1969 Fender Super Reverb
The Black-Panel Fender Super Reverb is a favorite touring amp for some of the biggest known players in history. With 40 watts of power and 4x10” speakers this model sits a little more than halfway on the scale of most power in the classic Fender lineup. It’s a big and heavy amp with lots great bass response and output volume - being a bit less loud than a Twin Reverb. The Super Reverb has a larger 50 watt output transformer (same as the black-panel Bassman) than the other Fender 2 x 6L6 amps' standard 40 watt transformers. The larger transformer adds output volume and headroom and gives the Super Reverb a distinct voice. The Normal channel has only Treble/Bass controls while the Vibrato channel has an added Middle tone control. The Super Reverb's 2 ohm output transformer supplies the negative feedback circuit with 41% less voltage so it has less negative feedback than the 4 and 8 ohm 6L6 AB763 amps. Less negative feedback leads to a thicker clean tone, earlier dirt and a lazier transition to overdrive. The Super Reverb, and Concert use .022uF mid caps where all other AB763's use .047uF mid caps, this shifts the Mid tone control frequency band higher and reduces the mid scoop. Notable users include: Stevie Ray Vaughan, Derek Trucks, Robben Ford, East Bay Ray, and Fred “Sonic” Smith.
This amp came in to my shop having been worked on a number of times over the decades. The amp had a lot of resistors and capacitors replaced and a few questionable modifications. The quality of the work was just okay, nothing great and nothing too egregious. The Reverb and Tremolo effects were both not functioning and the amp did not sound it’s best. The customer wanted to make this a stock 1960’s AB763 Super Reverb circuit, so that is what we set out to do with this restoration. This one needed a complete cap job for all electrolytic and film units, total de-modification, new power/screen/plate/misc. resistors, cleaning, new RCA cables, power switch, hardware, and new tubes.
Amp was completely restored to original AB763 circuit values. All filter/bias/bypass caps were replaced with upgraded voltage and temperature rated MOD brand electrolytics. New 2 Watt Metal Oxide/5 Watt Cement power dropping resistors were installed for better reliability and lower noise floor. The cathode resistors for V3 and V6 were replaced with 2 Watt Metal Oxide type units due to heat damage and for preventative maintenance. All plate resistors were replaced with 2 Watt Reduced Mass Metal Film type units for preventative maintenance and reliability. All screen resistors were replaced with 3 Watt Cement 470 ohm type units for same reasoning. 1 ohm 2 Watt Metal Oxide resistors were installed on pin 8 of the power tubes to provide an easy way to check the bias. All of the coupling capacitors were replaced with Mallory 150 630v film type units - the coupling caps present in the amp were almost all replacements and not at the correct capacitance ratings. Three 500v Vishay brand Ceramic capacitors were used for the Tremolo circuit. 500v Silver Mica caps were used for all positions in the Picofarad range. All capacitor and resistor values were chosen to make amp compliant with AB763 values.
A 1N4007 1000V 1A Diode was installed in the bias circuit for reliability. A brand new correctly sized 3AG 250V fuse was installed as the one in place was the wrong value. A .022uf 630v Mallory film cap was used to mod the Trem circuit to stop it from ticking. The death cap was removed rendering the Ground switch deactivated for safety. A new Carling SPST Power Switch was installed to replace the cheap and wrongly formatted replacement that was present. New vintage Fender style RCA cable were installed for the Reverb Tank as the units present were broken.
The original tubes did not all test good and the preamp/rectifier tubes were replaced. This was the final lineup: V1/V2/V4/V5 =JJ 12AX7S, V3/V6 = EHX 12AT7, V7-V8 = JJ 6L6GC Matched Pair, V9 = SOVTEK 5AR4/GZ34. These tubes were picked for best tone, and reliability. The 6L6GC's Fixed Bias was set to %55 Class AB Plate Dissipation with a B+ of 456VDC. The tube sockets were all re-tensioned to stop the tubes from jiggling or falling out while they hang upside down - they also were cleaned with a De-Oxit treatment to prevent noise from corrosion. The pots were sprayed out and the amp was cleaned inside and out. New chassis strap screws and nuts were installed as the originals were bent, rusted, and stripped. This amp is now a fine example of a Drip-Edge Silver-Panel Super Reverb.
