How to make tone and vol switches for Jazzmaster rhythm circuit  - Page 1
Forum section: electronics / beginners

author: Scornn
author_rank: Contributor
timestamp: June 27, 2023, 03:52:34 am
content: Hey, just wondering what exactly I would add to these switches and where for a rhythm circuit. Just for the tone and volume switches, the rhythm/lead works. Im quite sure theres usually a capacitor involved. Excuse the messy soldering, ive just been trying to get it to work before I clean it up.Thank you

author: Buriedcode
author_rank: Super Contributor
timestamp: June 27, 2023, 04:32:10 am
content: Depends on what guitar it is and what wiring scheme you're doingDifferent guitars have different value pots, capacitor placement, and "bleed" capacitors - Jazz Masters, Jaguars as well as various incarnations of Gibson guitars can all differ in that respect - and thats not even getting into Gretsch or Rickenbacker guitars.I can't really tell from that pickguard what guitar it is - the only guitar I've seen with multiple switches like that is a Jaguar - but the pickup curtouts look like they're for a humbucker.So ultimately, you'll have to narrow down what it is you want. "Rhythm" means different things to different manufacturers.If it is a Jaguar, does this help?https://www.fender.com/articles/instruments/jaguar-controls-past-and-present-what-you-need-to-know

author: Scornn
author_rank: Contributor
timestamp: June 27, 2023, 05:43:14 am
content: Hey, thanks for the reply, so its a jazzmaster style guitar with P90 pickups.

author: Buriedcode
author_rank: Super Contributor
timestamp: June 27, 2023, 10:31:20 pm
content: Gotcha - good choiceWell the internet is full of wiring diagrams, but I imagine as you've found - it's pretty difficult to find one that does what you want, because people seem to always want more and more mods. What also can muddy the waters is colour coding wiring - different pickup manufacturers can use different colours for hot/cold/split. It might help if you add some tape or something to one of the pickup's wires so you know what wire is for what pickup, and the colour tells you the polarity.What is it you want these switches to do? They look like they're where the volume and tone pots should be?I just realised - are you trying to add a phase switch to the rhythm (neck pickup) ?

author: Scornn
author_rank: Contributor
timestamp: June 28, 2023, 02:28:44 am
content: So ive been following along the lines of this type of diagram. So yes what I want them to do is change the volume and tone but so far ive only been able to have them in their standard configuration and then when I flip either of the two switches it just cuts the signal off completely.

author: Scornn
author_rank: Contributor
timestamp: June 28, 2023, 08:07:24 am
content: I guess the running theme im seeing is the switches I have are just DPDT and what these guitars usually have is a potentiometer which can have its value changed. Anyone know if this could be a problem?

author: donlisms
author_rank: Frequent Contributor
timestamp: June 29, 2023, 03:26:04 am
content: I have reconstructed a schematic for this circuit from the Frailin drawing. It looks to me like it should work, if it's wired correctly, so... should be doable.I'm a little confused about what you're actually asking, and what the picture in your original posting represents. Are you saying "I've got these switches, which currently have some wires on them. How do I make it do the Jazzmaster thing?" Or are you saying "I have a plan; I'm part way there, but don't know how to finish?" Or are you saying "Something else entirely!". :-) Try to be a little more verbose, and as precise as you can be. For example, when you say "change", do you really mean "swap from one set of volume and tone controls to the other set", or do you mean something else?

author: Scornn
author_rank: Contributor
timestamp: June 29, 2023, 06:23:43 am
content: So basically these switches were supposed to change between 2 presets each for volume and tone but they never did. Id like for them to basically do nothing when in one position and then when switched into the other, have the tone modified for one switch and have the volume reduced for the other.

author: donlisms
author_rank: Frequent Contributor
timestamp: June 29, 2023, 06:39:50 am
content: Yup: that's how I interpreted the schematic. So that's the ultimate goal.What was the first picture intended to represent? It doesn't seem to have all the required controls - you need four pots and the two switches, yes? The switches are DPDT and SPDT, but you could use half of a DPDT for the S. Have you got all that hiding somewhere out of frame on the pick guard? Or is still a problem to solve?

author: Scornn
author_rank: Contributor
timestamp: June 29, 2023, 07:46:43 am
content: Thats everything, hopefully that puts things into perspective a bit more.

author: donlisms
author_rank: Frequent Contributor
timestamp: June 29, 2023, 08:42:24 am
content: I see; thanks for those!I think the first step will be getting all the physical controls in place, on the pick guard and fitting into the control cavities. You will need to make some decisions about where you want to put the controls, with consideration of what holes and cavity space you already have, and what it will be like to play the thing. This is probably not something anyone else can help you with; you need to just think it through. It looks like you have two switches you don't need anymore, and you need one more pot, and the pots are all probably the wrong values so you'll need to swap those out.Once you get the control layout figured out, you can carefully redraw the Frailin diagram with the controls in different locations, but with the same electrical connections.Then it's a matter of soldering everything in place. And of course it will work perfectly the first time.

author: Scornn
author_rank: Contributor
timestamp: June 29, 2023, 08:50:10 am
content: Sorry im not understanding why I need another pot and why the others values may be wrong. Does that mean I cant use the two switches to swap between a preset of tone and a preset of volume?Also I thought I might show you a picture of what how it was wired when I first got it, just in case it helps

author: donlisms
author_rank: Frequent Contributor
timestamp: June 29, 2023, 06:29:47 pm
content: Oh - sorry! I misread your explanation in my haste. I thought your trying to duplicate the Frailin circuit.So... you want two volume controls with a switch to switch between them, and one tone pot that can be switched between two different tones. (Stop me if I'm off track!)The volumes will be easy. The decision is about what the two different tones are.Passive guitar tone is (usually) determined by tapping into the signal, and sending that tap through a certain amount of resistance (the pot), and a certain amount of capacitance, and then to ground. So to change it, you can change the resistance, or the cap, or both.Switching between two different caps would be a little unpredictable; the influence of the pot would be different between the two. In other words, the same setting might give 20% influence with one cap and 40% with the other, and different numbers at different settings. You get what you get.Switching between two resistances would be pretty easy, where what the switch would do is switch another fixed resistor into the circuit. This would be equivalent to changing the pot setting, so you could theoretically do some testing to decide on the two settings you want, by finding the pot positions that make the magic, and then measure the pot's resistance at both of those settings. Then... there are a couple of ways to do the switching. I'll maybe not go into that yet.Is this making some sense? Am I on the right track with what you wanted?

author: Scornn
author_rank: Contributor
timestamp: June 30, 2023, 01:18:55 am
content: Yes that is what I want for sure. This does seem to be making sense, mostly haha. So it seems I may need some resistors and capacitors of varying values?

author: donlisms
author_rank: Frequent Contributor
timestamp: July 01, 2023, 06:11:40 am
content: Yes; switching that somehow, one way or another, changes either or both of the tone resistance value or the tone capacitor value. For example, you could arrange the switching so that one switch terminal snags the signal directly from the tone pot, and the other switch terminal inserts an additional resistor into the circuit. That would be pretty much the same as just twisting the pot's knob to get a higher resistance value.Another way would be to put a big resistor in parallel with the pot, where resistors in parallel have a lower value. That's a little bit more in line with that I think you're after, because less resistance will result in taking out more of the high end.Or... just switch between two different capacitors. Easy peasy. The wire from the pot wiper goes to the center terminal of a SPDT switch, and one of the outer terminals goes to a bigger cap, and the other goes to a smaller cap. Pick the caps to give you the tone you want in either position. Experiments for this will have to take into account the position of the tone pot. (As near as I can tell, the only correct position for a tone pot is wide open, so... for me, that would be a simple thing!)

author: Scornn
author_rank: Contributor
timestamp: July 01, 2023, 08:01:49 am
content: Okay well by the sounds of the options, I think id like to go with either option 2 or 3. I dont think I quite understand how option 2 works but I have drawn what I think option 3 would look like and hopefully its correct!

author: donlisms
author_rank: Frequent Contributor
timestamp: July 02, 2023, 07:42:39 am
content: Yup - almost! The missing piece is that the other side of each capacitor should be grounded. There are (at least) two ways you could do that.One would be to ground the terminal on the "other side" from the "goes in". The upper, center terminal in your diagram.The other way would be just ground the capacitors directly. There's no real need for using both halves of that switch. So... pick a row -- the top or the bottom. The middle terminal is "goes in", left terminal goes to cap1, whose other end is grounded, and the right terminal goes to cap2, whose other end is also grounded. Ignore the other row of terminals.Either of those should work.There are other ways to do it, e.g., shorting out the capacitor not being used. In fact a minor variation of that with a "center off" switch could give you three different tone settings: positioning 1 could short (bypass) cap1, position 3 shorts cap2, pos 2 shorts neither, which would give you both caps in series.

author: Scornn
author_rank: Contributor
timestamp: July 03, 2023, 06:33:50 am
content: Okay! Ive got the tone switch working! Rewired everything and got some new capacitors. So theres the 47nF on the tone pot, then a 27nF is Pos 1 of the tone switch and a 33nF in position 2. Now for the volume switch I assume it has to do with resistors? If I want position one of the volume switch to act as if nothings changed, would I have to get a 500k one, the same as the volume pot? Then maybe something like 700k in position 2 to lower the volume? Hopefully this is making sense.

author: donlisms
author_rank: Frequent Contributor
timestamp: July 05, 2023, 05:44:44 pm
content: Ideally, if you learn enough about voltage dividers (including that that's what a volume pot is), you could explore different ideas until you find a circuit you like.For a simple approach, switching in a resistor on the "upper" terminal of the pot, the "goes in" terminal, would be an easy way to reduce volume. If it was the same value as the volume pot, it would reduce the voltage to half, which is -6dB. That might be too much - it depends on what you want. A smaller resistor would be a smaller reduction.I think my preference might be switching between two volume pots that I set however I like.But my REAL preference is a volume pedal! Much more versatile.

author: Scornn
author_rank: Contributor
timestamp: July 06, 2023, 01:56:00 pm
content: Thank you donlisms, I appreciate all of your help. Ive decided that I want one switch to be a low pass and the other to be a high pass but im going to create a separate post for that. Hopefully its a little more straight forward of a question. Thanks again!