Foot Drum Stomp Box

[Elijah-Baley]

Do you never seen this?  
https://www.youtube.com/watch?v=0BM0WNtJzcs

This is bass pick-up based, but I saw some with a little microphone.

Is there some tutorial or guide to know how to build this box?
Or maybe some DIYer have built it and can help me? I meant help us.

Thank you!!

[antonio.s]

Looks like there's too much electronic for the use.
If i were to build something with the same function I'd go with an inexpensive piezo disc:

[Elijah-Baley]

Well, if it works fine it could be an alternative.

Is this the same?
http://www.taydaelectronics.com/review/product/list/id/2833/

Thanks!

[antonio.s]

Well, if it works fine it could be an alternative.

Is this the same?
http://www.taydaelectronics.com/review/product/list/id/2833/

Thanks!

Yes, but it costs more, breaks more easily if hit frequently, and will be fixed with screws to your percussion surface, which means it will transmit vibrations less efficiently when compared to the other type which can be glued to any material.
You don't have to order your piezo elements online, any local electronics store will have a good assortment of sizes and types for a few cents each. I know because I built an entire electronic drums set, and I used the type you propose on my first HiHat, at the time I thought 'more expensive sensor, more quality' but in the end it depends on what you're going to do with that.

[Elijah-Baley]

Obviously in my tiny town I'll never find that... But, thank you, I'll remember this suggestion.

I wait further opinion about this kind of box.

[ashcat_lt]

Looks like there's too much electronic for the use.
If i were to build something with the same function I'd go with an inexpensive piezo disc:

What electronics?  It's a pickup in a box!  Your piezo disc is going to need a buffer and a whole lot filtering to sound decent.  The magnetic pickup just works.  Plug it into an amp like any other guitar.  The V and T are definitely just passive like you'd have in your guitar and could be omitted if you really want to KISS. 

Any magnetic pickup will work for this.  Doesn't have to be a bass pickup.  All of the variables that apply to guitar pickups apply hear, and the tone will be pretty predictable depending on which pickup you use.  One might be inclined to go completely nuts and wire in a full-on HHH system with local and system series/parallel configurations, phase switches... 

Pretty cool idea, and should be much less prone to feedback than a lot of other ways that I've seen.

[antonio.s]

We don't need to capture all of the nuances of a stringed instrument here, plus the level, tapping directly on the piezo (or on the surface it is glued to) should be decently high without a preamp. And we're taking about a simple and inexpensive device, compared to a magnetic pickup. However I should have some piezo discs left, and a wooden box. If I find a female jack I'll build one and check if it is a viable option, since it's a 5 minutes operation.

[Elijah-Baley]

Thanks guys!
I found just project with bass pick-up and no guitar pick-up. Probably it will work with any magnetic pick-up. Perhaps bass pick-up is better? I really don't know.
I prefer, eventually, have a tone and a volume, it might be useful.

Antonio.s, thank you for your experiment!

[PBE6]

Some musings on making a preamp for a piezo sensor "stompbox":

"Stompbox" Stomp Box
http://www.diystompboxes.com/smfforum/index.php?topic=110337

When I was looking at making something like a porchboard, lower frequencies are emphasized if the material is heavy and soft (ie less stiff). The stiffness is influenced by the geometry as well as the material properties, so there is some flexibility. If you're using a bass pickup instead, make sure you get a nice sounding piece of metal! Wrapping it in something soft like leather may also help lower the frequency of you want more of the muted bass drum sound.

Good luck! Let us know how it sounds.

[ashcat_lt]

As we saw in that thread, the piezo wants a relatively hefty buffer to be able to pass the bass frequencies that we want, but it also picks up a whole lot more of the treble frequencies than most people are looking for in something like this, so you need a filter.  The magnetic pickups won't put out much that you could rightly call treble to begin with, and get bassier when "mis-matched" to a lower than optimal impedance.  That is to say, with the mag you just plug it into a guitar amp or a DI and it'll probably work fairly well without any active electronics or EQ.  There is a reason why every piezo-equipped guitar has a battery in it and most mag-loaded guitars don't.

Every magnetic pickup (guitar or bass) is really just a bunch of wire wrapped around a magnet.  The only real difference between bass and guitar is the number and position of the pole pieces.  That's to match the number and position of the strings on the instruments for which they're made.  I'd imagine whoever started making these things had the mistaken idea that a pickup made for bass guitar would pick up more bass frequencies, and nobody bothered to think about it any further.  The truth is that a lot of bass pickups are wound a bit light and therefor have a bit of an extended top end compared to what we normally put in our guitars.  If we really want the most bass for the buck without any other components, a really heavy wound humbucker would be the best you could get, and most of those are made for guitar.

[anotherjim]

Also a speaker working backwards as a moving coil mic'. Actually used as a kick drum mic' in some quarters.
If you don't have a mag pickup spare, even an auto relay with a magnet stuck on it would work.

[antonio.s]

I don't know what kind of problem you people have with piezo elements, a magnetic pickup, even salvaged, is going to cost 10 to 100 times a piezo element. However here's a demo of how the piezo stompbox I've assembled in a few seconds sounds:
http://www.stateofmedia.com/pvt/stompbox_test.mp3

This is directly plugged in my audio card with no hardware or software effect, just a bit of preamp of the card (which btw is required for every instrument, and as you can hear in this case is even too much).
I haven't performed live in ages, so please don't comment on my performance (sorry about it).

Here's a picture:


where you can see the unassembled elements.  I placed the piezo inside the wooden box with duct tape, and put the rubber on the top of the box (not even glued anything as this is a temporary assembly). Actually rubber wasn't needed in this case as I'm wearing shoes with rubber soles today, but I had some spare from when I built a complete e-drums set, and you'll probably want to put some rubber on yours.
The piece of wood on the right was going to be my backup stompbox body in case the box (whose walls are quite thin) were going to resonate too much or produce unwanted vibrations, which were not the case after all.

[bool]

When I was a teen in 80's I made drum triggers out of fu**ed up telephone (dynamic) earphone pieces wired directly into a common-base BJT trigger amp. Worked very predictably.

[Elijah-Baley]

Thank you, man!

Well, it surely works, but, in your case or your building of fortune or with this recording or whatever, seems a little bit "bassless", I don't know how I can explain this. That it is a little far from a kick drum effect. Of course I'm considering what a foot drum box can do.

Maybe, with some tricks It could be better

My opinion, I could be wrong.

[PBE6]

It's possible the sound card has a relatively low input impedance which will lead to bass loss since the piezo is essentially a capacitor as ashcat_It has mentioned before. Some Googling seems to confirm that.

I've been building some different preamps for these sensors lately, and a high impedance output coupled with some double-pole low pass filtering is giving me some decent muted bass-drum sounds from a teeny tiny box. Of course, the box isn't really necessary, a simple piece of wood should do nicely..next step is for me to test that hypothesis.

[ashcat_lt]

The frequency response of the raw piezo element is almost exactly wrong for this application.  To make it actually sound good, it requires hefty active buffering and quite a bit of filtering.

The frequency response of the raw mag pickup is almost exactly what we're looking for.  It'll work reasonably well plugged into any commonly available input without any additional components.

I personally have a few pickups laying around that I've swapped out of guitars that would work fine for this.  They weren't exactly free I suppose, but since the pups that replaced them plus the low cost of the guitar itself still add up to a damn good price for a great sounding guitar, it's kind of hard to really say what the spare pickups really cost me.  I know I couldn't sell them for much if at all.

I'm not really personally invested in the debate either way, but I am a bit disappointed that we didn't think of this on the GuitarNutz forum years ago.

[antonio.s]

Well, the spectum analyzer totally disagrees with you guys.

This is my stompbox:


and this is the sampled bass drum from the basic kit of Sonomawire's Drumcore:



I could go on and explain some of the science under the hood, and how ridiculous is some of what has been written above, but I am not here for a flame war.

[ashcat_lt]

What flame war?  If you have something to contribute to the conversation, then do it.  We're all here to learn and discuss, no?

Those two traces you posted look nothing alike.  There's about a 40db difference at 450Hz...

[PBE6]

Here's what I was going by:

http://www.ti.com/lit/an/sloa033a/sloa033a.pdf

I was responding to Elijah-Baley when I agreed with him about the lack of bass response in your recording. Could be any number of things, even just the mix, I was just speculating that the sound card has a low impedance input which many of them do. If by "sound card" you mean an external interface then that probably isn't the case. How did you generate your "stompbox" graph? Is that the average or maximum frequency response for an actual stomp?

I'm goofing around with some sensors that came in the mail yesterday, so far I'm getting decent results by sticking one to the underside of a small plank of wood. It definitely does need filtering to get rid of the scrapey high-pitched stuff, but rolling of the frequencies above 70 Hz (or even lower) is giving me a good impression of a bass drum.

[ashcat_lt]

I was responding to Elijah-Baley when I agreed with him about the lack of bass response in your recording.

It might not even be lack of bass so much as excess treble.  It's all relative, right?