Pipe Bomb Mic Construction, by Jamie Heilman:
My own dimensions for my prototype are X= 36cm, Y= 5.5cm. This imparted a fairly high pitch tone but I like it.
The X and Y dimensions really should be played with to develop the precise tone your seeking, also I chose a telephone loudspeaker as well as a crystal mic so I got the funkiest tone I could think of. A dynamic microphone might limit the treble somewhat most likely make it sound less harsh. I’d be considering any mods produced to this style (ie. stories, suggestions, etc.) so feel free to e mail me.
The amps may be any old easy op-amp construction that can drive a loudspeaker or take a mic input. I just made use of some excess material I had lying around to make mine. The end product had all the circuitry inside the tube and the battery pack on the outside, with one control for the gain of the loudspeaker (mic was at fixed gain).
Note, in case you locate this in the front of the amplifier and turn every thing up, without having adding any dampening to the pipe, it will feedback just like you wont imagine! You'll most likely wish to keep away from this because it tends to hurt your ears. I put a bit of foam rubber in one end of the tube and an old sock in the other to dampen feedback. I like to leave my alternatives open though, so I also didn’t make this a permanent addition. My prototype is essentially a fuzz, as my guitar will overload the loudspeaker fairly simply and the pipe just adds a bit of strange overtone and what I believe is the smallest hint of reverb. Sounds excellent though! Clean tones via a similar set up would sound good too, but I haven’t constructed one of those yet. Possibly a larger speaker (4-5") and an old carpet pipe would probably add improved characteristics for clean tones. Attempt changing the tube material also for a various tone, I almost applied a bit of gutter piping when I 1st built this, right now I wonder what it would’ve sounded like.
Download the document about how to build Pipe Bomb Mic in PDF file: