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Sting Bass circuit mod project

Discussion in 'Pickups & Electronics [BG]' started by Greggo, May 1, 2009.


  1. Greggo

    Greggo Supporting Member

    Apr 30, 2009
    Newbie here, working with a cool tech/builder on a customized Fender Sting bass. Rather than just leave this all up to him, I am searching for ideas to throw at him. Want to rip out the volume and tone pots, and instead install three toggle switches, all of them simple two way toggles that are either on or bypassed. I normally play my passive basses wide open anyways and was just going to wire this baby up direct from pickup to jack, but this old school single coil that fender uses in the Sting signature bass is very hot and very bright, so I want to tame it down a bit. Here are some ideas, but I could really use your help:

    1) have one toggle simply be a roughly 3dB attenuator, so keep it on for most playing and turn it off for a bit hotter signal for solo's or something...

    2) have a second toggle activate a first order filter that slowly rolls of the highs at one x db per octave starting at around 4kHz or something or maybe look for a good passive eq circuit that would fit in the control cavity and compliment the sound of this bass..

    3) have a third toggle switch that offers a similar circuit to the above that has some use toggled on independently but also provides a usefull tone when used in conjunction with the other one...

    I am just starting some research here and on other sites to dig up anything similar. I have found some examples of folks being happy with a straight wire form pickup to jack on a regular P-Bass, but I am afraid it would be too hot and too bright with this particular stock single coil in the Sting bass and I want to keep the stock pickup. So maybe a resistor in place to help simulate a volume or tone pot, and then maybe some custom eq filters as described above, but I am still looking for examples/ideas here across the board. My main goal to make this bass unique is to simply have three toggle switches and no knobs of any kind (no pots to get crackly or cranky). I am going for a clean punk rock sound for recording and not worried about gigging with this thing. Only studio work to have an energetic bass in my arsenal that is only good for rocking out with a pick but has some range from piano like tones to aggressive punk rock raw energy.

    Thanks for any and all help.

    Regards,

    Greg Jensen
     
  2. koobie

    koobie

    Jul 11, 2007
    Portland OR
    I look forward to reading other suggestions you might get for your Sting, I stayed in a pretty basic direction with mine.

    For recording use, I wouldn't personally be satisfied with the buzz & noise the stock SCPB pickup (or any other SC pickup) can suffer from. To get a quieter noise-floor and increase the tonal options in my Sting, I replaced a Duncan SCPB-2 & then a Lollar SCPB with a Fralin stacked p.u. and was pretty happy with with the results. Well, I mostly dug it but I would have preferred just a bit more push in the mids like you can get from a conventional Split P pickup.

    The Fralin pickup has plenty of high end that can be effectively rolled off with the stock tone control pot. Prior to installing the Fralin, in an effort to get a more direct & focused tone I bypassed the tone and volume pots and was disappointed with the results, the highs got kind of harsh. If I wanted more tonal variations on a single-coil P bass I'd probably consider adding a second pickup closer to the bridge, instead of going the route of fixed resistors. My .02 worth is to stick with the pots, with the Fralin they allowed for a surprising amount of tone & drive shading.
     
  3. testing1two

    testing1two Gold Supporting Member

    Feb 25, 2009
    Southern California
    I know active seems like blasphemy in this type of bass but I think you would benefit greatly from the Sadowsky preamp with vintage tone control and active/passive switch.

    Like this:
    PBass1.
     
  4. Greggo

    Greggo Supporting Member

    Apr 30, 2009
    Thanks for the feedback so far guys, it is much appreciated...

    Testing1Two, that is a very nice looking bass and I bet it sounds great. Is that a Sadowsky bass or a fender or other build that you had modified with the Sadowsky preamp?

    Koobie, thanks for your thoughts on this and sharing your experience. I am hoping to get where I want to go with my unusual approach here and will certainly document my progress and do my best to give objective descriptions of the change in sound as I go. My bass chops may be a bit sad (just picking things up again after a 20 year break from music) but my ears and understanding of sound recording and reproduction is pretty decent (OK, I am an audiophile and I know that leaves me open to substantial ridicule, as does being a musician or audio engineer if you happen to participate on audiophile forums...)

    I don't think this Fender Sting P-Bass is the ultimate bass by any stretch, and probably not the even close to a flexible studio axe, but there is something I really like about the basic sound here and I am trying to just zero in on it and clean it up with this project, remove all pots and keep things very clean and simple with a few LCR circuit choices that help the stock pickup stay in the zone and be done with it.

    Regards,

    Greg Jensen
     
  5. Jjango

    Jjango

    Nov 16, 2007
    Los Angeles, CA
    Could one obtain the same results with the Sadowsky outboard pre?
     
  6. 62bass

    62bass

    Apr 3, 2005
    Nice bass. Is that a Kent Armstrong pickup?
     
  7. walterw

    walterw Supportive Fender Gold Supporting Member Commercial User

    Feb 20, 2009
    alpha-music.com

    ok, let's see here. a "3dB attenuator" might be tricky to preset, since the amount of actual volume drop you hear will vary depending on what the bass is plugged into. it might be better to make it adjustable. the sting bass pickup is not especially "hot", but it does have a strong attack due to the poles being right under the strings. as such, it would be good to load it down just a little, maybe with a 250k resistor across hot and ground.

    as for the other two toggles, again it can be hard to judge ahead of time how much treble rolloff you might need, as it can vary from amp to amp and situation to situation. as such, it might be advisable to also make the treble filter adjustable.

    so we'd have an adjustable output attenuator that puts a 250k load on the pickup, and a continuously adjustable treble filter.

    oh wait, that's what you have now. :D
     
  8. Greggo

    Greggo Supporting Member

    Apr 30, 2009
    Walter,

    Thanks for the feedback, I think... : )

    OK, so the stock pickup is not really that hot, but I was really speaking to the idea that if wired direct to jack, that the resonant feq and peak of the pickup would probably change with it and not for the better.

    3dB hard to pin down due to all those potential amp situations? what about cables too? Yes, there are plenty of variables out there but do they really defeat the possible upside of this experiment? This is a project for a bass that is going to be used 90% of the time in a home studio and the other 10% of the time going into my Hartke LH500 / Fender 8x10. I don't see other guys posting about how they normally dial back a tad on the volume pot to get their sound sqaured away and then open it up wide for a solo or something... and that the degree to which they do this changes dramatically with the amp/cable that happens to be in play. Does it really change that much, and would a rough 3dB be that hard to approximate? Help me understand further if you would be so kind.

    Anyone, PLEASE HELP... I am looking for good references on the internet as to exactly how a tone pot works, what are the components involved and do they create something like a first order slope roll off with the variable pot simply setting the frequency where the roll off begins or does it adjust the intensity of the roll off ??? And finally, the whole point of this exercise is to simply try something different: If I am going to use a single coil passive bass guitar for recording work, is there a benefit to sheilding everything as much as possible and using fixed value components and toggle switches to dial in just a basic sound at the guitar and save the fine tuning for preamps/mixing console rather than having pots in the signal path of the bass itself which I personally believe must cause some degree of noise that a fixed circuit (no potentiometers) would not?

    Appreciate any further insights into my proposed experiment.

    Once I get going with my tech/builder in the next week or so I will update this thread with his recommendations and our agreed upon path forward.

    Regards,

    Greg Jensen
     
  9. Greggo

    Greggo Supporting Member

    Apr 30, 2009
    ....and for anyone besides myself still reading at this point, here is the real objective of this project:

    1) I think this particular bass, and most basses for that matter, have a particular sound that seems to suit them better than most.. a kind of "zone" if you will where everything about that bass is working for the sound rather than against it. I am trying to find that sound and just fix it (with a fixed circuit that is simply on or off at any given moment, or maybe just a few very similar variations on the same theme, but fixed in value) rather than dial it in with pots on the guitar...

    2) I think pots introduce noise, obviously when they reach a point where they get a bit scratchy sounding and need cleaning, but maybe not so obviously even when they are in perfectly fine shape. If there was a setting that was reached with a combination of volume and tone potentiometers, would it be possible to replicate that sound but have an even cleaner signal coming out of the guitar if that circuit was "fixed" instead of being "variable", because in most things audio, that seems to be the case (not always, and certainly not with well engineered components, but with commodity components it seems to be the rule)

    3) Yes, there is a good reason for most of the common things we experience in our bass, our amp, etc... but if I don't feel the need for the ultimate in flexibility at my bass, and I am content to simply exercise all the wonderfull volume and tonal flexibility that my amp head or DI preamp or mixing board channel affords me, is it realy so bad to strip my bass down to the bare essentials in hope of getting closer to the soul of the instrment (strings, wood and magnets)???

    Again, any and all thoughts are much appreciated.

    Regards,

    Greg Jensen
     
  10. walterw

    walterw Supportive Fender Gold Supporting Member Commercial User

    Feb 20, 2009
    alpha-music.com
    my smartassery aside, good pots are not going to add noise, especially in something as simple as a p-bass circuit, where typically the volume is always full-up, and the tone is tweaked to taste for a given song. the faint "benefit" of replacing them with preset switches just doesn't begin to outweigh the real drawback of losing control over your bass's output.

    for example, if you're playing through a compressed and grindy rig, you'd need to drop the volume knob a good bit to get an actual volume decrease, while with a bone-dry clean "reference" rig, the slightest twist of the knob will drop the sound output immediately.

    considering the amount of time bassists spend playing "lead" vs. just playing bass, most will leave the volume on full (as that usually sounds the best), and just have a pedal or something. a bass player in a good band won't even need that, because the rest of the band will know to drop it way down when it's time for an actual bass solo. (assuming it's ever time for an actual bass solo. :rolleyes:)

    if you want to squeeze some extra "juice" out of that pickup, you could try opening up the circuit with 500k pots instead of 250k. (i like this sound with passive basses, and recommend a linear volume and an audio taper tone to keep an even sweep in both controls.)

    the 500k volume will move the resonant peak up, which some might like and some might not, but on a tone pot, it's a no-brainer, because all you have to do is turn a 500k audio taper tone down to like "8" or "9", and it's exactly the same as a 250k pot on "10".

    as for the tone pot itself, a few clicks on the google affirms that yes, it is a first-order filter. the capacitor value sets the "cutoff frequency" above which the filter kills the sound, and the pot itself determines how much sound above that frequency the cap kills (shunts to ground, actually). the higher the resistance of the pot, the less effect it has when all the way up. so a 250k tone pot still bleeds a little treble to ground on "10", a 500k pot almost none, and a 1 meg pot pretty much not at all.

    shielding is a good idea, but it won't help with the actual single-coil hum; it'll just reduce that extra hum you get when you let go of the strings.
     
  11. mongo2

    mongo2

    Feb 17, 2008
    Da Shaw
    Frankly, I think you should just leave it alone and learn to use the existing controls properly. Leo got it right the first time.
     
  12. Greggo

    Greggo Supporting Member

    Apr 30, 2009
    Walter,

    Thanks for the follow-up, it was very helpfull and much appreciated. I have put about 8-10 hours of solid internet research and googling and I could not find anything on what actually happens when you turn the tone knob... I understand first order filters fairly well for someone who knows nothing about electric circuits but going from the world of home built loudspeakers to electric instruments has been a challenge.

    Mongo2,

    Not what I want to hear, but I respect your comment none the less. I think I have a good handle on what I get with this bass in stock form, but as you can tell I am feeling restless... so I am having this thing substantially re-worked and having some fun re-thinking what I want from my bass (leave the bridge and pickup alone, but everything else on and in the body is getting re-thought and re-worked, and I might just replace the pickup at some point as well and see what happens...)

    I guess in general there does not seem to be much appetite around here for my ideas/objectives and that is cool, I will press on and post my finished product at some point and be done with it. It strikes me as a bit funny that I have controls on my guitar, controls on my rig, and controls on my board, and that the idea of dropping down on the guitar and depending on the other two seems like a fools errand to folks around here. Oh well....

    Regards,

    Greg Jensen
     
  13. mongo2

    mongo2

    Feb 17, 2008
    Da Shaw
    You won't get anything "more" from a passive bass and by substituting continuously variable controls with switches for dedicated functions. In fact, the tonal possibilities of the circuit will be hobbled by eliminating the continuously variable components.
     

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