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4 coils VVVV w/master V/T no switch help?

Discussion in 'Pickups & Electronics [BG]' started by toneseeker, Nov 27, 2013.

  1. toneseeker


    May 8, 2010
    Hi Ya'll, I haven't been to talkbass in a while. I tried some searches, but didn't find what I'm looking for. So I'm hoping for some wiring help and suggestions.

    I got an old National Semi Hollow Les Paul bass copy. The electronics barely worked so I ordered some new stuff on a low budget.

    I ordered the GFS lipstick tube splitable buckers 12k & 9k. I ordered 1 concentric and 4 regular 250k audio taper pots and a .047 cap.

    My idea was to replace the switch with the concentric as a master vol/tone, use the 4 pots as volume for each coil and wire the 2 inner coils in series and the 2 outer coils in series.

    I assumed that wiring all 4 coils and all 6 pots in series would create too much mud & resistance? Also I thought one bridge coil 6k and one neck coil 4.5k in series might be a nice medium output 10.5 k. Maybe I'm wrong and should just go parallel? At first I was just gonna do a mini toggle or push pull pots, but somewhere I saw someone suggest volume pots instead of switches for splitting coils, to blend them in.

    I think I'll mostly just be using the bridge inner coil (middle position like a p-bass) but would like the option to blend in the other coils as needed. I figured series to get maximum punch and mids (I don't like much high end).

    Any suggestions or wiring diagrams would be appreciated.

    Thanks everyone and have a great Thanksgiving!
  2. Four coils in series will probably sound terrible. However, you may have better results with two pairs of series coils, in parallel. Though there may be uneven blending of pickups, as the volumes are adjusted, because of their series wiring.

    If you go this route, let's call the coils 1, 2, 3, and 4, with coils 1 and 2 in series, 3 and 4 in series, and the 1 and 2 pair parallel to the 3 and 4 pair, with coils 2 and 4 being on the hot side, and coils 1 and 3 being on the ground side. The negative phase leads from 1 and 3 will be grounded, and the positive phase leads from 2 and 4 will each go through a resistor, and then to the master volume/tone circuit. Then, a pot will be placed parallel to each coil, in order to adjust the volumes by varying the impedance of the coils. The purpose of the inline resistors is to prevent the pots on either parallel pair of coils from being able to reduce the total output impedance to zero and mute everything, if one or both coils from the other pair are soloed.

    This setup will allow for independent control over each pickup's volume, and potentially, a usable combination of coils. (Albeit, with a lot of useless stuff in-between.) The problem, however, is that there is likely to be a lot of weird behavior and variation in volume, as the impedance of the circuit varies.

    Personally, I wouldn't bother with this sort of thing, as a switching-based scheme would be much more practical, but I can draw a diagram if you want.
  3. toneseeker


    May 8, 2010
    Thanks so much Line6man! Well I guess I don't need to reinvent the wheel. Can you suggest a switching scheme that would maybe allow vol pots for all 4 coils in parallel w/concentric master vol/tone and push/pull pots to at least switch the center coils to series? If not what simpler scheme would be more practical? Thanks again, Toneseeker
  4. You could keep it reasonably simple with a pickup selector switch, master series/parallel switch, and individual series/single coil/parallel switches. Wire them to split to inner coils.
  5. toneseeker


    May 8, 2010
    Well thanks for trying to keep me sane, but I think I'm set on trying that first idea with 2 parallel sets of series coils ,4 vol pots, w/ concentric master vol/ tone. Would you mind drawing that up with the required resistors? Can I reimburse you with any spare parts or anything? Thanks!
  6. Give me another day or two, and I'll have something drawn up.
  7. toneseeker


    May 8, 2010
    Awesome, Thanks!
  8. toneseeker


    May 8, 2010
    Hi Line6man,
    Not sure if this is similar or completely different to what you were gonna draw, but I found this old post:

    There is a way. At least in theory. Whichever pup is the one that's grounded in the series, i.e. the 'first' pup, use a volume pot to fade in and out. The 'second' pup, which goes to the output, also has it's own volume control, and acts as a master volume in series.

    If this is similar, I'd like to use the bridge pu inner coil as the set 1 sub master in series with neck inner coil, and the bridge pu outer coil as the set 2 sub master in series with neck outer coil. Of course I'm hoping to send all to a stacked master vol/ tone so I can set the 4 coil volumes and then only have to use the master stack for most live adjustments.

    I don't mean to be a pest. I see you're very busy on this forum helping lots of people. I'm very grateful for your help and I'm anxious to see what you draw up. Toneseeker
  9. If you want to do a volume pot on one coil in each pair, and then a master for each pair, you can do that rather easily. The advantage would be that you could avoid the use of resistors, and that is quite an advantage, since the resistors do reduce output. The disadvantage, however, is that you will lose the ability to solo two of the coils, since only two of the four will have individual volumes.
  10. toneseeker


    May 8, 2010
    hmm...So you perfer this idea with no resistors and each series pair having a volume on one coil, a master for each pair, and then going to a stacked grand master vol/tone to affect all?
    I think I can live without soloing the outer coils, so I guess I need to change my plans and make both inner coils the sub masters so they can each be solo'd. Guess I'll keep some sence of "normal" that way, and each humbucker will remain a pair of series coils.
    My only remaining question is, if I have all the coils on, but the outer coils turned way down, will I still here the fatter punchy mid effect of the series wiring?
    I really appreciate all your patience. You must really enjoy this or your just a saint!
  11. You could also stick with the original every coil has a volume idea. I can picture all the wiring in my head...

    Coil-> pot -> joins second coil in parallel -> joins other pair parallel -> thru tone -> thru volume -> output jack.

    I think this would be the only way as series+parallel would give either:
    2x (1 coil vol - pair vol) - master tone and vol
    Staged volumes (1 controls 1, 2 controls 1-2, 3 Controls 1-2-3, 4 becomes a master) - extra master and a tone

    Again this is all pictured in my head. Sorry if my imagery sucks!

    Edit: fyi, passive basses don't usually use resistors other than pots
  12. Early stacked-pot Jazz basses did, in order to give a tone control for each pickup. The use of resistors is the only way to do that passively.

    You are correct, however, that they are uncommon in passive control schemes. Most schemes simply don't need them for anything.

    They are a necessity here, however, as each pair of series coils' volume controls can control the output impedance of the bass. The reduction to zero Ohms that occurs when trying to solo one or two coils from one pair only will mute the bass if the resistors are not used.
  13. Huh. I never would have guessed...
    Then again I'm not very experienced in circuit design.

    The more you know!
  14. Here is the scheme I mentioned in Post #2

  15. toneseeker


    May 8, 2010
    Thank you Line6man and also BioWeapon for trying.
    If I use this drawing what value resistors do you suggest? The 4 pots are 250k as well as the stacked pot. The cap is .047. Each pair of coils in this scheme should be about 10.5 k (bridge 4.5k ea. neck 6k ea.) I don't mind some lower total output, but would like to use the scheme that will have the best tone and best interaction between coils. I think I'm ok with trying either plant. I'm hoping I can start working on it on my day off Monday.
  16. 250k is not a good value for the volume pots, because it places a relatively direct load on the pickup coils. Ideally, the resistance would be infinite at the full volume setting, and drop into a usable range for the given signal impedance, as the volume is turned down. You don't want to lose more output/treble from the pots, when you'll already be losing some from the isolation resistors. Most people use 500k pots when doing individual volume controls on series-wired coils.

    The optimal resistance for the isolation resistors is heavily dependent on signal impedance, so you can't really know what value to use without experimentation. Personally, I would use trimmer pots and adjust them until you get the best behavior. When the resistance is too low, the volume will drop when you try to solo a coil or two from one pair. When the resistance is too high, the maximum output from either pair will drop. When you're happy with the compromise between the two, then you've found your optimal resistance. I would imagine that resistance to be somewhere between 50k and 200k Ohms. So perhaps a 250k trimmer would be best.
  17. toneseeker


    May 8, 2010
    Uh oh, I've already just ordered and recieved the 4-250 k pots and the 250 k stacked pot w/knobs. Do you think they would be usable in the other plan or should I just return them and re-order? I've just been reading about variable coil splitiing (Spin-a-Split) and it certainly seems more common since I can't find anyone else that has done this 4 vol + master idea?
  18. toneseeker


    May 8, 2010
    For either plan does it make sense to keep the 250k stacked master vol/tone pot and exchange the others for four of the 1 megohm pots? Or should I replace all with 500k? Now I'm a little bummed cause I wanted to start on it tomorrow. :bawl:
  19. I would avoid low value pots. You want as little loading on the coils are possible, for this sort of scheme.

    ...However, 1M Ohm pots sound a bit high. Remember that you still want a usable taper on your volume controls. 1M pots may have the tendency to behave as on/off switches, since the usable range of resistance will be squished into a small area of the rotation. 500k sounds best. Then again, I am only speculating, since I've never heard any feedback from players on such a scheme.

    Yeah, I have drawn 282 diagrams on request now, and yours is the first of this sort that I have encountered. :hyper:
    Spin-a-Split controls are gaining popularity with guitarists.
  20. toneseeker


    May 8, 2010
    Line6man, thank you so much for the drawing and all your help!
    I installed the pickups using the existing pots (250 vol's/500 tone's w .022caps and 3way switch. First I tried just wiring up the inner coils in parallel, pretty typical barky bridge, woofy neck nothing great kind of bright unless I turn the tone to 0. Then I wired up the inner coils as a series pair and the outer coils as a pair :D Those inner coils have the sound I was hoping for, burpy, full, and punchy. Similar to my Danelectro's but just a bit different. The outer coils are more sterile sounding but with fuller lows and brighter highs. The middle position sounds similar to the outer coils, but has a fair amount of cancellation and volume drop. Dialing down either one of the volumes makes it all a bit more even.
    So, I was gonna go for it and be the first on my block to have the Line6man 4 vol, w/trim pots + master control scheme...
    But I finally realize what you were trying to say...Why bother? I'm getting 3 pretty usable sounds I like...Do I need more?
    My mixed up reasoning was if I'm installing 4 coils I want control over all 4, but now, I'm realizing, I have all the basic sounds I'm gonna get.
    I will install the .047 cap for the inner coils and since I also have two .022 caps, maybe I'll just use them in parallel for the outer coil set.
    So, I'll hang onto the drawing (Thank you so much). I'll play around with it awhile and see if any other changes are really needed, but the control cavity is so tight I barely got everything back in place, so I'll have to think hard before I decide to make any drastic changes.
    I'll let you know how it goes. Thanks again, Toneseeker :bassist: