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Combining passive and active pickups

Discussion in 'Pickups & Electronics [BG]' started by tZer, Mar 17, 2010.


  1. I need your help. I am in the end stages of a bass build and I have a question about pickups.

    I have a set of passive Bartolini J's and an active EMG CS 40. I was wondering if it were possible to use them all in one instrument.

    If so - would it be best to wire it 'either/or' using a simple switch to either use the EMG (active) or the Barts (passive) - or is there a way to combine them where they are all in play?

    I was thinking last night that it wouldn't be hard at all to install both sets and simply switch between them. But I don't want to overlook any other possible configurations if any exist.

    OR does trying to use them all in one instrument make no sense at all?

    Thanks for any input on my output needs!
     
  2. JMaris

    JMaris

    Mar 24, 2009
    Andrews, Tx
    This sounds interresting... I have thought about trying to use one passive jazz puckup and then an active pickup but haven't looked into it too much... Im definately interrested to hear what the people who know what they are talking about have to say...
     
  3. bongomania

    bongomania Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    If you use a preamp with an active blend (East, Glock, Audere, a few others) then there will be no problem combining them any way you like. If you use an either/or switch, there will be no problem whether you use another preamp or just a passive harness.

    Using a passive blend to mix them could work, it's not a total no-no, but I'd expect some weirdness with their respective levels in the blend, as well as possibly some tone funkiness. Hard to say, and probably something that could only be determined for sure by actually trying it out. Could be fine!
     
  4. You are going to need a buffer circuit of some sort to lower the impedance of the passive pickups, otherwise there will be an impedance mismatch.
     
  5. bongomania - I agree that it seems like using both passive and active simultaneously would result in an imbalance. The EMG is very a sensitive pup (well, technically it's 3 pups in one) and the passive Barts are as of yet an unknown quantity. I've had the EMG in another instrument so I know what they're like but I have not used these Barts yet.

    But it seems like the easiest solution IF I wanted to use all three in one instrument would be an either/or setup. It'd be the J's in the standard 60's positions with the EMG soapbar in between sort of like a Stu Hamm Urge Bass...

    I have already routed for the J's at this point.
     
  6. That would be if I tried to use them all at once, right? If I were separating them via the either/or switch, that wouldn't be necessary - right?
     
  7. bassbenj

    bassbenj

    Aug 11, 2009
    yes, so long as you are careful to maintain impedances in both conditions. It depends on the exact pickups you have but most EMGs actives work into 25k while passives usually work into 250k. That's a 10-1 difference!
     
  8. Implications being if I were to switch them while connected to an amp, I could end up shooting a huge signal boost when going from passive to active - right?

    That's a huge problem.

    If I am understanding that correctly, is there a way to make sure both scenarios are equal?

    Forgive me - I am a total newb when it comes to pups, wiring, impedance, etc...
     
  9. Lo-E

    Lo-E

    Dec 19, 2009
    Brooklyn, NY
    Bart makes simple buffer preamps that will drop the impedance of your barts without significantly changing their tone and enable you to use both types of p'ups easily. The added benefit is that you can blend them - much more versatile than an either/or arrangement.

    Since you need a battery in there for the EMGs anyway, just throw the buffer in, too.
     
  10. Thanks for the input.

    I looked at Bartolini's site trying to figure out which buffer I might need and quickly realized I have no clue what I'm doing...

    This all may simply be over my head at this point. Knowing what you do about my situation, can you point me at the right buffered pre setup I'd need to combine my passive J's with the active EMG's?

    If it's too complicated to explain - then don't worry about it... I'll need to do much more research and learning. But if you have a suggestion about what pre/buffer thing to look at, I'm all ears, er... eyes...
     
  11. Are the actives significantly hotter than the passives? The volumes should be about the same, provided that the pickups themselves are close to the same output levels.

    You should be fine when switching between the pickups, but it's combining them that would cause you trouble when the impedances are mismatched.
    The low resistance from the output to ground on the active pickup's circuit would kill off most of the passive pickup's output.
     
  12. I am not sure about their relative levels yet. I've used the EMG's before - alone. I've not used the Barts at all yet. I have no preamp for the Barts - just the pups.

    Before I started thinking about combining them with the EMG's I was just going to wire them up using Fender's standard passive J scheme.

    I'm interested on your opinion as to whether or not this seems like a good idea. I know it's subjective - and I am perfectly happy going with my original plan of a totally passive J setup. But if combining these seems like a good idea I am interested in your thoughts.

    Since this is my own build I can always add the EMG later after I get more savvy with this whole world. Installing the EMG alone is a breeze - wiring up the passive J setup is no prob...
     
  13. bongomania

    bongomania Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    Couple of thoughts:

    Adding a buffer to the Barts essentially makes them "active pickups" for purposes of this scenario. It's a good solution if you just want to blend the J's with the EMG and you don't care if the J's are/sound "active".

    The business about 25K vs 250K and the 10:1 difference is misleading. The reason for smaller values with active components is to keep the output impedance low--it has almost nothing to do with whether a 250K pot will work (perfectly well) for blending or attenuating active pups. If a person is planning to use passive pickups anyway, with their normal unbuffered output, then the output impedance of the active pup's signal post blend pot is totally irrelevant. It becomes even more irrelevant if the plan is to run the whole works into an onboard preamp.

    One other solution is to put a passive attenuator (volume pot) after the EMG pup. That will reduce its level and raise its output impedance, making it much more compatible with blending with the passive pups.
     
  14. OK. The EMG comes pre-wired with a tone and push-pull volume pot. The passive J's will be using a standard passive J wire up.

    So if I incorporated a a switch to go either/or/both and kept the EMG's volume and the J volume(s) in the mix - there'd be 3 volume pots and 2 tone pots total - each responsible for their respective pup.

    If I did no buffering at all and simply went as is, I'd simply balance my pups using these 3 volume pots in a blended scenario.

    So - I could have my 'J alone' sound set up (bridge dimed, neck at 90%) and in 'J mode' I'd be all passive, Jaco-sounding...

    Then switch to 'both' - I'd then dial up my EMG volume pot to balance with the J's...

    Then switch to EMG alone and it'd be all active, no J's - ...

    Am I making sesnse here? If so, that doesn't sound too bad to me... I really do want to keep the passive J's passive. I like that flavor. Adding the ability to access an active sound (Like my Music Man) and have the passive flavor of my Jazz on one instrument would be pretty sweet - I think... I think...
     
  15. bongomania

    bongomania Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    Are you able to tell whether the EMG's volume pot is just straight in line from the output of the preamp, like with one wire from the preamp going to one leg, and a wire from the other leg going to the output jack or tone pot (not back to the preamp)? Or does it loop back to the preamp from the volume pot, and then a different wire goes from the preamp to the output?

    Of course the push-pull switch will have its own wires going to the preamp.
     
  16. If the 25K pots for the EMGs are in the same circuit with the passives, the passives are going to lose most, if not all of their output.
     
  17. bongomania

    bongomania Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    ^^^ True, which is why I was wondering about the specific connection of the EMG's vol. pot. If all it is is a passive attenuator after the preamp, then it could be replaced with a 250K vol. pot.
     
  18. OK - first off, I've been referring to the wrong EMG... (duh) - the EMG I have is actually the 40TW - not the 40CS as previously stated.

    Here's a link to the PDF that goes over all the various hook-up details...

    http://emginc.com/content/wiringdiagrams/40TW_230-0139A.pdf

    I'm going to pour over that a bit and see if it answers anything for me. If you have an opportunity to take a look and have any thoughts - I'm very interested.

    Thanks again for all your input! I hate being in to dark like this!
     
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