'66 Fender Super Reverb Part 2: Showing the Completed Work

[@ctcards2636]

Oh you answered my question I had on the first video. So ya did end up putting a 4.7uf in for the vibrato. :-)

[@jeremysametz1699]

Hi! I appreciate your videos - you do good camera work, you have voice made for radio, and you describe very well. Thank you! I'm a bit confused as to what you are pointing at (and why) at the very beginning, when describing what I understand to be V4. It's kinda hard to tell which finger you are using. I've rewound it 20 times. It seems you are pointing at V4 while saying V3, corroborated by your description of swapping out the 3 noisy GE 7025s for new tubes. You then mention the vibrato V5 - no issue there. Further, you then point at the 2 x 12AT7s V"3" and V6 - V"3" being the reverb driver, and V6 the phase inverter. Again - no issue there as far as the tube chart goes. But am I to understand that the first 12AT7 in the 3rd position - is V4, and the 1/2 reverb recovery/1/2 trem driver in 4th position is V3? Please clarify: Fender Guru.com AA763/AB763 Tube layout (Seen from behind, V1 is to the right side) V1 12ax7 = Preamp normal channel V2 12ax7 = Preamp vibrato channel V3 12at7 = Reverb send V4 12ax7 = 1/2 Reverb recovery and 1/2 gain stage for vibrato channel V5 12ax7 = Vibrato V6 12at7 = Phase inverter

[@PsionicAudio]

Sorry for any confusion. You have the correct tube locations listed.

[@lager9342]

Will the amp have less hum with the two heater balance resistors vs using the PTs center tap? Or is it just for safety?

[@PsionicAudio]

It can, but it's mostly to protect the PT in the event of a heater short.

[@lager9342]

@@PsionicAudio Thanks, so a fuse on the heater wire will be as good?

[@huddyskiba1]

Any comment on elevating the center tap to a cathode? Not huge deal? Pain on fixed bias using a tube down the chain? Is there a benefit other than convenience/neatness to adding the heater balance resistors to pilot light as opposed to a tube’s heater pins somewhere down the chain? Thanks!

[@PsionicAudio]

Well, you can't elevate to the cathode in a fixed bias amp. You'd have to create a new DC node @50VDC for that. But in a fixed bias amp like this Fender, you can ground an artificial CT to other points in the chassis, so output tube socket to cathode (ground) or from a preamp tube to ground. The lamp is just convenient on these. On high gain amps it can be best to connect to ground close to the input point. In this AB763 it doesn't really matter.

[@huddyskiba1]

@@PsionicAudio yes that’s what I was getting at. I guess a preamp tube cathode doesn’t do much being only a couple of volts above ground. You mention high gain and close to input - would that be first gain stage cathode?