Replace cap in super mod + dual volume pot

[abou]

Hello,

I'm making a super mod like the Andy Rothstein super mod on my home made jazzmaster, and I was wondering what happens if I replace the cap of the low cut pot (normaly 0,0022uF) with a 0,022uF ? I use Lollar pickup with alpha reverse 1M pot.

And with a 0,001uF ?

Is it a bad idea?

Thank you !

[oid]

You change the frequency response of the filter.

fc=1/(2piRc)

1/(2*3.14*1*0.022)=7.23 hertz

1/(2*3.14*1*0.0022)=72.3 hertz

So you shift the frequency range down quit a bit and the guitar will effectively be off when you roll the tone all the way back.

[abou]

Thank you really much Oid !

So 0,001uF will be perfect (low cut at 159hz). Same cap as the treble bleed.

[oid]

Thank you really much Oid !

So 0,001uF will be perfect (low cut at 159hz). Same cap as the treble bleed.

It might be, it might not.

An RC filter is a first order filter, so frequency drops off at 6db for every octave with the equation above calculating the point at which the filter is down by 3db.

So your low cut, 159hz will be 3dbs quieter than 300hz and 80hz will be 9dbs quieter, not a huge amount of cut for that 159hz but can be enough depending on what you are playing.

We sometimes need to move the cutoff of low order filters abit further than the frequency we want it at to get things to sound right due to the gradual rolloff, it comes down to the actual use and the designers intent/expectation/experience. 0.001uF will certainly be a good starting place though.

[abou]

It works nice in that way ! :-)

But there is a strange thing with the dual volume pot in parallel mode:

When I select both pickups with the selector, and if I turn down the bridge vol, all the sound of both pickups are gone.
Same thing when I turn down the neck PU volume: full silence ! Where did I mistake ?

The wiring diagram I used is here: http://www.guitar-mod.com/mm5/merchant. ... JM_STB_KIT

A photo of the wired pickguard if it helps... https://www.dropbox.com/s/d197ljopc2xv9 ... 8.jpg?dl=0

Thank you in advance for your help !

Amaury

[oid]

It works nice in that way ! :-)

But there is a strange thing with the dual volume pot in parallel mode:

When I select both pickups with the selector, and if I turn down the bridge vol, all the sound of both pickups are gone.
Same thing when I turn down the neck PU volume: full silence ! Where did I mistake ?

The wiring diagram I used is here: http://www.guitar-mod.com/mm5/merchant. ... JM_STB_KIT

A photo of the wired pickguard if it helps... https://www.dropbox.com/s/d197ljopc2xv9 ... 8.jpg?dl=0

Thank you in advance for your help !

Amaury

Sorry on the slow reply, was out with a cold.

Your issue with the volumes when both pickups are on is normal, the volume controls just send some signal to ground instead of the output, the lower you turn the volume down the more signal goes to ground instead of to your amp, when the volume control is at zero you have a short to ground and anything in circuit goes to ground, including the other pickup. This is just the nature of such passive circuits. The standard way to use these dual volume controls is to set the volumes for your neck and bridge pickup up individually with the pickup selector switch set for one or the other, when you switch into the middle position you accept these levels and adjust with your technique instead of the pots. So if you need more bridge in the mix, just pick closer to the bridge pickup, or right on top of it, and vise versa if you need more neck. There really is no reason to turn the volume on one all the way down, that is more work than just flipping the switch to turn one off.