1967 Bandmaster AB763 - No Reverb

[dbishopbliss]

I have a '67 Bandmaster that I hacked when I was young and stupid in the early 90's. I bought a bunch of kits from Torres and tried to convert it to high gain, channel switching, EL34 output amp.  Now I want to rebuild it. 

Initially, I was thinking of buying new fiberboards (the old ones are very warped) and building as original.  Then I came across the "Hoffman" AB763 boards.  I like the better ground layout as well as the change to the tremolo circuit.  However, it appears the AB763 board is designed for amps with reverb.  Here are my questions:

Is there a non-reverb board available? 

If not, can I leave out the reverb circuit?

If so, would that change some of the values (I'm thinking power supply)?

Finally, would the "Hoffman" board fit in a non-reverb chassis?

Thanks for your help.

[sluckey]

Is there a non-reverb board available?

I don't think so. 

If not, can I leave out the reverb circuit?

Yes. You would not need V3 or V4 and associated circuit. We can help you with this if needed.

If so, would that change some of the values (I'm thinking power supply)?

No.

Finally, would the "Hoffman" board fit in a non-reverb chassis?

The standard Hoffman 2 channel board is 3.125" x 15.625". You will have to measure your chassis to see if you have enough room.

Another alternative would be to design your own board that is specific to the Bandmaster AB763. Hoffman has an app to do this.

[eleventeen]

Good plan. You're probably going to have to (or want to) do a bit of drilling to cause the Hoffman board to stand off from the chassis....versus the old Fender style with the fibreboard screwed to the chassis simply sandwiching a blank piece of fibre, screwed down the middle. Probably you want six or eight screws laid out around the perimeter of the Hoffboard versus 3 (or 4) screws down the middle of the fiber board. Get my drift?

You can download a layout and I would urge you to do so, print it out at 1:1 scale, and consider where you might have to drill [the] mounting holes. There could be some items of interference, none of which should be any kind of big deal. For example, you might have to take off the output tranny and/or the choke in order to drill the holes, then they go back where they were. Also, consider whether you might want continuously threaded standoffs...instead of simple tubes..(I do) ..which means you don't have machine screws and nuts sticking up and coming out of the finished chassis. Makes for a neater job. These are just little things that are an irritation if not planned for, that's why I bring it up.

And...as long as you are doing this, I would not reject the idea of going with channel switching or whatever voodoo you might care for. The board will be there and will accomodate without being kludgy. Or...if you want to go back to stock, that's fine too.

[dbishopbliss]

Another alternative would be to design your own board that is specific to the Bandmaster AB763. Hoffman has an app to do this.

I didn't see this before.  I will definitely check it out.

Probably you want six or eight screws laid out around the perimeter of the Hoffboard versus 3 (or 4) screws down the middle of the fiber board. Get my drift?

Got it.

Also, consider whether you might want continuously threaded standoffs...instead of simple tubes.....which means you don't have machine screws and nuts sticking up and coming out of the finished chassis. Makes for a neater job. These are just little things that are an irritation if not planned for, that's why I bring it up.

Yeah, I like neat.  I've built a few audio amps before and I always use threaded standoffs.

And...as long as you are doing this, I would not reject the idea of going with channel switching or whatever voodoo you might care for. The board will be there and will accomodate without being kludgy. Or...if you want to go back to stock, that's fine too.

I think I will hold off on this.  Channel switching requires an additional transformer (at least the original kit I bought said I needed it).  If could add it more easily, then I might consider it.  Do you know where I can find a circuit to use?

[Willabe]

I think I will hold off on this.  Channel switching requires an additional transformer (at least the original kit I bought said I needed it).  If could add it more easily, then I might consider it.  Do you know where I can find a circuit to use?

Yes, read this thread;

http://www.el34world.com/Forum/index.php?topic=14348.0

Our forum host Doug sells the relay PSU and relay PCB boards in his on line store. I have a few and think they are very good quality and well worth the price to boot.


             Brad