Fender Bassman 100 rebuild

[Mark]

Thanks for the tip about the Mojo boards Charlie, I noticed their boards were black which I didn't like, I think I'd be more hopeful if they were grey instead of black or Garolite.

I did try cleaning the board in my Bandmaster 6G7a with a brush and alcohol. I then dried it in a warm oven for about six hours, the board is still conductive. I can give it a try and see if it works out with the Bassman 100.

[Charlie Wilson]

I wasn't going to say this before since you have gotten some good ideas for modifying the amp but a stock Bassman 100 is actually a cool sounding bass amp. I just restored one back to the way it came out of the factory and I really liked the way it sounded. The bass player in my band has used his Bassman 100 for the last 20 years or so and it sounds great also. His has the PI like a Blackface with everything else stock.https://www.youtube.com/watch?v=BVy_lfngmUE
CW

[Mark]

That sounds very good Charlie, is that you playing the Jazzmaster?

Your feedback on the Fender pre-amp was good, I was wondering if I should put more valves in and make the bass channel like a 6G6 amp. Thankfully, I won't have to do that.

What are your thoughts on the normal channel with the mid control. I had thought of a Dumble pre-amp, initially I thought of the Blues Master, as it get a good wrap as a clean pre-amp, but it is usually mated up to a Tweed P.I. stage.

I spoke to John Manning of Mojotone and he says they cover the circuit cards with wax which prevents them becoming conductive. I dare say people at Mojotone think the conductivity it due to water ingression. Either way Garolite is the preferred material.

Did you keep the master volume in the Bassman 100 that you worked one. I really don't see a purpose for having it in a bass amp.

[Charlie Wilson]

Hello Mark, yeah me on the Jazzmaster. I guess it's not very Dumble style music. Anyway, here is what I suggest you do. WIre the amp up stock so you have a working amp. That way you have a reference point. Then make changes to suit your needs and ears. This assumes that you are not drastically modifying the circuit or want to add tubes. Can you get stuff from McMaster Carr where you live and not pay an arm and a leg for shipping? If so, I will again suggest the Garolite XX. It is way easier to work with than G10. As far as waxed fiberboard, that didn't work out so well for Fender in the 70s and 80s. Finally, I too am not usually a fan of master volumes but on a tube bass amp I do find it useful.
CW

[pompeiisneaks]

Look at Charlie shredding the surfer vibes! Excellent!

~Phil

[Mark]

I was busy pulling the boards out today and roughly measuring them. I haven't been inside any Bassman 100 amps, so it is hard to know what is stock and what has been replaced. Any thoughts?

IMG_1251.JPG

[pompeiisneaks]

That almost all looks new. The electrolytics in mine had been re done with sprague atoms, but I doubt rifa were in it to start, Also if I recall all the resistors were CC no CF like I see there. The coupling caps were a mix of those brown and blue style similar to the 6PS or 715p but original fendery stuff.

the diodes were the silver metal covered type and had no caps over them either.

Seems like a lot has changed in there.

~Phil

[Mark]

The main board is 2.5" X 14.87", the filter cap board is 3.75" X 5.5", the diode board is 2.125" X 3".

IMG_1255.JPG

[Mark]

I was thinking about putting Dumble EQ in the normal channel for a different tone. Is that likely to work out for a bass?

[norburybrook]

I was thinking about putting Dumble EQ in the normal channel for a different tone. Is that likely to work out for a bass?

Mark,

which one, classic or Skyline? Personally I've used my #102(skyline) as a bass amp in the studio and it works well. Dumble EQ is based around the circuit using a high/low plate /4.7 uF cathode cap which cut's low end compared to the fender 1.5k/25uF so perhaps the fender circuit would be better generally.

I suppose it's easy to try so no loss



M

[martin manning]

Skyline EQ is pretty much a more controlled version of the Fender AB763 stack. I've also run a bass into my ODS (low plate) and it sounds good.

[norburybrook]

Skyline EQ is pretty much a more controlled version of the Fender AB763 stack. I've also run a bass into my ODS (low plate) and it sounds good.

especially when you use a cab with the EVM12, perfect for bass at moderate levels and if you want some rock/indie grunge then the OD works well too


M

[Mark]

Thanks for your reply. I thought the Dumble circuit might control mids better than the Fender circuit. As you say there is no harm in trying these things.

A friend recently built a Fender Deluxe Reverb clone for a guy and he put the 6G (350K tapped pot) tonestack in it and loved it. That has been on my mind too.

There was a thread about building a 6G6 Bassman and the builder thought the Bass channel sounded bigger that the normal channel. If I went don't that route, I'd have to add an extra 12AX7. I'd need something to cleanly cut the steel, so I'm not overly fond of that idea.

[Mark]

I want to get the Garolite boards from Doug Hoffman. So far, it is going rather slowly.
I dare say I will have either ramp it up with him or find someone else.

[pompeiisneaks]

I want to get the Garolite boards from Doug Hoffman. So far, it is going rather slowly.
I dare say I will have either ramp it up with him or find someone else.

That's definitely weird? normally when i order from doug I get it within 2-3 days and he's in the east coast and I'm on the west...

I've never had anything but amazing service from him.

~Phil