1. Please take 30 seconds to register your free account to remove most ads, post topics, make friends, earn reward points at our store, and more!  
    TalkBass.com has been uniting the low end since 1998.  Join us! :)

Question about electronics....mainly pots and wiring.....will this work???????

Discussion in 'Pickups & Electronics [BG]' started by g4string, Jan 4, 2013.

  1. g4string

    g4string Supporting Member

    Sep 19, 2002
    Melissa, TX
    I posted a thread about helping me decide how to configure a new setup for a bass I am installing a pair of big singles in. I have 4 holes to fill on my bass body. I think I have decided to go V V T, with a dummy pot installed in the 4th hole. I opted away from using the blend. However, this got me thinking....can you do a master volume for the bass but still have volume controls for each pickup.....so each pickups respective volume control works in tandem with the others control to give you a blend effect. I would have a master volume, neck pup volume, bridge pup volume, and master tone. Would this work....or is it feasible. I like the idea of not using the blend and going V V T. However, I would greatly miss not having a "master" volume control. I think going V v v T is a nice compromise between the two. Whadda think.
  2. A lot of people have done it.
    It's no different, electrically, than a VBT setup.
  3. g4string

    g4string Supporting Member

    Sep 19, 2002
    Melissa, TX
    Hmmmm. Ok, I guess the thing about the blend knob is that it acts more like a switch than a true variable potentiometer when wired in a passive setup. So doing a V v v set up will work the same way? Weird. Ok....so the only way to get true variable volume control is to run V V.... correct?
  4. smeet

    smeet Gold Supporting Member

    Nov 27, 2006
    Woodland Hills, CA
    It's not really like a switch, it's just that the taper doesn't sound linear. You get most of the audible change pretty close to the center point. I believe you can still get all the same tones with either a VV or VB. The VV has a nicer taper on each V, but the VB has the advantage of being able to change your overall volume without changing the tone. They all do the same thing, choose the one that feels the best for the way you want to play.
  5. two fingers

    two fingers Opinionated blowhard. But not mad about it. Gold Supporting Member

    Feb 7, 2005
    Eastern NC USA
    OK I'm new to the electronics game (first year college student). But my gut tells me this. It will work. However, the roll off will be pretty extreme towards to lower ends of both the master and pickup volume controls. Let's see if I can explain what I'm thinking. Pots are variable resistors. The more you turn them to the left, the more resistance there is. Now, in series, if you were to turn the master from 10 down to (let's just say) 6 (or turn down 4 "units"), and then turn the pickup volume from 10 to 6, you have increased the resistance by 8 units (whatever those units wind up being on your particular pot value), not 4. Does that make sense? So while it would work, I bet it would roll off pretty quickly when using both the master and pickup volumes turning down. So, let's just say you want your overall volume (master volume) to be about 80% of wide open. But you want the neck pickup to stand out more than that bridge. I would dime the neck and roll off ever so slightly on the bridge using a lighter hand than you normally would with a regular VVT setup. Because already having reduced volume (increased resistance) using the master, you will lose the bridge altogether if you get heavy handed turning it down. That was way too long but I hope it helps. (And, heck, it could be totally wrong, but hopefully someone will come along a sweep me aside if it is..... ha!)

    Line6man has probably forgotten more than I'll ever know about this kind of thing, so I absolutely yield to him on this.

    I'm perfectly willing to take it on the chin if I'm wrong. Again, it's just my gut reaction to your question at a very early level of my training. Best of luck with your project.

    Paging! Line6man and B-string! Please come over here and straighten out my mess!
  6. JoeWPgh


    Dec 21, 2012
    I'm not a fan of blend pots. I see no reason to run a comparatively weak signal through multiple potentiometers. If you need to fill 4 existing holes, I would go with V/T/V/T
  7. walterw

    walterw Supportive Fender Gold Supporting Member Commercial User

    Feb 20, 2009
    yeah, but then you've got 2 tone pots that both affect everything, kinda pointless.

    the V vv thing could work, but would be kinda redundant, and too easy to mess up on stage (like if you have both "v's" down a little then maxing out the "V" would still not have full volume.)

    also, you'd again have the issue of too many pots loading down the signal, causing dullness.

    one way to avoid that is to not connect the ground tabs of the "v" pots, so they don't load the signal. this means they won't turn a pickup quite all the way off, but you'll still only really hear the other pickup. (this is the same principle of the "ungrounded blend pot" thing.)

    that, and using linear pots for V and vv might work reasonably well.

    you could also stick with a more logical V/V or V/BL, then use two master tones, each with very different caps, like a .01μF and a .05μF.

    the smaller cap would just chop off the high treble, the bigger one would be a normal tone rolloff, and both would add together to be a little darker still.
  8. Nah. Two tones doesn't work without resistors, which kills output. Not worth it.
    To answer the question, yes you can, but again, not worth the tone loss you get by adding another pot to the signal. Using two volumes takes about 5 minutes to master. Not a big deal at all.
  9. If you have a blend that behaves as a switch, one or more of three problems are to blame:
    1. Bad taper.
    2. Wrong resistance range for the signal's impedance.
    3. Impedance mismatches that cause funny behavior when blending.

    Yes, when you have a volume pot feeding into another volume pot, rolling both down increases the resistance in series with the signal path to the sum of the two resistance values for wherever the pots are dialed in. It also decreases the resistance parallel to the output, following this formula: R[SUB]Total[/SUB]=1/([1/R[SUB]1[/SUB]]+[1/R[SUB]2[/SUB]])

    Now with that being said, you don't normally turn both pickup volumes down at the same time. When you want one pickup, you turn one volume all the way up, the other all the way down, and then control the master volume with the master volume knob. If you want both pickups on full, you turn both pickup volumes all the way up. If you want a mix of two pickups, you turn one all the way up, and turn the other down to taste.

    The same goes for a blend pot. Note that a blend is simply two volume pots in inverse-parallel sharing one shaft. One pickup always connects to the output, while favoring one pickup is the equivalent of rolling one volume down in a VVT setup.

    GODSBASSMAN Supporting Member

    Feb 2, 2005
    S. Carolina
    I would do V V T push/pull for series / parallel switching. How about that?
  11. Cadfael


    Jan 4, 2013
    Germany, EU
    VvvT is no problem at all!
    Have a look at drwaing 1.4.21 (page 133 at the moment) in my bass wiring compendium.
    It showns you a Gretsh Bass with VvvT. The only difference is the toggle switch.
    The vv pots have to be wired like in a Jazz Bass without toggle switch. Just change the "middle an left wire" (right ground stays). Middle goes to PUs then and "left" to "left" of Master Volume.

    Drawing 2.1.11 (page 227 at the moment) showns you a Vvv Jazz Bass. just add a parallel T and you also have VvvT ...

    Here you find my 360 pages bass wiring compendium as PDF (5.5 MB):
  12. DaveyM69


    Jan 1, 2011
    I use VvvT... along a switch for series/parallel and another switch which adds another 47uF cap in parallel to the one on the tone pot to give a deeper roll off frequency. All this works really well!

    A lot of people say the V in a Vvvx is redundant but I disagree. I can balance my pickups as I like and still have control over the overall volume. I prefer vv to blend but it's essentially the same as VBT.
  13. T-34


    Aug 11, 2005
    France, Paris region
    And for the sake of saving one hole (like in passive Jazz having only three), it could be wired V - concentric vv - t...
  14. walterw

    walterw Supportive Fender Gold Supporting Member Commercial User

    Feb 20, 2009
    now that's just silly ;)

    if you have a 3-hole setup, there's no reason to shoehorn the redundant volume control in there; V/V or V/BL will do everything you need.
  15. T-34


    Aug 11, 2005
    France, Paris region
    Actually there is :)
    In the case of the JB wiring, the tone control behaves differently depending on wether volumes are full on or turned down: in the "both volumes down" positions the tone control cuts much more high frequencies than in full on. A balance control with both pickups at 100% in the middle position doesn't give this possibility one could be searching for.

    Now, I am not one of this people and I don't like this peculiar tone control behavior but I can imagine there are people who would like that (don't know, reggey or dub players maybe?)