Toggle switching multiple caps!?

[Feel_My_Twang]

Here goes another stupid question that will be frowned upon. .

Lets say I like the sound of three different caps in a certain spot on my circuit board and I wanted to toggle between the three with a toggle switch. How the hell would I connect them to do so. Is it as complicated as it sounds? Is there a better way? Also, is it always best to solder caps and resistors to their related potentiometers intead of running them off the circuit board?? I read in Teb Webers book that anytime you can do that you should to make the signal short as possible.

If you can answer these extremely amatuer questions in anyway.. please do!!

thanks guys! - kyle - www.myspace.com/kyleroop

[Enzo]

It would really make it easier if you put up the schematic you want this in. Switching cathode bypass caps is different from caps in tone stacks for example.

If you want a toggle switch to select between three options, then it pretty much has to be a three position switch. ON-OFF-ON, for example. Typically you would leave the lowest value cap wired in permanently. Then from one end, conect the other two larger caps together at the circuit point. RUn each of those to one end of the switch, and the center of the switch to the far end of your cap circuit. Now in either ON position, one or the other of the caps will be in parallel with the first. Center off leaves the first all alone.

The first cap would be whatever value you want. The other two would be what you want for them MINUS the value of the first cap, since it adds in parallel, If it is a cathode bypass cap and the choices are something like 0.068uf, 25uf, and 300uf, then the math is easy. The 0.068uf stays ther all the time, and the other switch in and out of parallel with it. WHen the 25 or 300 is switched in, we ignore the 0.068 because you will never hear the difference between 25uf and 25.068uf. Besides, I don't think anyone makes a 24.914uf cap.

To avoid pops, a high value resistor should be wired across the switch contacts and their common. This keeps the caps charged when not selected.

[loudthud]

One option Enzo didn't mention is the hard to find ON-ON-ON toggle switch. Example Mouser 612-100-L1111. They are a little tricky to figure out at first but you can make a single pole 3 postion switch.

Keeping signal wires short is always a good idea, especially in high gain amps. So if you wanted to select different caps in the typical tone stack, it would make more sense to locate the switch next to the pots and connect all the caps right there rather than running wires back and forth to a board. Try to arrange the circuit so that you don't need any extra connection points besides the switch and pot terminals.

[Feel_My_Twang]

One more question...!

Thanks for the replys guys. Out of all the books I've read, this forum has helped me the most! Long live this forum!

I understand completely what you guys are saying. I have one other question also...

I would like to design a pot in a high gain circuit where I can contol the way the signal is clipped by the tubes. Like at 1 the overdriven signal is very soft and smooth and at 10 the clipping is alot more "harsh and biting". I'm not talking about EQing here - I'm talking about the actual clipping of the signal itself.

Is that even a rational question? lol

thanks guys... -kyle

[soundmasterg]

Just to provide a minor correction so people who read this and don't know better won't get confused....

you must mean Gerald Weber's book, not Ted Weber's, as Ted hasn't written a book yet.

In an amp I worked on for my brother, I added a on/on switch in the cathode of one preamp stage and switch between two cap values for a slightly different tone. The point I am switching is after a cathode follower and before the tone stack and makes a small difference in the tone, but enough to tighten up the bass a bit that he liked.

Greg

[Don Moose]

That's really just a volume control between two gain stages - it's a bit more common to have a control before the first of two OD stages, and another one between the two - see the OD section of a Dumble ODS for an example.

Hope this helps!

[Feel_My_Twang]

whoops

I'm EXTREMELY bad with names.. but yes your right Gerald is the guy!

Don... When your taking about putting a volume control between two gain stages are you talking about volume of the clipping or something? Im talking about controlling the way the signal is being clipped by the tubes - not volume. I want to control the "shape" and "timbre" of the clipping if that makes any sense! thanks fellas!