Preamp gain with this simple and very useful mod. Reverb's Loose Low EndMake it sound more like a Twin Reverb.
#BANDMASTER AB763 SCHEMATIC MOD#
Two identical tone stacks? Mod one of them.
Presence Control Into Variable NFB Presence Control or Variable Use this late-in-the-circuit tone control to tame ice pick and tweak your tone. Pentode / Triode Switch Cut power tube output for lower volume In External Box External box goes between your amp and speaker to dump Iĭump 3/4 of the amp output for lower volumeġ0% Power Switch Dump 90% of the amp output for true bedroom level outputġ0% Power Jack Use your Aux jack as a 10% output jack Master volume AND late-in-the-circuit tone control. Simple Trainwreck Type-3 PPIMV master volume. Something constructive with your unused Normal channel.Īdd preamp gain with a simple resistor swapĪdd preamp clean headroom to the low voltage Deluxe, Deluxe Reverb, Vibrolux and ModApply reverb and tremolo to both channels the way Fender didĬhannels through the reverb and tremolo effects. Note the Preamp Plate Voltage difference between theĭeluxe Reverb and the higher powered amps.Ĭhannel Reverb Mod The preferred way to apply reverb and tremolo to both channels and There's alsoĮnough room for the addition of a nice little 6" practice speaker. Reverb tank and power transformer to keep hum pickup to a minimum. If you are considering building an AB763 with reverb in a headĬab I recommend you go no smaller on the head cab dimensions than the silverįace Dual Showman Reverb head cab. Is also a great place to mod away with to make that channel interesting and
#BANDMASTER AB763 SCHEMATIC MODS#
Mods that keep the amp's original tone in place. The AB763 circuit is considered by most to be For information about theĪB763 model differences see this. Vibroverb, Tremolux and no-reverb Deluxe. The "763" in the model name comes from the circuit change dateĭeluxe Reverb, Twin Reverb, Super Reverb, Concert, Band-Master, Showman, Pro, Vibrolux, 'AB763' was Fender's internal model designation for the 1963Ĭircuit. Use just one hand when working on a powered amp. Lethal shock can run between your arms through your heart.
Never touch theĪmplifier chassis with one hand while probing with the other hand because a High voltage then have an amp technician service your amp. If you have not been trained to work with Tube amplifier chassis contains lethal high voltage even when unplugged-sometimes These simple mods are completly reversable.Includes modifications for the 65 Deluxe Reverb Reissue and The picture below shows the additional "sag" power resistor. With three resisors, the Silverface Bandy is much more touch sensitive and responsive. At idle, there is a 7 volt drop across the resistor. A terminal strip was added to mount the resistor in a way that would allow cooling air around it. I lifted the red lead from the rectifier diodes feedding to the main filter caps. Closest I had on hand was a 10 watt, 100 ohm resistor. Rob's site suggested a 62 ohm resistor to simulate a GZ34 rectifier. But taking an idea from, I simulated tube rectifier sag with a resistor. More complicated would be a tube rectifier. Lowering the preamp and PI tube supply voltages gave the amp a less strident voice that was more bluesy but still classic Fender. I changed the Bandmaster 1K 1W and 4.7K 1W power supply resistors to 10K 1W resistors. Similar to the AB763 Bandmaster circuit is the AA763 Tremolux. Hesitant to heavily mod a vintage amp, I studied similar AB763 and AA763 schematics for some ideas to get me close to the tone I missed in my old amps. It is very loud through a vintage styled 2X12. The cranked sound of the Silverface Bandmaster I would describe as slightly strident, crunchy and yet Marshall like. It still has the original carbon comp resistors and blue Ajax capacitors. After replacement of the electrolytic capacitors, installation of all American made tubes and a bias adjustment, it is a great sounding Bandmaster. Today, my Bandmaster is an early 1967 Silverface drip edge that is one of the last Blackface Bandmasters inside. They were great for the Led Zeppeling flavored blues rock that I played back then but now they're gone.
Back in the 70's, I owned a Brownface 6G7-A Bandmaster.
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