yamaha rbx375 passive conversion.

Discussion in 'Pickups & Electronics [BG]' started by 2liveis2die, Mar 22, 2014.


  1. 2liveis2die

    2liveis2die

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    Ive been wanting to go passive with my Yamaha rbx375 bass.

    IIRC the pickups are passive with an active eq.

    My question is can I use leftover emg pots to replace the eq??

    I have 3 volume pots an active tone pot and a passive tone pot and a pickup bus spare due to missing parts from my EMG PJX pickups. emg sent me a complete wiring loom as a replacement so I have a surplus of parts.

    can this be done? I don't particularly want to pull the active eq out to find it doesn't work.

    Thanks

    Barry
     
  2. JustForSport

    JustForSport

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    Just bypass the EQ, and add a tone pot: 250k- 500k.
    Most EMG stuff won't work with your passive pups, unless the EMG stuff was for the EMG HZ series.
    You can use a push-pull vol pot to cut the EQ in or out (or temp use a toggle bypass switch) to see how you like it,
    but there'll be no tone pot 'til you add one.
     
  3. line6man

    line6man

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    What value are the pots?
     
  4. 2liveis2die

    2liveis2die

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    .
    All the pots are 25k

    Looks like I need to invest in some pots.
     
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  6. line6man

    line6man

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    That's too low for standard high impedance signals, so you will indeed need new pots.
     
  7. 2liveis2die

    2liveis2die

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    Thanks for the help. Time to go pot hunting. Dont think anywhere near me sells pots.:spit:
     
  8. JustForSport

    JustForSport

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    RBX375 has passive pickups, so vol/vol or vol/bal and tone pots should be 250k or 500k.
    Your pickup leads go straight to the EQ board?
     
  9. 2liveis2die

    2liveis2die

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    Its in my bands rehearsal room so I don't have access to it tonight. ill go out and have a look tomorrow.

    Are you saying that just the bass and tone pots might be the active circuit, and the volume and balance passive?

    IIRC I think its all on one board. ill have a good look tomorrow. I'm new to guitar/bass electronics so its a lot to wrap my head around at the moment.
     
  10. JustForSport

    JustForSport

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    If the pickups go to vol and/or bal pots before the EQ, they should be 250k or 500k.
    If you have all 25k pots, then the passive pickups must go straight to the EQ board (which lowers output impedance) first, and the signal goes thru the pots and out to the jack.
     
  11. 2liveis2die

    2liveis2die

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  12. subdude67

    subdude67

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    I posted that thread. I went for a V/T - V/T configuration so I swapped all the pots with quality parts.

    the pots were the main reason I went passive, the electronics are just not that great in this otherwise very well made bass.

    of the original pots, only the blend pot can be used in a passive circuit.
     
  13. 2liveis2die

    2liveis2die

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    Your thread was a great help. I probably should have used the search function before posting.

    Stealth really answered everything I've asked thus far.

    Do you think it's worth going passive??
     
  14. Stealth

    Stealth Supporting Member

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    Schematic author here. While I still haven't altered my RBX375 (I intended a preamp switch), I'd heard subdude67's and I really like how that turned out.
     
  15. subdude67

    subdude67

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    although I can say nothing bad about the sound in active mode, I simply didn't need it, the EQ was always in the exact same setting, even the blend pot got little use.

    when the pots started get noisy I decided to go all the way and turn it into passive.

    I would do it again in a heart beat!
     
  16. 2liveis2die

    2liveis2die

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    Ah brilliant, If I were to want a V/B/T would I put the blend first then volume them tone? similar to this schematic you drew?

     
  17. 2liveis2die

    2liveis2die

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    I think ill go passive as I don't own a passive bass, and haven't for nearly a decade now. I think its time again.
     
  18. Stealth

    Stealth Supporting Member

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    Essentially, yes, in that case, V/B/T actually has the blend first, then the volume, then the tone. The schematic I'd drawn is kind of reverse, because you have two individual tones.

    To summarize, if you wanted:
    • V/V/T/T wiring (individual volumes and tones like subdude67's) you'd use this wiring.
    • T/T/B/V (individual tones, blend and master volume) you'd use this wiring.
    • B/V/T (blend, master volume, master tone) you'd use this wiring.
     
  19. 2liveis2die

    2liveis2die

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    Thanks a lot. Great help.
     

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