[sdiy] tonal tilt

[JH.]

>Looking at it more closely, the headwize version might be more simplified
>than the Quad circuit.
>The Quad has two RC combinations in parallel - might be some staggered time
>constants stuff to create a more widespread rolloff than the headwize
>version.

ETA: Yes, it's true. The Headwize circuit does *not* create the same slope 
as the Quad circuit.

First, the Headwize has a wider range of adjustment.
But that's not the main thing: If you set the headwize pot for exactly the 
same amount of "Tilt" at the upper end of the audio range, it's slope for 
mid frequencies is more "S"-shaped.
The Quad, in comparison, has a more even slope.
The method how this is achieved is a bit like these 3dB/Oct "Pink Noise" 
filters, where you have several staggered time constants instead of one.
See how in the quad circuit  there are the 91k, 3n3 *and* 56k, 1n networks 
around the pot.

JH.