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Vintage threads from the first ten years

Super Reverb????

6/13/1999 3:40 AM
M/J	Super Reverb???? I just picked up a 68-9 super reverb. I have never seen one with the baffle board like the Blackface. Also it says AB763 on the tube chart. Anybody ever seen anything like this? Also the wiring inside is like a crossbreed of the 66 and a 70's silver face. It was twisted like in a BF but looked like cheap wires. They were small and plastic coated and stiff. It had a 15k resistor on the bias that for some reason I couldn't change to a 27k cause the bias was too low even though the bias pot was the same 10k pot as a BF. Everything looked original inside but I had to change and add caps and resistors to bring it to BF specs which makes me question the AB763 thing. Its 40 watts like the BF and sounds close tonewise. Any thoughts? M/J P.S. I hope T-boy can get this mess straightened out. This was a great page.

6/13/1999 3:40 AM

M/J

Super Reverb????

I just picked up a 68-9 super reverb. I have never seen one with the baffle board like the Blackface. Also it says AB763 on the tube chart. Anybody ever seen anything like this? Also the wiring inside is like a crossbreed of the 66 and a 70's silver face. It was twisted like in a BF but looked like cheap wires. They were small and plastic coated and stiff. It had a 15k resistor on the bias that for some reason I couldn't change to a 27k cause the bias was too low even though the bias pot was the same 10k pot as a BF. Everything looked original inside but I had to change and add caps and resistors to bring it to BF specs which makes me question the AB763 thing. Its 40 watts like the BF and sounds close tonewise. Any thoughts?

M/J

P.S. I hope T-boy can get this mess straightened out. This was a great page.

6/14/1999 3:52 PM
Jim S.	I've worked on plenty of these transitional early-model silverface Fender amps. They often make for great bargains on the vintage amp market, if you don't mind the look of the silverface control panel and are willing to pay someone or do the work yourself to "de-BS" them and perform an exhaustive restoration (new caps, resistors, wires). The very earliest silverface amps, manufactured around the beginning of 1968, are 100% blackface inside, in terms of circuitry, wiring, and components. They have the aluminum trim around the grille and also several thin black vertical lines on the faceplate. A bit later in 1968, things started to change. The thin vertical black lines went away. The vintage style cloth wires started getting replaced by really cheap plastic insulated wires. The lead-dress began to suffer. The blue tubular caps got replaced by very poor quality dull-brown "rabbit-turd" capacitors. Fender added .002 caps from grid to ground on the output tube sockets to cut out parasitic oscillation, probably resulting from the poor lead dress. Also, on the larger amp models, such as Super Reverb and Twin Reverb, the output section was changed to a combination fixed/cathode bias circuit that sounds terrible. This circuit utilizes 150 ohm/7 watt power resistors and non-polarized electrolytic caps. The bias control was changed to an output balance control. Plate resistors went from 1/2-watt to 1-watt. The input jacks changed to the longer "L" style and protrude slightly more from the control panel. By 1969, Fender had gone back to the regular fixed-bias output circuit, but most of the 1968 changes remained. At some point, they started using better quality stranded hookup wire and the lead-dress improved somewhat. It wasn't until 1970 or 1971 that Fender changed the cabinet construction to where there's a removable, velcro-attached speaker grille and the baffle is glued-in to the cabinet sides. The back panels changed from plywood to cheap pressboard, which tends to warp. Also, by now, the "-AMP" suffix was removed from the model names on the right of the control panels (e.g., "DELUXE REVERB" instead of "DELUXE REVERB -AMP"). I consider these 70's era silverface amps to be somewhat less desireable than the late-60's ones. By the way, one thing CBS-Fender did (starting in 1968) that I consider to be a big improvement was to use shielded cables for connection from input jacks and volume pots to preamp tube grids. I recommend keeping these even while the rest of the cicuit gets "blackfaced"..

6/14/1999 3:52 PM

Jim S.

I've worked on plenty of these transitional early-model silverface Fender amps. They often make for great bargains on the vintage amp market, if you don't mind the look of the silverface control panel and are willing to pay someone or do the work yourself to "de-BS" them and perform an exhaustive restoration (new caps, resistors, wires).

The very earliest silverface amps, manufactured around the beginning of 1968, are 100% blackface inside, in terms of circuitry, wiring, and components. They have the aluminum trim around the grille and also several thin black vertical lines on the faceplate.

A bit later in 1968, things started to change. The thin vertical black lines went away. The vintage style cloth wires started getting replaced by really cheap plastic insulated wires. The lead-dress began to suffer. The blue tubular caps got replaced by very poor quality dull-brown "rabbit-turd" capacitors. Fender added .002 caps from grid to ground on the output tube sockets to cut out parasitic oscillation, probably resulting from the poor lead dress.

Also, on the larger amp models, such as Super Reverb and Twin Reverb, the output section was changed to a combination fixed/cathode bias circuit that sounds terrible. This circuit utilizes 150 ohm/7 watt power resistors and non-polarized electrolytic caps. The bias control was changed to an output balance control. Plate resistors went from 1/2-watt to 1-watt. The input jacks changed to the longer "L" style and protrude slightly more from the control panel.

By 1969, Fender had gone back to the regular fixed-bias output circuit, but most of the 1968 changes remained. At some point, they started using better quality stranded hookup wire and the lead-dress improved somewhat.

It wasn't until 1970 or 1971 that Fender changed the cabinet construction to where there's a removable, velcro-attached speaker grille and the baffle is glued-in to the cabinet sides. The back panels changed from plywood to cheap pressboard, which tends to warp. Also, by now, the "-AMP" suffix was removed from the model names on the right of the control panels (e.g., "DELUXE REVERB" instead of "DELUXE REVERB -AMP"). I consider these 70's era silverface amps to be somewhat less desireable than the late-60's ones.

By the way, one thing CBS-Fender did (starting in 1968) that I consider to be a big improvement was to use shielded cables for connection from input jacks and volume pots to preamp tube grids. I recommend keeping these even while the rest of the cicuit gets "blackfaced"..

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