The Jazz Guitar Chord Dictionary
Reply to Thread Bookmark Thread
Page 1 of 2 12 LastLast
Posts 1 to 25 of 28
  1. #1

    User Info Menu

    Hi,

    I'm looking for references for the lowest-height possible, good-quality volume pot with a thumb wheel that'll work with the Kent Armstrong pickup on my The Loar LH650 (needs to have 3 terminals).

    Thanks in advance!

  2.  

    The Jazz Guitar Chord Dictionary
     
  3. #2

    User Info Menu

    <a href="https://www.stewmac.com/electronics/components-and-parts/potentiometers/schatten-thumbwheel-controls/" target="_blank">Schatten Thumbwheel Controls - StewMac</a><br>
    <br>
    It's usually used as a volume/tone combo, with the supplied capacitor. If you insist on just a volume control, it's designed to be broken in half, giving two separate potentiometers.&nbsp; I generally mount mine inside the treble f hole, because I don't like pickguards on archtops.

  4. #3

    User Info Menu

    I read that the tone control gets the sound darker, which isn't exactly necessary with the TI Plectrums I use. I'd prefer to buy only 1 pot though, and to order in Europe (Thomann have them). Schatten suggests this is a German brand?

  5. #4

    User Info Menu

    Schatten is a Canadian company. Volume Controls & Thumbwheel Controls — Schatten Pickups
    If you want only one pot, and can live with something slightly larger, look here:
    Guitar Parts Factory - Mini Potentiometers
    Scroll all the way to the bottom. The Schatten with tone control doesn't make the tone darker unless you roll the tone control back. They're 500kOhm, which makes them rather bright when full on, especially if you're using a single-coil pickup, but can be rolled back a little if needed. I've tried all that I linked, and prefer the Schattens by far. Easier to wire, easier to mount, and they work well. But they're not the cheapest available.

  6. #5

    User Info Menu

    I saw Schatten discontinued the 1-pot version, and was about to start asking around among former electro-engineer colleagues.

    You're referring to one of these?


    or




    Any significant differences between the two?

  7. #6

    User Info Menu

    According to the site, there are 3 models. Two are 500k, one linear taper and one audio taper, and one is 250k with taper unspecified.

  8. #7

    User Info Menu

    Thanks, I went for the audio-taper one (WD500 or something like that). Around 6€ with 5€ shipping; still pretty expensive but as a former mentor once taught me, you have to bill your own hours you spend searching for a cheaper deal

  9. #8

    User Info Menu

    Still cheaper than StewMac. But then almost every place is. StewMac is reliable and honest, but not cheap.

  10. #9

    User Info Menu

    Quote Originally Posted by sgosnell
    Still cheaper than StewMac. But then almost every place is. StewMac is reliable and honest, but not cheap.
    Hey,

    Do you happen to have experience with the WD500TW? Just looking for confirmation of the wiring (as a volume pot) and how to fix it under the pickguard (2-sided tape or hot glue?).

  11. #10

    User Info Menu

    When using audio taper (aka logarithmic taper) thumbwheel pots you have to consider that the log curve must work reverse compared to normal pots for correct audio application, i.e. clockwise for increasing volume. This is due to the fact that you will swap the pot (bottom upwards) for fixing to the pickguard. The Schatten thumbwheel pots have this reverse curve.
    Standard thumbwheel pots like those shown above are supposed to be with standard log curve (indicated as e.g. "A500k" or "500kA").
    If you install them in correct audio application, they will work in reverse rotation, i.e. counterclockwise for increasing volume.
    To avoid that, I would recommend linear pots as thumbwheel pots.

  12. #11

    User Info Menu

    Quote Originally Posted by bluenote61
    If you install them in correct audio application, they will work in reverse rotation, i.e. counterclockwise for increasing volume.
    To avoid that, I would recommend linear pots as thumbwheel pots.
    I already have the logarithmic one... Not that I care about the sense of rotation but usually there are 2 ways to wire a pot; if one way "goes up" for a given sense of rotation, the other goes down... The WD500TW has 4 contacts so it must follow this same principle I think...

  13. #12

    User Info Menu

    See attached spec sheet from alpha, page 2.
    1 = input from PU
    2 = output to amp
    3 = ground

    Alpha pots like those as shown in the pictures above have 3 Pins, not 4.
    Attached Images Attached Images

  14. #13

    User Info Menu

    Quote Originally Posted by bluenote61
    See attached spec sheet from alpha, page 2.
    1 = input from PU
    2 = output to amp
    3 = ground

    Alpha pots like those as shown in the pictures above have 3 Pins, not 4.
    Thanks!

    I have this one: WD500TW 500K ohm Mini Thumbwheel Pot Jazz Guitar Under | Reverb

    which looks very much like the ones shown in the Alpha documentation. I suppose I can verify if it's the same by measuring the resistance between contacts 1 and 2?

    Clearly I can no longer count reliably from my visual memory; I should have claimed (erronously) that mine has 5 contacts. The 2 external arms are no contacts then, but braces to fix the thing with?

  15. #14

    User Info Menu

    The two outer arms are ground. That's what would be the case of a normal pot. The center pin is the wiper, and the two in between are the ends of the strip. It's identical to a normal pot, except that there is no case, just the outer semi-ring. The center pin goes to the hot side of the output jack. The ground from the output jack goes to the ground strip, as does the ground from the pickup. You need a jumper from the ground strip to one of the pins, which would be one of the outer pins on a normal pot. The hot from the pickup goes to the other pin. Off the top of my head, I can't remember which pin get the pickup hot and which goes to ground. Solder it up and see what you get. It will work either way, but full volume may be reversed. You can then switch the wiring. I like the attached wiring scheme, just ignore the tone pot. I can't remember which way is up for the thumbwheel, you're on your own there.
    Attached Images Attached Images

  16. #15

    User Info Menu

    OK, thanks, I'll figure out the rest.

    So how would you fix it to the underside of the pickguard?

  17. #16

    User Info Menu

    3M mounting tape. It's thick enough, and flexible enough, to hold it securely. It's similar to what comes with the Schatten thumbwheels, but thicker and I think stronger.

  18. #17

    User Info Menu

    I just dug out a couple of my old thumbwheels like yours, and the pin on the right is grounded, looking down at the thumbwheel. It mounts with the pins up, against the bottom of the pickguard or f hole, as the case may be. That's really the only way to mount it. That makes turning the wheel to the right, towards the bridge, increase the volume, which is a clockwise rotation looking from above, same as for a normal pot.

  19. #18

    User Info Menu

    Quote Originally Posted by sgosnell
    I just dug out a couple of my old thumbwheels like yours, and the pin on the right is grounded, looking down at the thumbwheel.
    Thanks! To be certain, "pin on the right" means the right one of the inner triplet, looking down on the contacts with the pot laying on the thumbwheel? I'd thus have to exchange the green and black wiring on your Bravo scheme? That scheme doesn't send the signal to ground when you turn the volume down?

    I still think there should be a way to figure this out with a multimeter but I can't seem to wrap my head around how, at least not with just an amp meter, I think the fact there are 3 ground contacts confuses me.

    EDIT: I'm not near my guitar right now but I'm quite certain there's a black and a white cable coming off the PU, soldered to 2 tabs on its side. It's the stock KA-style pickup which I suppose is pretty standard on archtops like mine. Can I assume that the red and white wires from the Bravo scheme are already shunted together inside the casing, and probably connected to that case? I imagine they could serve a purpose though?

  20. #19

    User Info Menu

    First, different pickup makers use different colored wire. I have no clue about the wires on your pickup. On the Benedetto pickup, as the diagram says, the red and white are soldered together, and the ends are inside shrink tubing. They can be unsoldered and connected to a switch for coil splitting if desired. That's also a feature on many humbuckers. They're the other ends of the windings of the two coils. Some humbuckers have only two wires, and are already connected inside the pickup. It sounds as if that's the case with yours.

    As I said above, the three pins in the diagram are the three inner pins on your thumbwheel, and the outer two thumbwheel pins are the case. Don't let that fool you. There are not three grounds, just two pins for connection to the case. It's one continuous piece of metal. But trust me, one of the outer pins on a standard pot must be soldered back to the case, and the same on the thumbwheel. It won't work correctly otherwise. With an ohmmeter, there should be zero ohms with the knob turned all the way one way, and somewhere near 500k ohms turned to the other extreme. It won't be exactly 500k, because of the tolerance, but should be within 10% of that.

  21. #20

    User Info Menu

    The confusing part about this, at least to me, is that standard diagrams show the potentiometer upside down, with the shaft hidden underneath. The photos of the thumbwheels show it the other way, and the shaft would be pointing up toward the viewer, not away. Turn the thumbwheel over, and it becomes easier to understand, but somewhat more difficult to solder.

  22. #21

    User Info Menu

    I finally got around to measuring the resistances, with the pot upside down as it would also be installed.

    Ignoring the outer arms: Turned all the way CCW, the 450kOhm resistance is between the left and middle contacts, with middle-right being 0 Ohm. Turned all the way CW, the left-middle resistance becomes 0 and the middle-right resistance becomes 450k.

    If I understand things correctly, we'd thus connect the middle contact to the PU's hot wire, the left contact to the output jack tip; the right contact and the PU's ground wire go to the pot's ground arms?

  23. #22

    User Info Menu

    There are multiple ways to wire a potentiometer, and they all work, although I have my preferences. I wire the center to the hot to the output jack, and the hot from the pickup to the outer pin, the way Benedetto does it. But the way you want will work.

  24. #23

    User Info Menu

    Are any of them more susceptible to humming, or is humming a sign of another problem (or an inevitable normality)?

    I didn't particularly notice any when I plugged into my preamp/interface but today it was the 1st thing I noticed. Much of it came from the power supply to my ART preamp (which outputs 9VAC). Fortunately the SNR is good enough to clean up afterwards but what annoys me is that closing the volume pot on the guitar actually increases the noise. I think that didn't happen with the big pot that I had under the previous pickguard.

    Heh, I remember making a few mental remarks about the lack of shielding when I saw the wiring being done...

  25. #24

    User Info Menu

    Humming is sometimes an indication of poor soldering, IME. With a single-coil pickup, though, there is likely to be humming in some situations. If the volume changes with orientation and/or location of the guitar, it's the pickup, and as comes love, nothing can be done except to get a humbucking pickup. That's why they were invented. Shielding the controls won't help, because the pickup itself is receiving and amplifying the EMF energy. Getting rid of all the electronic devices in the area can certainly help, but that isn't really practical. Humbucking pickups do work.

  26. #25

    User Info Menu

    I'm guessing the hum is picked up via the magnetic field, so outside of the metal enclosure around the pickup?

    Either way, hum picked up via the PU shouldn't get louder if I turn the volume down. Could that point to a ground loop? We followed the wiring scheme where the "off" pin on the pot is shunted to ground.

    Or, I'll just have to live with it. I certainly can playing with the electric sound at home. It's just annoying that I went all out to find a low profile thumbwheel pot and apparently could just as well have removed the component alltogether