JB, 1 vol, no tone!

[UCSDBoy]

Hey guys,

I'm going to take the invader out of this all mahogany set neck I have (esquire gt) and throw in a JB... Usually people pair this up with 250k tone pots to help with the highs but in my case I only have 1 volume - should it be 500k or 250k? Should I throw in a resistor to simulate a tone pot?

 

[mjsever]

Re: JB, 1 vol, no tone!

Is it a one or two-pickup guitar?

 

[Artie]

Re: JB, 1 vol, no tone!

Should I throw in a resistor to simulate a tone pot?

You can do this with no problem, just make sure you include the cap also.
Put the resistor and cap in series, (in line), with one another from across the output jack.

 

[UCSDBoy]

Re: JB, 1 vol, no tone!

thanks artie! =)

hey mjsever - it's a one pickup guitar - sorry I don't have a picture - it's basically shaped like a tele, except it's an all mahogany, set neck guitar. The electronics are setup like a Stink182 guitar, one invader and an a volume knob. I dig the invader in an alder body, but you know it doesn't sound that good to me in a mahogany body. I'm not into the high gain pickups too much anyway... I think I'll be way more happy with a JB in this thing than an Invader... my only qualm with the whole thing is I won't have a tone knob - which might be a disservice to the jb...

 

[Benjy_26]

Re: JB, 1 vol, no tone!

You can wire up the resistor and the cap using a push/pull pot to take them in and out of the circuit, kinda like PRS's old "sweet switch". I'm not sure of the schematics, but it can't be that hard. I'll try to figure it out.

 

[mjsever]

Re: JB, 1 vol, no tone!

Should I throw in a resistor to simulate a tone pot?

You can also do this without even opening the electronics panel- just unscrew one of the ends of your guitar cord, and bridge those connections with a resistor (and capacitor, I guess... I've never tried that).

Here's a great tutorial on what resistor values to use:

http://www.projectguitar.com/tut/potm.htm

 

[Artie]

Re: JB, 1 vol, no tone!

You can also do this without even opening the electronics panel- just unscrew one of the ends of your guitar cord, and bridge those connections with a resistor (and capacitor, I guess... I've never tried that).

Here's a great tutorial on what resistor values to use:

http://www.projectguitar.com/tut/potm.htm

That link, while a good one, is for something completely different, that may only confuse UCSDBoy. With a JB, he should just use a 500k resistor.

 

[Kent S.]

Re: JB, 1 vol, no tone!

You can wire up the resistor and the cap using a push/pull pot to take them in and out of the circuit, kinda like PRS's old "sweet switch". I'm not sure of the schematics, but it can't be that hard. I'll try to figure it out.

Just so you know the sweet switch did not work off any of the normal principles of a tone control ... and switching a cap and resistor simulating a tone knob at ten wouldn't be hardly worth it.

 

[Kent S.]

Re: JB, 1 vol, no tone!

You can also do this without even opening the electronics panel- just unscrew one of the ends of your guitar cord, and bridge those connections with a resistor (and capacitor, I guess... I've never tried that).

Two things here, not that much room one, and then that cable can only be used with that guitar two ... if you see what I'm saying.

 

[Kent S.]

Re: JB, 1 vol, no tone!

That link, while a good one, is for something completely different, that may only confuse UCSDBoy. With a JB, he should just use a 500k resistor.

You know Art, this would be a great place for a concentric pot ... with a 500k/250k he could pick which half he wanted to use ... say the 250k on volume and a 500k on tone; or a 500k on volume and a 250k on tone. Of course that's if you aren't picky about which part of the knob you want.
Personally I'd go for the 500k volume and 250k tone. The JB is most often preferred with a 250k volume, that might work out well by itself, as without a tone it would bit a bit brighter.

 

[mjsever]

Re: JB, 1 vol, no tone!

Two things here, not that much room one, and then that cable can only be used with that guitar two ... if you see what I'm saying.

correct... please allow me to clarify

What I meant to say was, you can bridge your guitar cord with a resistor to simulate the switch to 250k pots and see if like the sound before going through all the trouble of soldering, rewiring, etc. It's definitely not the permanent solution..

 

[Artie]

Re: JB, 1 vol, no tone!

You know Art, this would be a great place for a concentric pot ... with a 500k/250k he could pick which half he wanted to use ... say the 250k on volume and a 500k on tone; or a 500k on volume and a 250k on tone. Of course that's if you aren't picky about which part of the knob you want.
Personally I'd go for the 500k volume and 250k tone. The JB is most often preferred with a 250k volume, that might work out well by itself, as without a tone it would bit a bit brighter.

Yup . . . I shoulda thought of that. :smack:

This is the perfect application for a concentric pot.

 

[Benjy_26]

Re: JB, 1 vol, no tone!

Just so you know the sweet switch did not work off any of the normal principles of a tone control ... and switching a cap and resistor simulating a tone knob at ten wouldn't be hardly worth it.

I thought the Sweet Switch was just a way of taking caps and resistors in and out of the circuit. How did the PRS system work?

I spent all night trying to figure ot a way of ding it with a push/pull pot. :blackeye:

Oh well, I don't need sleep that much. :dance:

 

[Kent S.]

Re: JB, 1 vol, no tone!

correct... please allow me to clarify

What I meant to say was, you can bridge your guitar cord with a resistor to simulate the switch to 250k pots and see if like the sound before going through all the trouble of soldering, rewiring, etc. It's definitely not the permanent solution..

Ah, okay ... Ya know the SD amps did something similar with passive R and RC loads applied to the input jacks in the form of small plug over thingies.

 

[Kent S.]

Re: JB, 1 vol, no tone!

I thought the Sweet Switch was just a way of taking caps and resistors in and out of the circuit. How did the PRS system work?

I spent all night trying to figure ot a way of ding it with a push/pull pot. :blackeye:

Oh well, I don't need sleep that much. :dance:

Since PRS still offers the sweetness switch component (ACC-4113 I believe is the PRS part number, if you want I'll verify that for you ...I've got it written down in my notes), I won't go into any technical details as to what it is or how it works (sorry). It does have a similar effect of rolling off some highs, but does other things as well. There were later versions of a push/pull tone knob that either put the sweetness switch in or out along with the tone control, this may be what you are more specifically referring too.
The original PRS's like mine (circa '83 or there abouts) has what were called PRS Standard treble and bass pups .. later on they outfitted them with the HFS treble and Vintage bass pups; the standards were ideal for playing thru pedal boards etc. (kinda like the DMZ Paf Pro is as well), but they were a bit to bright into an amp direct; Hence the only way to get them to scream was thru the switchness switch. I shouldn't have said that the principles weren't remotely the same, but the manner in which it does what it does is different. And not related to the way a tone control works.

 

[Kent S.]

Re: JB, 1 vol, no tone!

Yup . . . I shoulda thought of that. :smack:

This is the perfect application for a concentric pot.

Yeah the Fender # 001926800 (they always put extra zeros at the beginning and most often times the end of their numbers) is a 250k-A and 500k-A concentric pot, the ring is the 250k section and the center is the 500k section (the 250k is closest to the shaft) ... they used those on the '62 Jazz basses the 500k was the volume and the 250k the tone. But you could wire the 250k for volume and the 500k for tone if you wanted, you might have to use their knobs though. Stemac has some and I think Allparts as well that are a bit more attractive as far as the knobs go, don't know how good the pots are though. Either way, I think that would balance that JB out just about right in this case.

 

[UCSDBoy]

Re: JB, 1 vol, no tone!

Just an updater - the JB in this thing rocks! =) Just put it in and man, is this ever a dark guitar - right now it has _no_ tone pot and just a 500k volume pot and even at full volume it's not too bright in most cases. I find myself dialing it back quite a bit just to tone it down, but it's never an icepick in the ear; that was really surprising.

The guitar itself is just a cheap mik fender esquire gt - an all mahaogy, set neck fixed bridge. It's got a very warm, bright singing tone. I'm really happy - it turned a cheap 200 buck guitar into something I want to play all the time. The bad part is, it makes me wonder what it would sound like if I put it in a more expensive guitar.

 

[UCSDBoy]

Re: JB, 1 vol, no tone!

Actually, I just noticed something - it's been a while since I took circuits, but if I'm reading my old notes correctly, a volume pot uses all three terminals, while a tone pot uses only the middle and one end terminal. Therefore, the volume is a variable voltage divider while the tone is a variable resistor.

Since the tone acts as a variable resistor, it should be necessasary to put a resistor across the pot terminals like we see in the link above - you should be able to turn an audio taper pot to 5 and a get 250k resistance, correct?

I'm just trying to figure out what the capacitor does - I mean, you don't need it, right? The tone pot will already bleed off the high end from the pickup...

 

[Kent S.]

Re: JB, 1 vol, no tone!

Actually, I just noticed something - it's been a while since I took circuits, but if I'm reading my old notes correctly, a volume pot uses all three terminals, while a tone pot uses only the middle and one end terminal. Therefore, the volume is a variable voltage divider while the tone is a variable resistor.

Right .....

Since the tone acts as a variable resistor, it should be necessasary to put a resistor across the pot terminals like we see in the link above - you should be able to turn an audio taper pot to 5 and a get 250k resistance, correct?

First off unless you are using linear pots it won't do that ... an audio taper (commercial approximation-twoo segment) turned halfway down will be about 10% of the pot's total R/Z. Not sure what you are referring to (haven't checked the link), the reason for putting a resistor across the CW and CCW terminals of a volume pot is to load the system as if the pot's value was the paralleled value of the pot and resistor. That's a volume pot, it's not quite that same for a tone control. The reason that someone would put a resistor there would be to damp the resonant peak of the pup. Therefore the tone at ten will always be just what it is, the maximum allowed by that addition of R. If you planned on using the extra brightness at times it wouldn't make sense to do this, but if you didn't ... well it wouldn't make much sense to have you tone control sitting on 7.5 all the time would it? If you are referring to a lrager vaued cap, and limiting the maximum attenuation level of the tone control ... that's a whole different thing altogether.

I'm just trying to figure out what the capacitor does - I mean, you don't need it, right? The tone pot will already bleed off the high end from the pickup...

The capacitor only allows higher Fcs thru so when you turn down the tone control the lowest Fcs are blocked from ground, but the highs aren't ... hence they are removed from the signal ... That's a greatly overstated simplification, but it gets the point across. You take the cap away, and all you have is a variable load the ground, it will damp the resonant Fc of the pups (amplitude of it that is), but will not cause a low pass filter slope to form ( attenuating higher frequencies past a cut-off or corner Fc more and more the higher they go), the only thing that would happen without that cap is you pull down the peak, then eventually cause some roll off, but the whole time your level would be dropping as you'd be changing the ratios of the voltage divider ... You, might eventually get the roll-off of highs you want, but what good does it do you when your guitar level is sitting at about -40dB compared to where is was? The cap establishes a filter in conjunction with the source impedance and controlling resistance of the pot. It's a first order low pass filter with a limited attenuation control, I'm sure you covered those in electronics.

 

[Marcel]

Re: JB, 1 vol, no tone!

I use the JB with 500K Vol and no Tone! screams like sh!t! :headbang:
no problems with it!