Monday, February 2, 2009

Kick Pedal mod for Guitar Hero: World Tour

[EDIT] I made the pedal a bit tougher and added some more pictures along the way.

Well, it had to happen. I broke my kick pedal again the other day. I had a bit of a hard time fixing it up (more on that later), so I figured I'd go all-out and build a real kick pedal controller for my Guitar Hero: World Tour drumset (like the ones you can buy on various sites).

If there's one thing I appreciate about the Rock Band / Guitar Hero instruments, it's that they're very simple. The drums, for example, are simply piezoelectric vibration sensors that you can attach to pretty much anything you like, such as a tabletop, a real drum kit, a book, or anything else you can think of. Piezo sensors create DC output when they vibrate, so basically, the drum controller uses this electric signal to tell when you've hit something, and also how hard you hit it. This is why an overly sensitive drum head sometimes experiences 'crosstalk', because the sensor is picking up vibrations that it's not supposed to (or it's badly soldered onto the wire and coming loose).

The GH:WT kick pedal also has a piezo sensor, contrary to the Rock Band 1 pedal, which uses a magnetic switch. Both are about as simple, however: each one uses two wires connected to a mono audio connector like the ones you can buy in electronics stores. This makes it really easy to create a functional replacement pedal (it doesn't even have to be a pedal at all).

I went to a local music store and bought a cheap, run-of-the-mill chain-driven kick pedal. I was talking to the guy behind the counter when he mentioned he had a drum practice pad with a broken sensor inside of it. Since the sensor he was talking about is for real electronic drums, I took the pad off of his hands.

The pad looked pretty cool, since it had a socket for a 5/16" bolt on the back. I figured it would fit nicely on a metal pole, especially if I could find one that was pre-drilled with holes. At my local hardware store, all they had were solid lengths of steel pipe. I'm not equipped to drill holes in pipes, and they couldn't do it on request either, but I brought a suitable length home anyway, thinking it was at least good enough for a prototype.

My friend Bob, plastic guitarist extraordinaire, has participated in my fake instrument mods since we started playing Guitar Hero a short while ago. I enlisted him to give me a hand in creating a suitable base for my new practice pad. This monstrosity is what we came up with:



Yes, those are tie-wraps. We used a whole bunch in this prototype, mostly because we're lazy, and we like cheap things that do a great job. It's easier than drilling holes through steel pipe, at any rate.



The first thing we did was grab a piezo sensor I had lying around and soldered the wire from my broken GH:WT pedal to it. Connecting a piezo sensor to an audio connector is simple: take one end of a two-conductor cable (the GH:WT wire resembles a regular audio or speaker cable), solder one of the wires to the ring on the outside of the sensor, and the other to the the inside of the sensor, which is usually white. Then take the other end of the cable and solder each wire to one of the audio connector's terminals. I'll write a separate entry on this later, with pictures, since this is basically everything you need to make a trigger for Guitar Hero: World tour and Rock Band. This is also called a contact microphone, and you can test it by plugging it into a set of speakers, putting the sensor against a surface, and then tapping on the surface. You should hear a kind of scratchy thump if it's wired correctly. There's not much else to it: if you've soldered the wires to both ends correctly, it'll work, nothing else is needed. As you can see, this one has been used a few times, but these kinds of sensors are pretty tough and the extra bits of solder don't do any harm.


In order to protect the sensor, we wrapped it tightly in electrical tape. The solder could get shaken loose if you leave it exposed, especially if you have a tendency to be rough. You'll also want to make sure the wires aren't exposed. This is what the finished sensor and cable looks like.


Once the piezo sensor was wired up, we glued the sensor to the inside of the practice pad, as this image shows. We used some quick-set epoxy, which is a pretty resistant glue that bonds almost anything. We also taped the wire down in a few places in order to avoid having any extra hits being created by the wire moving around. Adding some sort of soft foam on top of the sensor in order to contact the practice pad's drum skin might enhance the sensitivity, but we didn't have any lying around, so we saved that option for the updated version.

We reassembled the pad and strapped it securely to the length of pipe I bought.


So far, so good. Bob went to work, creating a suitable wooden base that allows us to drop the steel pipe in and attach the pedal. We had something much more ambitious at first, but Bob's love of tie-wraps took over, and we ended up with this:





Okay, so it looks a bit weird. The question is: how does it perform? I've only tested it once, but so far, it's been great! Double and triple kicks have never been easier, it hardly makes a noise, and every bass hit is accompanied by a solid thumping sensation, which is way more interesting than playing on a plastic pedal.

The great thing about this kind of mod is that once you've wired that piezo sensor up, you can connect it to almost anything you can tap, whether it's with a drum stick, your hands, feet, or anything else.

35 comments:

  1. Well tie-wraps are for simplicity's sake. Some building materials, tools and techniques are sometimes out of reach. Now that the basic prototype is built and fully functional, we can only improve on the design... Soon I hope.

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  2. Of course. Don't get me wrong, it's a great prototype... just slightly unwieldy for now. Ideally, I'd like to make it compatible with all fake drum kits, and compatible with any pedal (including my neighbor's double pedal!).

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  3. So in theory you should be able to do the same with a rock band pedal

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  4. Yes, and in fact, I already have... it's just a question of swapping out the piezo sensor for a magnetic switch... the rest of the wiring is exactly the same. I'll be putting up a guide on how to do this soon.

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  5. A better question is, could this same application be used in the other drums or cymbals of a GH set?

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  6. Hi Jude,

    The answer is yes: I actually replaced a broken orange cymbal by swapping out the broken piezo sensor with another one. The drum pads and the cymbals of a GH:WT set all have exactly the same electronics as the pedal (a piezo sensor wired to a connector is all you need).

    I'll be putting up more guides on all of this stuff shortly (I'm a bit swamped by work at the moment, but I should find the time to do this before the weekend).

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  7. Hi raphael. this is a great mod. i have a GHWT drums and i play with it for few hours and my kick pedal stop working. i think my problem should be a bad cable conection in the piezo sensor. can you tell me what can i do to check it without brake my kick pedal? i can't see what can i do to disarm it. really thanks for your help and sorry for my poor english.

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  8. Hi Fiannolo,

    You can test your kick pedal by plugging it into a pair of speakers (you may need an adapter). The connection is a mono audio connector, like a computer or mp3 player (but those have stereo connectors instead). When you press on it, it should make a thump sound (a bit like a bass drum). This is an easy way to see if the pedal works or not.

    If you need to fix your pedal, you can open it by removing the foam under the front part of the pedal. There, you should find a few small screws that you can remove. Be careful, though, they're hard to turn.

    In the kick pedal, you will find the same kind of sensor as the one above. You can look for a loose connection by moving the wires a little bit. The white glue might be keeping the wires in place, but the connection might still be bad. You should remove the glue and resolder the connection.

    My post about the broken cymbal covers everything you need to repair a broken pedal.

    Raphael

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  9. I've had this game a week and already I wanted a better kick pedal, you have confirmed my supistions of whether or not a diy pedal could be made, thank you so much.

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  10. Great job man, the wooden frame for the pedal is probably cheaper than buying one of the standard steel frames for usual practice pad kits.

    Quick question though, would there be any reason a magnetic reed switch as used for many rock band pedal mods, wouldn't work for guitar hero?

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  11. Hi Jack,

    First of all, thanks for the comments.

    The short answer to your question is that a reed switch won't work due to the electrical output. As far as I can tell, the RB pedal is wired like an alarm system: current is sent down the wire, and the switch either lets it through or not, triggering the 'pressed' state of the pedal. The GH pedal, like all the other drum pads, uses a piezo element that actually creates DC when you mash it.

    I think the fundamental nature of the electronics used would make it difficult to switch the components around.

    For the record, I have tried a reed-pedal based switch in GH:WT and a piezo element switch in Rock Band... it simply doesn't work.

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  12. For everyone who wants to use an e-drum kick trigger with rockband(doesn't matter if bought or DIY as long as it uses a piezzo), here is the soultion: http://img204.imageshack.us/img204/4063/kickcircuithx6.jpg

    This little circuit basically use a transistor to transform the voltage from the piezzo to a switch-signal readable by the bockband drum-brain. Also including an operation amplifier and a timer, this circuit delivers good results. With the 2 trimmers you can set the input sinsibility and the length of the output signal(this way you can prevent unintended multiple triggering).

    I got this one from this post in the rockband forum: http://www.rockband.com/forums/showthread.php?t=116211&highlight=kick+pedal

    If you want to connect a complete e-drum set to rockband, you can find the schematics for an operation amplifier for this purpose in the same thread.

    If you are not good at soldering or don't have the time to built this, there is a commercial verison of the kick circuit called "Kickbox", but it costs $65!!!

    I use these circuits connected to the "brain" of an old rockband drumset (Xbox360) to be able tu use my e-drum set(incl. cymbals) as a rockband controller. I've beat ALL my personal highscores since im using this setup, so i guess it works pretty well^^

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  13. MrBrown666,

    Thanks for the info! That's really awesome stuff. I was actually planning on doing a similar move with my GH:WT drum set (taking out the brain and hooking up a real e-drum set), but I don't actually have any e-drums and I don't have the budget to get a set right now.

    When I do get around to it, I'll document the process here.

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  14. I am interested in using a piezo element to control some stage lighting. I want attach the piezo element to my kick drum and have a light go off anytime it senses the vibration. You have any ideas how i could do this? Thanks.

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  15. tyler,

    It should be pretty simple to rig something like that up. What kind of lights are you planning on using? If you want to use small lights, like LEDs, you could probably get away with a small microcontroller, like an Arduino (http://www.arduino.cc). In that case, it's just a question of hooking up the piezo sensor, watching for a signal, and turning the light on/off. You *may* be able to get away with hooking up an LED directly to a piezo element, but I am not an electronics guy, so I wouldn't bet on it.

    If you want to use conventional lighting, you'll probably have to use relays to turn it on and off, since a small board like an Arduino can't supply the required power to drive the lights directly.

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  16. This mod looks really great. I have two questions. 1. How do I take apart the Guitar Hero pedal without completely destroying it? and 2. The wiring and soldering part kind of confused me. Once i get my pedal apart, do I use the black wire with the purple jack and then solder the two wires to the peizo thing?
    Thanks for your help, I've been looking into this for awhile but didn't want to spend $100 for a video game.

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  17. Hi willowens,

    The Guitar Hero pedal is a bit tough to take apart. The screws are hidden under the anti-slip surfaces on the bottom of the pedal. Once you've removed the screws, the pedal should come apart.

    If you're trying to do this with a working pedal, you may be able to get away with no soldering at all. However, the wiring is very simple: you have a mono audio connector at one end, and a piezo element at the other. The cable contains two wires: one of them goes from the inner (white) circle of the piezo element to one of the mono audio connector's terminals (doesn't matter which), and the other wire runs from the outer (copper) ring of the piezo element to the other terminal on the audio connector. Once you have things soldered together, you can test it by hooking it up to a cheap pair of speakers as a line-in. As you tap on the piezo element, you should hear a dull thump from the speakers.

    You may want to check out my cymbal replacement post, as the electronics are identical.

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  18. awesome do you know what kinda of practice pad that is??? found one online looks close to yours its a remo tunable practice pad for around 20 bucks

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  19. http://www.samedaymusic.com/product--REMRT

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  20. I bought it used from a music supply store, and it didn't have any specific branding, but what you've found looks absolutely identical to what I've got.

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  21. Raphael,
    My my kick drum cable disconnected from the sensor,
    I opened the kick pedal and removed the sensor.
    but,
    I found 2 metal wires at the sensor side(one is red and the other is light brown)and they are not seperated with any plastic isolator (like in your picture).
    they are both coming out from 1 cannal.
    can I still connect each wire to each of the sensor rings?

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  22. hey, um the yellow thing. i decided to twist it thinking that it would get tighter but, i twisted the whole thing and now it broke the orange/yellowish/redish thing is expose and i need to put it back in but, how? an will it work?

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  23. Let me clear it up. The Yellow plate. It was kinda lose. so, me being the dumbass that I am i decided to twist the WHOLE thing which led to breaking of the chord and now my yellow plate doesn't work. the chord is exposing the yellow/red wires that are inside the black covering wire. what do I do? please help me.

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  24. Hey y3ll0wac3z,

    You just broke the wire. Strip the ends of each wire and re-solder them together. Just match the colors up and you should be good to go.

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  25. Hi...hope you can help me. On our Guitar Hero kick pedal, the wire pulled out of the kick pedal. We unscrewed and removed the sensor but do not know which wire goes where. There is a red/orange and a light brown. Which goes on the middle and which connects to the outer brass? Thanks for any help!!

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  26. does it matter what color wire i solder?

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  27. Hi franklinmknight,

    No, it doesn't matter so far as I can tell. As long as you solder one wire to the inside of the sensor and one to the ring on the outside, you should be golden.

    That goes for others wondering about which wire to solder as well.

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