snarling dogs - black bawls

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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devastator
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Post by devastator »

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I tried to draw the schematic, seems to be a varation of classic inductor wah (crybaby/vox) with some change (cap values, resistor). The sound is deeper and softer than other pedal.the range is also bigger compared to other wah pedals (a little bit like the colorsound's pedal I guess). The center frequency is lower (two cap in // where in Dunlop circuit a 10n cap is present) .

The metalic stuff close to the footswitch is the.....inductor ( :shock: ) (I haven't tool to know its value)

The boost section is a bipolar transistor with the pot. (with a big cap on the wipper) placed in // with the emetter's resistor (that's not really a lood boost , by the way )
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mundry
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Post by mundry »

i draw the schematic
http://www.fennecelectronics.it/smf/ind ... 5#msg45395
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analogguru
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Post by analogguru »

mundry wrote:i draw the schematic
If I could seee it....

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Post by mundry »

here is it

there's something strange in this schematic:parallel C9-C10 and R6-R7 but that was their placement.

E1-E2 are the connections to inductor..i don't know the value of the inductor...i think is a classic 500mH
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snarling_dog_bb_wah_rev1.jpg
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Fender3D
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Post by Fender3D »

Hey mundry,
I guess you reversed C and E in your transistors CAD models...
(drawing only, 'cause schematics seems ok regarding B-C-E labeling...)
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mundry
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Post by mundry »

Is because i didn't find the exact model on the eagle CAD library.... so i signed E-C-B on the schematic by reading the datasheet (but with a generic symbol)
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Post by analogguru »

Thanks for the schematic. I invested three minutes with the windows program "paint" to change E and C and add the missing resistor R4. Below is the result.

The parallel R6 and R7 appear to be a factory routing mistake. R6 should be in parallel with E1 and E2. This can be corrected easyly with a stanley knife at the pcb. The value of R1 is also suspiciously high but also used in the "Wonder-Wah". In the "Mold Spore" it has the (correct) value of 68k.

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Post by chicago_mike »

Speaking of the Mold Spore, does anybody have a schematic of that nasty thing?
Skyline FX 2013
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mundry
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Post by mundry »

did i missed that resistor (r4)? :shock:
gotta check again :slap: :scratch: , thanks for the revision Analogguru! :thumbsup
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