Talkbox from megaphone?

[ManuVel]

Hey guys, I was wondering if it would be possible to build a talkbox using the parts from a megaphone?

[FUZZZZzzzz]

you probably can make something 'talkbox like'.. the megaphone is mostly a simple amplifier that is probably based on a 386 ic (most cheap megaphones are in my experience)
that can be used as a cheap guitar distortion as well..

http://www.instructables.com/id/Make-A-Talkbox/

[ManuVel]

you probably can make something 'talkbox like'.. the megaphone is mostly a simple amplifier that is probably based on a 386 ic (most cheap megaphones are in my experience)
that can be used as a cheap guitar distortion as well..

http://www.instructables.com/id/Make-A-Talkbox/

I'm having troubles finding a cheap Horn driver is the only problem. Don't really want to spend a whole lot on this project, ya know? Having troubles finding a horn loudspeaker :p

[pinkjimiphoton]

search for "so ya wanna make that thing talk?"

you need to go to ebay... you need a full-range screw flange horn driver, around 40-60 watts, probably 16r.

make sure the frequency goes low enough... most horn drivers roll off at 1k, you wanna go down more like 80hz or so to get the full range of the guitar.

you can make something "talkbox like" with any driver, but without the proper frequency range it simply won't work right, and you'll need a ridiculous amount of power to get vocal = volume out of it.

it has to be at LEAST as loud as you sing. and 1k, like a lot of people argue about, rolls off half your guitar signal.

trust me.

you can get the proper drivers on ebay, you want community/altec/university

probably cost ya 30-80 bucks.

[R.G.]

What really needs done is a throat speaker. I had a friend who had his larnyx removed due to throat cancer. Talked with a throat buzzer. If you could do a speaker that drove the tissues like that buzzer, it would be simple, only speaker leads to a driver on the side of the larnyx.

[pinkjimiphoton]

i actually offered to "supe up" one of them for a gent in a head and neck cancer support group here, but he never took me up on it.

seems like it would be simple enough to do in a case like that, but i think flesh is kinda opaque sonically. it's easier to put sound into something than push sound thru it i'd think, but hey, i'm wrong most of the time

[petemoore]

 Requires stuff like:
Mic [headphones or PA for monitoring].
The 'other half' is the amp and transducer.
I can pretty much find an amp with ~20watts and wideband audio by the time it rains, by whittling the bandwidth or other effects, pass or fail.
It might not be battery friendly or as compact an LM386, but it's easy to ''outgun'' a battery-amp with more power/better response.
The driver shouldn't be asked to do 'bass' but low mid sustainability [I've 'popped' a few horn drivers]
'Great' transducers for these projects are less common, it's tricky to put together a diaphram, coil, dome etc. and trying to get lower frequencies out 'nicely' and without popping or cooking the coil [we I've found myself looking for better, or not yet blown diaphrams].
It'd be interesting to find out if anyone's used a straight pipe with a short tube instead of a long tube, or lighter weight driver mounted on heavy duty [weighted] mic stand.
Can be cool fun, - another amp and transducer setup requirements {cables for AC and 'prepped' Signal + Mic n PA] I put that by the mic, but 1 long speaker cable could connect a behind the cab amp to the transducer.

[PRR]

> i think flesh is kinda opaque sonically.

It's just water.

Water is heavier than air. You need different leverage in the speaker. We use a big paper cone to catch enough air to be worthwhile; driving water we do not need that.

Sonic scans inside the body are routine for doctors.

Sonic scans through the ocean are routine for submarines.

You can even sonic-scan dirt. They just ran a "ledge detector" up the road from me. It knows the difference between dirt and rock. They are re-building a bad road, and the contractor *needs* to know how much rock he will have to break up before he can give a ballpark price for the job. Since dirt is even heavier than water, we need yet another leverage, where speaker force is concentrated to a small area (anti-cone).

There used to be underwater speakers for swimming pools, a good starter for a throat-speaker.

If you can find a horn-driver with a small exposed diaphragm, this too might work against a throat. (The horn is much of the to-air leverage, so minus the horn is more like the leverage we want against water. Or flesh.)

----------------------------

A megaphone has a horn-driver and this "could" be extracted and used through a mouth-tube to do Frampton. Depends how well the driver comes out; it may be molded into the horn and amp-case.

----------------------------

There's tons of prior art. Airplane and tank operators used throat-mikes which were plentiful on the surplus market. Stock they modulated DC into voice current. Alvino Rey modulated his guitar with his wife's voice to make "Singing Guitar", later known as Sonovox, the voice of Casey Junior the train in Dumbo, and many-many-many PAMS jingles.
http://en.wikipedia.org/wiki/Talk_box

[pinkjimiphoton]

paul..

hold your hand over a small speaker and see what happens to the sound
exciting water molecules results in heat. microwave, anyone?
you've gotta get the sound to where the vocal cords would normally be. easier to do from inside than outside. i'm sure where there's a will, there's a way, tho.

pete, i used the same 40 watt community sound (altec/university) 16r driver for over 30 years until the positive terminal broke. i ran it with up to 100 watts, no problems, the frequency range on them is around 80 hz  up to about 12 k or so. i posted a scan i think on the thread i mentioned earlier.

the one i built is a 60 watt driver, sounds virtually identical.

the big requirement is to have it be at least as loud... and preferably LOUDER ... than you sing, when the sound is reflecting outta your beak back into mr. micaphone.
frampton's used the same deal... most commercial ones use horns that just plain don't go low enough.

once ya try the proper driver, where ya get the full range of your guitar, there's no going back bro.
i've even played bass thru it.... with cranked up tube amps distorted. if it can survive that (and i tend to play bass hard, and use a 3.0 mm dunlop big stubby for a pick) it can survive, no popped diaphragms.

what kills drivers is UNDERPOWERING them, not OVER powering them. once that little amp clips, unless the speaker can handle the full peak to peak signal of that square wave driving it back and forth to it's extremes, that voice coil is gonna smoke.

headroom makes a big difference. you can run a thousand watts into a five watt speaker  as long as ya don't push it past the physical limits of the cone's excursion with no ill effect. you can get max SPL that way.

also.... pete, i use the rubber boot that comes with "three prong" replacement power cord plugs, it fits on the screwed flange of the driver well, a hose clamp to secure it, and ya stuff your hose thru the hole where the wire would go. works great, and really focuses the sound up the tube.

i use the opaque white harder plastic tube from the box up the stand, and then softer clear tube from that into my mouth, with just enough so i don't gag sticking past the end of my mic. it totally kicks ass.
i drive it with a crate fifteen watter with reverb off an a/b/y after my fuzzface and univibe before the rest of my pedalboard.
the amp is fifteen watts at 8r, so i figure at sixteen ohms i'm probably hitting it with around 8 watts or so, if even that. it's the minimum amount of power i've found to work with my particular requirements, ymmv

[PRR]

> hold your hand over a small speaker and see what happens to the sound

I did say "leverage", dinnt I?

That's using a fishing pole to pry a nail.

Also your experiment mis-levers *twice*. Air-speaker mis-levered into wet flesh, then whatever sound does propagate through your hand is again mis-levered where it passes from water to air to get to your ear.

Put your ear on the back of your hand it will pass a *little* better.

Hit yourself in the temple with a drum stick. The drumstick *is* adapted for putting energy into a fairly solid object. My Irish skull is a lot denser than a drum skin, but I know I can hear a pretty good thunk (under the airborn "Ouch!").

Sound is sound. But flipping a fishing lure is a different problem than prying a nail, you use different levers.

Water (or flesh) is 1,000 times denser than air. when pulling a nail you probably need 1000 times the force (and 1/1000th the swing) of casting a lure into the lake. That's why we don't fish with pry-bars, or de-nail with fly-rods.

As a rough guess, when sound passes from air to water (or water to air), there is a loss like the difference in densities. About 1:1000. Like the pry-bar casts a lure about 1/100th of the way to the lake, or the fish-rod gets the nail 1/1000th loose.

An 8-inch cone speaker may have a 1 inch voice coil. Removing the cone concentrates the energy in 1/64th the area. Not 1000 times, but makes a big difference. Electrodynamic underwater speakers can be quite effective.

For maximum transfer you go to large piezos or electrostrictive motors. When you put a big magnetic field on a bar of Nickel. its length changes. If you resist the change, as with some water, you get very high forces in small area.

[pinkjimiphoton]

and you can take a huge bucket loader to dig up a molehill, or just a spade.

it surely could be done, but is the cost/effort worth it, when you get better results, cheaper, in an easier way?

i wouldn't try removing the cone of a speaker... true, you will concentrate the sound to the smaller area, but (newbs don't try this cuz:) without the cone, the spider will pop off the magnet frame... the cone and it's resistance are part of the failsafe to keep the voice coil and it's gap intact.

i mean no disrespect whatsoever to anyone;

just trying to save others from the dead ends i encountered repeatedly that i see people do again and again.

i've tried bass shakers, i've tried piezos, i've tried even telephone speakers from old phone handsets. not too great, tho sound could be had out of any of them.

the run of the mill ubiquitous "midrange" horns most people try (and indeed, are inside cheap crap like rocktron's banshee) cut off too high. you only need a couple watts to run them to get the talkbox "effect" and they're ok in a bedroom or studio, but they just can't dish it out enough at "live" stage volumes... at least not at the levels most of the drummers i work with generate (ever hear jack "scrapper" scarangella? he ain't quiet, tho he's impossibly dynamic)...

if ya check where the frequencies lie of the guitar, you'll see 1k is about smack dab about your b string somewhere. if you use a driver that rolls off everything below 1k, you're doing the equivalent of taking an equalizer and shelving everything off at a rather steep slope. suddenly the guitartone that entered the driver is coming out with not only it's nads removed, but very tinny and wimpy sounding... i mean... you have about a 5k range to work with. this clearly will not do, and that's why you need to look at the specs.

older pa drivers were often "full range".... while 80hz may not seem that low by today's standards, that will reproduce a kick drum still enough to recognize it's sound as a kick drum. and you get almost the entire signal range out of the guitar.

figure in the "shatterproof" voice coil... and you're in a pretty good position, mr framptoon.


or, ya can experiment, and buy a whole bunch of different drivers, and ultimately spend a lot of frustrating (tho amusing) time and money to eventually figure out why so many of these great ideas just plain don't work in application like they should in theory.

i mean, flesh is for all intents accoustically opaque. if i stand directly in front of my amp, i can make it seem like i turned down if i'm being yelled at. if i need to be heard better, i can step away from it. granted, i have a LOT of flesh to work with, but the same basic principle applies. the flesh in the front of your neck is around the same thickness as your hand, which is why i suggested covering a speaker with one's hand. the bones actually will HELP transfer the sound... being crystaline in nature, they can carry vibration better than water. but the basic principle remains the same. you need a LOT of power to get the dynamic range of your voice, and probably a thousand times that power to make it work THRU the flesh... where injecting it into your oral cavities is a tried and true easy way to achieve aural bliss.

and finally, the drivers i suggest on ebay are about 50 bux, but i buy them at hamfests and junk stores for 5 bux usually. carry around a 9v in a baggie with a couple hunks of wire, and if the terminals cherp when ya touch 'em, you're golden.

newb alert: NEVER EVER EVER carry an open terminaled 9v battery in your pocket... if it shorts, it will set your pants on fire if you're not lucky.

anyways... paul, i understand your points. do you understand mine?
peace

[ManuVel]

I ended up using a smallish 20W speaker and my tiny practice amp..

I tried my best to insulate the speaker with foam and such. But it is unfortunately not very loud. Much more experimenting to come I suppose.

Also gonna pick up a thicker tube, that might make it a tad louder. We shall see!