Found an old Thunderbass in my garage.

[rotiart]

Hi. I'm new here, and I recently found an old Thunderbass in my garage, serial number: 6060.
It works, as I have tried it on my friends cab. I've been doing research on it and I came across this site, and I read that it is a good idea to replace the original plug, seeing as it can electrocute you?
Here is an image:

 

[capnjuan]

Hi rotiart; welcome to LTG and congratulations on the amp. Yes, it needs a 3-wire cord.

If you can't do it, give it to a pro and, while they have the amp, let them check the bias for you - it's easy on that model because it has bias test ports on the back.

If you get a chance, gently rock one of the power tubes out; is it a 6L6 model or 8417? It makes a big difference in total power out. Congrats again and good luck with it!

 

[rotiart]

Tubes are: 8417

Also, here are the guts:

 

[capnjuan]

Well ... you hit the jackpot. Guild's adverlit for the model (gotta squint) rates the 8417 version at 100 watts:

I don't know how techie you are with this stuff but if you're taking it out for work - and I strongly suggest you do - there's a school of thought that believes, like cars, a clean amp runs better than a dirty one. This one needs some love; clean/re-tension the tube sockets, clean/lube the controls ... that kind of stuff every day, change-the-oil kind of thing.

Get it running well and the amp will pay you back with interest. The 8417s are out of production, not much NOS out there, and what there is is a little 'spensive. Although if you're sitting pretty, this might not be such a problem.

I think the power supply in these was made to last; Guild was really trying to compete with the Ampegs back in the day. The 8417s use less voltage to generate more power than the 6L6 versions. Anyway, the amp is worth sticking some money in.

 

[rotiart]

Thanks Capn!
I'm planning on taking it to a tech.
And I'm in the process of selling my Line 6 Spider III and Schecter so I can put more money into this, I really think once I get it going, it will be worth all the money I put into it

 

[capnjuan]

I prefer farty old Gibson 6V6 amps but I did dumpster-dive once on a magenta-painted 8417 Thunderbass head (Juan splashing in). Since I'd bought it as a project with the intention of selling, I changed it to a 6L6 version (yacked it to death in this thread) mostly by fiddling with a couple of power resistors and the bias resistor.

Anyway, I put a couple of #3 Groovey Tube 6L6s in it, a 7247 I mooched off a friend, and fired it up ... (at first blowing out the bias cap that I'd put in wrong) and got a big, clean, glassy soundstage ... filled my garage with 50 watts of warm Guild tube goodness. 8)