[Harry Axten] turned the diminutive Korg Monotron into a playable analog synthesizer, complete with a full-sized keyboard spanning two octaves and a MIDI interface.
Korg Introduced the Monotron analog mini-synthesizer back in 2010. They also dropped the schematics for the synth. Hackers wasted no time modifying and improving the Monotron. [Harry] incorporated several of these changes into his build. The Low-Frequency Oscillator (LFO) has been changed over to an envelope generator. The ribbon controller is gone, replaced with a CV/gate interface to sound notes.
The CV/gate interface, in turn, is connected to an ATMega328P which converts it to MIDI. MIDI data comes from one of two sources: A two-octave full-sized keyboard pulled from a scrapped MIDI controller or a MIDI connector at the back.
The user interface doesn’t stop with the keyboard. The low-cost pots on the original Monotron have been replaced with much higher quality parts on the front panel. The tuning pot is a 10-turn device, which allows for precision tuning. All the mods are mounted on a single board, which is connected to the original Monotron board.
The fruit of all hard work is an instrument that is a heck of a lot of fun to play. Check it out in the video below. Want more? You can read all about hacking about the Monotron’s bigger brother, the Monotribe.
Continue reading “Monotron Gets All the Mods”
On a dreary night in November, [Smecher] collected the instruments of electronic life around him to infuse a musical spark into FrankenKorg — a resurrected keytar.
This hack is a “re-braining” of a RK-100 Korg Keytar, replacing the original circuits with an ATMega32 — the original functionality and appearance are preserved allowing any restored version of the original boards to be seamlessly re-integrated. In light of that, the original boards were ditched after a brief investigation, and a haphazard building process on a protoboard began. Three LS138 3-8 demuxers that accompany the ATMega handle scanning the keys since there weren’t enough pins on the ATMega alone for all the Korg’s features. Check out [Smecher]’s breakdown of his process in the video after the break!
Continue reading “FrankenKorg: The Modern Remote Keyboard”
Bitrot is setting in, and our digital legacy is slowly turning to dust. Efforts preserve our history are currently being undertaken numerous people around the Internet, and [Jason Scott] just got an automated CD ripper, so everything is kinda okay.
However, there is one medium that’s being overlooked. ROMs, and I don’t mean video game cartridges. In the 80s, mask ROMs were everywhere, found in everything from talking cars to synthesizers.
[Ali] bought a Korg i5m workstation from eBay a few years ago, but this unit had a problem. Luckily, he had a similar synth with the same samples stored on board. There was only one way to find out if bitrot was the cause: desoldering the chips and dumping all the information.
After fiddling around with his broken synth, [Ali] still had a problem with the sound output. Deciding the ROM chips had to be the issue, [Ali] desoldered the chips and ordered a breadboard SOP44 adapter after deciding soldering wires to each lead of the chip was a bad idea. This adapter was connected to an Arduino Mega — still the best tool for weird tasks like this — and the contents of the ROM were dumped to a PC with the help of a helpful Arduino sketch.
Dumping the ROMs took about 15 minutes, and that’s if he was able to maintain a good connection between the chip and Arduino for that long. [Ali] wrote an improved ROM reader after much trial and error, and was eventually able to get the same data out of the same chip eventually.
While the broken synth hasn’t been repaired yet, at least [Ali] has the important bits off of this antique instrument. That’s good enough for now, but [Ali] intends to take this project to completion and get those vintage samples playing out of this great old synth.
Earlier in the month, [Elliot Williams] quipped that it had been far too long since we saw a VFD-based amplifier build. Well, that dry spell is over. This week, [kodera2t] started showing off his design for a VFD headphone amp.
Here’s the thing, this isn’t using old surplus vacuum fluorescent displays. This is actually a new part. We first covered it about 18 months ago when Korg and Noritake announced the NuTube. It’s the VFD form factor you would find in old stereo and lab equipment, but housed in the familiar glass case is a triode specifically designed for that purpose.
Check out [kodera2t’s] video below where he walks through the schematic for his amplifier. Since making that video he has populated the boards and taken it for a spin — no video of that yet but we’re going to keep a watchful eye for a follow-up. Since these parts can be reliably sourced he’s even planning to sell it in his Tindie store. If you want to play around with this new tube that’s a pretty easy way to get the tube and support hardware all in one shot. This is not a hack, it’s being used for exactly what Korg and Noritake designed it to do, but we hope to see a few of these kits hacked for specific tastes in amp design. If you do that (or any other VFD hacking) we want to hear about it!
And now for the litany of non-traditional VFD amps we’ve grown to love. There is the Nixie amp where [Elliot] made the quip I mentioned above, here’s an old radio VFD amp project, in this one a VCR was the donor, and this from wayback that gives a great background on how this all works.
Continue reading “Now is the Golden Age of Artisanal, Non-Traditional Tube Amps”
Sometimes we get lucky and find a part we need for a project in our parts drawer. [Scissorfeind] got even luckier and found a part for his project lying around in the street. It was a Crybaby Wah pedal, a classic effects pedal typically used for a guitar. Since it was somewhat damaged, [Scissorfeind] got to work creating a control voltage (CV) and volume circuit for his Korg synthesizer.
For those who aren’t synthesizer aficionados, CV is a method of controlling the pitch of a tone. A higher voltage creates a higher tone and vice-versa. The wah pedal has a rocker on it that allows one’s foot to control the effect, but this particular one has been modified for CV instead of the wah-wah sound these pedals normally make. [Scissorfeind] built in a switch that will allow it to control volume as well, which makes this pedal quite unique in the effects world.
[Scissorfeind] built the custom circuit out of other parts he had lying around (presumably not in the street) and put the entire thing together on perfboard, then fit it all back together in the pedal. Now he has a great control voltage pedal for the vintage Korg synthesizer he recently restored! [Scissorfeind] knows his way around a synth, but if you’re looking to get started on a synthesizer project we have a great tutorial for you!
The tubes you’ll find in guitar amps and high-end stereos were first designed in the 30s and 40s, and when you get to really, really advanced tube technology you’d be looking at extremely small tubes made in the 70s for military applications. For 40 years, there really haven’t been many advances in tube technology. Now, at last, there’s something new.
The Nutube 6P1, as this curious invention is called, is a full triode or half of a 12ax7 you’ll find in just about every tube amp ever. Unlike the 12ax7, it consumes 2% of the power required of a normal tube, is 30% of the size of the normal tube, and lasts for 30,000 hours.
This new tube-chip thing was brought to life by Korg, makers of fine musical equipment and Noritake Co., manufacturers of vacuum fluorescent displays. There’s no word on what these tubes will be used in and there’s no data sheet. There will be further announcements this year, so don your speculation spectacles and head to the comments.
Korg, everyone’s third or fourth favorite synth company, but one of the only ones that still in business, recently put out a new line of synths, drum machines, and groove boxes. They’re called Volcas, and they’re cheap, analog, and very cool. [Jason] has a few of these Volcas, and while he enjoys the small form factor, using an off-the-shelf mixer to dump send the audio from these machines to his computer takes up too much space. He created a passive mini mixer to replace his much larger Mackie unit.
The circuit for this tiny passive mixer is an exercise in simplicity, consisting of just a few jacks, pots, and resistors. [Jason] overbuilt this; even though the Volcas only have mono out, he wired the entire mixer up for stereo.
The enclosure – something that looks to be a standard Hammond die cast aluminum enclosure – was drilled out, and a lovely laser cut acrylic laminate placed on top. It looks great, and for anyone interested in learning soldering, you couldn’t come up with a better first project.