I have on the bench an Epiphone Explorer with EMG active humbuckers and what looks like the standard EMG control harness. It all seems to work fine, now that I have replaced the switch, but I am noticing something I never saw before: the tone cap comes off the center tap of the tone pot and is attached to the hot lead on its way to the jack, not to ground as usual. The junction does not look "factory", but I don't like to assume too much, and of course, EMG's website is not responding today. Any ideas?
Thanks for your response. Are you speaking of a cap across the in and the out of the volume pot, aka treble bleed? I don't think that's what is happening here, but since i don't know, i'm asking.
The circuit is as follows: 2 emgs (85 neck and 81 bridge), to two volume pots, to a 3 way toggle switch, and the output of the switch goes to the tip on a ring-tip-sleeve jack. On the way to the jack, the cap is tied into the output and the other end goes to the center lug of the tone pot. In other words, the path to the tone pot is THROUGH the cap. One outside lug of the tone is open, the other is grounded. That's the only capacitor in the system. Is it acting as a tone cap AND a treble bleed?
I know 'if it works don't fix it', but I'd like to know why it is that way, and if it is standard on EMG systems.
104k is stamped on it, so .1 mF?
Sorry, I visualized the circuit incorrectly. After re-reading, it's not what I thought. I'd have to see a schematic and look at the actual circuit. I'm an amp guy for the most part, and don't do a lot of guitar wiring these days. What you're describing is still a tone circuit, although not the kind I usually see. In the configuration that you're describing, the signal always has a path to ground through the cap, and adjusting the pot attenuates the signal passing through it. It's a capacitor and a resistor is series. Depending upon the value of the cap, with the sweeper of the pot turned all the way to ground, it probably sounds muddy, and with the pot in opposite position, you're still filtering some highs out.
As you said, if it "works" (AND you're satisfied with the sound), you can just leave it the way it is.
you are correct. sir. it was broke, and now i have fixed it. standard signal path sounds a lot better, it turns out. thanks to you and Tom.
I called EMG but they haven't yet called back. They may not call me down here in New Zealand. :)
The circuit i would expect to see would be
I just thought maybe it was something specific to their systems that they wired it that way. Unfortunately, all the diagrams on their website seem to refore to more recent solderless circuitry. Maybe they figure, they sold the whole harness as one, why do you need to know how it goes? And anyway, they've moved on?
I'm not satisfied with the sound but i rarely am with EMG anyway. heat up the soldering iron and try it the other way...
It's only another way of achieving a tone circuit. You can either :
-hot>cap>middle leg of pot>right leg of pot>ground
-hot>middle leg of pot>right leg of pot>cap>ground
It's most of the time the way Fender or Gibson does it : http://www.dominocs.com/Gibson/WiringLibrary/wiringModern.jpg
It was as in your first example. But it sounds better as in your second example.
Had not seen Fender do it that way (first example), but there is always more to learn.
Thank you for your information.