HomeFender Amplifier Models by Optical "Vibrato" Circuit Category

The four different categories are defined in Figure 1 of "A Closer Look at Fender Optical 'Vibrato'". The schematics examined for that study were reproduced in "The Tube Amp Book," 4th Edition (1993), by Aspen Pittman (full reference follows schematic lists). All of the Fender and Fender/Rhodes models whose schematic diagrams (1) were included in that book, and (2) indicated use of optical tremolo, were included in this analysis. [This schematic set was also used in a more recent study: "How Linear is Fender Optical 'Vibrato' (Really Tremolo)?"]

Models With “Category 1” Vibrato Circuit (17 schematics)

Fender Amplifier ModelPage Number in Pittman (1993)
“Bandmaster-Amp AC568”362
“Bandmaster-Reverb-Amp AA768”364
“Concert-Amp AB763” 400
“Deluxe-Amp AB763” 406
“Pro-Amp AB763” 434
“Pro-Reverb-Amp AB668"437
“Showman-Amp AB763"443
“Showman Reverb-Amp AA768”444
“Dual Showman-Amp AC568”445
“Super-Reverb-Amp AB568”462
“Super-Reverb-Amp AB763”463
“Tremolux-Amp AB763” 470
“Twin Reverb-Amp AB763”483
“Twin Reverb-Amp AC568”484
“Vibrolux-Amp AB763”497
“Vibrolux Reverb-Amp AA964”498
"Vibrolux Reverb-Amp AB568”500

Models With “Category 2” Vibrato Circuit (8 schematics)

Fender Amplifier Model(s)Page Number(s) in Pittman (1993)
“Bandmaster Reverb-Amp AA1069”365
“Deluxe Reverb-Amp AB868”408
“Pro Reverb-Amp AA1069”436
“Dual Showman Reverb-Amp AA769”448
"Twin Reverb-Amp AA270”480
“Twin Reverb-Amp AA769”482
Fender/Rhodes 135 Watts RMS Amp w/ Reverb and Vibrato; Part No. 013694
(“Used on Vibros. Rev., Sup. Six Rev., Quad Rev., D.S. Reverb, Twin Rev.”)
488-489
“Super Six Reverb” “Dual Showman Reverb” “Twin Reverb” “Quad Reverb”
[Note: apparent typo for cathode bypass capacitor in driver stage; says 50@5V; likely meant 5 microfarad at 50 V; cathode voltage is shown as +13 V]
491

Models With “Category 3” Vibrato Circuit (4 schematics)

Fender Amplifier ModelPage Number in Pittman (1993)

“Bandmaster Reverb-Amp AA270” 

363

“Pro Reverb-Amp AA270”

435
“Dual Showman Reverb-Amp AA270”447
“Super-Reverb-Amp AA270”460

Models With “Category 4” Vibrato Circuit (4 schematics)

Fender Amplifier ModelPage Number in Pittman (1993)
“Bandmaster-Amp AA763”361
“Deluxe-Amp AA763”405
“Showman-Amp AA763”441
“Super-Reverb-Amp AA763”461

Schematic Reference: Aspen Pittman, "The Tube Amp Book," 4th Edition (1993) Published by Groove Tubes, Sylmar, CA. The page numbers in the above lists are where the indicated Fender amp schematics are reproduced in Pittman's book. I'm fairly confident all of these schematics and more can be located online by entering the model number into your favorite seach engine along with the keyword "schematic."


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Initial Note on Fender Optical "Vibrato"


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