Fender Bassman AC568 To AB165 / AA864 Hybrid Pt1

In for a full restoration and mains conversion.
We also decided to make this one sound as good as we can, originality be damned.
The AC568 circuit is regarded as one of the worst sounding Bassman circuits from the era.
We get the best parts of some more desirable designs and graft them together.
What we end up with is a pretty versatile amp.
Stay posted for part 2.

[@ididavila962]

this is so satisfying to see you work on that amp, i used to have a 1965 fender bandmaster ab763 a 1964 princeton aa64 and a 1973 fender bassman 100, thank you for posting great job.

[@bambule5268]

Hey Brad, I'm building one at the moment. Any tips beyond the obvious? I'll remove the 500pf from the normal channel and put it on the bass one. Also going to put a 10nf as per usual on the phase inverter. Currently rewatching all of your and Lyle's vids in case I'm missing something. Thanks in advance

[@edwardhannigan6324]

Great amp, and cool video of your initial walk thru and initial repair..I'm a newbie so it's a bit difficult to follow, but I'll catch up..Great job..Ed..uk..😀

[@aviedelson945]

Hi - Great results on this Bassman and fantastic execution of the video (your playing does justice to the technical work as well) ... I see you briefly explain the output design of the 568 at the 12:30 mark and also go over the 864 cap and resistor values that went into the doghouse at 27:00 ... but there still seems a lot of design changes to wrangle around the PI going from 568/165 to 864. I did catch your comment cautioning reversal of output jack in your pt 2 vid (critical - thanks). However, I am looking for how you determined your conversion to the non-inverting configuration coming out of the 3rd 7025. Obviously, you have to flip the signal around and some additional component values would likely have to change - didn't notice you discussing that. Do you have any more notes or resources on that you can share?

[@BradsGuitarGarage]

Not sure I follow. Why would I have to invert the signal? The channels are in phase on the AB165 and AC568, but out of phase on the AA864, but that would only be an issue if you linked the channels. From memory (over a year ago) I left the channels in phase as per the original AC568 and the AB165 circuit.

[@kbkman7742]

Ab165 is quirky but my favourite circuit. Great rock n roll amp.

[@tedmich]

Chazzy! Its so great when you forget to use Yank pronunciations! ; )

[@russellesimonetta3835]

The good Brad!

[@rightlurker4674]

This is great. Thanks, Brad.

[@georgebush8038]

did Noah use that amp as a boat anchor ????

[@BradsGuitarGarage]

Dunno, I'm a bit old for fairy-tales.