This is the Hoffman AB763 board kit that has had cathode and grid resistors added to the power section to support four output tubes. I call this the AB763x4 board. This board is a good replacement for the "reissue" amps, or to "roll your own" if you can build the chassis, cabinet, etc.
This board is mainly to replace the old AB763 circuits which had four output tubes, or for those who want to build their own, and just can't seem to get enough power from two 6L6's or two 6V6's.
The board comes "stuffed" with all components soldered in place via the standard "Hoffman" turret lugs. The board has a bias pot installed for bias adjustment, and comes in two versions from TheAirtightGarage, standard and upgraded. The standard version comes with all of the "stock" parts: carbon composition signal resistors, precision flameproof resistors in the power section, signal caps chosen for tone (Sprague, Poly, Mallory). Sprague or other high quality electrolytics are used in the cathode bypass.
This board differs from a "vintage" AB763 in that the tremolo does not use the optoisolater (which are hard to get and noisy). It uses the tremolo from a 1963-1964 Vibroverb. We then take that unit and add a little bit of gain to it so that it is BIG like the original. We get nothing but compliments on this circuit, so we have decided to leave the little mod in as stock.
The upgraded version consists of the same components as the standard version but the signal capacitors are replaced with high quality film in foil types.
Both versions use silver wire for the bus connections between turrets, and include the following:
- Potentiometer harness with Alpha pots
- cloth covered colored wire
- shielded input cable
- standoffs and mounting screws
- switchcraft inputs jacks and input jack resistors
- ring terminals for ground connections
- heat shrink tubing for shielded cable
- Grid resistors for output tubes
You will also receive the Hoffman install manual, and some "tips and tricks" notes from TheAirtightGarage to aid in installation.
- The picture of the AB763x4 shown here has a "half upgrade" in that the front end capacitors have been upgraded. If you would like a full upgrade select it as an option below, or if you would like just a front end upgrade, email or call.
- Note: The optional film and foil caps below will almost certainly add to the lead time on this board as they are not always in stock. Please be mindful of this when ordering.
- Chaissis, knobs, transformers, cabinet, speakers, tube sockets, tubes, switches, and "everything else" not included. You will receive the Hoffman board and the associated parts listed above.