I’m not too surprised that you are getting more hum in series than parallel modes, because this seems to be normal based on 5 guitars I’ve done. If you have perfectly balanced coils in a series pair, then the hum should cancel out, but even then, there may be a small amount left. And when you wire those coils in parallel, the hum is reduced even more, by a greater extent than that of the basic level. Its partly due to the lower impedance of a parallel combo, because this makes it less susceptible to the buzzy kind of hum in addition to the main 50 or 60 hz component.
But there’s another effect too in parallel modes, which is not well known. In fact I’m not sure that anyone else knows this - its just a theory that I have. In a series combo of two coils, the two signals add up or cancel in a simple way, and if hum is different in two different coils, then cancellation is only partial. But in a parallel combo, two dissimilar coils can compensate and still achieve a high hum cancellation. If you have a coil with more turns, it picks up more hum, but this is offset by its higher impedance. I have two guitars where a single coil on one pickup, combined with a series out of phase (hence humming) arrangement on the other pickup, combined in parallel, can cancel the hum. Ie i’m getting good hum cancelling in a parallel combo of a 4k coil and an 8k pickup, where in series the combo would hum. Of cousr, it depends on lots of things, but I found this more than once.
In summary, I think what you are getting is probably normal. cheers John
I agree that what you said would lead to a greater degree of hum in the series and the parallel, but based on my experience of two coils in series with your Strat lovers strat confg and various two coil configs the difference is marginal, basically you just hear louder of everything - signal and noise.
But in this case, signal is series isnt much greater if at all than when in parallel, but then the middle pup is 'weak', but moreover the noise level between parallel and series is literally night and day. There has got to be something not wired right.
If something was shorting to the shield I would get no sound right? If it was just the case of a ground wire not having one end to ground and the other floating it would act as an antena right? Which is what seems to be happening here. Or could it be a series ground is not wired well - cold solder etc? Should we check DC levels on the jack?
I appreciate you don't want me to revist the 'pain zone' but I am one tenacious SOB and the mere fact that it 99% works and I can screw the thing down with everything inside has spurred me on.
Yes, but if you did a strat lovers strat, maybe that was with three roughly similar pickups? whereas here, if i understand right, you have very different pickups, and what Im suggesting is that the parallel modes are better able to deal with that than the series ones.
Id suggest a good low-risk check would be another complete set of resistance readings across the jack , all at full volume. They will be useful for troubleshooting later anyway.
I understand what you're saying, but remember I had the same three pickups in before with the same wiring and I didn't get such a night/day difference in hum and RF levels then. Series was not as noise free as parallel is now but a lot less noisy than now. I will try the jack impedances later to make sure the hot and grounds are not 'compromised' and then when my head is clear I will 'go in' and take a close up look. Actually I had the three components mounted on the guitar body in and out 2-3 times and they were quite stable. I didn't solder all wire shielding to component/copper tape grounds in order to avoid 'ground (shielding) loops' but all ends are soldered to at least one other, usually 3-4 together, therefore one end should find its way to the ground on the jack and therefore connect all others to ground. Of course I didn't go through it methodically, so its quite possible that through either bad combinations of shield wires and/or broken solder points to the back plate that I have made the shield into an antenna when I flick to series.
EDIT: In the clear light of day looking over the shield wire didnt make sense especially as it is also screened with copper tape. I did a tap test through my amp and I found that all worked except in series no MOP, where the M pup was NOT coming through. Just checking the wiring diagram to see which connection could be responsible.
EDIT 2: It would seem that the middle pup hot is being shorted to ground/shield in the series no MOP position and so the neck still sees ground and therefore the series chain starts at the neck. Can't see where the problem could be for the life of me.
EDIT 3: What if the two orange wires on the pin next to 'para' on the parallel/series switch are soldered together but poor soldering to the pin plus possibly shield wire contacting it means 0V going into the ground end of neck pup? Could that be it? I'll check tomorrow. Cheers,
Last Edit: Nov 15, 2012 16:24:23 GMT -5 by dannyhill
Well, I just dived straight in. Tidied up some connections, broke and fixed one.
The long and short of it is though that d lower and middle are hard wired. I removed the purple wire that goes to the rotary and they were then isolated in series mode. So I suspect that its me using old wires that did it, the shielding and signal carriers at the rotary end are shorted. Anyway, broke another 3 dodgy wires whilst in there. So that's four to fix/replace tomorrow evening. I'll let you know if that does the trick.
Persistance pays it seems! Finally sorted out my connection troubles. Had to sort a few more after fixing those mind! I need to glue an extra plate on the back plate so it wont warp and improve the screw fixings. But thats it! All sounds check out strumming and in tap test.
Noise cancelling isn't optimal (some low hum remains) and Nbypass+M is quiet so maybe when I get time one day I will get the hairdryer out and turn the coil over inside the original middle pickup and swap that back in. But basically the wiring seems good except for some small RF noise in some positions at high gain. Can't remember which but will investigate just for curiosity. Could have just been one pup closer to RF sources.
It was tough, but we did it. Many thanks for the scheme it has some great sounds!
Last Edit: Nov 25, 2012 19:22:33 GMT -5 by dannyhill