1960s Jazz Bass - Isolated Dual Stacked Vol/Tones - How does it affect tone?

Discussion in 'Pickups & Electronics [BG]' started by Antisyzygy, Jan 1, 2016.

  1. Antisyzygy


    Dec 8, 2014
    Yep, it would help with that. That is if we're talking about the mod I didn't do. I did a modified version that didn't have the 15k summing resistors.

    RobbieK VTVT.jpg

    However it's basically the same as if you kept both of your volume knobs at 90%. Your 100% volume becomes just a bit quieter than it used to be.

    Try keeping both of your volumes at 90% then turn down pickups from there. That's pretty much what it would be like.
  2. boomsville


    Jun 25, 2016
    Ok got it. I actually installed a set of ultra jazz's on it yesterday and the roll off is much more gradual than before and I don't seem to have a problem with tone roll off either so I'm gonna leave it as is. It originally had Fender '69's in it, or wait, maybe CS 60's. I don't remember what I'd ordered.
  3. okabass


    Mar 19, 2005
    View attachment 894636

    I had 1960 wiring, It's ok but feel something is missing, perhaps it is a bit too mellow. I put that wiring (pic) and feel it is more open and a bit louder. Sounds kind of nicer now.

    Attached Files:

  4. flatwound62p


    Apr 24, 2017
    Rather than starting the zillionth stack knob thread I’ll resurrect this one ...
    I just rewired my stack knob Flea signature jazz from re-issue style to original 60’s wiring. As expected I got a drop in volume and a darker tone.
    I like most of what it does with 60’s wiring but I’ve lost my favourite sound for pick playing, which was neck pup at or near 10 and bridge around 0 or just audible.
    Am I likely to get closer to my previous favourite pick sound if I change the value of ONLY the resistor on the neck side? I much prefer the way the bridge pup sounds in the 60’s configuration but don’t so much like what it’s done to the neck pickup.
  5. RBrownBass

    RBrownBass Thoroughly Nice Guy Supporting Member

    Aug 22, 2004
    I sure hope you two are still here... line6man, the system wouldn't allow me to tag you for some reason, so I just quoted you.

    I'm trying to wire up a stack-knob harness. I have here a schematic (actually, it's just a drawing- I don't know how to read the other kind) that I had planned to use, but I want to make sure that it isolates everything the way I assume your schematics do. I have some 15K resistors to replace the 220K that are supposed to go into the original wiring. Is there anything I need to do other than wire this up just like it is, but with the 15K resistors?

    Thanks so much for any help you can provide.

  6. That diagram won't work with 15k resistors. Notice in the schematic I posted, the pickup hot wires go to the wipers (middle lugs) of the volume pots. This is like the standard VVT wiring. Then the resistors are used to sum the signal from the clockwise lugs of the vol pots.

    IOW, if you use that diagram, you'll have to swap the yellow (pickup hot) wires to the lugs that show the resistors and vice versa.
    RBrownBass likes this.
  7. RBrownBass

    RBrownBass Thoroughly Nice Guy Supporting Member

    Aug 22, 2004
    Okay, I think I've got it. Thanks so much. I've wired v/v/t more times than I can recall, but the descriptive terms ("Clockwise" "summing" "wiper") used here were throwing me off. I'll wire it up over the next few days, take a photo, and see if I've done it right.

    The bass in question is in the finishing stage, so I have some time...
  8. Musical Low B

    Musical Low B

    Aug 8, 2005
    So, from everything I’ve read here, there is really no wiring for this control config that doesn’t have a drawback of some kind. Seems easier to simply do the VVT harness...as kewl as the VTVT setup looks and seems.

    Im towards the end of a build myself that consists of a P Bass p/u in traditional neck, but a split coil soapbar... more or less a hum cancelling J Bass p/u at the bridge. Even though I was going to also have a 2 band active pre, I wanted to originally have VTVT available when in passive mode. The Nordstrand pre allows for a passive tone to be wired in, but it now sounds like having two separate tone controls will be more hassle, no huge benefit over having just one.

    That said, is there any useful difference in how Fralin has their VTVT harness wired?

    Attached Files:

  9. Antisyzygy


    Dec 8, 2014
    Awhile back I did end up installing dual V/Ts on a G&L SB-2. I sold that bass to a fellow TB'er I don't remember the name of at the moment. Trucker guy that hung out in the Seattle Bass Shop.

    The tone isolation worked, but it operated a bit non-intuitively. Basically I had to roll down the volume a bit on the pickup I wanted to isolate the tone for.

    So if I rolled down the bridge pickup to 90% volume, it's tone knob was isolated. If I rolled down the P pickup to 90% volume, it's tone knob was isolated.

    It sort of worked on the SB-2 because you typically don't have the bridge pickup on 100% anyway. Also when I was after the scooped sound I was not typically wanting to use the tone-knob much anyway. The point of the scooped sound for me is to use it for slap techniques so I wanted those highs.

    One nice feature of that mod was I used 2 different capacitors, so if I had both pickups at 100%, I had access to two different master roll-offs. The bridge tone knob cut into the highs less the way I had it configured. So I could use the bridge tone knob for a more honky sound, and the neck tone knob for a more thumpy sound, if either was used by themselves.

    If the P was at 100% and the J was at 90% volume, then the P tone was the master tone, and J tone isolated, so I could sort of bleed a bit of presence off the J pickup without affecting the contribution of the P.

    In practice though the isolation didn't really do much for me. Rolling off both knobs in varying amounts, when isolated, produced some different sounds but it wasn't so different that I'd want to do it again.

    I think a varitone and series/parallel switching is probably closer to what I'd go for the next time. However I've mostly been playing on stock one-pickup basses these days, like P-basses or Stingray-style. Usually Stingray but the P comes out when I need that thump.
    Last edited: Mar 12, 2021
  10. sunbeast

    sunbeast Supporting Member

    Jul 19, 2006
    Los Angeles, CA
    That Fralin diagram is just the modern style of Fender stacked-knob Jazz, with no isolation resistors added. To make this one follow @RobbieK ‘s variation, you would just solder a 15kohm resistor and lead from the outside lug of each volume pot to the hot output jack lug (and omit the Fralin connections from those volume lugs/jack lug).

    I wouldn’t necessarily say there’s a huge trade-off inherent to this scheme, except that in general your tone will be a bit darker than with a standard VVT setup and you may not find the isolated tones all that useful as has been noted a few times in this thread.
    Wiring it directly like the Fralin picture can actually add some extra versatility and you can get the same isolation by just rolling both volumes down a little bit. I would recommend using linear taper volume controls in this case (or really in any dual volume passive blending circuit on a bass) because you can get much more exacting pickup blends this way than with the more typical stock audio taper volume pots.
    RobbieK likes this.
  11. grocker

    grocker Supporting Member

    Dec 1, 2007
    Ormond Beach
    Can someone post a modern quality wiring schematic for a jazz bass with VT VT...stacked....also what pots to use and resistor/capacitor size......i understand some guys like different cap size for more or less treble......
  12. Bestjammin jj

    Bestjammin jj

    Jun 18, 2021
    I don’t know if this helps but when using the stereo output on my PJ, concentric knob with Rickenbacker dual outputs, there is no interaction between the volume knobs, conversely when using my mono output they do interact (not using any resistors at all) and volume at zero on either acts as a master, and you can hear a change in volume when mixing the two pickups.
  13. Brad Alan Self

    Brad Alan Self

    Jul 20, 2021
    PXL_20210720_130331737.jpg PXL_20210720_130331737.jpg
    grocker likes this.
  14. sunbeast

    sunbeast Supporting Member

    Jul 19, 2006
    Los Angeles, CA
    Sounds like your Volumes are wired like a Gibson, with the output on the middle lug of the pot and input on the outside. Jazz basses are wired the opposite, with input on the middle lug and output on the outside lug.
  15. Brad Alan Self

    Brad Alan Self

    Jul 20, 2021
    If you're ambitious you can take the pots apart, make the A250K tone pot no-load (decent videos on that can be found, I'm a nail polish advocate, not a trace cutter,) and swap out the A500K lug wafer for one from a linear taper B500K. The linear volume pot will give you a smidge more volume sweep when the tone pots are in circuit. No-load tone pots wide open let you blend volume with the full sweep of the volume knobs.

    (Speaking of knobs the stacked black plastic knobs from the 90s-00s American Deluxe active JB fit the CTS shafts and aren't as spendy as the Fender chrome & black metal knobs. Most inexpensive Asian knobs are for 8mm/6mm & don't work, even w/beer can shims... Ask how I know.)

    You'll run into some unexpected surprises, for instance the tone pots will still interact when you've got one volume all the way down, despite the summing resistors, give it try & you'll see. For ex., if your necks V & T are up and bridge volume all the way down spin the bridge tone knob and it'll suck treble out of the neck. It's not quite as bad as a Les Paul, but it still happens. The volume pots don't do any sneaky Les Paul tricks tho.

    I'm trying a treble bleed on the bridge volume (but t.b.'s are sketchy on 2 volume controls, so,) and a couple of different Series/Parallel switch schemes. There might be a way to keep separate volume controls with a 4pdt toggle switch, maybe. I'll post a diagram if it works.

    Personally I like the double stacks better than VVT (def better than VVT) and it's quieter on my machine, for whatever reason. I get why people think it's fiddly, but certainly no more than DAW twiddling. I can get both the best scooped echo-y clank and tooth-loosening mids-heavy thump at once with a pick close to the bridge that I cannot get with VVT, it's really fantastic! If I keep buffered bypass pedals out of the chain then 2 transistor fuzz pedals works great, cheap(er) optical compressors, germanium distortion mayhem, all that. Good reasons. I am altho perhaps rambling... Good luck!
    grocker likes this.
  16. Brad Alan Self

    Brad Alan Self

    Jul 20, 2021
    Marked pots backwards above, revised expanded: PXL_20210721_195826685.jpg PXL_20210721_195826685.jpg
  17. Primary

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