Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Madison on August 14, 2013, 08:42:45 am

Title: Gibson GA40 LP on bench
Post by: Madison on August 14, 2013, 08:42:45 am
Just wondering if the tremolo frequency pot is normal or reversed on these?
I mean, it works in reverse as I rotate it.
IOW dimed the speed is slowest.

Amp is all original, even the tubes.
Did a full cap job, sounds superb and pretty darn loud.
Think I like it better than a 5E3.....and I LOVE 5E3s!

Too bad it is a bear to work on!
The put most of the caps under the board.grrrrr!
Title: Re: Gibson GA40 LP on bench
Post by: sluckey on August 14, 2013, 09:33:52 am
Quote
Just wondering if the tremolo frequency pot is normal or reversed on these?
I mean, it works in reverse as I rotate it.
IOW dimed the speed is slowest.
If you want it to be slowest when rotated max CCW, then move the wire on the outer lug to the other outer lug.
Title: Re: Gibson GA40 LP on bench
Post by: Madison on August 14, 2013, 07:12:16 pm
There are only 2 lugs on that pot.
Tried reversing the wires but , as I suspected, no change.
Thanks.
Title: Re: Gibson GA40 LP on bench
Post by: Willabe on August 14, 2013, 10:01:46 pm
There are only 2 lugs on that pot.

What? Since when does a pot, which is a variable resistance, have only 2 lugs?

Can't be.


                Brad      :think1:   
Title: Re: Gibson GA40 LP on bench
Post by: eleventeen on August 14, 2013, 10:10:17 pm
Might have been cut off at the factory..? If so, you'd have to try to solder to the rivet on the little piece of bakelite where the lugs usually come out. Dicey.
Title: Re: Gibson GA40 LP on bench
Post by: PRR on August 14, 2013, 10:47:58 pm
It wants to be a Reverse Audio taper.

A hack is to use a Normal Audio taper, use the other side, let the knob work "backward".

Which way is backward? Look at the volume control on a radio etc. Now find an old-fashioned gas stove. Those knobs turn the other way. It's arbitrary.
Title: Re: Gibson GA40 LP on bench
Post by: Madison on August 16, 2013, 08:07:38 am
Slapped a 3M RA pot in there.
Works good enough to R&R.
Customer was very pleased, so was I.
Nice amp.
Title: Re: Gibson GA40 LP on bench
Post by: HotBluePlates on September 15, 2013, 11:01:24 pm
Was your version the one with 2x 5879's & 6V6's? Just a single tone control?