Building a vocal effects unit for a guy and he wants a "megaphone" sound....

[ggarms]

An old friend of mine wants me to build him a vocal effects unit and aside from delay and reverb he wants something akin to a megaphone sounding effect. It seems like that "megaphone" sound is a combination of a lot of treble, compression, and distortion, but i'm not yet sure how to tackle it. Any circuit suggestions or ideas?

[davent]

would something like the LofoMofo or the Geofex low fidelity/telephone-noise-circuit fit the bill, no experience with either.

http://www.geofex.com/FX_images/lofi.gif
http://www.generalguitargadgets.com/effects-projects/filters-other/lofo/

Some info on the geofex here.
http://www.diystompboxes.com/smfforum/index.php?topic=81197.0

[midwayfair]

Some of it's not reproduceable, because it comes from the horn itself.

Tom Waits tried everything he could think of to find this sound, and he bought a megaphone in the end.

Anyway, the "megaphone" effect in Garageband does the following:

High pass at 76Hz.
Compressor with 10mS attack and 48mS release and a ratio of 5.8:1.
American (read "Fender") style amp simulation with the bass at 0 and the mids and treble halfway up.
Distortion with a 2900Hz treble cut
EQ with a +8dB peak boost centered at 3450Hz.

In that order.

That's actually quite a lot of circuitry, but it's a VERY close emulation. Still not quite the same, though.

[ggarms]

Thanks guys. I'm a bit intrigued by the lofomofo actually. In our old band, we ran a few of his vocal parts through a proco rat and the guts of a snare, and it ended up sounding super cool.  As long as I give him something that somewhat even remotely resembles the feel of a megaphone, he'll be right as rain.

[dont-tase-me-bro]

This is the easy way

[alanp]

IIRC, there's a vid of Tom Waits doing the same thing on some USAian show

[peterc]

When I build a megaphone sound in a post session, it is basically a honky thing with no bottom or top.....

Start with a high pass filter with a corner freq between 250-400.

Low pass filter set to 2-4 khz

Peak eq boost at about 1.8/2k, 5 or 6 dB

A dB or 2 of cut at 800hZ

Touch of distortion to give it  a slightly metallic feel.

Compress the crap out of it....

Some slap back echo finishes the picture!

[lars]

This is where the idea of a tiny speaker and a condenser microphone in an enclosure would get you hypothetically the sound you want. Instead of trying to mimic the sound of an AM transistor radio, just convert one into a circuit that takes an input. It's actually pretty easy to do on old radios because the input from the tuner is usually a connection on the volume pot itself. Then you just add in a condenser mic circuit to pick up the sounds inside the enclosure and viola, you have real soundwaves bouncing around in there that would already be very LoFi.

[ggarms]

Lars, I actually thought about doing that! I'll keep you guys posted on what I end up doing. Thanks for all the input.

[Matt]

This is the easy way

just make sure the sound man is aware! 

[lars]

The funny thing is, an easy circuit that would probably work for this is the Dora the explorer sing along microphone. My friend's bought one for their daughter, and if you sing loud through it with the microphone close up, it distorts and feeds back just like a bullhorn. Right there you have a battery-powered circuit with the speaker and mic all ready to go. Just put the guts in an enclosure and figure out a balanced line driver circuit for the XLR input and output, put a stompswitch in there, and then you could hook it up to any PA system.