Author Topic: Boss AW-2 sounds like poo  (Read 2373 times)


Boss AW-2 sounds like poo
« on: August 11, 2004, 03:10:30 PM »
Does anybody know of any way to get the Boss Auto wah-2 to sound decent.  This thing is way too trebly.  Could I put a cap across the signal to ground to bleed off the highs?  Any other things people have done or know about this harsh sounding pedal? Thanks!
All good things in all good time

Mark Hammer

Boss AW-2 sounds like poo
« Reply #1 on: August 11, 2004, 03:25:54 PM »
Do you mean it sweeps too high, or that there is always too much treble regardless of where it is in the sweep cycle?


Boss AW-2 sounds like poo
« Reply #2 on: August 11, 2004, 03:28:49 PM »
It seems to lose bass and is generally always too trebly!
All good things in all good time


Boss AW-2 sounds like poo
« Reply #3 on: August 11, 2004, 03:30:25 PM »
Probably sweeps too high, I had the same problem trying the pedal out in a store. Which is why I decided to try something better myself :P
I don't like Holland. Nobody has the transistors I want.

Mark Hammer

Boss AW-2 sounds like poo
« Reply #4 on: August 11, 2004, 03:59:28 PM »
Common grumble about swept bandpass filters.

These filters usually have their range of sweep set by a pair of equal value capacitors.  I don't have a schem of the AW-2 handy at the moment, but if you can find two identical-value caps near an op-amp and sitting near each other, those may be the ones.  If they happen to be in the .001uf to .05uf range,  even more likely.  If you can trace one lead of each cap back to either the output pin of an op-amp or one of the input pins, even MORE likely.

Making these caps bigger will drop the range by a proportional amount.  So, if they happen to be .01uf right now, making them .02uf will drop the range by an octave, and making them .039uf will drop it by almost another octave.

Best strategy is to experiment with parallel values on the *copper* side of the board until you know whether a) these ARE the ones, and b) whether the suggested changes deliver on what it is you're looking for.

Boss AW-2 sounds like poo
« Reply #5 on: August 12, 2004, 03:00:12 PM »
Being unable to find the schematic for this pedal I decided to trace it myself.

This pedal is greatly misunderstood because Boss tried to pack too much stuff into a stompbox and the manual doesn't do a great job describing what's going on with the knobs.

The circuit is an LDR, Inductor opamp implementation of the classic wah. There is a trimpot that sets the LED's idle brightness.

There's an LFO which works like having somebody rock the pedal up and down at a time set by the rate pot. The Depth pot actually mixes the LFO signal with wherever the "manual" pot is set at, which is nothing but a buffered DC offset that if the "depth" pot is set to zero will work as if the rocker pedal in a regular wah was left to a fixed position.

And then there's the "Sens" pot, which is the envelope detector's sensitivity.  The output of the envelope detector is mixed with the other two controls (manual and depth).

All this MESS is what is controlling the brightness of the LED.

A very helpful mod that I did on this pedal and that actually transforms it from useless to a very fun and usable pedal is to put another LED in parallel with the one in the LED/LDR package and mount it thru the front panel. This way you know what's going on.

A few other tips that MAY or MAY NOT work (experiment!)
R46 sets the "Q"
C21 sets the "center frequency"
Try different LED/LDRs
Add parallel LED and mount in enclosure
Change inductor (which stock is a transformer)
Can be transformed to Tremolo/envelope controlled volume/volume pedal
Do the later switchable
Add expression jack for "manual" control

And the regular things:
Change to a large enclosure to be able to add all sorts of pots and switches.
Make it true bypass.
anything else you can think of.

Don't be fooled by the bad reputation this pedal has. There is a potentially GREAT wah in there that just needs some understanding.


ps: don't ask me for the schematic, It's not ready for posting and I don't know when or if it will ever be. : Effect PCB Layout artwork classics and originals :


Boss AW-2 sounds like poo
« Reply #6 on: August 12, 2004, 03:11:10 PM »
It sounds like the filter is opening up too much. Are you hitting it with a hot signal? I use both the volume and tone controls on my guitar to *tune* the threshold at which an envelope filter triggers. Try turning down both your guitar volume and tone a bit.

Kerry M


Re: Boss AW-2 sounds like poo
« Reply #7 on: February 21, 2009, 02:04:58 PM »
so, has anyone had good luck w/ the mods mentioned in this thread?  I have an AW2 on my board and i have all of the same complaints.  Anyone ever locate a scheme for this little sleeper?

I'm basically looking to adjust the envelope section to bring it down to a usable (non-ear-splitting) range.

Any input is welcome.


post script: yes, it's an old thread but it directly applies to my problem...


Re: Boss AW-2 sounds like poo
« Reply #8 on: August 12, 2018, 11:00:59 PM »
Super necro post but thought it'd be better to reference this thread than start a new one. I'm looking to implement some of the mods tonepad mentioned in above post about the AW2 (one of my first pedals I bought about 20 years back!), I'm especially interested in the one where I could turn the wah effect into trem/voltage controlled volume effect, is this easy enough to do? Sort of like connecting the output of the LFO/envelope circuit to another section of the circuit later on after the wah induction circuit (possibly bypassing it)?

I have decent experience in building and modding pedals (though usually by standing on the shoulders of giants and following other peoples work rather than coming up with my own designs, etc). I also have the schematic for the AW2 if anyone wants me to put it up here.

Thanks for reading guys!
« Last Edit: August 12, 2018, 11:24:23 PM by dwrockdoctor »



Re: Boss AW-2 sounds like poo
« Reply #10 on: August 13, 2018, 05:39:00 PM »
Thanks DFX-PCBS!

I already found the schematic so I'm just trying to figure out a way to reconnect the LFO/envelope to bypass the wah section to be able to get it to control amplitude a'la tremolo/envelope controlled volume swells as mentioned in the earlier post by tonepad.

I'm hoping it is as simple as rerouting the LFO/envelope to later down stream from the wah for this to work without having to bring in extra components besides a toggle to go between wah or volume control via LFO/envelope.