a very simple pedal idea

[necromantis]

I probably shouldn't be here. I know very little about electronics. However. I just want to check with knowledgeable people to see if my idea is even close to correct or maybe even understand a way to build it.

I want to make what I call a "Devolumizer Pedal." No need to tell me that that isn't a word. I am aware.
Function of the pedal is this: I have my amp (In my case a JCM2000 dsl100) cranked up to gig-volume on channel 2 with a pretty saturated overdrive. Then you kick on this pedal and the volume drops and the bottom end falls off. it sounds like you kick on a wah and leave it all the way forward (or most of the way forward) and roll you volume way off. (actual volume not just gain)
very similar to the bridge of "Born of a broken man" by rage against the machine if you care to have a listen.

My thinking is buy a standard pedal box. Get a volume potentiometer (so I can tweak the sweetspot depending on my amps volume). and either a tone pot or preferably a resistor/cap/I-know-nothing-about-this-kind-of-stuff and stick them in a passive box with a true-bypass switch and some jacks. Voila!
I can solder just fine so the only problem is knowing what to buy to solder and figuring out what to solder to what. lol

I need something with a narrow Q (like most wahwahs) with the focus on 1000hz-1.5mhz or so. Since I know nothing about resistors or whatever i don't know which one to pick or if it would work .. or if my idea stinks even. A boss metal zone works great for the effect (Volume, gain and lows down, highs and midhighs @3oclock) but I try to keep boss effects out of my signal chain and I don't want to shell out 80-100 bucks for something so seemingly simple.

[Mark Hammer]

Actually, the idea has shown up in a variety of forms, most recently the EHX "Signal Pad", which is a volume pot in a box with a switch.

I suppose where yours would be different might be the inclusion of a compensating cap across the pot.  On many guitars that use single-coil pickups, you'll often see a small-value capacitor between the input and wiper of the volume pot.  This preserves the highs as you turn down so that the guitar doesn't get quieter and duller at the same time.

I like to stick a cap of a much higher value than is typically employed.  What this tends to do is act like a bass-cut control, by not only hanging onto the highs as you turn down, but the mids as well (depending on the cap value).  This is something you can easily build as a passive box.  A good idea might be to use a 3-position toggle to either leave the pot uncompensated, minimally compensated, or over-compensated.

[necromantis]

Awesome! Thanks for a quick response. Do you have any suggestions as to what value cap to get? Is there a order number? dual lead dlj700 (dual lead jumper 700hz-- i clearly made this up) or some such name that I would never be able to decipher?  As I said I am lost on this type of thing.
An analogy would be I can use a computer program really well but I couldn't write the code for one.
I really appreciate it.

[GGBB]

Would a sweepable cap value instead of the toggle be appropriate here?  That would prove a second pot for dialing in how much of the mids are cut along with the bass.

[Mark Hammer]

Depends what you want.  The OP used the phrase "simple pedal".

[aron]

Why don't you get a used wah - rip out the circuit, set the pot to where you want and then put a pot on the end?

[Mark Hammer]

I may have gotten it wrong, but me sense was not that the OP wanted a resonant sound, but simply a slightly wimpier one, with a modest drop in volume and bass content..

[aron]

He mentions a wah twice, so I think he should just get a crappy wah circuit - modify the one (or two) resistors that make the wah "stronger or weaker", then tack on a volume pot. That's what I would do.

[necromantis]

Yeah the idea is there is a fairly significant drop in volume and a cut over the bass and low mid frequencies. I have found a good sound for recording by using the volume pot on my guitar and kicking on a wah nearly all the way forward. I am looking replicate this with a simple pedal. The reason I say a very simple pedal Idea is because I made the assumption that a volume pot and some sort of cap or another pot or something could accomplish this.
I guess I could buy an eq pedal and pull all the faders down except 1.3mhz or whatever is on it but they are generally more money that I would like to spend on something like this. Plus, it would be pretty cool to say "oh that? That is a cool little box I build, it does this...**Stomp**"

what about a pot with a large range like a wah has (or some people put in there guitars) that you use just like a wah, except you twist it by hand to set the peak. Its just a knob on the pedal. counter clockwise is towards the low end and clockwise is more top end (or the opposite). I wouldn't even mind if the knob looked like that elogated gear on the pot inside of wah, though I'd prefer a knob of course. personally I don't know if it would sound like I mean for it to.
just another Idea.

the sound is similar to this http://www.youtube.com/watch?v=NInGsBLwmhg -- at 3:25
Hope that is ok to post here.

[DiscoVlad]

it sounds like you kick on a wah and leave it all the way forward (or most of the way forward) and roll you volume way off. (actual volume not just gain)

Tom Morello achieved that sound by doing exactly what you describe... Back the guitar volume off (or switch to another pickup with lower volume), and use a fixed wah.

You've answered your own question there

[necromantis]

I was hoping to make a pedal that did that without kicking on a wah and switching pickups/channels/rolling off volume. I am not looking to sell this pedal on a mass scale. I just need one to meet my own needs.

[artifus]

tim e's idiot wah is a low parts count simple build. http://www.jiggawoo.eclipse.co.uk/guitarhq/Circuitsnippets/snippets.html. you could also google inductorless wah for others. there's an article over at geofx the technology of wah pedals you might want to read.

*edit* for super simple you could try a passive high pass filter http://www.muzique.com/schem/filter.htm. as you're backing off your volume to achieve the tone you want signal loss should not be an issue. use a pot for r. tack a volume pot on the end to attenuate the output further. this will lack the wah's characteristic peak but may get you close to what you want with minimum fuss.

[markeebee]

Mad Bean's Karate Shop does exactly what you're after.  A bit more complex than a single resistor and cap, but still an easy project.  You can buy the pcb from Bean for less than ten dollars, and his documentation always makes things easy.

Do it.

http://www.madbeanpedals.com/projects/KarateShop/docs/KarateShop.pdf


EDIT
Actually, to make it do EXACTLY what you want you'd need to add an Output Level pot but that's a piece of cake.  If you're interested I'll show you how to do that latrr today when I get bac from work, unless somebody chimes in first.

[GGBB]

Would it be possible to hook up a dual-gang pot to function as a simultaneous high pass and low pass filter?  Something like this (not sure about values):



I am really just guessing.  As Mark pointed out earlier, the OP asked for something simple that stomps on and off, and the thread seems to have gone in the other direction.

[nocentelli]

I think a volume pot with a bypass cap (as Mark Hammer suggested) would work just fine and would be a relatively easy first build.

[rousejeremy]

Telecasters have a .001 cap between lug 3 and 2 of the volume control, when backed off a bit it gets pretty bright and drops bottom end. Give it a try.

[krister]

I would use my Dano Fish & Chips graphic eq for this. It has the 7 band frequency control, a volume control and an on/off switch. The pedal costs about $30 tops. Done deal IMO.