Date: Thu, 20 Sep 2001 17:28:49 -0400 From: The Bernadettes Subject: Re: A couple of questions...tremolo switch
> Date: Tue, 18 Sep 2001 17:33:20 +0200 > From: David Garcia > Subject: A couple of questions > > > 2.- I'd like to build a switch (not necessarily a footswitch) for the > tremolo in my Princetons, but I don't know how I gotta make the soldering > in the switch, and if I have to put any kind of resistor or something in > between...Any idea? Here is a nice invention, > http://www.highpines.net/sk66/sk/Images/jacksw.jpg. It's another option, > but it'd need an RCA adapter to use it with the amps -and I don't know how > to make it inside, neither...- > > Regards, and, specially, peace...Please... > > David
Unfortunately on Princetons, you can't use a true vibrato disconnect switch, since the Princeton uses a bias modulation vibrato, truly disconnecting the vibrato would cause the power tubes to lose bias and blow. What this means is that the vibrato circuit is always on, whether or not you are actually engaging the effect, the vibrato circuit is always sucking some signal out of the amp. On blackface/silverface amps other than the Princeton you can wire in a true vibrato disconnect pot to replace the regular intensity pot, a mod I recommend. (In fact I just ordered a couple vibrato disconnect pots from Hoffman yesterday for a couple of amps.) Now to your situation; on the Princeton your options would be to simply short out the footswitch jack and turn the intensity pot all the way down when not using the vibrato effect. Easiest way to short out the jack is to get a RCA plug and solder a little piece of wire across the outside and center terminal, then place the RCA plug on the jack, you're done. The second option would be to replace the footswitch jack with a SPST switch. Open up the amp (I presume you know how to do this and drain the filter caps, if not you shouldn't be in there fooling around.) Desolder the lead to the footswitch jack and remove the stock RCA jack, and save it in case you ever sell the amp. Find a SPST toggle switch that will fit into the hole, without having to drill or otherwise hack your amp up. You'll have two terminals on the switch. The original lead you desoldered from the jack will now be soldered to one terminal. On the other terminal solder a short jumper that will go to a convenient grounding point on the chassis. When the contacts are open, the vibrato will be off, when the contacts are closed the vibrato will be on. This is the way the stock footswitch operates. Of course another option would be to just buy a replacement footswitch, they're available nowadays from some vintage amp parts dealers and I think through Fender also.
