DIY Keytar - a pipe dream?


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I have this Idea, since noone makes keytars any more and the ones on Ebay are allways rediculously overpriced, why not make a home made one?

for the basic design, I would want three sounds - a piano, an organ (pipe or hammond-y-rock-organ style sound - or both!) and a warm synth sound ala VanHalen, cos they're the sounds I mostly use on my current keyboard. for the neck (handle) It should have a pitch bender. I was considering (mibbie) putting an octave of small keys on the neck for playing rootnotes with my right hand? besides a pitch bender I don't know what else features on a keytar's neck.

The way I was thinking of doing it is by canibalising a cheap, 2nd hand home keyboard.
-I've looked a little at pitch benders made by circuit bending enthusiasts, it is possible at least with some keyboard models - i think one way it's done is there's a resistor for controling pitch and you put a variable resistor in parralell with it for going one way and in series for bending (the note) the other way.

-the left hand keys could be off another, smaller eg: kiddie's keyboard - since the keys themselves are just on/off switches, just connect each kiddie's key in parallel with keys on the main keyboard and pressing either key would produce the same sound.

-the body would be eg: a heavily routed block of plywood - made by glueing several sheets of thick stuff together. If you open up a home keyboard, most of the casing is empty space - the keys are on one circuit board, connected to a second one with buttons etc. by ribbon cable. so the case could easily be down-sized without any electronic alterations. I thought, since these keyboards almost always have speakers and/or can run a set of headphones they must have a built-in amp. If I removed this amp entirely, the whole thing would require alot less battery power ( assuming most battery power goes to the amp - which is acceptable, consider the amount of power a calculator requires next to an MP3 player's portable speakers...) and could be run off smaller batteries (of a similar voltage). this, coupled with a lack of speakers would account for any the extra weight caused by a wooden body. In any case, I'm a bass player, i'm used to heavy guitars! the signal would go down a jack lead and be amped externally.


or, I was thinking of just starting from scratch and sacrificing the selection of tones for something simple eg: squarewave, sawtooth, sine, or something - Build it like a kind of semi-preset rudementary analouge synth. the thing is, I'd want it to have polyphony, which (i've heard) is quite complex...

What do you think?

Do you know common uses for the buttons on a keytars neck?

DO you know anything about installing pitch wheels? is it even do-able? where do you get the parts?
 
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It sounds like a cool idea, that actually might work. I don't know anything at all about building your own stuff, though, so I can't really give you any advice on that part.

Like you said, the keytars on Ebay are rather overpriced, so I wish you the best of luck, and please tell us your results :)
 
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I'm currently designing one which sounds quite similar to your idea!

My first suggestion would be make it a MIDI controller. Trust me. You do not want to be building a synthesizer into it, as it suddenly become a whole lot less portable.

At the moment, I have a 49-key controller (Evolution MK-149) as the starting point. It has PB, mod, transpose, 8va shift etc already built in. It is simply a case of redoing the bodywork (wood or maybe plastic if anyone who owes me favours has a vacuum former) and moving the controllers around. I may try to replace the PB wheel with a ribbon, but that might be too tempremental.

For the bass keys, I'm thinking about using ordinary off-the-shelf PTM switches, as chances are I won't be doing anything complicated on them. These would also be MIDIed (on a different channel, obviously), chances are I would end up with 2 MIDI cables, unless I could combine the 2 signals on the instrument. It all depends on what I find in the controller case.

I'll let you know how I get on, and feel free to ask for any MIDI advice!
 
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Best of luck with your one mourndark. I bet it will be gawdroppingly awsome.

nah, I wouldn't build a full synth into it if I was going to build it from scratch, like.- I was thinking of getting polyphony by wiring each key with it's own signal generator - but I don't know how you would get a pitch bender with that setup. If I could do it, though, I'd have a pitch bender, and mibbie vibrato and tremolo in the neck, effects like echo, reverb, wah, phaser etc. would all be done using guitar pedals and stuff.

Could you use fibre glass for the body? i've never worked with it before, But I think it's as simple as you build a mould out of wood or similar and Just slap the sheets on with resin, Like high tech paper mache. The thing about that would be getting the moving parts exactly the right size. What you could do mibbie is cut the keyboard in half so you keep the bit that holds the keys on aswell, then fibre glass the rest of the body round it, and paint it all the same colour. However I have no idea how you'd make the back easy to get open and put the electronics in, Plus it'd take real skill to make it not look shoddy.

I had a quick google image search for MIDI controller schematics: most of them look alright eg:

however, I have no idea what the chips are and how much they cost. I'm not really up on my digital elecrtonics in general.
I have a question about MIDI actually, I posted it as a thread, But I think you might be able to answer it?
is there any way to convert midi to sound without using a computer? I think you get keyboards with "MIDI in" bits, but can you buy something that's just like, a "box with knobs" style thing for using a MIDI controller the same way you would use a keyboard?

I suppose if there isn't i could just buy an old laptop with windows 95 or similar and use it, would that work?


i had a look in the back of my keyboard. It has this screw thing in the back for tuning it, But if you turn it whilst playing it you get the same effect as a pitch bender. Assuming it's just a vairiable resistor or a pot I might be able to replace it with a wheel or such, I would add an extra knob aswell keeping the thing itself in tune.
 
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nah, I wouldn't build a full synth into it if I was going to build it from scratch, like.- I was thinking of getting polyphony by wiring each key with it's own signal generator - but I don't know how you would get a pitch bender with that setup. If I could do it, though, I'd have a pitch bender, and mibbie vibrato and tremolo in the neck, effects like echo, reverb, wah, phaser etc. would all be done using guitar pedals and stuff.
Wow! Best of luck with that...

Could you use fibre glass for the body? i've never worked with it before, But I think it's as simple as you build a mould out of wood or similar and Just slap the sheets on with resin, Like high tech paper mache.
That sounds good! You'd probably have to make it in two havles so you could mount the electrics before sticking it together.

I had a quick google image search for MIDI controller schematics: most of them look alright eg:

however, I have no idea what the chips are and how much they cost. I'm not really up on my digital elecrtonics in general.
You need this guy. Just connect up your switches and you have instant MIDI messages!

I have a question about MIDI actually, I posted it as a thread, But I think you might be able to answer it?
is there any way to convert midi to sound without using a computer? I think you get keyboards with "MIDI in" bits, but can you buy something that's just like, a "box with knobs" style thing for using a MIDI controller the same way you would use a keyboard?
Yes you can - they're called a number things, generally such as "sound module", "synth module" or similar - just a synthesizer without a keyboard. I personally use this one but there are many available depending on what you want.

i had a look in the back of my keyboard. It has this screw thing in the back for tuning it, But if you turn it whilst playing it you get the same effect as a pitch bender. Assuming it's just a vairiable resistor or a pot I might be able to replace it with a wheel or such, I would add an extra knob aswell keeping the thing itself in tune.
Wow, what sort of keyboard is it? Keyboards haven't had those since the digital age - sounds like you have a good bit of history there...
 
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http://www.midi-hardware.com/pedscan.html
That'd suit me to a T i think - I don't need much from it. I didn't realise it was that easy though - is it quite common to make controllers out of old keyboards etc.?

I'm gonna look into MIDI a little more I think.I've got no experience with it other than music writing software where you put in the notes and it plays it back as music. I don't even know if I can do it with my PC, do you need anything extra to use it? is there stuff you can download for it?

my keyboard is an old casio: CT-420 is the model no. I've grown kind of attached to it though, It sounds better than my pal's trendy newer casio. I think if I was gonna ruin a keyboard I'd have to buy a noname one second hand haha.
 
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http://www.midi-hardware.com/pedscan.html
That'd suit me to a T i think - I don't need much from it. I didn't realise it was that easy though - is it quite common to make controllers out of old keyboards etc.?
That's the one I'm using, and yes it is fairly common amongst DIYers to plunder old gear for the keys. My advice if you're new to MIDI is to by a cheap MIDI controller off ebay, and use that as the basis as it may have more functions such as touch sensitivity and easy channel/8va shift.

I'm gonna look into MIDI a little more I think.I've got no experience with it other than music writing software where you put in the notes and it plays it back as music. I don't even know if I can do it with my PC, do you need anything extra to use it? is there stuff you can download for it?
That's where I started, then I started messing around with more advanced stuff and generally picked it up as I went along. There's so much you can do with it. You can connect a keyboard to a pc fairly simply with a MIDI-USB connector (ebay again) and windows has all the drivers. Most music software will recognise it easily. Have a look around at some of the freeware sequencers etc available online.

my keyboard is an old casio: CT-420 is the model no. I've grown kind of attached to it though, It sounds better than my pal's trendy newer casio. I think if I was gonna ruin a keyboard I'd have to buy a noname one second hand haha.
I love the old Casio gear, but that's one of the oldest I've seen! They do sound gorgeous though...
 
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well, I'd feel guilty ripping appart a perfectly functional MIDI controller, But I suppose it'd be alot easier than buying all the parts 2nd hand. a major factor for me though is cost.

Is 8va, like, an octave-up switch kind of thing? Or is it something else? I thought It might be cool to have a button that took the note you were playing on the keyboard up an octave when you press it - to get a sound something like a pinched harmonic on a guitar. I suppose you could do something like that by hand though with enough practice just by skipping up an octave on the keys.
 
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Is 8va, like, an octave-up switch kind of thing? Or is it something else? I thought It might be cool to have a button that took the note you were playing on the keyboard up an octave when you press it - to get a sound something like a pinched harmonic on a guitar.
It instantly shifts the keyboard up/down an octave, although not in the guitar harmonic style. I guess it would be possible to create a patch that did that though, for example assign the mod wheel or another controller to introduce the harmonic. Sadly General MIDI wasn't designed for that sort of thing...
 
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aye, I wouldn't want expect it to sound the same, it would just be for a similar kind of, musical effect, You know? I'm trying to think of an example...
 
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A quick update. I haven't actually made anything so far yet, but yesterday I got my casio MT-100 back (a friend had borrowed it) and I took it apart to clean the keys (they were all sticky cos of those sticker things you get for beginners to see the notes, you know the things I mean? the keyboard is second hand...)

MT-100: (nb: not my photos)

I happened to notice the tuner dial on that is a 100k pot - so it would be easy to slip a wee mod wheel in it's place heheh. HOWEVER, it's mini keys and lowfi sounds make it a less than ideal keytar candidate...




I have also had the back off my CT-420, but It's kind of...weird. the screw head is like, a component on the ciruitboard itself - I can't tell if it's a pot or what. I might get a multimeter on it if I get the chance, but justnow It's a mystery what it is.
CT-420:




I was oggling old yamahas on ebay though - they seem to feature wheels more than casios I think. I might buy one if they're cheap after christmas.
 
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I wish you the best luck man! Great project!
Make out of wood like a guitar. That'd Lincoln.
 
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^ :D this post has made my day.

do you think the ones on ebay will come down in price, now that you can buy one new?

I might still make my own - like Dr. clock said a wooden one might look nice. plus I've seen you can buy those resistive strips on the internet...
 
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Almost certainly, thankfully - they're being sold second hand for twice their original price!

But yes, I'm still designing my own, as I can build in all the features I want. I found this site which is absolutely brilliant for home-build keyboards, and I'll post the link to a site I found selling ribbon controllers when I remember what is was.
 
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That is a great site Mourndark. I have an old SY-22 maybe I can do something with it :)
 
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I've done it! It works!



The new "head" is sandwiched wood with the original wheels inserted. On the other side behind the wheels is a push button switch for holding notes. I've also reversed the polarity of the pitch wheel, so you push up to bend up. I'll probably give it a slightly nicer paint job at some point in the future too.
 
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I love it! It's so much fun being able to get out from behind the rack of keys and solo away (and push the guitarist out of the way). Especially with a guitar lead sound, and ability to bend and dive all over the place without effort. Then switch on mono and tap away...

Expect some videos soon!
 

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