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Adding 'Sadowsky-like' Vintage Tone Control to Aguilar OPB-3?

Discussion in 'Pickups & Electronics [BG]' started by ElMon, Jul 5, 2014.


  1. ElMon

    ElMon Supporting Member

    May 30, 2004
    Oklahoma City, OK
    Curious if you could add a vintage tone control to an Aguilar OPB3 preamp? I've searched through some threads, but people seem to be talking about a tone control that works in passive mode only, another mode that has to also be wired in/modded.

    I'm very much a noob on this subject but essentially want to add my favorite feature of Roger's pre, the VTC, to an MTD US 6String with an Aguilar OPB3.

    Thing is, I could've sworn that I read of someone doing this already. If you're out there buddy, swoop on in and school me.
     
    Igor Porto likes this.
  2. It's just a pot and a capacitor. Same as any passive bass. There is nothing special about it.

    You can wire it for passive only, or active and passive.
     
    StayLow and ElMon like this.
  3. ElMon

    ElMon Supporting Member

    May 30, 2004
    Oklahoma City, OK
    I have a five knob with a switch set up. I imagine I would have to turn the bass and treble into concentric pots as well.
     
  4. ElMon

    ElMon Supporting Member

    May 30, 2004
    Oklahoma City, OK
    Anyone with direct experience?
     
  5. rojo412

    rojo412 Sit down, Danny... Supporting Member

    Feb 26, 2000
    Cleveland, OH.
    I've done it many times! The OBP-3 is a great and functional preamp and it's relatively simple to wire, especially with the diagrams they keep so handy.
    http://aguilaramp.com/pdf/support_wiring_obp3.pdf

    You basically are wiring a passive setup and sending into an active preamp, no matter which way you choose to wire it If you are using the bypass switch, it's a passive bass with an active option and tone works on both.
    You may have to get a stacked pot for B-T operations, if you don't want to drill a hole. But you could get a push/pull switch to activate/deactivate the preamp, then run the new pot in the switch hole (which you'd have to widen). Best bet, get the stacked pot and some knobs.

    Wire the pickups as shown in their diagrams, but from the VOLUME OUTPUT, wire in a tone pot like a J bass would have. Send the output of the tone pot to the switch, wire up the rest as shown, KABLAMMO! Passive tone pot is in play.
     
    TonyP- likes this.
  6. ElMon

    ElMon Supporting Member

    May 30, 2004
    Oklahoma City, OK
    I just knew you were out there sir, and I thank ya. On top of that your avatar has probably my all-time favorite character.
    "Smokey, this isn't 'Nam. This is bowling. There are rules."
     
  7. rojo412

    rojo412 Sit down, Danny... Supporting Member

    Feb 26, 2000
    Cleveland, OH.
    Tis my pleasure, sir!
    I'm always happy to hear more obscure quotes from the movie as well :D
     
  8. wvbass

    wvbass Supporting Member

    Mar 1, 2004
    West Virginia
    I have an OBP-3 in my Lakland, and it has five knobs. I wired it V-V-T, so it has a passive tone control. The tone control is push-pull; pull to bypass the preamp. I put the bass and treble on stacked pots, and the mid knob is push pull for the mid frequency shift. I run it at 18V.
     
  9. rojo412

    rojo412 Sit down, Danny... Supporting Member

    Feb 26, 2000
    Cleveland, OH.
    I did that setup in a Squier Deluxe Active J 5, but added a push/pull for the pickups to go into SERIES. Tone monster!

    100_0793.

    DSCN0026.
     
    ElMon likes this.
  10. wvbass

    wvbass Supporting Member

    Mar 1, 2004
    West Virginia
    I was just looking for a picture of my Lakland's innards, but could only find the "before" picture.

    Very cool Squier you've got there.. I did the series mod on my passive jazz bass. Very big sounding. I also put phase switching on a push pull - not the greatest mod for live playing because the "perfect" setting is touchy, but with the neck volume backed off just right, the phase switch doesn't lose all its low end AND has some nice bark.
     
    ElMon likes this.
  11. rojo412

    rojo412 Sit down, Danny... Supporting Member

    Feb 26, 2000
    Cleveland, OH.
    I had a Lakland with an OBP-3 and BigSplits...

    100_1810.

    I actually wired that with the Treble pot missing. I wired in resistors to keep it at the "Middle notch" setting.
    It was Vol-Vol-PTC-B-M with the push/pulls for Active/passive, series/parallel, and mid shift.
    I did that because I never found a use for boosting treble and wanted the PTC in there, but no extra holes in the bass. I also didn't have the stacked pot with that either.

    100_1809.

    Like I said, I've played with a few OBP-3s and had a lot of fun.
     
  12. ElMon

    ElMon Supporting Member

    May 30, 2004
    Oklahoma City, OK
    Stupid question I'm sure, and again I'm SHOCKINGLY ignorant of electronics, but I wanted to make sure that we're actually talking about a tone control that will work in ACTIVE MODE. Not interested in having a passive option that gives me a tone control like a Fender. With my Sadowsky basses, I love to boost the treble and then back off the VTC to taste. Lots of great sounds there.
     
  13. scotch

    scotch It's not rocket science! Supporting Member

    Nov 12, 2006
    Albany, NY USA
    Please see Profile for Endorsement disclosures
    Putting the traditional tone pot "in front" of the preamp will allow you to use the tone control in either mode.

    The preamp just sees whats coming in, so if it is your pickups output with the treble rolled off, that's what it will process.
     
    Last edited: Jul 9, 2014
    ElMon likes this.
  14. rojo412

    rojo412 Sit down, Danny... Supporting Member

    Feb 26, 2000
    Cleveland, OH.
    Having PTC with active is the bee's knees. I enjoyed that a lot with my East preamps. You can mellow the active flavor without killing the treble. It acts differently than an active "treble cut", if you will.
     
  15. ElMon

    ElMon Supporting Member

    May 30, 2004
    Oklahoma City, OK
    Thanks for the reply and to everyone else for the patience. I feel like a 33 year old who is just now realizing how baby's are made. Next stop I'll start a thread asking people to define what 'punchy' means. Or else maybe a thread entitled "Foderas are Too Expensive". Which of course is all relative. If it gets the 'tone in your head', you got a deal at any price.

    (Steps off of soapbox)
     
    scotch likes this.
  16. ElMon

    ElMon Supporting Member

    May 30, 2004
    Oklahoma City, OK
    One more question for you fine folks who have actually taken the plunge (looking at you rojo412): what tone control would you reccommend?
     
  17. scotch

    scotch It's not rocket science! Supporting Member

    Nov 12, 2006
    Albany, NY USA
    Please see Profile for Endorsement disclosures
    Tone control value (250 or 500k) choice really should depend on how bright the pickup/s are. Have a dull humbucker? Use a 500k Pickups a little bright? Use a 250.
     
    ElMon likes this.
  18. wvbass

    wvbass Supporting Member

    Mar 1, 2004
    West Virginia
    I'm a fan of the 250k pot and .022uf capacitor for a tone control. I have one bass that I modded the pot to be no-load. I never decided if I was imagining the difference I heard or not.
     
  19. scotch

    scotch It's not rocket science! Supporting Member

    Nov 12, 2006
    Albany, NY USA
    Please see Profile for Endorsement disclosures
    Oh, audio taper, generally is my preference for passive tone pots. Any value from say 100k to 1meg ohm will work. 100k bleeding more treble and 1meg sounding really bright (with the pot wide open). For instance: standard Fenders come with a 250k, Rickenbackers 330k, a Gibson humbucker 500k, etc...

    Active circuits use much different values.

    For the capacitor, .047 is typical. Anything from about .001 to .1 uf will work. Larger values will roll off more highs.
     
    ElMon likes this.
  20. ElMon

    ElMon Supporting Member

    May 30, 2004
    Oklahoma City, OK
    Just realize you can't see it when I bow towards my iPad
     

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