Bypassing the tone pot with push/pull P Bass

lifer_

lifer_

Oct 19, 2011
151
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4,581
Bulgaria
#1
Hello fellows,
I'm looking for a schematic for bypassing the tone pot and to leave just the volume straight to the jack. I saw some old threads where this approach was discussed and line6man (he helped me once long time ago with a different project and I'm grateful to the day!) gave a schematic but the illustrations are no longer available.

Basically the idea is to have a 500k pot for volume and 250k push/pull with 0.047uF cap.
The reason I want this is the P bass with vintage Barts to sound a little bit closer to my main player which is a PJ bass also with Barts. My PJ is with two 500k volumes and active preamp, without passive tone. I'm using it mostly passive and I'm really happy with the bright tone it gives me!

I know they will be different after all (like output for example) and they are, and this is good thing. With this mod I hope to be less complicated to use them both with my effect pedals and my amp, and easily to change them on the stage.

The main reason to think that 250k pot for tone is the way to go is because I hope to save some of the classic vibe and tone of the P and to be able to use it when needed.

What do you reckon? Any advice will be welcomed!
 
#2
Sounds like a lot of work for little to no payoff, but that's is not the question, is it? Anyway, I'm not in a position to draw you a diagram, but it should be easy enough to describe. Simply wire the lead from the volume pot to one of the center lugs of the pot switch. Then solder a wire from one of the upper lugs (assuming orientation of the pot) to the hot terminalon the jack. Solder one of the lower pair of lugs to the center lugs of tone pot. Easy peasy.
 
#3
Thank you FugaziBomb! Is it something like this?
Screenshot-2018-5-29 PrecisionBass_Standard pdf.png
 
#4
lifer_ said:
What do you reckon? Any advice will be welcomed!
Click to expand...

Why don't you use a no-load tone pot? It does the same thing when you turn it all the way up and is wired exactly like a normal pot.

The only time a pull bypass would be better is if you want to switch back and forth to a preset tone roll off.
 
#5
lz4005 said:
Why don't you use a no-load tone pot? It does the same thing when you turn it all the way up and is wired exactly like a normal pot.

The only time a pull bypass would be better is if you want to switch back and forth to a preset tone roll off.
Click to expand...

Well, you are right, a no-load will be an easy solution, but like you said a fast switching option of a push/pull pot looks more practical.
 
#10
Oh, so basically it means I just have to remove the tone pot and the cap out of the circle?
Click to expand...

With a ptc, the tone cap is simply in series with a variable resistance between two lugs of the pot. This little chain goes between the hot signal from the pickup and earth. You could put your switch anywhere on that chain and the tone control would be defeated. IOW, also between the cap and that middle lug, or between the cap and earth. If your bass is wired like that diagram, then where I've put it is probably the easiest to solder a switch into.


Is there a way to avoid the pop thing?
Click to expand...

Yeah, you could use a 1M resistor across the two switch terminals, but honestly, just try it as is. The pop is really tiny. Any more components you add to a passive circuit will just start interacting with the pickup signal, the sweep of the pots, etc etc...
 
#15
Just like I imagined it. There is not a big difference between the bypassed tone and the pot on max with the cap but still you can feel the difference quite well. Without the pot the sound has a little bit more bite and it's a little bit more aggressive. It's more obvious when the signal pass through my pedal board and all the dirt. Now I can switch faster from one tone to another. The ""no load" I will use for the heavy parts in the songs and if I want a P bass sound it will be there, pre set for my needs.
 
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