Ultimate No-load Ungrounded Blend Pot (Pics!)

Discussion in 'Pickups & Electronics [BG]' started by walterw, Aug 13, 2014.


  1. walterw

    walterw Supportive Fender Commercial User

    Feb 20, 2009
    alpha-music.com
    Yep.

    I think j basses had audio pots because all fenders had audio pots, they used the same pot for everything.

    Linear volumes will have a smooth sweep from off to full rather than that "kick" right near the top.

    Tons and tons of threads about this (I'm in lots of them:))
     
  2. vin97

    vin97

    Mar 7, 2016
    Germany
    Small update: I got a 100kΩ M/N blend pot from here, cut the traces (no-load), sawed off the excess shaft and installed it according to walter's diagram (unground).
    As walter suspected, it's right in the sweet spot and offers the optimal blending IMO (I also tested 250K and 50K pots).
    Little bonus: The pot is quite robust (compared to the Bourns), making the "no-load mod" much less of a hassle and it fits the standard hole diameter.
     
    Last edited: May 12, 2017
  3. Hi walterw. will this work with a PJ? Thanks.
     
    PawleeP likes this.
  4. walterw

    walterw Supportive Fender Commercial User

    Feb 20, 2009
    alpha-music.com
    sure, any two pickups.
     
    Arnel M. likes this.
  5. BunchyMutt

    BunchyMutt Supporting Member

    Jul 3, 2014
    Nashville, TN
    Any chance you could repost direct to TB? I'm only seeing the photo bucket "please update your account.." message.
     
    Last edited: Aug 16, 2017
  6. JayGunn

    JayGunn Supporting Member

    Jan 24, 2010
    Chapel Hill NC
    Me too!
     
  7. BunchyMutt

    BunchyMutt Supporting Member

    Jul 3, 2014
    Nashville, TN
  8. vin97

    vin97

    Mar 7, 2016
    Germany
    jazz bass ungrounded blend.jpg
     
    PawleeP likes this.
  9. walterw

    walterw Supportive Fender Commercial User

    Feb 20, 2009
    alpha-music.com
    yeah, g*****n photobucket just erased half the internet; i'll re-do the pics pretty soon.

    [edit: TB has pulled off a miracle and fixed it!]
     
    Last edited: Oct 12, 2017
    GentProvocateur likes this.
  10. BunchyMutt

    BunchyMutt Supporting Member

    Jul 3, 2014
    Nashville, TN
    Thanks! That would explain the sudden lack of photos across the board
     
  11. rhaas

    rhaas

    Aug 26, 2017
    I just did this mod while installing a set of Area J's in a second-hand MIM Jazz that I recently picked up. Played with some buddies this afternoon and I don't think I'll ever go back to a VVT setup.

    Thanks @walterw !
     
    Arnel M. and 4StringTheorist like this.
  12. tallboybass

    tallboybass Supporting Member Supporting Member

    Feb 25, 2003
    Tulsa, Oklahoma
    What a great thread...thanks to all who have responded!
     
  13. WhtMtnGrv

    WhtMtnGrv Supporting Member

    Nov 1, 2015
    Crestline, CA
    I'm thrilled to have come across this thread as I wade through my PJ build (Low End PJ Build (With Pics!) Complete with Questionable Squier DNA). I'm looking to do the master volume, blend, and master tone set up, however Im having trouble reconciling a couple things in my mind. Keep in mind I'm not an expert- quite the opposite, especially with wiring.

    Here is one example- Also I'm aware that I need to really start studying this stuff so I can not only understand what to do when I want to wire something up, but WHY I need to do it to achieve a certain result:

    p_j_bass_blend.jpg

    I'm trying to match up your diagram to ones I've seen online (Seymour Duncan above for example) and it's not exactly a replica (not saying it should be- I just really don't know what I'm looking at as far as actual electrical implications of different wiring options, this lug to that lug, this wire to that lug, etc). I see in the above what appears to be an extra wire between the outermost diagonal lugs on the blend pot, an extra wire connection from middle lug of tone pot to jack tip.

    What I've read (trying to find the thread) is that there is a standard way to wire up a PJ setup where:

    Blend rolled all the way toward neck= 100% Neck
    Blend at center/middle position= 50% neck, 50% bridge
    Blend rolled all the way toward bridge= 100% bridge.

    Instead what I've come across poring through the interwebz and what I'd like to achieve is a set up where the middle/center position on the blend knob yields 100% neck and 100% bridge. Is that even possible or am I making things up?

    Lastly, I'm trying to determine the difference between a M/N blend pot and a non M/N blend pot. I can't seem to pin down the difference, if any. I've got an Alpha 250k blend pot on order from Stewmac but no indication of M/N'ness is listed in the product description...

    Screen Shot 2017-09-30 at 10.57.44 AM.png

    Since the vast majority of the time I'll have the blend pot in the middle, I probably don't need to cut the traces so as to completely isolate one pickup or t'other, but I'd like the option to if the mod is as simple as it seems.

    My bigger objective would be the 100% neck and 100% bridge volume at middle position on the blend knob. Does that require special wiring or is that achieved using a standard PJ wiring, whatever that is?

    My apologies for my ignorance on the subject and I appreciate any help you lovely folks might be able to lend!

    EDIT- Of course about 4 minutes after I post, I find the difference between MN and AC pots- MN gives you the 100% neck and 100% bridge at middle, AC is 50/50... Now to determine if the alpha blend pot I ordered is MN or AC :rollno:
     
    Last edited: Sep 30, 2017
  14. walterw

    walterw Supportive Fender Commercial User

    Feb 20, 2009
    alpha-music.com
    talkbass has done the impossible and rescued all their photobucket pics! they've literally gone back and fixed a good decade plus of TB posts wrecked by photobucket.

    i'll delete these, they're no longer needed.
     
    MovinTarget and khutch like this.
  15. khutch

    khutch Praise Harp

    Aug 20, 2011
    suburban Chicago
    One of many reasons why we love TB so!
     
    MovinTarget and BlueTalon like this.
  16. screefer

    screefer

    Nov 7, 2017
    The Island
    Hello, New member here.
    Regarding cutting the traces on the blend pot.....when you cut the traces, where is the knob position? Center detente or either side? I understand the why but am struggling with the how. I have a 250K Alpha blend pot from stew-mac.
    Thanks all
     
  17. khutch

    khutch Praise Harp

    Aug 20, 2011
    suburban Chicago
    It can be anywhere really but you don't want it in the way of the cut or close enough to get damaged so center detent is fine, or turned all the way the other way.
     
  18. screefer

    screefer

    Nov 7, 2017
    The Island
    Thank you very much. I want to employ this scheme on my new Mikro...
     
  19. screefer

    screefer

    Nov 7, 2017
    The Island
    So I performed the cuts with a needle file and the top works like this...when looking at the pot knob end up and the two probes on the center and right lugs of the top row, the reading from center detente is SHORT. Turning the knob counter clockwise it reads 0-239 and when it reaches the end OPEN. As I understand this is right?
    However on the bottom row now matter where I put the probes, the reading is OPEN no matter where the wiper is. So I took the bottom apart and attached is a pic of the lower wafer.
    Where am I going wrong?
    Thanks DSCN0599.JPG
     
  20. vin97

    vin97

    Mar 7, 2016
    Germany
    Maybe you damaged the little rotating metal arms.
    Happened to me with the Bourns pot, it's not very robust. Did you disassemble the pot to do the mod?
     
  21. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
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