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Jazz Bass series with no-load VVT

AndyPanda

AndyPanda

May 11, 2014
2,901
4,661
Alameda, California
#1
My Jazz Bass was wired standard with 250K audio taper for volumes and tone. And I was mildly annoyed by having all the volume control happen between 8-10. Read posts about using linear pots for volume. But I was also interested in trying out series with the VVT blending as has been shown previously. The series VVT diagrams I have seen used 500K pots (I assume so there would be less loading) and they were linear.

Now just as an experiment, I was curious how it would work and sound with 250K audio taper (since that was what was already in there) and to my surprise, the volume taper is really nice that way using the series wiring. Now the volume is affected pretty evenly across the whole sweep (a bit more between 1-5 but not bad). The sound of series is much more to my liking and the volumes blend so much better now.

I was thinking I'd cut the resistor trace on the Vol pots so they are no load when Vol is at 10, but I haven't actually done it yet. It sounds great just as it is so I may not bother - but I drew it up anyway.
JazzBassSeriesWiringDiagram.jpg
 
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#2
AndyPanda said:
My Jazz Bass was wired standard with 250K audio taper for volumes and tone. And I was mildly annoyed by having all the volume control happen between 8-10. Read posts about using linear pots for volume. But I was also interested in trying out series with the VVT blending as has been shown previously. The series VVT diagrams I have seen used 500K pots (I assume so there would be less loading) and they were linear.

Now just as an experiment, I was curious how it would work and sound with 250K audio taper (since that was what was already in there) and to my surprise, the volume taper is really nice that way using the series wiring. Now the volume is affected pretty evenly across the whole sweep (a bit more between 1-5 but not bad). The sound of series is much more to my liking and the volumes blend so much better now.

I was thinking I'd cut the resistor trace on the Vol pots so they are no load when Vol is at 10, but I haven't actually done it yet. It sounds great just as it is so I may not bother - but I drew it up anyway.
View attachment 969749
Click to expand...
DO NOT cut the trace on the volume pot. The outer lug must be grounded to work as a volume pot. Removing the ground will give little control if any on the volumes. That only works on tone pot to remove it from the circuit for less loading. Get 2 250k-B linear taper pots for the volumes and leave the tone pot as audio taper
 
#3
LoveThatBass said:
DO NOT cut the trace on the volume pot. The outer lug must be grounded to work as a volume pot. Removing the ground will give little control if any on the volumes. That only works on tone pot to remove it from the circuit for less loading. Get 2 250k-B linear taper pots for the volumes and leave the tone pot as audio taper
Click to expand...

Look more closely at the wiring scheme. This is NOT a traditional VVT arrangement for parallel pickups. The pickups are in series, and hence, the volume pots work by shunting the coils, to varying degrees. The pots do not and should not provide any path to ground.
 
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#4
Yes, @line6man is exactly right.

@LoveThatBass -- without the cuts (that's how I'm still playing it today), when the volumes are at 10 I have the resistance of the pots (in my case 250 ohms) shunted across each pickup. By cutting the trace I would still have the variable shunt when the pots are anywhere but full on - but when full on, the wiper would be across the cut and there would be no load on that pickup from that pot.

Without the cuts:
Series_VVT.png

with the cuts:
Series_VVT_noload.png
 
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#6
honeyiscool said:
Every time you read reviews of no-load pots on Amazon or whatever, it's always 3 stars because a bunch of Jazz Bass users complain that their pot doesn't work.
Click to expand...
I didn't even know you could buy them no-load (I've always just made my own)... but I just looked at Amazon and just as you said :) here is a review that caught my eye "tiny, harmless, unknown sound" ... classic! :) :
"This is the worst thing you can buy for your guitar (fender telecaster in my case).. it totally kill the tone... turns your beautifull awesome tone in a tiny, harmless, unknown sound... well, i'll just put this pot gently in my neighbour garbage!!!"
 
#7
Heh. You should totally try a no-load tone pot, though! That will do what you want it to do.

I recently re-wired my Jazz Bass with a 250k M/N blend pot (ungrounded), a series/parallel 500k push pull pot, and a 250k linear volume pot. The thing about a volume pot value is that you can't just up it to 500k and get something for nothing. You can pretty much do whatever you want with the tone pot, get a meg pot, get rid of it for all you might care, and all you get is a brighter sound. But to me, vintage voiced pickups respond weird without the 250k volume pot in front (which, if I understand correctly, would be the same as if you used a grounded 500k M/N blend pot with a 500k volume pot).
 
#8
AndyPanda said:
Yes, @line6man is exactly right.

@LoveThatBass -- without the cuts (that's how I'm still playing it today), when the volumes are at 10 I have the resistance of the pots (in my case 250 ohms) shunted across each pickup. By cutting the trace I would still have the variable shunt when the pots are anywhere but full on - but when full on, the wiper would be across the cut and there would be no load on that pickup from that pot.

Without the cuts:
View attachment 970121
with the cuts:
View attachment 970124
Click to expand...
Gotcha Thanks
 
#10
I am considering performing this mod to my jazz bass, minus the no load option. I had a series/parallel switch in there before until it stopped working and really enjoyed the series mod.

With this mod, how is dialing in the volume of each pickup? Is there any loss in volume from both volumes all the way up when only one is solo'd or some variation between the two? Also, how is the tone knob affected?

Seems like this mod setup is almost too good to be true, where's the rub?
 
#11
On my jazz bass, I just used the stock pots and I never did cut the traces so it isn't "no load". It works great in my opinion and it's easily reversible so if you don't like it you simply wire it back the way it was. It is simply a wiring change.

Dialing in a blend of the pickups is smooth.
With both pickups all the way up it is actually louder than it was before the mod (because of the series vs parallel).
Either pickup solo'd is same as it was before the mod.
The tone control works the same as always.

There really is no rub (other than giving up parallel mode). I haven't found anything not to like about it.
 
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#13
AndyPanda said:
I was thinking I'd cut the resistor trace on the Vol pots so they are no load when Vol is at 10, but I haven't actually done it yet. It sounds great just as it is so I may not bother...
Click to expand...
If you cut both volumes AND the trace near the unused terminal on the tone control, with all three controls full up, you disconnect everything. It's like wiring your pickups directly to the output jack. You're bass goes to 11 LOL!
 
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#14
You do NOT have the pickup grounds soldered to the back of the pots and you don't have any legs of the pots bent over and soldered to the back of the pots. If your cavity shielding or output jack happens to be soldered to the back of the pots that is fine to leave it but you don't need it.

Yes there is only one ground. The first pickup gets to ground by going THRU the second pickup (or across the pot if the pot has turned the second pickup off) to get to ground.

No extra buzz. In fact you can get a single pickup sound that has less hum than stock by dialing in just a little of the other pickup and you get some of its "humbucking" noise reduction without adding much of its volume to the mix.
 
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#17
Here's a representative schematic of the VVT with all three no-loads cut into the pot traces. Certainly don't have to do the no-load cuts, but if I was doing this circuit, I'd do it for the full power and full audio spectrum availability. Controls shown maxed into no-load area.:
Series VVT.jpg
 
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#19
bthiemann80 said:
I gotta ask, are there any sound clips in existence of this series VVT wiring mod?
Click to expand...
I'm not a very good player yet (started learning bass at the tender age of 65 and arthritis/tendonitis etc. keeps putting my practicing time on hold) --- but I can record something simple to show the sound. The main difference you'll hear is with a stock Jazz Bass, if you are playing just the neck pickup and then start to roll up the bridge pickup you hear the sound start to hollow out and get lower in volume as both pickups get to the same volume == and doing the same on the series VVT as you start to roll on the bridge pickup you hear the sound gradually fatten up and get higher in volume.

I'll record something for you when I get a chance.
 

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