Please check my schematic -> Idea for a talk box

[AChiz]

Hi everyone,

I plan on building a talkbox, putting it into a stomp enclosure, and I'm looking for a little help. It's basically the Jfet Buffer-Splitter from amzfx (www.muzique.com) split between my signal chain and a Noisy Cricket from Beavis Audio Research (www.beavisaudio.com), which will run into an 8 ohm horn driver. I threw in some DPDT switches to act as mute/indicator switches for the two channels. My thought process is to be able to split the signal so that I have the option of running the noisy cricket while also driving my main rig, running just the noisy cricket, or running just my main rig. Here is the schematic I came up with:

Thank you very much for any insight! It is VERY much appreciated!

-Al

[AChiz]

I feel I should also mention, I will not be running this off batteries, I will be using a DC jack.

[syndromet]

I tried building a talkbox with a little gem some years ago, and found I needed a more powerfull amplifier. If you have an efficient speaker, the noisy cricket might be able to drive it. I ended up using a class D chipamp, and dropped the buffer/splitter for an passive A/B-box. Worked like a charm.

[AChiz]

If you don't mind my asking, what did you use as the basis for your project?
I might give the noisy cricket a shot and see what happens. I think I'll use an LM386N-4 chip instead of an N-1. According to the datasheet, the N-4 typically puts out 1W as opposed to the N-1's 3/8W.

[pinkjimiphoton]

in my extensive use of talkboxes over the years, contrary to public opinion that 5 watts or less is plenty, i find that to be completely untrue.
yes, it WILL work...but ya need 30-50 watts to drive it hard enough where you can effectively use it on stage. if the amp pushing the driver can't get louder than your voice, you're
pretty much screwed.

i bought a rocktron banshee, that's 5 watts...i had to have it pegged onstage at all times unless i had a separate mic set up just for it, with the mic REALLY hot.

needless to say, i don't use it.

i use my homebrew into my normal vocal mic, push it with 30 watts on average...it can get a little louder than i can sing, which i find to be perfect. you can always turn down the guitar a little if need be, but you can't always get louder.

believe it or not, even 100 watts isn't that loud, and it won't make you deaf, rattle your fillings, or make your brain get pounded into flux capacitance.


just my two cents mate.

props on taking the plunge.

[Gurner]

i use my homebrew into my normal vocal mic, push it with 30 watts on average...it can get a little louder than i can sing, which i find to be perfect. you can always turn down the guitar a little if need be, but you can't always get louder.

believe it or not, even 100 watts isn't that loud, and it won't make you deaf, rattle your fillings, or make your brain get pounded into flux capacitance.

Your dentist will be pleased :-)

(I seem to recall there were some scare stories wrt loose teeth when used with high power amps back int eh 70s - can't be sure, but hey, it's a good 'un so worth resurrecting)

I actually have a decent compression driver (that I paid too much for just for a talk box - but don't tell the missus) waiting for me to get around to kludging something together!

[pinkjimiphoton]

it's stupid easy. if ya need help, let me know. you will want to hit a hardware store for a couple parts, but then it's a cakewalk once ya know the secret ingredient..lol

if pushed, i will reveal it...lol

no loose fillings...i've pumped dimed 100 watters thru my talkbox. it's not even really all that loud.

[pinkjimiphoton]

now that i'm awake, here's the secret weapon...

go to a hardware store, and look at their selection of replacement 3 prong grounded ac plugs...like what you'd plug into the wall.

you're looking for the kind where it has screws going in from where the blades that go into the socket are into a rubber (?) boot.

the boot is the secret weapon...if ya discard the useless plug part, you should be able to screw the boot onto the threads of the horn driver.

stick it on there, put an appropriate sized hose clamp on, and now ya have a reverse nozzle that you can use to stick the hose to your beak with...just stick it thru the hole where the 3 conductor wire is supposed to go, and use the strain relief clamp that comes with it to make sure the hose stays in place.

that's it. works great, under 3 bux for the part.

that said, i reccomend if you can't run a separate amp for the talkbox driver, make a simple a/b box for the speaker output of your amp.

all ya need to do is swap the hot wire...the grounds can remain connected..

from amp out tip to center pole of spst switch....from pole 1 to hot of jack one, from pole 3 to jack two..

connect the grounds together, done deal. plug the talkbox in one side, and run a speaker cable to your amp speaker on the other side.

i know some people are gonna freak, "you can't do that!! you'll blow your amp!!"

but you won't. remember, it's an impedance, not a resistance. if ya hook up a fast meter to your speaker output while playing, you'll see the dc resistance go all over the place with say an 8 ohm speaker...including NEGATIVE...where the speaker's not transducing, but conducting. this doesn't hurt your amp.

if the switch were to fail, it could...but after doing this for 30 years with the same box, i've never had a problem. if concerned, use a dpdt switch and wire both sides of the switch in parallel as a failsafe.

good luck!

btw, to MY newb eyes, your schematic looks pretty good...but i don't think you'll get enough drive out of a 386 to really drive the talkbox well enough to really be useful. remember, you can drive a 1000 watts into a 20 watt speaker with no issues, unless you clip the power amp, or completely drive the speaker to the point where the basket gets blown off the spider and the voice coil melts... that's not because the speaker couldn't handle the power alone, it's from pushing the speaker harder than it could survive.

my point is, better to have too much power and turn it down, than to have not enough and try to make up for it later.

peace