Other Amps

Custom Fender Bassman by Billy Zoom


Prior to the crash I had posted a thread about a '69 Fender Bassman head that I found in my friends trash pile at the curb. It had become someone's science project , totally gutted from the original circuit.


Here are some interior shots


Knobs were moved, new holes were drilled in the faceplate


The only original parts were the power transformers and bias adjustment


This amp was rough on the outside, and even rougher inside... What to do? After some discussion on the GDP it was decided that it would go to Billy Zoom for a rebuild and Ness Mess mod. (Overdrive bass channel and 6G6-B normal channel, as well as a multi-watt switch)

I just got the amp back from Billy last week and I love it!


Billy did a great job inside and out, plugging the holes in the chassis, straightening the faceplate, installing new 3 prong cord, and filling in some missing pieces


Multi-watt switch location in the former A/C power outlet so as not to drill any more new holes


The 6G6-B channel sounds great, very much like an original (I have a '64 blonde that I usually play out of) and the overdrive bass channel is a fantastic addition, 2 amps in 1! The multi-watt switch has 3 settings, low, med, and high and you can really get some full on tube overdrive at non-face melting levels.

Just a couple of questions for Billy Zoom that others may be interested in:
What are the wattage levels at the low and medium settings? I'm assuming its half, around 20watts, and maybe 1/4 power, 10watts, but please correct me if I'm wrong. Also, how does the bright switch on this amp compare to the presence control on an original 6G6-B? Thanks for the great amp, can't wait to really crank it up!


That sounds fantastic! I've hear of the power switch Billy can do, wonder if that would make any difference on my 69' Twin Reverb so I can push it a little harder.

Mikep13p, so you have a brownface channel and a blackface channel on the same amp?


Gee, you know something, that was the amp the first guitar player in my first band had. Just looking at the pics makes me all misty.

Damn that was so long ago, I wonder how he's doing these days?

Nice gear, I hope you get it all back together and sounding the way it used to, only better.


@ SecretAgent The 'Normal' channel is definitely a 6G6-B brown face circuit, but I'm not sure what u would call the 'Bass' channel. Its a hotter circuit with more available overdrive than the Normal channel. I'm thinking it's based on what was originally there (AB-165) and then modded, but since the amp was gutted when I found it, only Billy Zoom knows for sure


Mike what power tubes did you wind up with?


Where is break up point on 6g6b side when low multi is used? Also how is volume at that point?


Not even close.

– Billy Zoom

I love a mystery... All I know is that it sounds good!


Mike what power tubes did you wind up with?


Small bottle 5881's for power, 12AX7's for preamp... All Sovtek WXT's


I really hope you didn't change the tubes after you got it back. I gave you the best ones.

"Where is break up point on 6g6b side when low multi is used?" Please note that I've never claimed there was a 6G6B side. I don't understand the rest of this question. There are three power choices. The 20 watt setting breaks up at 20 watts, the 10 watt setting breaks up at 10 watts,etc... just like any amp.


No, I didn't change 'em I just made a mistake in my previous post, they are the Sovtek 5881WXT's that you installed.

Billy: The 6G6B Normal channel info was something I thought that you said in one of your emails about how you would re-build the circuit. To me, it does sound like a Fender is supposed to, and I thought it sounded similar to my 6G6B... but if it's "Not even close", do you have a name for the circuit, or is it based off of anything in existence?

As for SLICKFASTER's question about the breakup point, I think he meant: Where on the volume knob am I when the amp begins to break up at the three multi-watt settings? I just got back from Christmas vacation so I'm hoping to really crank it up this week and let you all know.


Billy did one if these in a '68 drip edge for me. Hands down the most gigable amp I've ever owned. It's a chore to find a setting that isn't usable and the bass channel is pretty remarkable.


Multi-watt changes the wattage. The setting and tone will stay the same. The first Ness Mod I did was to a 6G6B, so when I do a SIlverFace to the same specs, some of it ends up like the parts of the 6G6B that I didn't change. It's not intended to be a 6G6B clone though. It's a Ness mod clone. BZ

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