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V-B-T for a newby

K

kelto

Dec 25, 2009
28
0
Killeen, Texas
#1
I just got a P/J and was wanting to:
1. mod one of the volume knobs into a blend knob (read a lil bit and heard from Jazz Ad stat if you use good enough Pots the loss of volume on a passive bass won't be a problem)

I am VERY knew to wiring pickups/preamp etc. and was wondering if someone could "dumb down" the wiring of it (saw a Seymour Duncan schematic that seemed about as simple as it could get but didn't think to save it).

I am kinda ashamed to be playing bass for about 5 years and just now starting to think of doing this kind of stuff and please be kind to my stupidity :help:

edit: i have done a good bit of research but am still finding it mind bending, music is my thing, not electronics
 
#4
IF you use a REAL blend pot that has no resistance from center to one extreme of both gangs, then at center it's exactly like a typical Jazz bass V/V/T with the addition of the effect of the extra (master) volume pot. There are apparently some pots sold as blend or pan pots that have both PUPs at half in the center, though I've never had one in the years I've been doing this. Yes, there is some slight high frequency loss that may or may not be important to you, but a severe loss of volume in the middle position is either out-of-phase pickup wiring, incorrect wiring of the blend pot, or an incorrect pot choice.

Search this forum, as the topic used to come up about every two weeks, and always generated the same plethora of misinformation, corrections, and esoteric details of the physics involved...

John
 
#7
yeah, but no different than with two volumes full-up.

a big loss in the center would be from the wrong kind of blend pot, one where the center setting left both pickups turned down a bit.

the right kind is called an "M/N"; in the center, it's the same as two regular volumes full-up.
 
#8
I have modded my MIJ Jazz to V-B-T. Very happy with results.

Used Bourns type M/N blend pot, 500K ohms per this schematic:

http://www.talkbass.com/forum/f38/jazz-mod-vol-blend-tonestyler-w-para-series-switch-803149/

Use the '2.2' diagram for the Bourns A-C blend pot. Here's the Bourns web page:

http://www.bourns.com/data/global/pdfs/Bourns_PDB182_Blend-Balance_Guitar_Pots_AppNote.pdf

The type M/N blend pot gives you 100% of both PUPS at the center detent. Turning it one way keeps one PUP at 100% while the other is gradually diminished to zero. You have to ground one lug of each pot as shown in the Tonestyler diagram or the PUPs will never go to zero when you de-select them.

Somebody may have something to say about using a 500K blend pot, but Tonestyler recommended it and the bass sounds great. Plenty of output.

My complete mod can be read about on this page:

http://www.talkbass.com/forum/f38/jazz-mod-vol-blend-tonestyler-w-para-series-switch-803149/

Have fun!
 
#9
I just got done modding my PJ. I used a 500K volume pot, a 250K tone pot and a on/off switch for the J pickup.
This was after much experimenting.
The 500K volume brings the output up and sounds much better than a 250K volume pot. It also helps the J humbucker stand out a little better.
 
#10
phyfe said:
You have to ground one lug of each pot as shown in the Tonestyler diagram or the PUPs will never go to zero when you de-select them.
Click to expand...
almost :D

leave the grounds off, and the blending will happen a little more smoothly (especially with a 250k M/N), you'll have no tone loss from the extra blend pots, and the middle will be just like a switch, i.e., no loss at all.

technically yes, the pickups won't be all the way off when dialed away from, but they'll be off enough to where you only hear the "on" pickup while playing.

search "unloaded blend" or "ungrounded blend" on TB for a bunch of my results with the idea.
 
#13
I'm a lover of blend and master volume. I find that if you like say a 70/30 % split between the PUs then by setting the blend to your fav setting and then just using the master volume - IMHO you have all you need. You can use the volume control and set-up with 80% volume at the bass so I have a bit spare if I need it. It is so much easier than using two volume controls and then having to set up the blend again each time I turn them to zero.
 

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