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Push/pull tone pot for different capacitor values?

Discussion in 'Pickups & Electronics [BG]' started by Finbase, Jun 3, 2014.


  1. Finbase

    Finbase

    Oct 12, 2010
    Espoo, Finland
    Greetings!

    And my apologizes if this is already talked to death. I tried to do the search, but didn't find any precise answer to my question. If there's a similar thread on which the topic has been covered already, please give a link...

    So here's the deal: I have a passive PJ-bass, wired like a regular jazz bass (vol-vol-tone). I'd like to have a single push/pull tone control so that I could use two different capacitor values: 0.047uf and 0.022uf (mainly for soloing the bridge J-mic).

    How should I install the caps and wires to the push/pull potentiometer?

    Thanks in advance!
     
  2. 3747857353_85b885edcf_o.
     
    capicva and jwsturgis like this.
  3. Finbase

    Finbase

    Oct 12, 2010
    Espoo, Finland
    Thanks, line6man!
     
  4. photogdude

    photogdude ustonsucs Supporting Member

    Jul 30, 2010
    Houston, Tx
    Finbase

    did this work out for you, and what effect dd it have?
     
  5. iiipopes

    iiipopes Supporting Member

    May 4, 2009
    In my decades of experience, .022 is too bright for bass, even soloing. I would suggest a .033, which you can get rather inexpensively in an orange drop, which will let more mids through.

    That said, if you have a 500kohm tone pot, with it dimed out for soloing, it doesn't matter much whether the capacitor is .068, .047, .033 or .022, because there is enough resistance to ground that hardly any loading off the top end happens anyway. It only matters when you start rolling off the tone knob.
     
  6. bassbenj

    bassbenj

    Aug 11, 2009
    In all my years of experience I disagree. In effect you are saying is that turning a tone control to the maximum "bright" position is never used in bass playing even for soloing. Excuse me if I"m sceptical. My bass is wired with two caps: .015 and standard value (,047), but I don't use a push pull knob for that. I have a on -off-on mini switch. This gives me three values of cap where the center "off" is as bright as the bass goes. Also it lets you flip from no tone control to some preset tone setting without twiddling knobs.

    But everything else you say is right and anyway, my opinion of bass tone is only valid on MY BASS. On your bass the cap values you choose are what sounds best to you for your kind of playing. With this kind of switching setup it's easy to experiment with various values of caps to see what works for you.
     
  7. iiipopes

    iiipopes Supporting Member

    May 4, 2009
    I believe you read my post backwards. What I said was in my almost 40 years of experience, with a high value tone pot, when it is dimed out there is very little loading to ground, and as a corollary, it doesn't make much difference what tone cap is used if a player only solos with a dimed tone pot.

    But when a tone pot is actually used as it should be, then it does make a difference. A big difference, as you relate. And yes, it can be tailored to the player, in an almost infinite combination of pot values, cap values, and switching arrangements. And that doesn't even take into account further tailoring by bridging the pot wiper to ground with a resistor to tailor the effective load and taper of the pot, or such esoterica as diodes or other circuitry to change the fundamental waveform, or other items such as coils or chokes, as on original EB3 wiring or Bill Lawrence's Q-filter to further tailor the frequency response, or finally, Les Paul's low-impedance approach, which sees modern usage in the Epiphone Jack Cassady. The only one I haven't seen is having an infinitely variable capacitor, like the tuning knob on an old radio, that varies the capacitance to function as a fixed slope with a variable hinge frequency, instead of a conventional tone circuit which has a fixed hinge frequency and variable slope, although the Varitone rotary, with its array of caps, does get close to that by having incremental steps instead of an infinitely variable sweep.

    In other words, for a solo tone, there are many ways to develop a personal tone and style out of passive electronics without resorting to actives.

    Your observation is correct. In my personal playing style, I don't solo that much. It's a personal philosophical thing. I started piano lessons in 1970. I played trumpet, then tuba in school band starting in 1972. I still play tuba. I have played lead electric guitar in many other bands over the years starting in 1975, and I still have my first electric guitar. If I wanted to solo, I'd play one of those instruments. I get more satisfaction making sure the foundation is secure so others sound good soloing, having started on electric bass by reading jazz charts in band camp in 1976, adding tuba that fall, and finally adding double bass a few years ago. I use my tone knob to find a tone that compliments the song being played, so it gets a lot of use, from clank to dub and everything in between. What I have found most useful is the EMG EXB as a variable flat-to-scoop, or vintage-to-modern, or straight-to-slap contour all in one knob so there is no fiddling with knobs between songs or risk of grabbing the wrong knob in the middle of a song.

    That is why in my opinion that a .022 if it is the only tone cap, is too bright for soloing. By itself, it does not give the range of tonal options that other values do, because the hinge frequency is too high. But I can see how, in an array, or a switchable circuit, it can be a viable adjunct as an addition to a more conventional value of cap for straightforward rolloff.
     
    Last edited: Nov 5, 2014
  8. bassbenj

    bassbenj

    Aug 11, 2009
    Yeah, that's what I was saying. The problem I found in experimenting and years of using a standard passive tone control is that sometimes you want the tone turned down and sometimes you want it dimed. I decided that while playing it's better not to fiddle with knobs. Hence the switch. Then buying the switch I saw I could buy an on-off-on spdt switch for the same price as an on-off one. So I did. Then experimenting with various caps (like I recommended) for me what I discovered was that sometimes I want the tone bright but I still want to take the very top end "clank" off of it. The standard cap (.047) just always rolled off too many of the mids and if you tried that you got too much "dub". So I started trying smaller values. Well if the cap was too close to the standard value (like .033) it didn't seem to change much from the standard value. So eventually I decided it really needed to be half or less of the standard value to really be "different" enough. Also the "open" position gives you a brighter sound than when tone is dimed because the tone pot is always in the circuit. If you make the pot a higher value to make the bass brighter, then the tone control doesn't start working until you've gone through quite a bit of rotation so that doesn't work so well. The switch simply disconnects the whole tone circuit and it's like one of those passive wired to jack basses.

    I agree that a small (.022) cap as the only tone cap is not going to work. Nor was I happy trying caps larger than .047. There seems to be a reason why that value is standard. But when you can switch around that is a different story. I've never tried a lot of choices like a varitone, but the quick mod with a cheap switch worked out just fine for me.

    As for push-pull controls, my favorite is to put series/parallel selection on the push-pull knob.
     

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