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Old 03-24-2011, 09:26 PM   #1
von Layzonfon
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Join Date: Dec 2010
Location: 22 Acacia Avenue
My Homebrew Talkbox

Disclaimer: I am by no means a talkbox guru. But I have made one (that works pretty well) and I'm not particularly dumb, so I'm just putting what I know out there in the hopes that other people may find it useful. If anyone wants to make corrections or additions, then you're more than welcome.

Before we begin, it may be worth giving a quick breakdown of how a talkbox works, as I've seen some posts* that seem to make heavy weather of it.

The basic principal is this: the guitar (or whatever) sound is channelled down a pipe which is placed in your mouth. Making various articulations with your mouth changes the tone of the sound which subsequently escapes your mouth. Essentially, the sound coming out of the tube is replacing the sound that would normally be made by your larynx (vocal chords).

That's all there is to it. It's not rocket science, but we can deduce two key points that need to be addressed for a successful project:

1. The sound coming out of the tube needs to be at a reasonable volume.
That means the guitar signal is going to have to be amplified somehow before it gets pumped down the tube.

2. In a performance situation, the sound coming out of your mouth will need amplifying too.
The talkbox isn't an effect pedal in the usual sense: it doesn't take the signal, modify it, and give it back. Once the sound gets into your mouth, that's the end of the line unless you do something about capturing it (i.e.: a microphone).

So the signal chain will look like this:

Guitar -> Amplifier/Talkbox -> Your Gob -> Microphone -> PA


Achieving point 1 is, I think, where a lot of the trouble starts. Obviously there are various ways to amplify your signal, with various levels of effectiveness. Inevitably everyone will have their own ideas and experiences of what works best, but you'll nearly always find someone who's used any given method and been happy with the results.

Essentially there are two things you can do. Either take the amplified signal from your amp and feed it to a speaker in your talkbox, or take a line level signal and have some amplification built into your talkbox.

Let's take these in order.

To use the signal from your amp, either you'll have an auxilliary speaker socket you can tap into, or (if you're feeling confident) you can make one. Some people have even opted for making a switched output so they can choose whether to send the signal to the amplifier's speaker or the jack socket. Obviously it is important in this case (essential for valve amps) that you use a speaker in your talkbox that is the correct rating for your amp: 4, 8 or 16 ohms, or whatever. In this instance, many people seem to favour a horn driver for the speaker.
Note: Some people choose to use a small practice amp for this, keeping it separate from their main amplification and turning it into a (rather large) stand-alone unit.

But if you don't have a spare practice amp, and don't want to start hacking your main amp about, then I would suggest that the following method is the way to go. This is the true "ghetto" talkbox, as featured in the infamous Moot Booxle video. It's very simple, low cost and low quality, but there's no reason why it can't give excellent results. The key point of this build is that it uses powered speakers to provide the amplification, removing the need for a separate amplifier. You may not get the same power to your mouth as the previous method, but if you're mic-ing up then it should be perfectly adequate.**

Ingredients

1 Old pair of powered PC speakers
1 2.5m washing machine hose
1 " mono jack socket
Duct tape
Sundry "acoustic insulation" (polystyrene, cotton wool, &c.)

The only things I didn't have lying around were the hose and jack socket, so the total cost of this project was about 7.50 ($12).

Your main objectives of the build are to get the guitar signal into the speaker and as much of the noise from the speaker down the tube as possible.

One of the first things to do is get rid of the extra speaker, so just cut the wire and throw it away. The one you want to keep is obviously the one with the knobs on.

The next thing to think about is how to get the guitar signal into the thing. Right now, it's probably got a 2.5mm stereo jack plug on it, designed for plugging into a similar headphone socket. Probably the best bet is to replace this with a " mono socket. For the simplest possible build, you could get a line one like this - http://www.maplin.co.uk/metal-1-4-mono-line-socket-1267 - and bung that on the end of the wire. If you do this, it's feasible you could complete the build without even breaking into the speaker box. I opted to drill a hole in the speaker case and fit an internal one.

Note: You're connecting mono to stereo here, so there's a conundrum. Obviously you've thrown away one of the speakers, so as long as you connect the right two wires to the jack socket you'll be fine. What I did, just for tidiness, was connect both the left and right wires to the same terminal of the socket. As long as you don't mix the 'signal' and 'ground' wires it'll be fine. Getting it wrong is not dangerous; you'll just get no sound.

The other thing I did at this point was re-route the power cable so that I would be able to lie the box on its back, with the tube sticking up in the air, once it was finished.


Next job is to attach the hose so that as much sound as possible is channelled into it from the speaker. Fortunately for me the speakers I had featured a removable, raised plastic grille, so I was able to pack the space behind it with polystyrene block and punch a hole through it just big enough to take the hose. I then fixed the grille back on and duct-taped the whole lot down. They key thing is to get the hose as snugly mated with the speaker as possible without interfering with the speaker cone.

(sorry, I couldn't be arsed to take it completely apart again.)

That's it. Job done. Although I actually filled the rest of the speaker box with more polystyrene and stuff in order to minimise the amount of ambient noise it genereates - but in a gigging or recording situation this shouldn't be audible. You could always bury the whole lot in a box full of sweaters like Moot did.

And here's a sample of the finished product. I took the output straight out of my "vintage" Korg A5 multi-FX pedal and recorded it with a crappy laptop mic. I suppose I could've done something a bit cooler (or could I?) but you get the picture - couldn't even be bothered to re-record after the slight fluff. Whatever. It's not a tune I've dedicated many minutes to.
talkbox.mp3

Of course, in a live situation you're going to want a way of switching the thing on and off. If you're using the signal from your main amp via an auxilliary socket - even a switched one - I can see this being problematic. Even if you rig up a remote switch, I gather that some amps don't take too kindly to having their load switched while they're powered up. It may well result in a god-awful click too.

If you have a standalone unit then you just need a way of switching your pre-amp signal between it and your main amp. My plan is to make a simple A/B stomp switch that will send the output to one or the other. Oh, and if anyone could post a diagram of one of these, incorporating LEDs to show which output is live, I'd be most grateful - I don't really do electronics. I suspect I need 1 DPDT stomp switch, 3 jack sockets, two LEDs, a battery holder and a project box, but the spaghetti eludes me for the moment.

Happy drooling!

Paddy von Layzonfon

================================================== ==============================
* kudos to james4 for his heroic efforts here
** I actually tried this setup with my guitar plugged directly into the talkbox. It just about worked and was audible through my stage PA rig. I guess the FX pedal adds a little heat.
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Old 03-24-2011, 11:48 PM   #2
LeviMan_2001
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I did it the practice amp and horn driver method. It may sound daunting when you say horn driver but the truth is, you can get one of these bad boys:


You can find them at thrift stores, old car alarms, etc. I found mine under the hood of a truck my dad bought. He didn't want it, so I got it! It has an attachment that works great for cramming a 1/2" hose down too. Here's a video I made about it.

Ooops I forgot this video didn't show the squier amp. But anyhow, I found that to be necessary in order to play into a mic at roughly the same level as you would sing aka audibly.
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Last edited by LeviMan_2001 : 03-24-2011 at 11:51 PM.
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