Bassman Blackface rebuild and mods

greengoblin · #1 10-11-2011, 10:04 PM

Hello all,

So I know some people use these for bass and they do have a great tone. I picked up this one as a gift for my brother and I wanted it to be special so I am redoing it myself. I am not an amp-tech, but have been into electrical fixing for years and I really want to learn how to repair and custom amps. Figured the best way is to pick one up and start playing.

THE PLAN: My brother plays guitar so it will be modded and voiced according. I know this is a bass forum, but hoping some can offer suggestions and advice along the way. Also though some may enough the read and info. Anyhow, we are big Social D fans and he really wants that Mike Ness tone. I emailed Billy Zoom as he used to do Mike amps. Also, since this is a project I would like to complete for him I hate to send it out. But I emailed Mr. Zoom about some things so I hope he reads his emails.

From what I have read the Ness amps run a 6G6-B normal channel and a custom bass channel wiht the two connected internally. So this is the plan. The 6G6-B layout "looks" to be the easy part, just scared of what to do with the bass channel. But I am looking for that Mike Ness tone.

So onto the patient: 1966 Fender Bassman Blackface that started out with an AA165 tone circuit.

So as some may cringe or pass out, the amp arrived on my doorstep, I plugged it in just to see if it was 100% working order. The normal channel was working well with a few noisy pots. The bass channel was dead.. Checked all of my connections and everything seemed fine. Since I picked it up as a project I figured I would open it up and take a look. Found a ground wire came off on the bass channel. Resoldered it up and the bass channel was alive!! First repair in the bank! lol... After I checked everything out, out came the guts and she was in pieces and the surgery begins!

I'll post pics along the way. Have the filter caps done with all new Sprague caps and new metal film resistors. I have been reading everything and anything I can for tube amp repair and what to use, what not to use. Alot of people have their opinions, a lot of good info out there as well. Some may not like that I went modern on the resistors, but I read some remarks from a few techs that they liked them.

Also started on the layout of the board starting on the normal channel in a 6G6-B configuration. Right now I just have about half of the board mocked up and nothing on it soldered yet.

So sit back and enjoy! I would also appreciate if anyone has suggestions, tips, etc!!

And hope no one is too upset about a Bassman project that is more guitar oriented.

greengoblin · #2 10-11-2011, 10:05 PM

Sorry about the picture lighting, I need a new flash.

Here is one of the board as it arrived and one of the way the chassis sits now.

greengoblin · #3 10-11-2011, 10:08 PM

Last for the evening..

The new filter caps, soldered on one side and I just got my wire in so I can finish up the other side this week.

Also, one of the main board with a partial 6G6-B mock up. Metal Oxide resistors, Mallory 150 and Silver Mica caps..

greengoblin · #4 10-11-2011, 10:13 PM

I am on internet link reading overload right night and have been studying ever 6G6-B layout I have saved. Many more articles and posts to go so I took a break at this point. Gave me time to think and write this post.

Also, I picked up Gerald Webers "A Desktop Reference to hip vintage Guitar amplifiers" and "All About vacuum tube guitar amplifiers". Reading material for my trip to Germany next week...

**B-string** · #5 10-11-2011, 10:25 PM

Since it will be a guitar amp.....you should keep carbon comp. resistors for the plate resistors as a general rule (just double the wattage). Makes me cringe to see a Black face in that condition, but I'm in for watchin.

johnk_10 · #6 10-11-2011, 10:40 PM

+1.
no offense, but i liked the way that it looked the way that it arrived.

greengoblin · #7 10-12-2011, 10:01 AM

Man, tough room.

But I respect your guys opinion and input.

You guys are the true techs and I am just a hopeful at this point. I try to recreate everything with quality though.

I have a few pics that Mr. Zoom posted on the net and was trying to go from when creating the new layout. I could post those pics as well.

I am not changing anything that cannot be put back to original if need be and not modifying the chassis in any way..

BassmanPaul · #8 10-12-2011, 11:46 AM

The amp was a damn good guitar amp as it arrived. Not so much now!

greengoblin · #9 10-12-2011, 12:03 PM

When it is done it will be a damn good guitar amp as well. With a better tone.

will33 · #10 10-12-2011, 12:24 PM

While I'm not a tech I am a big fan of bassmans and I have to agree with the other guys here. It needs no "improvement" or "better tone".

Hang on to everything so the next guy can put it back like it was.

Farfetched · #11 10-12-2011, 03:13 PM

*sigh*

MAMMOTHvolume · #12 10-12-2011, 03:24 PM

Quote:

Originally Posted by greengoblin

When it is done it will be a damn good guitar amp as well. With a better tone.

Looks great dude, the original circuit is awesome for guitar though so need to tweak it. Replacing all the nackered caps and putting in metal film resistors is a good idea though. It'll kill the noise and mean it won't do funny things in the future!

John D · #13 10-12-2011, 04:05 PM

Quote:

Originally Posted by BassmanPaul

The amp was a damn good ~~guitar~~ bass amp as it arrived. Not so much now!

Fixed.

BassmanPaul · #14 10-12-2011, 06:14 PM

Quote:

Originally Posted by John D

Fixed.

You fixed nothing! The Bassman was the WORST bass amp I ever had the misfortune to own!

dog1 · #15 10-12-2011, 06:23 PM

Yeah. I owned 2 pre '68 Bassmans back in the day. They both came with 2-12 cabs with kick back legs. Maybe they would make good guitar amps.....I don't know. But as bass amps, they sucked. Still, I wish I had one of them back. Just because.

**B-string** · #16 10-12-2011, 06:28 PM

The room wouldn't be so tough if that was a Silverface. Be careful with metal film and metal oxide resistors as the voltage rating can be as low as 200Volts.
The ground plate under the pots can be a noise problem, solder a piece of buss bar along the pots, to the plate and the input jacks.
Save the parts if you like from the eyelet board, but if it gets resold the value of the amp is down 60% unless you put everything back (except the electrolytics of course).

**B-string** · #17 10-12-2011, 06:30 PM

Quote:

Originally Posted by BassmanPaul

You fixed nothing! The Bassman was the WORST bass amp I ever had the misfortune to own!

You never tried modding a Silverface? They can sound pretty sweet (would not do it to a Blackface though).

BassmanPaul · #18 10-12-2011, 06:36 PM

Quote:

Originally Posted by B-string

You never tried modding a Silverface? They can sound pretty sweet (would not do it to a Blackface though).

No Jon I didn't. I owned the Bassman for two gigs across a weekend. It went back as fast as I could get it there. They had even sold the Epiphone Constellation I traded in to get it. I left it anyway!!

Billy Zoom · #19 10-12-2011, 07:11 PM

Please stop spreading rumors about me not being in business any more. It takes money away from my family.
BZ

greengoblin · #20 10-12-2011, 07:38 PM

Sorry Mr. Zoom. I edited the post and removed that info and did not mean to do any harm as I would like to be customer. Hopefully you get a chance to look over the email I sent you.

Thanks and sorry again!