Passive and Active Pick-ups looking to Share a Bass, how is this possible?

B

Bassiclyspeakin

Guest
Aug 30, 2017
5
2
4,531
#1
bass pre-amp.jpg Dear Bassheads that are wired with the skills, experience and / or knowledge to pick up (in this case comprehend) and subsequently answer a few questions related to the subject of electronics, if so may I ask you to share your wisdom? Is it possible to have a bass pick-up configuration of two (2) passive side by side jazz bass pick-ups (one being an Seymore Duncan SKT-J2 Hot Stack and the other an S.D. SJB-5 Stack) wired with a series/split/parallel toggle switch, in an active 3 band, 9 VDC pre-amp circuitry? Again these are two (2) “stack” pick-ups placed side by side in the “bridge position”. In the “neck position” I want to put a single EMG-81 or an EMG–HB. Both the EM G’s are active types. That said, can I power both circuits off of a common 9VDC battery and a common output jack? Lastly, how would I wire this all up? And, does any of this need or should not have pick-up cavity shielding or bridge to electronics grounding? I look forward to your literary and schematic answer(s) old or not-so old dear Instrument Wise Wired Wisdom One(s)
 
Last edited:
#2
Passive pickups with a preamp is the typical pairing. If you have active pickups, it is preferable to stick to passive controls. Pairing active pickups with preamps is done on occasion, but it reduces headroom and raises the noisefloor. There isn't much benefit to it, anyway. Mixing active and passive pickups requires either buffering of the passive pickup, or a dual input preamp. (Or active blend pot.) EMG makes a blend pot that can be used, otherwise, it is best to build a buffer from an opamp and a few resistors and capacitors.

Series/split/parallel switching is not functional with split coil pickups. The single coil mode leaves you with output on only two strings. If you try to split things so that two strings come from one pickup and two strings come from the other, then you are still left with the problem of having a very weak output from what is effectively a pickup would with half as much wire as usual. If you have split coils, just do series/parallel switching.

There is no need for multiple batteries or jacks, or any other nonsense. One battery and one output is most practical.
 
  • Like
Reactions: Clark Dark and Crater
#3
^ this is good advice. Pairing active & passive pickups usually has some problems along with it. For the bridge, I'd rather use something like a passive NYC soapbar pickup, which is internally wired for several sounds. Have a pair of them with an active preamp (with a passive switch to turn it off) and you have a seriously versatile bass.
 
#4
First I want to open by expressing my sincere gratitude to any and all your responses to my wiring challenges / inquiries. Dear line6man and other interested parties, my bass was originally wired with The EMG–HB at the bridge position and The EMG-81 at the neck position. The electronics configuration consisted of one (1) volume pot. and one (1) tone pot. for each pick-up, for a total of (4) four pots. All (4) four pots. are identical and rated the same; @25K with a 2A473K capacitor (which I’ve been told are rated at 0.1mf, which all active EMG’s supposedly use) in between the tone and volume pots. Although having EMG’s at both the bridge and neck positions was quiet, punchy and somewhat bright, that combination gave me very little mid-range emphasis. Subsequently, I am hoping to use half (1/2) of that system, IE… one (1) EMG pick-up along with one (1) each prior stated volume and tone pot. and capacitor.
I was hoping to solve my mid-range concerns with The Seymour Duncan pick-ups which I acquired sometime ago. So, apparently with them being passive I can use them with my 3 band pre-amp. But, being that The S.D.’s are “split coil” which I guess is another way of saying “stacked’, right? I cannot do a series/split/parallel wiring, but rather I can do
series / parallel switching instead. That said, do I need a different type of toggle switch? And, if so what type?
Also, in operating both The S.D. passive pick-up / pre-amped circuit along with The EMG active circuit my understanding now is it, “requires either buffering of the passive pickup, or a dual input preamp. (Or active blend pot.) EMG makes a blend pot that can be used, otherwise, it is best to build a buffer from an opamp and a few resistors and capacitors. “ Well, taking in consideration that I’m trying to work with the components I’ve got on hand for the most part. I.E. the active and passive pick-ups, pots, and pre-amp. Can I use the Blend Pot on the Pre-Amp to wire both a single EMG pick-up and circuitry on one lug and the (2) two sets of S.D. stack pick-ups with a series / parallel toggle switch on the other lug of The Blend Pot of The Pre-Amp? And, if not can you Sir / Mr. line6man and / or other such talented types share knowledge on how to “build a buffer from an opamp and a few resistors and capacitors.”
About me, I am a free-lance cover band / home studio bassist, with some skills in lutherie and even less in electronics. But, I’m trying to learn to do some of my own electronic repairs and modifications. Subsequently, I appreciate any and all help on this matter. SE-EMG Pick-ups-Pot's-Cap..JPG SE-EMG Electronics_bk.1.JPG SE-EMG Electronics_frnt.JPG bass pre-amp.jpg
PS. Also thank you Zoobiedood I will be researching the passive NYC soapbar pickup. It sounds very interesting.
PSS. I’ve included some extra pictures as a visual aide. Again help, wiring / block diagrams and /or schematics with components and value rating is seriously appreciated. Sincerely Bassiclyspeakin
 
#5
Bassiclyspeakin said:
these are two (2) “stack” pick-ups placed side by side in the “bridge position”.
Click to expand...
no point in that at all. in parallel you'll get a weaker sound while in series you'll get a muddier sound compared to the EMG in the same place, while the actual tone character won't be all that different (location is the most important factor in what a pickup sounds like).
Bassiclyspeakin said:
I was hoping to solve my mid-range concerns with The Seymour Duncan pick-ups which I acquired sometime ago. So, apparently with them being passive I can use them with my 3 band pre-amp.
Click to expand...
most active preamps will work just fine with active pickups; your most logical path might be just putting that preamp in the bass with the EMGs already in it.

yes there's some "duplication of effort" there as @line6man pointed out but in the real world it works just fine, active EMGs into an active pre on the bass is a very common setup and sounds great.
Bassiclyspeakin said:
being that The S.D.’s are “split coil” which I guess is another way of saying “stacked’, right?
Click to expand...
no; split-coils are not stacks! split coils are end-to end coils, like taking a P bass pickup and stuffing it into a J pickup shell. stacks have one entire single coil all the way across and another one underneath it just to cancel the hum.

dimarzios are split coils, most duncans are stacks (that recently changed with duncan's new "apollo" series J pickups).
 
  • Like
Reactions: Zoobiedood
#6
Thanks Walterw for your technical input and assistance. I am now seriously contemplating utilizing the (active) EMG’s in the bridge and neck positions instead of mixing the combined (passive) Seymour Duncan Stacks in the bridge position and one of The EMG’s in the neck position as I was leaning prior to reading your thread. With that in mind, do you Sir (or anyone else with expertise on these matters) know if it’s possible or I would get any additional tonal benefits from using an on/off toggle switch to interrupt power to The EMG’s, thus fooling the pre-amp to act as if it was reacting to passive pick-up’s? This is kind of a variation inspired by what Zoobiedood contributed “…. an active preamp (with a passive switch to turn it off) and you have a seriously versatile bass.” As you can tell I’m really looking (using for the most part the electronic parts I already have) to get a lot of mid-range tones from my electronics. This is of course without sacrificing powerful, undistorted, tight lows and snappy highs. And, anytime I think of the higher frequencies it brings to mind signal to noise ratios, unexpected noise, hum and buzz. That said, I ask again as I asked from my initial thread. Does any of this need or should not have pick-up cavity shielding or bridge to electronics grounding? I look forward to your replies old or not-so old dear Instrumentally Wise Wired One(s)
 
  • Like
Reactions: Zoobiedood
#7
Bassiclyspeakin said:
With that in mind, do you Sir (or anyone else with expertise on these matters) know if it’s possible or I would get any additional tonal benefits from using an on/off toggle switch to interrupt power to The EMG’s, thus fooling the pre-amp to act as if it was reacting to passive pick-up’s?
Click to expand...

That's not how it works. Active pickups have a preamp stage between the pickup coils and the output leads. If there is no power, then the transistors cannot conduct. This means that you have no signal, except for whatever tiny bit passes through the circuit's resistors. EMG pickups will always require 9V DC power.
 
#9
Thanks line6man. For clearing up my understanding on "tonal benefits from using an on/off toggle switch to interrupt power to The EMG’s, thus fooling the pre-amp to act as if it was reacting to passive pick-up’s". Now I understand that It won't work.
In reference to the 0.047uF capacitor that you noted that the "473" indicates. Could that be part of the reasons why I have such limited mid-range tone variation coming from my EMG pick-ups, since I heard that active EMG's utilize an 0.1uF capacitor? Do you or anyone else know the real deal on this matter?
 
#10
Bassiclyspeakin said:
Thanks line6man. For clearing up my understanding on "tonal benefits from using an on/off toggle switch to interrupt power to The EMG’s, thus fooling the pre-amp to act as if it was reacting to passive pick-up’s". Now I understand that It won't work.
In reference to the 0.047uF capacitor that you noted that the "473" indicates. Could that be part of the reasons why I have such limited mid-range tone variation coming from my EMG pick-ups, since I heard that active EMG's utilize an 0.1uF capacitor? Do you or anyone else know the real deal on this matter?
Click to expand...

0.047uF is the standard value for most basses, however, EMG pickups have a lower output impedance than ordinary passive pickups, so the frequency cutoff is shifted upward with that value. Higher values like 0.1uF are often used to bring the frequency cutoff back down to where most people like it, but it all comes down to taste. If you want to experiment with other values, the effect is analogous to adjusting the frequency knob on a parametric equalizer.
 
#11
Once again (Mr.) line6man thank you for your obvious expertise, answers and patience on my several questions related to pick-ups, wiring related components. And, of course thank you Talk Bass for allowing us Bass-Heads in, and providing us with a great and needed forum and environment to nurture, learn, share, inspire and avoid being strung-out by our well intended yet still low down tendencies to be at the very root of note worthy things:bassist:
Ciao for now Bassiclyspeakin
 
  • Like
Reactions: line6man
You must log in or register to reply here.
Top Bottom
Back