Craig Anderton Frequency OVERDRIVE

[The French connection]

Craig Anderton Frequency booster OVERDRIVE
I've tried to put amz booster or LPB in the same pedal with CAFB but does'nt work for some obscure reasons...So having a free pot, i've think to use it for the CAFB and came up with this:



Nothing special, i've just tacked the drive section of a TS to it and it became a pretty versatile overdrive. I recommend it, it will replace any TS clone on my pedalboard for sure. From bass rumbling to bright overdrive through co'c'ked wah sound and mid boost overdrive. I'm boxing it up and will follow with the vero layout. I use a rotary for caps selection and a DPDT for diode switchin' so it can work as a booster or an overdrive.

Salut
Dan

[The French connection]

Heres's the vero layout! Not verified because i've use the Booster version (http://www.aronnelson.com/gallery/main.php/v/French+connection/Vero+Layout/CA_Freq_Boost.jpg.html) and make an addon for the drive section. But it looks ok to me.

[Mark Hammer]

I whipped up a somewhat different slant on pretty much the same thing, but sequenced things a little different, using the Frequency Booster to provide a simple pre-clip EQ, with a variable scoop after the clipping section.  I loaned it to one of the senior managers at work and he just had to have it, making it difficult to provide any samples.  But I describe it as "instant Slash".  Putting the resonant boost before the clipping changes the quality of the clipping tone.

What you showed is quite good and provides a sonic improvement over the basic clipping circuit it uses.  The 4khz and 10khz boost settings will not likely be of much use to you, given the rolloff coming from the 100pf feedback cap.  That suggests either using other cap values to target some other resonant frequencies, or using a 3-position toggle, like I do below, to get 3 selected resonances and save some panel space and wiring.  Your choice, obviously.  Some folks like more choices, some adapt to less.  Note that R7 in your drawing can be interrupted with an SPST stompswitch if you want to make the resonant boost switch-selectable.

The features to note in the "Boost-N-Scoop" are as follows:

1) Anderton's frequency booster uses two caps to set where the resonant boost is.  You can see the range of values to consider in the schematic found either in Mr. Huge's schematic gallery here or at AMZ.  I used a .1 and .047uf cap in series to sub for each of C1 and C2.  By wiring up a DPDT on-off-on toggle to shunt the .1uf in each pair or the .047uf, or neither, That yields nominal boosts at around roughly 200hz, 425hz, and 625hz.  You can use other cap values but these illustrate what can be easily done.  These resonant frequencies produce tones similar to a %^&*ed wah, which lotsa folks seem to like.  You can also use a rotary switch with more caps, but the shunted-series switching is pop free.

2) The Frequency Booster provides a nominal gain of two, given the resistors labelled R6 and R7.  When the SPST switch is open, it reverts to unity gain.  Note that the extra gain of 2 is multiplied by the gain in the clipping section so you end up with more push.  That helps out with other things (see below).  Note that the amount of resonant boost increases as R1+R8 gets smaller.  So you could make the resonance a little more outrageous by dropping R1 to 4k7, as well as permit greater subtlety by increasing R8 to 25k or even 50k.

3) The output of the booster is normally followed with a 10k volume pot but I went directly into the input of the clipping section here.  Note that the typical .047uf cap found in the ground leg of a DOD250/Dist+ is replaced with .22uf here to preserve bottom end at higher gain.  You will also note that the max gain is increased by use of a 3k9 fixed resistor instead of 4k7, and I've dispensed with the pointless low-gain end of the gain pot's spectrum by going directly for a 100k pot.  I used linear and it is absolutely fine, but reverse log is probably a little more appropriate.  A 22pf feedback cap is added to the 1m feedback resistor for stability and hiss management.

4) To preserve signal level, in anticipation of the loss coming from a passive scoop, I used a 4k7 output resistor instead of 10k, and a pair of silicon diodes instead of the usual back to back pair of Ge or Si diodes found in the Dist+ or DOD250.  This gives a hotter output, and also provides a higher clipping threshold.  Between the max gain of 257 in this stage, and the gain of 2 preceding it, that's a gain of x514, which is more than enough to net us seriously intense clipping.  And with the 2+2 diode complement, you get plenty of output level, even if you don't want clipping.

5) The passive scoop formed by the pair of 10k resistors, .0022uf bypass cap and .1uf cap to ground is adapted from the Superfuzz.  I wired up a 100k linear pot to provide two concurrent changes.  On the one hand is varies the resistance to ground from the .1uf cap, which varies the degree of scoop.  At the same time, it varies the resistance to ground of a second cap in parallel with the clipping diodes.  So at the one extreme, it lets through more treble and cuts the lower mids, while at the other extreme it brings back the lower mids and tames the treble a bit.  Feel free to experiment with other values of the .0022uf bypass cap and the .01uf treble-cut cap to ground.