Bill Lawrence Q Filter + Normal Tone Wiring

[Kirfew]

Hi everybody, I was wondering how to wire a guitar to have a master volume, tone and q filter (so three knobs). I've seen this schematic on the Bill Lawrence website: Wiring Diagrams :: Q-filter picture by wildepickups - Photobucket

Would I just add in the tone pot and capacitor in parallel to the q filter circuit? And would I need to use pots that are double the resistance for the tone and q filter circuits pots, since they'd then be in parallel?
Thanks

[52 Bill]

Would I just add in the tone pot and capacitor in parallel to the q filter circuit? And would I need to use pots that are double the resistance for the tone and q filter circuits pots, since they'd then be in parallel?
Thanks

Welcome to the place. The Q filter works more like a midrange tone control. Having both that and a normal tone control may have a lot of overlap in the way that they work. You may need to experiment with cap values to get the system to work the way you want it to.

Because the two pots are isolated by their individual capacitors they are not really wired as parallel resistances, so use the normal values.

[Fluoroscope 5000]

Hey guys. I just signed up here. I've been interacting on the Wilde-Gate site for several years, so I'm well versed with the Q-tone. I've also talked tech with Bill on many occasions. I think I can be of service. This may appear complicated, but it's worth understanding, and we can clarify it all with a few back and fourths. First thing to appreciate is that the guitar is an LCR network:

L = Inductance provided by the PUP, and any passive coils like the "Q-filter". H (Henry) is the designated L measurement value.
C = Capacitance provided by caps and the guitar cable.
R = Resistance from pots and resistors.

Various caps have different reactance values at different frequencies. That would explain why one cap sounds different than another when the tone is up all the way. That difference is very subtle, and can be compensated for in different ways. Otherwise, the cap value doesn't even come into play until below ~4 on the knob for an average audio taper pot. Above that, the tone knob just lowers the gain on the resonance peak set by the interaction between the PUP L and the guitar cable C and any other caps in the signal chain, like those on the input of some amps.

So, the first thing to do is use a cable with the pF value that tunes the PUP to the sound you like. Since the bridge PUP usually has the highest L, it makes sense to configure your C-load based on it. You need to know the PUP's L to do that. If you know it, there is an online calculator to figure the resonance with a given C-load. Generally, if you want good articulation, you'll need to tune it to either 4.2-4.5kHz for a "bell" tone, or above ~6kHz for a smooth sweet high end.

The Q-filter is simply a high quality shielded L tuned to a certain H value. If you wire the tone and Q-tone in parallel, you would actually need to use double value pots to retain the same R-load as one pot of half the value. In a way, the Q-tone acts like a mid-range, but it's more complicated. Since the Q-filter is just an L, the L of the circuit is reduced as you lower the knob. Since the cap doesn't come into play until below ~4, the resonant frequency of the circuit is increased until the cap comes into play at ~4. From there, it is determined by the total C-load including the cap, and then begins to rise again from ~4 to 0.

You can wire the Q-filter in many ways. On my NiteFly, I use it on one knob, and a 0.047uF cap on another knob with Wilde NF series PUP's ranging from 2.4H - 4H, and a 190pF cable. With that configuration, bass is also reduced when I turn down the Q-filter knob. I can tune various "cocked wah" resonances between the two knobs below ~4, and get several subtle useful sweet sounds above that. It's much simpler that way, but you may not want the bass reduction. Finally, if your PUP's L and C-load is very low, the Q-tone won't do much above ~4, because the resonances would be above the guitar speaker range.

Finally Finally, if you want to use the standard Q-tone wiring with a standard tone in parallel, you could possibly determine a resonance for a point of travel of both knobs combined (like both at 4) and come up with a cap for the tone knob to get it. There are several good options for that. You can always change it, or fine tune it later. I've done a little of that and gotten great results. I hope this isn't too confusing. The main points are that the pots will combine in parallel to lower the the R-load value, and the caps on each knob will combine when below~4 with the cable C to produce one variable resonance.

[billyvitale]

Forgive my ignorance.. since you seem open to back and forth... First off I would love to understand the tecnhicalities of what you describe here so any pointers to learn more would be helpful.. but can you describe in terms of "tone" what the q-tone can do and perhaps a simple way to wire it.. here is what I understand the q-tone can do:
- it can open up new possibilities for the sound of a guitar .. instead of simply cutting highs like a tone control.. it can tweek the signal to give it different tonal characteristics.. some say even sounding more acoustical in certain settings.. I also understand that is hard to put a finger on exactly what it does because of the factors you describe.. in other words the variables are such that it is very difficult to describe exactly how ones instrument will respond because each instrument has different variables.. unlike a tone control in which basically cutting highs is cutting highs..

Since you see very knowledgeable .. I would like to also know if you have any insight on another "quest" I have in terms of guitars.. and that is the question of "Phase"... My experience teaches that in certain live playing situations I get a good sound and can focus on playing.. in others the sound is just not there and I spend most of the engagement struggling with tweaking nobs .. if I can (sometimes playing through a PA for example simply means you are confined to trying to tweek some effects).. In general my Fender Strat seems to be better and "cutting" through .. but even with that sometimes I struggle.. I have been told that it is a "Phase" issue.. just like with speakers.. if you guitars phase is not in sync with something else you will get cancellation which screws up your sound.. and no matter what you do it will be very hard to fix this. Even playing louder .. which doesn't help anyway cause if you do that the others will follow (:-)!)... anyway looking forward to your response.

[Fluoroscope 5000]

I can't really explain any further how a tone, Q-tone works. Perhaps you might read it again until you understand it. If you have a specific question, let me know. It's not so much about the qualities of your instrument, it's really about the L of your pickups regarding where the resonance of any kind of tone knob will fall. There are a few general standard cap values you can use. If you want a standard Q-tone that operates with one knob and retains the guitar's bass at all values, refer to this diagram: Wiring Diagrams :: Q-filter picture by wildepickups - Photobucket

There's also a diagram in that set for switching to a standard tone knob. For higher L pickups and pots, you might want to alter the values, but it's not really necessary.

As for your second inquiry, it does sound like phase issues. If your sound comes from multiple sources, you alway face phase issues. Running in stereo will further complicate matters. It not traditionally done live unless you have really well configured systems and a well damped environment. There's no easy answer, but try to have one source for monitoring live.