maestro boomerang wah- info, innuendo and inference

[joegagan]

a few findings on boomerangs, inspired by the wacka thread:

i can say definitively that a hotpotz 1 or 2 with a 33k resistor ( or any other limiting resistor) will not sound, sweep or react like a correct 25k pot.

my findings after a few years of boomerang obsession. richard mintz, whose company built all of the boomerang2s, told me that the original spec was even a little different than a standard reverse log. he also was adamant that the higher value pot with limiting resistor was not going to interact with the circuit correctly.

before he told me this, i had previously done hundreds of experiments with dozens of pots in real boomerangs, and boomerang clones in CB cases. also bought a couple dozen 25k,30k, 50k pots from ebay and surplus places trying to find a suitable replacement. none of my experiments yielded a feel like the original. ( PEC does make a rev log 25k rv4 spec pot, which is next on my list to try, around 12 bucks from digi-key)

we have in our collection a real 67 BG1, ( sounds best of any i have heard ), a half dozen BG2s, and have sold quite a few 2s as well.

it is exceedingly rare to find a BG of any vintage with a non-scratchy original pot. when i finally found a bg2 with the original pot, i was blown away. not only did the wah sound closer to our holy grail 67 than any other, the volume pedal function actually works beautifully. it actually gives a slight boost in vol mode, and sweetens the tone. mintz had been telling me for a couple years that a correct bg2 will not suck tone in bypass, i finally found for real what he was talking about. you can hear the wah sound of this 100% original non scratchy bg2 here:


back to the sweep question. the reason that a hotpotz2 ( or hotpotz1) will not give the correct reaction is that the taper has a fast kink in the sweep. this is why some people prefer the more gradual icar. when you put a limiting resistor across this quick ramp, it simply condenses the ramp, making it even worse! i went so far as to fabricate offset cam type gears to try and slow down the ramp on a hotpot ( hotpotz 1 and 2 have same taper BTW). it got close but then required a spring load pusher for the straight gear to keep it on the gear! and again, the limiting resistor changed the tone vs the stock comparison unit.


when measuring the actual resistance of the original 25k pot while in the actual boomer case, the reaction is very close to linear.. imagine that, they had to use a log to simulate linear, due to the physics of the rack gear! what is funny, is that an icar does something quite similar, although not quite as linear.

so, some wah guys have mentioned they like icar with limiting resistor for boomer, which helps, but most icars are closer to the original 180k, which again moves us in the wrong direction.

one more wrench to throw into the monkey farm:
if you build a boomer clone in a CB case, you have a slightly shorter throw, and the pot is running opposite direction, making all of the specs for std boomers backwards regarding taper. so if you build a boomer clone in a CB/vox case, try a 25k log ( PEC as mentioned above)

in an attempt to get a hotpotz1 or 2 to work correctly in a boomer clone in CB case, i worked up another non-concentric cam-like mechanism that gets me as close as anything i have tried so far- a clone in CB/vox case


you might be wondering, why does a quicker taper matter?, i can just adjust my foot action. it is possible you could be this accurate, but the beauty of a boomerang is the super extended play area across the mid hump sweet spot, as heard in jj cale's crazy mama. boomers are popular with swamp guys too because of this ability to ride the sweet spot in detail.



there is a tone and electronic component to all of this that few have considered, but one that in my research seems to explain why a slower taper also effects the tone. an inductor wah is constantly charging and discharging a cap to ground off the inductor. think of it like filling and emptying a bucket. if the ramp is too fast, or the resistance on either side of the two sided pot equation is too low ( think of the narrow or wide slope shape of Q on a parametric), the cap may never get to a full charge as it passes across. just a theory i am working on.

that's the gist of what i've found so far. i have approx 20 or 30 youtube vids on my channel relating to boomers, check em out!

[joegagan]

also, some of you may have heard about the taper changing tricks, using 2 resistors across both halves of a higher value pot. again, i tried hundreds of combos, none got me near close enough to mimic the stock 25k boomer taper.

[jagermonster]

So...is there anywhere to obtain a pot with the correct value? I am suddenly nonplussed with my Hotpotz/limiting resistor setup.

[joegagan]

buried in the above miasma was mention of a PEC at digikey, which i have yet to try. for stock boomer case, rev log 25k,

if in a CB/vox case=log taper.

if anyone tries this, post your results here, please!
(digikey doesn't take paypal, i got to checkout and then didn't have time to do all the rest of it, didn't get back to it)

[tekbow]

i don't think there'll be anymore wacka threads from me.. This has just about cleared up everything i wanted to know about the boomer. Really and sincerely cheers Joe, an awesome post!

[jagermonster]

Honestly, I forgot to mention in my above post: THANK YOU. Educational post to say the least.

[tekbow]

Joe i've been checking out your vids, how did you tune the RMC3 to emulate the boomerang?? and how wasit possible to do it given the difference in pots etc

[Nick]

hah, you have me convinced sir. and you've also ruined the wah that has done me well for years i did always suspect that the Hot Potz trick wasn't the same as having the real 25k in there and desoldered it and put it back in just to make sure it was right and the right value... even had tech guys assure me it was the same dealio and that it was just my wah technique that sucked. but i'm just comparing my BG-2 with that first vid posted in this thread doing the same chords with the same feel and it brought back all my worries not that i hate my BG-2... even with the 100k/33k trick it's still way better than the various Italian, Shin-ei and Colorsound wahs that i have played alongside this one. the BG-2 always blows them out of the water but thanks to you i need to get another
have you tried adapting the Ernie Ball 25k pot for this pedal?
please keep us updated with your findings on the PEC 25k thingamabob

[joegagan]

jager - thank YOU for reading it, - ha!

tekbow, you are welcome as well. i should extend my gratitude to my partner at proximity, zac zagar,as he pulled me out of mothballs and continues to be a helluva partner in crimes against boring tone. ( you gotta hear his take on the DOD 440 env filter!)

if you are referring to the june 2010 vids where i compared a teese rmc3 to the original 67 BG1, i started with the factory setting in the old rmc3 manual called 'john shaft' *( teese said in a long forgotten forum post that this was sent to him by a customer), then spent about 30 minutes fine tuning the center freq to be as close to the maestro as possible.

the end result, the settings were pretty far from the manual. i wrote down the settings but have long since gotten rid of the notes as this was a customer wah, and my experience with rmc3s is that they vary, plus we have no way of knowing whether the guy who sent the settings to teese was all that accurate + what did HIs boomer sound like etc etc.

all that said, the teese sounded freakin excellent! when i listen back to that comparo, i always am amazed at how much i like both of them. thinking back, the sweep of the teese was quicker ( he uses an icar taper, however), i probably adjusted my foot action. not to mention, he uses incredible parts and puts them together so well. they are delicious. don't forget, the rmc3 does a VERY good boomer tone, plus pretty much every other inductor type wah you can think of.

side note: i have an an '02ish rmc3 in our collection that sounds even better than the one in the vid btw. at least to my ears.

nightraven , thank you. you ask an excellent Q. i actually went out and bought the current style 25k ernie ball vol ped in an attempt to possibly use it as a base for a boomer clone. i can't tell you how much i love the engineering in that pedal. however, the pot was linear, and somehow sounded completely awful when hooked up to a vintage boomer circuit. for whatever, reason, it would not go full treble, and sounded boring. end of experiment. now zac has a nice volume pedal.



* pretty sure this setting was removed from the manual a long time ago?

[fuzzface6669]

That wah sounds really damn good and nice playing !

I hope the pec pots will work out good for you. I really like pec's pots and old sealed allen bradley pots for other types of pedals.