AW2 AutoWah Mods

Here are some interesting mods for the AW2 AutoWah, the child of the TW-1 Touch Wah.

  • Instant Attack switch for more psychedelic sounds; this can also stutter with some settings!
  • Up/Down switch, like the TW1 for a second Wah direction
  • Triangle LFO Mod changes the sinusoidal LFO into a Triangle wave for a subtle yet noticeable effect; sounds best at high LFO rates

These mods are of my own design and I have not seen them anywhere else. The schematics are not documented for the AW2, but its predecessor the TW1 is documented and is nearly identical. BOSS, AutoWah, Touch Wah, and AW-2 ARE TRADEMARKS OF THE ROLAND CORPORATION AND ARE USED FOR REFERENCE ONLY. THIS SITE IS NOT AFFILIATED WITH THE ROLAND CORPORATION IN ANY WAY.

Schematics


The AW2 Schematic seems to be unavailable on the internet (leave a comment if you know where to get one). However, the TW-1 schematic is available and the circuits are nearly identical.

Click on an image to enlarge it.
The upper image is the TW1 doctored up with the additional LFO found in the AW2. The lower image shows the 3 areas of interest for these mods: the Up/Down switch (missing on the AW2), the LFO Mix resistor R20, and the LFO diodes D7/D8.
The functionality of the two devices is nearly identical: an envelope detector follows the strumming pattern. It modulates the LED in opto-isolator FC1 which modulates the photo-resistor half, which sets the gain and center frequency of the bandpass filter formed in part with the inductor found in the transformer L1.
The added LFO is built around IC4 which connects to the Rate and Depth controls. Some of the component equivalencies are here:
TW1 AW2
-------------------
C7 C22
C9 C9
P.C. FC1
Q4,Q5 Q6,Q7
D6,D7 D5,D6
R27 R14
R28 R19
R29 R21
R34 R28
R32 R26




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