Modding a Bass Balls for CV expression sweep?

Discussion in 'Effects [BG]' started by rnilson, Jul 29, 2009.

  1. rnilson


    Mar 8, 2008
    Kansas City, MO
    How hard would it be to mod a Bass Balls to have a input jack for active CV (0-5 volt) expression sweep of the main freq knob?
  2. dont have much experience in modding, i just clicked the thread cause you obviously mispelled bass balls in the title :p

    modding a bass bass! :p
  3. *chants* bass bass bass bass bass

    My guess is that is may be very hard, if not impossible to do; I have inquired about having a few pedals modded for CV inputs- some where there was already an exp input, and some where there were currently no inputs, and the creators/builders of each basically told me that it would not be possible for various reasons- wrong voltage range, cost prohibitive, etc.

    For instance, I asked Howard Davis about having the Polychorus modded for CV control over Manual and Resonance on a Polychorus- It would take some redesigning of the pedal, ie labor cost, and take about 12-13 volts to maintain a full sweep. The Resonance knob could not be controlled with an active CV, but could have an input controllable by a 50k volume taper volume pedal.

    I've also had a passive CV input changed to active in my Photron, and that one seemed to be an easy change, although it took me a bit to figure out the scaling- now that I've been through the process I could figure it out in a few hours with another pedal, assuming it was at or below the 0/5v range. My photron was done before Mario implemented that CV scaling knob in your pedal so mine is at a fixed range, with full sweep (full sweep in relation to the moog at +5v) happening at about .7v.

    Anyway thats all the info I have- The Bass-bass may be rigged up to easily accept the input, but from my limited experience, there's also a good chance that it may not be feasible. Im interested to find out either way.
  4. dannybuoy


    Aug 3, 2005
    It would be easier to mod it to use an expression pedal (which is effectively just a potentiometer) in place of the knob, but if you want CV it will be much trickier because you're trying to replace a component that varies resistance with a variable voltage supply.

    It might be possible to use CV to control the manual sweep of a filter though, by applying the CV voltage instead of the envelope follower to part of the circuit that controls the filter cutoff. The BYOC 440 clone does something similar with it's 'fixed wah' mode, it cuts off the envelope follower to the LDR and instead feeds in a constant voltage that's controlled by a knob. It depends on the circuit design as to whether a DC signal can pass through to achieve this, it works on the LDR in the 440 but no idea about the Bassballs!
  5. biftaclyro


    Mar 10, 2009
    Sorry if this is a noob question (did a quick search) but what's the difference between cv expression input and a normal expression input ie just contolling the sweep of a knob?
  6. As mentioned above, a CV input supplies a variable voltage.
    An expression pedal supplies a variable resistance.
  7. biftaclyro


    Mar 10, 2009
    hmm, i think i understand, cheers