Big Willy's Phat Middle

A Parametric Equaliser For Extra Girth

Sometimes guitarists find it hard to be heard amongst all the noise of the other pesky band members. Whether you are on stage, recording, or just playing with yourself in your bedroom, we all feel the need to be heard.

With Big Willy's Phat Middle, you can adjust your bass and treble frequencies but it is the middle frequencies that are crucial to a good sound. You may need to add some girth to your single coils or tidy up a muddy humbucker. Fine control of your middle frequencies will help get you heard in the mix without simply turning the volume up to 11.

This elegant and classy peddle from Big Willy's Guitar Emporium is based upon a Wien Bridge equaliser with a switchable Q. The bass, middle and treble frequencies can each be boosted or cut by +/- 16 dB. The middle frequency cut or boost can be swept over a range of frequencies from 300 Hz to 3.3 KHz.

The Q value, which is a measure of the broadness of the frequency band modulated, can be switched from values of 2.4 (Hi Q) to 1 (Lo Q). One of the features of this circuit is that Q remains constant regardless of the frequency selected. The volume of the output also remains constant when the frequency is changed.

The peddle has a master volume control. This can be used to add some boost when the peddle is switched or to balance your volume when the peddle is turned on and off if you simply wish to modify your tone. An LED indicates when the peddle is on.

The input from the guitar comes in from the right and the output goes out from the left. It can run either from a 9V battery (included) or from an external power source (9V negative tip as standard).

The 9V input is converted into a +/- 9V signal using a charge pump chip which provides a large headroom for the signal. This means that the signal is unlikely to clip unless driven very hard.

This peddle is a fully featured version of our Phat Middle Parametric Equaliser PCB that was designed to fit inside a guitar but which only provides direct access to the middle boost/cut and frequency controls.

Power requirements

The peddle can run either from a 9V battery inside the peddle or from an external power source. You must use a 2.1 mm DC Jack plug with the tip at -9V. The peddle may be damaged if you apply the power the wrong way round.

With the external power disconnected, the peddle will work from the battery. N.B. If an input jack is inserted, the battery will power the circuit even if the LED is off.

NAH Guitars
Letchworth Garden City, SG6 1SA.
Mb: (+44) 07751 088686
Nick Hartell