Yuku free message boards

...From the Man himself:

The Q-Filter is an LCR network - a 1 henry, low Q noisefree inductor in series with a .02 micro farad cap in parallel with an 8 kilo ohm resistor. Wired like a cap to a tone pot, you can gradually decrease the impedance of the circuit but maintaining a slightly higher impedance below 1100 Hertz. Also available without the cap and the resistor to gradually decrease the impedance of the pickup.



The EQ system is the most versatile system to alter the sound of a guitar and can be used for multiple functions. The basic components are a 900mh low Q inductor in series with a capacitor and a variable resistor (tone pot). We used to ship it as a complete pre-tuned unit to replace the cap at the tone pot, limited for one basic function. However, in conjunction with different pickups in different positions, it's much more versatile when the inductor is separated from the cap, like [shipped now]. In the past, this caused severe problems when players used the wrong caps and resistors, especially when the EQ was wired to a switch only. The system must be wired to a control or you totally limit its functions, as follows:

Function A - the L Filter - the inductor, wired like a cap to the tone pot.

When you turn the pot from 10 to 0, you slowly reduce the impedance of the pickup. This is equal to taking turns off the pickup or making a sweet clean pickup out of a high power, overdrive pickup. This works fine for the neck pickup. With the control set below 3, the impedance is much too low so we block the control with a fixed 10 kilo ohm resistor or don't turn the control below 3 or 4.

Function B - the EQ Filter

On the bridge pickup, we want to maintain more lows so we block the inductor with a resistor in parallel with a cap. Now, when you turn the control to zero and you use hi-fi speakers, you can duplicate the sound of an acoustic guitar. With the controls on 3, you can get out of the bridge pickup, the #4 position sound of a Strat.



Here are some of the options you have with a volume and tone control with push pull.

Push Pull:

L to EQ1
L to EQ2
EQ1 to EQ2
EQ1 To Tone Cap only
L to Tone Cap only

EQ1 is standard crossover at 1200 Hertz
EQ2 is similar to a tone cap without choking the highs.
L reduces impedance over the total frequency.
L = 900 mh low Q humbucking inductor
EQ = L in series with .02 cap up to 1200hz high Z and above 1200 hz low Z.
EQ alone maintains too much of the lows below 1200hz
EQ1 reduces low by 60% (10K resistor over the cap)
EQ2 reduces low by 25% (25K resistor over cap)

All it takes is a different resistor to change the function.



Here are a couple of "standard" diagrams for wiring the Q-Filter:





Heres a nice computer-drawn version, courtesy of Vito:



The basic diagram, courtesy of fuzzy beard:



fuzzy beard says:
"Bill has indicated that you can change the value of the resistor. I use 15K or 20K ohm for both neck and bridge pickups. You keep more bass with the bigger values.
Of course you might also try a 0.01F cap (or any value you like)."



Q-Filter