7/30/2023 0 Comments Bandmaster ab763 schematicThe Mid control is set to 6.8k to simulate a fixed 6.8k Middle Resistor. This is what's meant when people say the TMB tone stack "loads down" the signal. Relatively flat but the guitar signal is losing about 25dB to the tone stack. With the Treble and Bass tone controls set to minimum the tone curve is (Treble, Mid, Bass) tone stack sets this mid frequency scoop. The AB763 blackface tone is known for its "mid scoop." You can firm up the Deluxe Reverb with a larger firstįilter capacitor or even an upgraded power transformer but you will lose some of Have higher output power supplies that do not suffer from the Deluxe Reverb's The other AB763 amps like the Twin Reverb The AB763'sĬlean, clear tone comes from the use of lots of negative feedback.ĭeluxe Reverb is known for its under rated power supply which gives the ampĪ lot of feel and touch response but leads to a loose low end and even "farting This trait also makes the AB763 circuit very pedalįriendly-it can play loud and clean to let the pedals do their thing. Ubiquitous voice are its mid scoop tone and loud and clear, but not too sterile character, especially when compared Some of the elements that give the AB763 Deluxe Reverb such a Output Transformer are attached to the bottom of the chassis. The AB763 Deluxe Reverb ChassisĬontrols in front, Circuit Board inside, tubes on bottom and out of view. Page dedicated to the magical 5F6-A tweed BassmanĪmp and the ever popular 5E3 Deluxe. Tube theory and other introductory material here so check it out if you have Tubes work in the very simple Fender 5F1 Champ. I recommend you take a look at my How Tube Amps Work and How Vacuum Tubes Work webpages for a detailed The "blackface" nickname comes from the control panel Of how the amp circuit works, what each component does, and how changing those I will try my best to give a not-too-technical explanation Vibroverb, Tremolux and no-reverb Deluxe. The "763" in the model name comes from the circuit change dateĭeluxe Reverb, Twin Reverb, Super Reverb, Bandmaster, Showman, Pro, Vibrolux, 'AB763' was Fender's internal model designation for the 1963Ĭircuit. Have comments or corrections? Email rob at: robinette at These simple mods are completly reversable.DRRI & 68 CDR Mods ] ] How the Fender AB763 Blackface Deluxe Reverb Amp Works The non-electronic tech's guide to understanding the classic AB763 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.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |