series/split/parallel tone problem, got me stumped

[stringfreek]

Hello all. I have been banging my head against the wall for a while on this one, so hopefully someone will have some ideas.

I have a humbucker in the bridge position with a series/split/parallel DPDT on-on-on switch, 1 vol and 1 tone. the pots are both 500K audio taper and the cap is an RS guitar works .022.

The problem occurs when the P/U is parallel or split. As soon as the tone reaches 7 (10 being the most bass sounding), the P/U starts sounding out of phase.
I have tried using a 250K pot for the tone, a .047 cap, different P/U’s, but this happens every time.

Has anyone else out there experienced this? Anyone got any ideas what might cause it?

[Mike Richardson]

Firstly, on a tone control (or any other control), 10 = all the way UP. Secondly, does your pickup have four different colored wires? If so, do you have two of them connected to the tone control? That could be your problem.

[jhng]

Hi Stringfreek, and welcome to GN2.

This sounds familiar. I once (many moons past) had a problem involving a strat wired to have two separate volume controls. When either control was wound down the sound started sounding out of phase.

The problem turned out to be that the volume control was effectively, grounding the hot of one pickup (that it was meant to switch off) in such a way that it ended up wired in parallel and backwards (i.e. out of phase).

You could have the same problem depending on how the series/split/parallel switch is wired.

So check the wiring of the switch (and check teh colour codes). Then disconnect the tone control totally and check that the DPDT works as intended (and that you get actual series/single/parallel).

Also if the tone control is wired straight to the volume pot (with the other end wired to the ground) it should be impossible for it to affect a pickup's phase. Try it. If it still happens then it isn't a phase problem.

Hope this helps,

Hastings

[stringfreek]

Thanks for the replies. I am glad to see the forum is being carried on from guitar nuts. I have been a big fan of John’s site for years.
I know the switch is wired correctly and all the colours are in the right places. I have built this circuit I various forms around 30+ times, but have never been able to resolve the issue. I have actually even tried switching all of the colours to see if it made any difference. The schematic I used is:

www.seymourduncan.com/support/schematics/2hum_2vol_2tone_3way-w-ssp.html

I don’t believe the problem is with the volume pot. What’s strange is that in split and series, it sounds fine until the treble cut hits around 2/3 +.
If you look at the diagram posted on Seymour Duncan’s site, you will notice they use a .047 cap rather than a .022. This helps cover it slightly, but it’s still very noticeable.

Has anyone else out there ever wired a series/split/parallel? If so, did you have the same problem?

Although the P/U sounds out of phase after 2/3, I don’t know that necessarily means it is actually going out of phase. In fact, I really can’t see how that would even be possible. However, the sound is unmistakably different and reedy.

[stringfreek]

Sorry, I forgot to mention as far as connecting two of the 4-cores to the tone, I always apply the principles in the shielding the beast to all of my guitars. All circuit grounds go to a central point.


Stephen