skibum5545 Posted July 10, 2006 Report Share Posted July 10, 2006 (edited) I just finished wiring up my bass, and it works fine-- mostly. There are a few issues I'm finding-- but first, it's wired up like so: Neck Vol Bridge Vol Tone N/Hum/S Neck pickup N/Hum/S Bridge pickup Kill switch Here's the wiring diagram I drew. When both the volumes are all the way up and both pickups have the same single coil selected exclusively, if you turn either volume down slightly, the low end of the notes drops out, and the bass has a very hollow/midrangey sound. With both pickups in humbucker mode and both volumes all the way up, the entire low end drops out, leaving it with a very thin, trebly tone. Turning the bridge volume down slightly makes it worse, but turning the neck volume down slightly seems to add a little bit more bass into the tone. Finally, turning either volume all the way down and leaving the other one at max cuts the signal from both pickups, except for the tiniest bit which gets through to the amp. I have a couple guesses at what's happening, but they're pretty uneducated, and even if they're right I wouldn't know how to remedy them. Since the volume pots are wired in parallel (I think) it seems that cutting one wouldn't affect the other, so maybe I just wired it wrong there. As for the tone issues, it might be a phase problem, and since I don't really understand phasing too well in the first place, I'll leave troubleshooting there to the experts. Any help you guys can offer would be astoundingly valuable right now. I'd like to enter this thing in this month's GOTM, but don't want to do so until it's actually a completely playable instrument. Thanks again for any help you can offer. Dan D Edited July 10, 2006 by skibum5545 Quote Link to comment Share on other sites More sharing options...
Prostheta Posted July 10, 2006 Report Share Posted July 10, 2006 (edited) Without thinking about it (midnight here - tired!) I think that you're getting crazy phase cancellation. Low frequencies have much longer waves than higher ones, so the cancellation produces a comb filter attenuation which at lower frequencies can be pretty dramatic. If I remember correctly that is. It might be worthwhile reversing the phase of one pickup to see what result that gives you. Incidentally, wouldn't reducing the volume of one pickup in your design ground the entire output of the circuit? Bad move man! Sorry I don't have much time to think about this more, but I think the design is flawed a little....I would consider semi coil taps using pullpots to fully tap the coils out on your humbuckers or dial out a coil as a "tone control in the middle of the bucker", and a linear pot to blend between the two outputs (pickup to either side of a pot, wiper is your output) and you could even pullpot this to reverse the phase of one pickup. Three controls there - a fourth (space permitting) would be an overall tone control or overall volume. Oh the possibilities!! Oops. Better sleep. Hope you get your head around this better than me man! Edited July 10, 2006 by Prostheta Quote Link to comment Share on other sites More sharing options...
skibum5545 Posted July 11, 2006 Author Report Share Posted July 11, 2006 By all descriptions I've heard of what out of phase pickups sound like (intentionally or otherwise), I'm pretty sure that's what I'm getting. The obvious solution for that, anyway, is to reverse the phase, but I'm wondering how the two 'buckers got out of phase in the first place, and what wires I need to switch up to get them back in line. As for the volume pots grounding out, my intention was that turning one all the way down would ground only that pickup. I'm wondering if my diagram creates a path-of-least-resistance-esque effect, wherein turning one volume knob all the way down takes one of two parallel paths to negligible resistance, causing the other path--the other pickup-- to become effectively eliminated from the circuit as well; the little bit of signal left, then, would be due to the 50-some Ohms of resistance still coming from the turned-down volume pot. This is all just extrapolation from my 8th grade science crash course in circuitry; it'd be great to have a professional (or at least competent amateur) opinion on this one. Not bad for a midnight analysis, though, prostheta! Quote Link to comment Share on other sites More sharing options...
Prostheta Posted July 11, 2006 Report Share Posted July 11, 2006 Ugh. Morning. Too early to think. Tell me what you want the circuit to do, how much space you have for pots/switches and I'll come up with something for you tonight. I tell you what though - dialling out a coil from a bucker with a semi coil tap is way cooler than tap switches! Quote Link to comment Share on other sites More sharing options...
skibum5545 Posted July 11, 2006 Author Report Share Posted July 11, 2006 Quite frankly, I just want the circuit to do what I mentioned earlier, and hopefully using the same parts I already have-- Neck Volume Bridge Volume Master Tone 3-way coil tap (N/Hum/S) for each pickup Momentary Kill Switch It's not so much about having someone draw me a new circuit, though I certainly appreciate the offer; there's a guy I know in town who will, for $20 or so, redo the whole circuit and rewire my bass for me-- but I'm hoping I won't have to go down that path. Really, I just want to figure out what I can change in this circuit to fix the problems I've been having, and then rewire the bugger myself. Quote Link to comment Share on other sites More sharing options...
JoeAArthur Posted July 11, 2006 Report Share Posted July 11, 2006 (edited) Quite frankly, I just want the circuit to do what I mentioned earlier, and hopefully using the same parts I already have-- Neck Volume Bridge Volume Master Tone 3-way coil tap (N/Hum/S) for each pickup Momentary Kill Switch It's not so much about having someone draw me a new circuit, though I certainly appreciate the offer; there's a guy I know in town who will, for $20 or so, redo the whole circuit and rewire my bass for me-- but I'm hoping I won't have to go down that path. Really, I just want to figure out what I can change in this circuit to fix the problems I've been having, and then rewire the bugger myself. Your circuit looks good, but the only thing I can't verify is that you have the pickups themselves wired correctly - you didn't mention what pickups they are, or if they're both the same or different manufacturers. Color code does vary. It does sound like from the symptoms that it is a pickup phasing problem. edit: Oh and yes, your diagram does have the pickups wired "interactive" which means turning down either one all the way will silence the bass. Switch the leads from the hot and center terminals of both volume controls to make them non-interactive - as much as possible with a passive circuit that is. Edited July 11, 2006 by JoeAArthur Quote Link to comment Share on other sites More sharing options...
skibum5545 Posted July 11, 2006 Author Report Share Posted July 11, 2006 Thanks very much for the advice on the volume pots; it seems like I should've been able to see that on my own, but hey... The pickups are both G&L MFD bass humbuckers, and I suppose I might have gotten the wiring a little mixed up; I figured out the wire colors based on the schematics for the G&L L-2000 bass (http://www.glguitars.com/schematics/ASATbass_L-2000_L2500_version1.pdf), and the wiring for the switches from guitarelectronics.com (as seen on my previous post's diagram); if you can spot any discrepancy, let me know. If there is no discrepancy that you see there, it's equally likely that I just mixed up some of my wires along the way. The only question I have left-- on the theoretical level, anyway-- is what would cause pickups to be out of phase in the first place, both sonically and electrically. Thanks again for all the help, guys. Quote Link to comment Share on other sites More sharing options...
badsnap Posted July 11, 2006 Report Share Posted July 11, 2006 Unfortunately, you are the only thing that can cause your pickups to be out of phase. Check the wiring and correct it. Current needs to flow in the same direction through both pickups (as if they are in series) for them to be in phase...Rog Quote Link to comment Share on other sites More sharing options...
skibum5545 Posted July 17, 2006 Author Report Share Posted July 17, 2006 Okay, so I've finally gotten around to working on the wiring of this bass--again, that is-- and fixed one of the problems; my volume knobs are now non-interactive. That said, I've discovered some interesting things about my other problem. For instance, when one pickup or the other is rolled completely off, the remaining single coil modes work swimmingly. However, when either pickup is alone in humbucker mode with the other pickup off, the bottom end -still- drops off. So, if it's not some weird interaction between the pickups, it has to be how each pickup is wired in relation only to its own two coils. Which then raises the question-- can a pickup be out of phase with itself? Allow me to refer to the following diagram when asking any more wiring questions (it's the same as the last one, but with the volume pots corrected): The green one has to correspond to South-Start because it's soldered to the pickups baseplate, so it has to be the wire that goes straight to ground. That would make the yellow wire South-Finish, because it's the only other wire from the south coil. The only option left that I can see is switching the black and white wires from how I have them in the diagram. If that in fact were the solution, would it solve the problems I've been having? I'd rather not re-solder things unless I at least have some idea that I'm on the right track. Once again, any help you all can provide would be greatly appreciated. Quote Link to comment Share on other sites More sharing options...
JoeAArthur Posted July 18, 2006 Report Share Posted July 18, 2006 Yes, it is possible for a humbucker to be out of phase with itself. Switch the connections for the black and white wires. Try one first in humbucking mode. You should get your bass/volume back. If so, do the same with the other pickup. Quote Link to comment Share on other sites More sharing options...
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