Jaguar Rhythm Circuit Tone Pot Volume Drop

[dugwolf]

Recently got a jaguar 50th anniversary in LPB. It wasn’t functioning properly when I bought it and when I opened it up the wiring was all over. It was like a plate of spaghetti in there. Rather than try to DIY, I ordered a wiring harness. So I installed it last night and everything works great EXCEPT, when I roll down the tone on the rhythm circuit the volume almost totally drops out. It’s barely audible. My avri jag doesn’t behave this way. There is some drop, which I guess would be expected if you’re removing the highs, but it’s not nearly as drastic. Just curious if this can be normal or if something is wired incorrectly. I’ve attached a pic below. In the wiring diagrams I’ve seen the capacitor it wired directly to ground from the tone pot. But on the harness it goes over to the back of the rhythm volume pot and is connected to the back. Could that have something do do with the volume drop? Any thoughts would be appreciated.

[SY6655321]

I remember reading on here somewhere that moving the green wire on the tone pot to the same lug as the white wire helps with the volume loss.

[alexpigment]

I suspect the volume and tone are wired with "50s wiring" - which relates to the interplay between the volume and tone knob. On 250k pots on a normal circuit, I recommend this all day long since the tone stays bright when turning your volume down. The downside is that you lose *a small amount* of volume when you turn your tone knob down from 10, but it's pretty negligible. In my experience, this has a greater effect on the roller pots of a JM/Jag, and I'm not sure if it's due to the 1meg + 50k pots, the particular cap, or what.

I believe SY6655321's suggestion would effectively put it in "modern wiring" mode, and solve this volume drop (but cause the tone to get darker as you turn your volume knob down from 10). Then again, if the volume drop is really drastic, it could just be something wired wrong - although it doesn't look obvious to my eyes that it is.

Have you checked your AVRI to see what the wiring differences are?

[timtam]

There is a known variation in the way Fender has done the JM's rhythm circuit's tone pot wiring ...
http://www.tdpri.com/threads/jazzmaster ... on.516890/
Not sure if this has been noticed for the jag too.

[alexpigment]

Vintage/modern wiring aside, I noticed that the cap used in the picture above is .1 (uF presumably) rather than the .02uF that I usually see in diagrams. I honestly don't know if it would fully explain the severity of the problem the OP is running into, but it would certainly change how the tone roller behaves through the sweep.

After getting a little curious, I found the wiring diagram for this guitar and it usually has a .01uF cap:

https://www.fmicassets.com/Damroot/Orig ... A_SISD.pdf

So either the cap is using a different base measurement and is the correct part, or it's been replaced with the wrong cap that's an order of magnitude off. In either situation, switching it to a .02uF cap could help put it in line with your other guitar.

[SY6655321]

^ Eagle eye! alexpigment is correct, that cap is too big

[chrisrnps]

...also, make sure that nowhere from the solder point on the tone pot until it gets to where the lead goes into the actual cap has anywhere some stray solder, wire, lead, that could be making contact with the metal bracket, another lug on the pot, or anything else that could be grounding or shorting it out - otherwise that tone pot could be completely or partially acting as a volume pot...(full range signal shunts to ground rather than just highs shunt to ground)

[jorri]

Yup its not broken. The circuit is designed like that with '3 pins'. You can use the 2 pin version as in a jazzmaster lead circuit (i. E. 99% of guitars) or replicate that resistor on the jag lead vircuit which i think is there to help the volume drop. A jag uses a 0.01uF, so anything above the cutoff frequency is lost, there is no treble so there is less volume. 2-pins tone pots dont just remove the treble, the interact in such a way that on lower settings there is a big peak at the cutoff so its about similar volume, as there is no resistance blocking the signal path to force it to ground.

The sound will be different though and have more of a resonant peak on the 2pin method.
I personally find something like a series switch more useful than rhythm circuit, even though i liked its tone it was never used except as occasional killswitch. I love the series though, its like a really loud weird HH guitar. Never tried wiring it with the rhythm pots but it could be useful to lower volume to balance, and use the second pot as a bass cut.

[alexpigment]

I personally find something like a series switch more useful than rhythm circuit, even though i liked its tone it was never used except as occasional killswitch. I love the series though, its like a really loud weird HH guitar. Never tried wiring it with the rhythm pots but it could be useful to lower volume to balance, and use the second pot as a bass cut.

I second the idea that a series switch could be more useful, but just wanted to point out that it will definitely not sound like a humbucker due to the location of the coils. It will sound like exactly like the normal middle position with the tone knob rolled down to ~80% and ~1.5x as loud. The only way it would sound like a traditional humbucker is if the coils were right next to each other. Sorry if this sound pedantic, but not a lot of people realize that the the *timbre* of the middle position in series and in parallel is virtually identical, it's just that you end up with more output and as a result, a darker sound. The bass cut you mentioned is a nice way to deal with this, although I think you might be fine with just having 250k pots in the main circuit and 1meg pots in the rhythm circuit so that the tone is more balanced between the two circuits.

[bjornsynneby]

I had the same problem with my Jazzmaster which has the same rythm circuit. When you roll off the tone the volume decreases and not the tone. The fix is easy. Unsolder the green wire on the tone pot and solder it back at the same lug as the white. If you are insecure image google ”jazzmaster wiring seymour duncan” you can find the wiring diagram. This is not to say that your harness wiring is wrong. It is just another version which can be found by image googling ”jazzmaster wiring”.

The cap is wired correctly but 0.1uF perhaps is a bit dark when the tone pot is turned down. I believe 0.02uF will be enough for jazz. Good luck!

[dugwolf]

UPDATE:

Thanks everyone for your input. It was very helpful. I had replaced the pickups at the same time as the wiring harness with some Seymour Duncans so I was using their wiring diagram as a guide. After alexpigment linked the Fender 50th anniversary jag wiring diagram I realized he was correct, the cap was too large! And the Duncan diagram was wrong. At least for the 50th anniversary jag and the 62 avri as well. Tracked this down as well:

So I replaced the .1uf cap with a .01uf cap. Guess what... all is well! The rhythm circuit tone control now behaves the same as my avri with very little volume drop.

[jorri]

I personally find something like a series switch more useful than rhythm circuit, even though i liked its tone it was never used except as occasional killswitch. I love the series though, its like a really loud weird HH guitar. Never tried wiring it with the rhythm pots but it could be useful to lower volume to balance, and use the second pot as a bass cut.

I second the idea that a series switch could be more useful, but just wanted to point out that it will definitely not sound like a humbucker due to the location of the coils. It will sound like exactly like the normal middle position with the tone knob rolled down to ~80% and ~1.5x as loud. The only way it would sound like a traditional humbucker is if the coils were right next to each other. Sorry if this sound pedantic, but not a lot of people realize that the the *timbre* of the middle position in series and in parallel is virtually identical, it's just that you end up with more output and as a result, a darker sound. The bass cut you mentioned is a nice way to deal with this, although I think you might be fine with just having 250k pots in the main circuit and 1meg pots in the rhythm circuit so that the tone is more balanced between the two circuits.

Cant say its ever sounded anything like the parallel timbre. Maybe the opposite

[jorri]

As in, it sounds like a humbucker. A big WEIRD one. Yes probably due to the spacing, but it sounds absolutely nothing like the parallel selection from maybe 4 different examples.

[alexpigment]

As in, it sounds like a humbucker. A big WEIRD one. Yes probably due to the spacing, but it sounds absolutely nothing like the parallel selection from maybe 4 different examples.

Weird. I've done the A/B tests. Assuming you've done the same, I'm not sure how you disagree. Having said that, you would certainly have to take the tube amp factor out of the equation, because driving the front end of a tube amp does change timbre; that is the useful part of the series wiring.

Here's how to test:
Record yourself in parallel with the volume knob at ~100% and tone knob at ~80%.
Record yourself in series with the volume knob at ~80% and the tone knob at ~100%.

Compare the two. Allowing for some variances in percentages due to resistance of your pots, caps used, and 50s/modern wiring, they should sound the same.

[jorri]

I can just hear it. Are you sure you actually wired in series?

I have a middle pickup. Especially that one. Its extremely thin and plucky, a bit like rick type sounds, in parallel. It sounds like a pbass in series.

There is no 'scoop' or 'combing' going on to give the typical combined 'twang'.

Particularly the inductance changes massively. And phasing isnt occuring as in theory.