Replies to This Discussion

Permalink Reply by Charlotte Henry on February 6, 2013 at 3:15am

Rather than offer definitive answers, I'll tell you what I "think" is true and offer my own confusion as well.  The two basic pot values are 250k and 500.  250 generally is for piezo and single coil magnetic pickups and 500 is common for humbuckers. Beyond that pots are available in audio taper and linear taper and the practical difference between those is in how soon you can hear the changes in the turn of the knob. I'm on the low end of the knowledge base here and I'll ask the question, "what is a 10K pot good for?"  I've seen the on the Gitty website and always scratched my head.  

The things you want to know are already here, so do a search and read.  Everything you want to know is all over the web, as well.  Dig around in the groups and you will likely find all of your questions have already been answered.

Permalink Reply by Gene Elzy on February 6, 2013 at 4:43pm

Thanks Charlotte for your input.  According to the CBGitty website, the 10K are for tone control and Scott (below) indicates they are for amplifier circuits as well.

Permalink Reply by OldNick on February 6, 2013 at 4:21am

this may help you get some basic understanding:

http://www.stewmac.com/freeinfo/Electronics/Misc/i-4000.html

-nick

Permalink Reply by Gene Elzy on February 6, 2013 at 5:13pm

This is a great link.  I am working on it now and finding it answers many questions.  Certainly, the place to start.  Thanks.

Permalink Reply by Scott aka Farmer Ted on February 6, 2013 at 6:05am

Charlotte's info is right on the money. To add further, 10K pots are generally used for volume control on hand built cigar box amplifier circuits, using the LM386 IC chip schematic that is readily found in a google search. But a 10K pot doesn't really do much, since as soon as you turn the pot up, it is at full volume.

Also, when using a volume & tone pot combo with single or humbucker pickups, a capacitor is added to the tone pot. See the group Wiring & Electronics on this site to see what I mean and how the capacitior is wired.

Typical capacitors are .022uF or .047uF.

For piezos, I first recommend using two piezos wired in parallel (see aformentioned group "Wiring"). A tone pot is not necessary, and for volume a 250K pot is adequate. The nice thing about havign a volume pot on a piezo setup is that while the guitar is plugged into an amplifier or PA, it can be played acoustically with volume turned down, and then amplified by simply turning volume pot up.

Piezos are microphonic, and will pick up any and all vibrations from sliding hand up n down neck, touching or even brushing against box, and they are notorious for feedback (there are ways to reduce this phenomenon).

Rod piezos do sound better, but they require that the string saddle have direct contact with the rod, which is fitted underneath in the bridge.

 

Permalink Reply by Gene Elzy on February 6, 2013 at 4:57pm

This info is very helpful, but I still wonder when I would consider either a 500K or 1000K pot.  It appears that some degree of experimentation is necessary. The parallel configuration for the two piezos appears to be reasonably common.  I think I will put both the 2 parallel disc piezos and a rod piezo on a CBG with a selector switch to see which sounds better.  

Permalink Reply by Dave Lynas on February 6, 2013 at 6:16am

I agree with Charlotte on this one. I will add that the size of the capacitor will determine the amount of treble cut made by the tone pot. The larger the number, the more bass tone possible. There are several books to have in your reference library and interesting reading. Thanks for starting the discussion.

Permalink Reply by Gene Elzy on February 6, 2013 at 5:00pm

Interesting.  Clearly my CBGitty order should include 2 or 3 different size capacitors to try.  Fortunately, they are inexpensive.

Permalink Reply by Charlotte Henry on February 7, 2013 at 4:01am

Gene, I am not a fan of the "reinventing the wheel" genre. I've known guitarists who have swapped out their 500k pots on their humbucker equipped guitars going for a different sound or thinking they were going to discover something and they all switched back to original configuration.  My question about the 10 K pots was sort of rhetorical because it is so far from the range of what is commonly used it seemed pointless to me to even attempt to use one.  I feel the same about the 1000K pots.  If I want to experiment with something I'm going to use different pickups and keep the pot values that have proven themselves to be appropriate.  Look around this site for the folks that make custom wound pickups and resonators.   Your efforts will be better spent.

Permalink Reply by BrianQ. on February 7, 2013 at 12:14pm

250K-500K is good for a piezo, I would use a .033uf or .047uf for a bleed cap,

rather than a .022uf,piezo are known for being more on the treble side,

this will bleed off more of the tinny treble sound. my fender piezo has a .033uf.

as for 10K pots, they are used typically for active pickups,

anything over 500K is probably a waste & will probably not sound very good?

Stick with the stock formulas for pots,they're that way for a reason: because they've been

road-tested & work.

Permalink Reply by BrianQ. on February 7, 2013 at 12:42pm

I would also use da same value you used for Volume for Tone this should b fine,

I've been using 500K in my boxes with much success.

Permalink Reply by BrianQ. on February 7, 2013 at 12:49pm

Here's a diagram from somewhere on the nation.

just solder the other end of the Tone Capacitor to the Back of the Tone Pot.

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