Circuitbenders Forum
Circuitbenders Forum => Circuitbending discussion => Synths & Samplers => Topic started by: gmeredith on March 16, 2007, 03:37:13 AM
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I just bought one of these. Eagerly awaiting delivery. Has anyone ever bent or modded one of these? I think it lends itself very well to bending, basically being a standard cheesy casio keyboard in it. I can see already that you could do a separate drums-out socket mod on it, as it has a separate volume control for the rhythms.
Cheers, graham
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oooh - i think you're right. That'll be fun!
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But will bending it stop you prancing around like a camp deviant the second you strap it on? I think not as the lure is irresistible. ;)
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This is standard issue equipment for camp deviants, so no amount of bending will stop the prancing :D
Cheers, Graham
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Hmmmm...I've toyed with getting one of these for one basic reason:
supposedlly, the synth engine of the DG-20 is the same as the HT-700. If that's true, then the DG-20 should have, as does the rest of the HT-series, a nice little custom 4-pole analog filter chip (NJM2090) that's 'underutilized' in the stock Casio design.
You can bring out manual controls for cutoff, resonance and make some really scary and warm noises with it. I did this to my HT and my MT600.
http://www.youtube.com/watch?v=BMi6kqhd_1M
I've even harvested the chip for installation in other keyboards - nice that it runs off 0-5V supplies!
Looking at the DG-20's manual, though, I'm not sure the chipset is identical, because there are fewer overall sounds and some different ones. also, doesn't seem to have onboard chorus like the HT's do...
When you get the DG and crack it open, can you let us know if the DG DOES have the onboard filter chip? ;)
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I certainly will!! If it does, I hope you'll share with us how you did the filter controls. Those filter mods you did were EXTROARDINARY! You took a cheesy casio keyboard and turned it into a Roland Juno!!. If mine has a similar synth engine to yours, I'd be very keen on modding my DG20. I'll take circuit photos as soon as I get it. I'm already planning to build into it a DOD distortion pedal and a boss stereo chorus pedal, and I don't even have it yet!
Cheers, Graham
Update: Hi KB, I think I found your HT/MT filter mod site:
http://home.earthlink.net/~kerrybradley/id7.html
Nice work!! I've been heavily modding my casio sk-8 sampler for a while now, and one of the plans I had in mind was for an add-on filter with res. The trouble has been to find a simple filter circuit that runs off +5V DC and a CV input. Pleeeease think about working on the standalone filter you mentioned you were planning to do sometime using this casio chip!!! The SK-8 is already set up to run the filter chip with an ADSR line from the processor, so I could tap that as well as use your manual controls. I could have 8-bit samples running resonance filters!!
Cheers, graham
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Hi Graham,
Yup, that's my lame-ish vanity site you've found. I'm no web designer so I just used the webtools provided by my earthlilnk acct. Sorry that the MT filter page is incomplete - I have to get the schematics I used and some more explanatory images together and get 'em posted.
I've been tracking your SK-8 posts on electromusic and the casio board - excellent stuff! I wanted to pick your brain about the RAM chip you added.
So, if you like, let's talk offline about the filterchip et al. My email address is on the homepage of the ~kerrybradley acct (it's not a link, it's text-ified to avoid spam).
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That filter mod is amazing. :o
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The DG-20 just arrived in the mail today, WOOOOOOT!!!! ;D ;D ;D
In immaculate condition! Haven't had much time to play with it though, a thing called "work" got in the way! I did do a few things, though, tightened the strings, set it up better. I must say that people such as myself who have very big hands and fingers will find the fretboard a little narrow, I often put my fat claws over more than 1 string every now and then and trigger 2 notes while doing a solo. But I'm sure I will clean up my act, I'm a bit clumsy like that on a real guitar as well (I'm a bass player, not a guitarist!).
After playing around on the preset sounds for a while - which aren't too bad at all, surprisingly - I MIDI'd it up to my TX81Z module and started doing what I actually bought it for - play bass synth guitar. The TX excels at really fat synth bass sounds, and it sounded FANTASTIC hearing those sounds being played with a stringed instrument. I love it! It wasn't too long before synth bass lines such as Devo's "Freedom of Choice" and "Whip it" were heard emanating from the music room! A real 80's inspired piece of equipment.
I suspect that the DG-20 will lend itself very well to modding and bending. The first thing I'm going to do is permanently wire up some Ni-Cad batteries into it and install a charging socket, so I can ditch the mains adapter.
Then I'm going to put in a drums-out socket that will switch the drums out of the main out socket when you plug into the drums socket, so you can have separate outs for mixing.
On some of the presets, I have already noticed that it has 2 types of LFO's - triangle and square. The mandolin has the square wave tremolo "chopper" LFO on it's volume. The trumpet, clarinet and several others have a triangle pitch vibrato. There is here the possibility of bending these to affect any VCF that may also be present, according to KB's post, or one installed into it.
Definitely going to build a distortion pedal into this thing! The 8 guitar sounds are clean sounds, rather than preset digital "distortion" sounds, (it does have one listed as "distortion" but it's more of a sawtooth synth wave) and should drive a pedal nicely and sound very realistic overdriven. I'll post up some mp3's when I try this. I could bring the pedal's controls out onto the DG somewhere, there's ACRES of room to add stuff.
I'm going to try to change the strings for a better feel. The DG-20 uses 6 nylon strings that are all the same thickness (about the small E string on a nylon string guitar), and you don't tune them - you just tighten them to some nominal tightness. Since the sounds are actually produced by switches under the rubber fretboard, the strings are there simply to trigger the "keys" you hold down, and to give a "guitar" type feel to the neck.
The 3 bass strings feel unnaturally thin. I'm going to try thicker nylon ones for those (don't use metal strings - they will cut the rubber fretboard and frets up - also, they may not bend enough when you press on them to trigger the fretboard switch underneath them). This will also enable me to put more tension on them so they're less bendy and sloppy feeling.
Last of all, a set of straplocks for the strap - you don't want this thing hitting the concrete!!
I'll take internal shots as soon as I get a chance to open it up. Does anyone know where I can get the service manual for this thing?
Cheers, Graham
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Signal:Noise: thanks! everytime I turn that MT600 on, I'm really amazed how much you can open up the sound with those filter controls. if you can find any of those HT boards cheap, they're definitely worthwhile.
Graham: congrats on the DG safe arrival!! looking forward to pics of the innards! ;)
it rains, it pours: matrix just put up a post on another fellow demoing his DG-20 on YouTube. surprisingly nice instrument.
funny how so many of these old 80's Casio consumer 'toys' are getting a new life:
- bending has unveiled amazing sounds and sequences from bread and butter Casios, most of which are nominally cheesy laptop organs
- alternative controllers, like the DH and DG, are being recognized for their expressiveness (of course, without MIDI they'd really be toys...) and their prices are going up
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Did all te casio mt-s have that filter chip? because i had an MT-55 that i modded and later sold that didn't really seem to have much, I'll be gutted if i missed this. :(
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OK, here is some pics of the inside of my Casio DG-20.
The case opened:
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The main board, track side:
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Closeup of the 2 chips on the track side
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Main board, component side:
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I'd be a bit wary of messing with those big square chips but the one at the bottom middle on 'The main board, track side' with one of the main chips to the right has got bendability (and i'm trade marking that word) written all over it.
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You mean "main board, component side" instead?
Here are the 3 main board component side chips:
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More pics:
The bottom, secondary board:
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The secondary board main chip:
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The speaker (5"), and the output socket board with MIDI out. I suspect that this whole module contains the speaker amplifier components also, as there is a lot of components in it:
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This synth appears to be very modular. There are quite a few discrete circuit boards in it. I really like what seems to be a completely separate amplifier module. That will lend itself well to inserting effects circuits, separate drums output etc. As you can see from the inside shots, there is a HUGE amount of space in there to work with. The front and sides of the guitar also are vacant lots waiting for controls. This thing ain't no tiny SK-1 or something!!
I'm in the process of ordering the DG-20 Service manual from these guys:
http://www.wdgreenhill.com/
I'll let you know what it reveals when I get it.
Cheers, Graham
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Signal:Noise:
regarding the filterchip, I'm pretty sure that the MT600 was the only MT that had that chip. The 600 was a bit of an odd duck and, I think, the very last 'Casiotone.' So you probably didn't miss out when you sold your MT55.
Graham - thanks for posting these - at long last the secret innards of the DG20 are known!
my guesses at the hardware:
- first of all, no obvious filterchip :(
- the D931’s gotta be the music LSI. My HT uses the D935 and has a SMD form factor. Tablehooters (thanks for link to archive!) says the D931 is the main voice chip for the MT800 and the wonderful MT400V/CT410V, so whatever bends apply to those might apply to your DG? And by the way, what’s going on with that ‘tunnel’ along side the D931???
- I’d venture that the M6294-06 is the percussion chip, because my HT has M6294-03,04 chips for drums.
- The D78C10 is in my HT, so that’s shared. Probably the main CPU?
- The D23C256 is also in my HT. Program ROM, likely.
- The MB64HB119’s certainly turn up on a Google search, but only as a listing from distributors. Not sure what they are, perhaps RAM?
Now we eagerly wait for you to bend the DG!
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Hi KB,
The "tunnel" next to the D931 chip is just a resistor network bank. It's glossy and so gives the appearance of being cylindrical, but it's flat and vertically mounted.
So it's sounding very much like it is the sound engine for some MT/HT casio keyboard, modified. The sounds are definitely not sampled PCM, they're synth sounds (except for the drums, they're the familiar PCM sounds, with the snare drum that sounds like a large plastic bucket being hit by an enormous stick of salami), which is why they sound very clean, compared to the PCM sounds released after this era. Interesting in that the Tablehooters website MT800 page mentions that the MT800 was one of the only casio's to run off 9V DC instead of 7.5V DC. My DG-20 specifies 9V DC supply, so that could be another bit of evidence.
I'm going to buy the service manual from www.wdgreenhill.com which will reveal much about the processor and sound circuits. This thing is so well spaced and uncluttered on its board that there is ample room for mods.
Cheers, graham
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Just got the DG20 service manual, wooooot!!! It has revealed a wealth of info for bending. So far, I've installed large capacity D-cell nicads in it, and a charging socket, working well. Now I can prance for hours!
I've tried disabling the auto power off feature, but to no avail (see my other topic on this subject). I may come back to it and try again later.
The one thing that the schematics reveal is that the DG20 has very modular, discrete sections, very good for bending. It has an LFO section, an analog chorus section with a BBD chip and it's own VCO, and a flanger section (an additional part of the chorus), and a discrete distortion ciircuit!! It also has a LP filter circuit, although it does not appear to be CV controlled or have resonance, just a basic fixed filter, however it does have several selectable R-C networks in it to give different cutoff frequencies. This would lend itself to some analog pot controls very easily.
I'll scan them when I get the chance and show you all!
**update**
I've just uploaded the DG10/DG20 service manual and schematics here:
http://www.jz-server.de/forum/e107_plugins/forum/forum_viewtopic.php?1134
Cheers, Graham
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:o YOU'RE POST HAS FORCED MY HAND :o
I'm drooling at the prospect of hearing what you're going to do!
I've got a DG-1, but my bending skills are so bad, I'd be on here basically having all of you tell me exactly what to do!
........................................... :-[...............................................
No takers? no?...no?
Anyway, I'm very excited to hear what insane stuff you come up with.
Great board! Hope you guys don't mind an enthusiast hanging out and cheerleading!
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I'm storing up all my bends for when I take holidays, so I haven't done any on it yet, but I've been cataloging circuits and all the bend points on it, so that when I get time, I'll do them all. Probably one of the most important bends I want to do is the 1 octave drop mod. I can't believe that Casio didn't provide some bass sounds on this thing. The octave drop will enable me to get this, Kerry Bradley has been helping me design the clock circuit that will do this. Another mod I want to do is add a filter circuit with resonance, which I've been drawing up the schematics for. I'll post them when I finish them.
The DG-1 should be pretty much the same in essence as the DG20, so the same mods should apply to it also.
Cheers, Graham
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SLOBBER!
That's hot!
RE: Casio and missed opportunities.
I don't know how old you are, but as I remember it, when Casio hit it big as the maker of THE SYNTH that every family owned, wild sound options weren't 'cool'. Parents wanted a piano alternative, not a box that went 'bzzzzzeeeeoOWOWOWOWO' y'dig?. In fact, there was a real backlash to the whole 'synth sound' generated by analogs. They were seen as confusing and archaic. 'Beep Boop' and 'Devo' were playground insults. I got called 'Devo' a few times myself. No, sound emulation was what John Q. Consumer was looking for.
Basically, all of the things that you can dig up on your garden variety synth that would turn them into a modular monster was probably avoided on purpose!
Any other theories?
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Yeah, I remember those days, in 1985 my keyboard player in my band borrowed this "amazing keyboard" from the music shop he worked at - he rocks in with this Ensoniq Mirage under his arm. **Wow, real instrument sounds!!**
From then on, DX7 electric piano sounds were dead. Everyone wanted real sounds, no synthesis crap. TR909's landed on the market but couldn't sell. Noooooo, it HAD to be a Linn Drum or SCI Drumtrax. My God, even TR707's were considered "real" drum sounds, with their 0.5 second crash and ride cymbals.
I picked up my BLUE SH101 with matching handgrip in the late '80s for $120 in a 2nd hand shop, as well as a Yamaha CS01 and SHS-10 keytar for less than that again together! I got a TB303 bassline for $100, I snapped up 2 TX81Z's for a couple of hundred each at the time, a Casio CZ101 for about $100 and a Casio SK-8 for about $30. None of those keyboards were more than about 6 years old when I bought them. So the'80s were kind to me, look at all of them now (maybe not the TX's) and the prices they're fetching! And the embarrassing old "analog" TR909 has had the last laugh of them all!!
I'm a real sound tweaker, I rarely end up using the preset sounds on a keyboard, so I'm grateful to still have "synths" that you can tweak. I do have a Casio FZ-1 sampler, which is more a synth than it is a sampler because it has an amazing amount of parameters to apply to samples, and a DCF with wicked resonance!
The 80's. What a crazy time!
Cheers, Graham
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ahhhh, the Casio FZ-1 resonance parameter, the stuff that lo-fi dreams are made of ;D
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I didn't get the synth bug until '94 (although I was feverish for the DG-20 when that came outin the 80's, I'd wail on it in the 'Service Merchandise' store until a clerk would come and tell me to stop), but by then they started to catch back on, prices rose and I was a broken down post-grunge wastoid. I scored a Roland GR 700 and a half cashed Crumar Trilogy. The Roland was actually awesome, I kept it for years before selling it in financial desperation. The Crumar was pretty horrible, but it got me interested. Circuit bending really sold me, though. I got a patchbay SK-1 and my brain lit on fire! These are new sounds!!
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hello, i just received a casio dg-20 and i get no sound at all. the strings are really loose but i don't know if that has anything to do with the guitar not working. if anybody has any ideas could you please let me know. also, is there anybody who could look at it and do some of the cool mods ?
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Does the red LED come on when you plug a 9V plug pack into it? If yes, then the string tension does need to be somewhat tight for it to trigger properly, but not too tight.
Cheers, Graham
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why did this thread die?
tis one main reason I joined here -was to find out about this casio.
I had always wanted one -and finally got one -and searching the web -this page seems the ONLY page I can find that discuss this DG- and from what I see in this thread [the links that DO work] I am so excited to know what became & know more info on this. the schematics were posted in a link -yet that link is dead. If the posted sees this -or anybody knowing about this -or any DG-20 project -would you please let me know.
Thank you
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That's what happens when you get married and start a young family - no sleep, no time for gadgets!!
Things are quieter now but my band is doing a lot now, so I've been doing a lot more recording and playing than modding. I never did get to try out all those things I was planning on the DG20, but recent work with my band is starting to me back to doing stuff with those things. Here's my band, by the way;
http://www.warningwillrobinson.com.au/ (http://www.warningwillrobinson.com.au/)
We use lots of Casio gadgets and lo-fi keyboards.
The DG20 service manual is on my band's website also now, you can download it there:
http://www.warningwillrobinson.com.au/index_files/InstrumentManuals.htm (http://www.warningwillrobinson.com.au/index_files/InstrumentManuals.htm)
I will try and revisit the DG20. At least the service manual is available for everyone now!
Cheers, Graham
P.S. I saw a great lo-if solo artist on the weekend, a girl going by the name of KYKUYU - she has a yamaha portasound keyboard, a looper pedal and an SP404 - that's it. Her show was amazing! Total lo-fi goodness, totally mesmerising:
http://www.kikuyumusic.com/ (http://www.kikuyumusic.com/)
I talked to her after the show - I've invited her to do a house gig at my place whenever she's touring this way again and I'll have a stack of people for her to play to :)
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Thanx again Gram -and I kikuyu -from a link on the WWR web page... Yeah pretty cool stuff indeed...
cheers
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Hey all
Just wanted to share two quick shortcuts I've sound to getting a DG-20 usable in a modern setting, especially if you order a faulty one. The best way.
The most common fault on these is that someone plugs the wrong power adaptor in at some point and it blows the T3 transistor on the board. All this controls is a battery saving mode, essentially and on/off switch for it with three pins, the signal, and then one path for mode on, one for mode off.
If its blown its usually obvious, the transistor is normally cracked. Get a pliers, crush the casing and expose the three pins. Run a jumper cable to join the pin on either end. Viola. Always on, no battery saving mode (if you're not using it as a toy why is that even necessary?)
Second thing to make it more usable... if you look on ebay, you can find cables with a usb plug one one end with a 9v-5v transformer built in, and a standard 9v jack on the other end. I mean you can use this with a usb battery and plug it in the bottom sure... but if you cut the 9v jack off, solder the two wires to there the battery compartment points usually reach the board, you can run the usb cable into the now empty battery chasm on the back, and jam the usb power bank in there, meaning you have a chargeable guitar midi controller.
Just the two tricks I've been using to make these things more usable. If you want the battery save mode go ahead and drop a transistor in, I aint gonna stop you. ;)