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View Full Version : 1967 BassmanSF- Starting the New Year Right

saltydogg
01-02-2009, 08:26 PM
I just received my "new" 1967 Fender Bassman SF. It's my first vintage amp and would appear to be all (or mostly) original down to the 2-prong power cord.

After I let her thaw out from her travels to Northern NJ I plugged it in tonight. I'm happy to say everything seems to work including the blood wrenching hum coming out of my Marshall 4X12. I am using the 4ohm setting on the cab. The hum is worse (of course) when my hand is not on the fretboard and the strings are open. I do also play at above average volume levels.

Which brings me to my questions: Will replacing the 2-prong with a 3-prong power cord reduce this hum? I intend on doing this sooner than later but I'd like to know in advance if this may be a contributing factor.

What parts replacements can I make (not mods) to improve the sound without sacrificing the originality of the amp? Caps? Tubes? Pots?

The power tubes in the amp are currently GE Electrone SM188-5 and I don't know what the preamp tubes are. Are these GE's original to the amp?

And one day... at band camp.... I stuck a flute in my p*&@sy.
Sorry, I couldn't resist after reading my long winded story....

Any advice, makes and models would be much appreciated.


Thanks a million!
davemccarthy707
01-02-2009, 10:53 PM
Your gonna want to do the filter caps,bias filter cap and install a 3 pronger. Bias her up and see what you got. ;)
Ronsonic
01-02-2009, 11:10 PM
Like he said.

And clean. Tube sockets, pins, any noisy pots, jacks including the shorting contacts, fuse holder, everything. Scrub the board while in there. Dirt sounds like dirt. Everybody wants to talk about parts, but cleaning is something that anyone can do and is almost always in order.
saltydogg
01-03-2009, 08:13 AM
What are your thoughts on the tube replacements? The existing tubes appear to be working fine and sound fine, but if these GE tubes are original to the amp then I might remove them keep them on a shelf- should I ever sell it. Any suggestions for replacements? Naturally, I'd like to keep the original Fender tone & mojo.

Thanks for your help!
GuitarsFromMars
01-03-2009, 08:55 AM
What are your thoughts on the tube replacements? The existing tubes appear to be working fine and sound fine, but if these GE tubes are original to the amp then I might remove them keep them on a shelf- should I ever sell it. Any suggestions for replacements? Naturally, I'd like to keep the original Fender tone & mojo.

Thanks for your help!

It might make sense,to use what you have,until you bias it up,and see what may be occurring electronically.You may not need to replace the tubes.
Ronsonic
01-03-2009, 08:57 AM
Why let the next schmuck get the good tubes. If they're still good then they're more valuable for their sound than cash. I'd keep using them.
triodeamps
01-05-2009, 04:48 PM
Definatley do not turn it back on until you change those probably very old PS caps. Your cooking your PT and we dont want to do that. It will be quiet as a church mouse after you change those caps....
rockstarjay
01-08-2009, 05:31 AM
Clean the jacks and tube pins with deoxit. I had a similar problem. Changed the V2 tube out and it stopped.

Just cause its a GE doesn't mean they last forever. An RCA greyplate was causing all my problems.

make sure you're plugged into the left speaker jack too.

A 3 prong plug is probably a good idea to avoid dying though.
rockstarjay
01-08-2009, 05:53 AM
Try adjusting the hum balance too.