input tube be driven without the rectifier action of an overloaded control grid resulting in a sound with a little less buzz, slightly cleaner tone than ordinary tube overdrive. TUBE is an all tube structure for a classic tone

You can footswitch between the TUBE and FET setting when you are plugged into ABNORMAL input and the TUBE/FET switch is turned to FET position.

VOLUME sets the gain of the preamp
MIDDLE works as normal midrange control except it's affected by FOCUS
BASS works as bass control except it's affected by FOCUS
FOCUS is a four position rotary switch which selects two different center frequencies for the T-filter, with or without a mild treble boost. The tones are OPEN SYMBOL with or without treble boost and SOLID with or without treble boost
TONE BALANCE this controls the balance between bass and treble, work similar to most treble-knobs on other amps.
TREBLE controls treble
BOOST sets how much level-boost is obtained when boost switch is pressed
PRESENCE controls the treble response of power amp - works by removing feedback at high frequencies
MASTER controls output level - works by attenuating level at power-amp input.
STANDBY ensures longer tube life
PILOT LAMP

Back panel

MAINS FUSE
HT FUSE
THREE PRONG AC-INLET
ON-OFF SWITCH
SEND (preamp output - drives a 100K-load without losses)
RECEIVE (power amp in with an input impedance of about 300K)
LOOP LEVEL SWITCH (2-POSITION SWITCH)
There are two level options. One for low-level effects, driven by a 9V supply, and one for line level effects, like tape echoes and certain studio or rack gear.

FOOT-SWITCH (for external foot-switch controlling FET and boost function)
5 SPEAKER OUTPUTS (2x4 ohm, 2x8 ohm, 1x16 ohm)
4 POSITION "POWER SUCK" SWITCH to get great tone with lower volume.
Levels: ARENA, CLUB, PUB and BEDROOM

Inside the amp

There are bias test points behind the back panel and you set the bias for the different tubes by using just a normal Volt meter.
A Bias switch to switch between Hi and Low bias for EL34 or other types of tubes.
Wide range bias trimmer to set the bias for different tubes.
It takes only few minutes to change the power tubes and you can do it yourself.

Design philosophy

All parts are deliberately overrated to ensure reliable and safe operation.
Circuit is to be as far as possible original or at least nonstandard.
Construction should be neat and build to last. It should be the best amp ever built.
It must be an inspiring amp to play!!!