The Xotic AC Booster a well loved booster/overdrive pedal, this demo shows why -
And here's a scheme for you:
You can clearly see it is a traditional style opamp based clipper. With one interesting addtion, it has an active tone stack present after the clipping section! Here's some more info, available on the Xotic site: http://www.xotic.us/effects/ac_booster/
Kusi of the freestompboxes.org forum contributed these mods to change the xotic AC booster into the xotic RC Booster:
C1 = 47nF
C2 = 1uF / NP
R8 = remove and bridge
C4 = remove
R5 = 22k
R7 = 250k
Clipping-Diodes = 3x 1N4148 each side
Thank you for the information. About the RC booster mod, what do you call 3 on each side?
ReplyDeleteRegards
Me again,
ReplyDeleteI am not able to find the 4557. It is probably obvious for you which opamp should be used, but I am a complete starter in this field. Could you then please give the complete name of the opamp and/or a potential replacement for it?
Regards
"3 4148 diodes" would be 3 diodes in the feedback loop of the opamp positively biased and 3 diodes negatively biased, parallel to one another. Basically something like this:
ReplyDeletev----| Gain Pot
|-/\/\/\--|
|-->->->--| Diodes
|--<-<-<--|
The opamp you should be able to find at all the major retailers such as mouser e.t.c I would recommend trying other dual opamps too - the LF353 is a good 'un for example, or the clasic JRC4558, the choice is yours.
Hi, any news for the PCB?
ReplyDeleteHave someone tried to figure out a layout?
Thanks a lot!
so waiting for a pcb or layout for this baby...
ReplyDeleteBUMP
Any body test these schem??. What are the results, sound great?.
ReplyDeleteGhosteaser I think that the JRC4558, 4559 are equivalent of 4557.
Bye!
i found your site when i search scheme use IC LF353 (gift from my bro). well i don't promise too build that :-). good site...Deux.
ReplyDeleteHas anybody ever seen a 4557? I haven´t... ;-)))
ReplyDeleteThe new spec RC which is the same as the Scott Henderson has a 1uf cap as C1. Thats the only difference according to Xotic. Im assuming they use a metal film cap.
ReplyDeleteR8 on the schematic should be 1K resistor not a 10K as shown.
ReplyDeleteFind NEC 4557 op amp at
http://www.dalbani.co.uk
Regards
this is version 1,version 2 has 4 diodes,gain 1meg lin,vol 100k lin,r8 1k,led is powered via a mosfet circuit.
ReplyDeletealso r18 is carbon comp
ReplyDeleteGreat info Alex, Cheers for that...
ReplyDeleteany idea about the AC-Comp Booster? does it have additional circuitry to achieve the compression or just a siwtch that selects differently valued components for something already in the circuit above to achieve a more compressed sound?
ReplyDelete