Picture of DIY Spring Reverb
I recently spent some time at my parent's place. As I opened an old box I found one of those toy echo mics.
This gave me the idea to build a small homemade spring reverb!

But how does it SOUND!?!?!
Glad you asked. Like this. (soundcloud link)

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Step 1: What You'll Need

- echo mic toy ($2)
- little amp & speaker (I got mine from a 1-watt Marshall amp I had laying around) ($35 for the Marshall one I believe)
  (you could of course use something more DIY like a little Kemo amp for example. Make sure your speaker fits the specifications of the amp)
  (You might want to get an amplifier for after the piezo mic as well. I don't have it- I just use the instrument inputs on my sound card and it works fine. But in situations where you don't have gain, it might be useful.)
- In the case of the Marshall MS-2, an extra 9v battery connector ($0.5)
- jack socket (you might need two if you're working with a more DIY amp.) ($0.5)
- a box in which it will all fit. So speaker, amp, spring, etc. will have to co-exist in this space. My box was around 18x13x7 cm.
 (make sure the box can close with everything in it. Mine can't fully. It's no biggie tho. ($0)
- 9v battery to power amp
- piezo element ($1)
- 2 small paperclips/metal hooks/thingies to glue to speaker/piezo so you can attach the spring.

- Soldering iron!
- Glue gun!
- Drill!
- Saw!

Step 2: Saw open the mic, get that spring!

Picture of Saw open the mic, get that spring!
First you'll need to cut open the echo mic.

I used a saw for this and just sawed along the side until I could get to the insides.
The spring might be stuck inside, but with some force on the outsides of the mic, you should be able to get one side to detach.

The other side however, is a bit tricker.
I used a pen and a paperclip to kind of "fish" the other end out.

FInally, you'll have a detached spring! :)

Step 3: Prepare your amp...

Picture of Prepare your amp...
So you'll either be removing the amp from something like the Marshall MS-2, or putting together your own amp.
This is pretty straightforward.

Test it when you've taken it out.
I had to resolder the battery compartment to a more flexible one.
Ignore the pot in the picture.

Step 4: Prepare the contact mic + speaker

Picture of Prepare the contact mic + speaker
So, we'll need something to connect the spring to.

I glued (with my gluegun) SMALL paperclip-like objects to the conus of the speaker and to the contact mic.
See pictures.

Make sure it's sturdy and dry before you continue.

Step 5: Solder piezo to jack output (or another amp with output)

Picture of Solder piezo to jack output (or another amp with output)
Solder your piezo element to a jack output...

Step 6: Glue it into the box!

Picture of Glue it into the box!
First test if your spring will reach both sides, then glue the speaker and piezo into the box!

Step 7: Test if it works

Do a quick test if it works! Connect the spring to the hooks,

Hook up something that makes sound to the amp (like a little keyboard/synth/whatever).
Make sure the spring can vibrate freely, and the glue will hold.
Connect the output to an input on your audio interface, preferably with instrument inputs.

Go wild!

Video of my prototype:

Step 8: Finish it up

Picture of Finish it up
When it works, you can continue.

Drill holes for the pots of your amp, jack input/output, light (if your amp has one).
Glue it to the inside of your box with the glue gun.

I extended the wires for the battery compartment and glued it to the top.

Then, you're done! Only thing you'll need now are some nice knobs for the pots. But I still have to find those for mine as well...


How it sounds. (Soundcloud link)

If you like it, please have a look at my other instruments, sounds and compositions at: http://www.markijzerman.com
Metalman0007 months ago

Hi, great instructible! :)

I really want to make this, could you give me the exact name of the piezio element, or even better a link to where I could buy one? I don't really know what it is. Thanks :)

has291 year ago
great project, how come the speaker being used as the transducer doesnt make sound though?
Really nice!
profpat2 years ago
great projects, i still have some of the reverb assembly i salvaged from old guitar amps, they have been lyin on the parts rack for a long time, maybe i could re-use them using your amp circuit!
jimdkc2 years ago
I love it! I knew how a reverb tank works, but I never really imagined it would be so easy to build one... or that a homemade one would sound so good! This goes on my project list!
szdonick2 years ago
My dad had a Chevy convertible from the 1960s back in 1975 with a spring reverb unit in the trunk. It made some funky sounds when we went over rough roads.
wb8nbs2 years ago
I'm old enough to remember those things in cars. Very subject to noise and would let out an awful racket if you drove over a rough railroad crossing. The better ones put the signal into the spring in torsion rather than push-pull. That had less noise pickup.
lewisb422 years ago
Nice. My dad has an old tube amp (probably from the 60s or 70s) with a spring reverb in it. I "borrowed" it in college to jam with my friends; it was always fun to kick the cabinet, which would shake the spring and do crazy things with the reverb.
markijzerman (author)  lewisb422 years ago
Awesome. I want to build a HUGE one some other time though, to use as an instrument! :)
Garage up-and-over door springs. You know you want to.
markijzerman (author)  MikB2 years ago
Yes, awesome idea! are those "springy" enough though? Something as flexible as a slinky works best.
I've just gone and "pinged" the one on my door, a good 5 second reverb tail there ... No they're not very flexible, but they are springy, not something to mess with under tension :)

Can you ever get any tension into a slinky? They're probably too far the other way (floppy).
markijzerman (author)  MikB2 years ago
Slinky/floppyness indeed depends on size and of course how far you stretch it.

Sounds awesome. would be cool to be able to bow a spring like that! :)
gorrat2 years ago
great work! a nice extension would be to add a wet/dry mix knob to control the level of reverb. I think it could be as simple as a pot with the ends connected to amp (dry) and piezo (wet) outputs (with series resistors to balance signals) and the center connected to the main output. it could require a 2nd amp for the piezo to get the signals to balance the way you want them.
markijzerman (author)  gorrat2 years ago
yes, that would be my next addition, but for now I tried to keep it simple!
And it works quite well as an external effect. I can send the amount of signal I want to the reverb :) But for standalone-purposes (or if you want to make a guitar fx-pedal), then YES, this is needed :)
Thanks for the clear explanation!
billbillt2 years ago
markijzerman (author)  billbillt2 years ago
blkhawk2 years ago
Cool! It creates nice sound effects!
markijzerman (author)  blkhawk2 years ago