This Old Korg Can’t Have Too Many Samples

April 20, 2019 by Jenny List 4 Comments

The Korg DW-6000 is an entry-level synthesiser from the mid 1980s that has the classic sounds, but not enough of them. At least that was [Mateusz Kolanski]’s view, as he hacked his model with a 16-fold increase in its wavetable memory.

At the heart of the DW-6000 is NEC’s UPD7810 16-bit microcontroller, a device stuffed with ports aplenty. The Korg doesn’t use all of those ports, so he was curious as to whether its relatively small 256 kbit ROMs could be upgraded to something much bigger with the use of four unused lines to drive their addresses. This proved to be no easy task, not least because the UPD7810 is hardly a chip with a lot of published work to learn from. A manual for it came from an unexpected source: an obscure game console used it so there is support within MAME.

A significant quantity of hardware reverse engineering and software experimenting later, and he had a ROM piggyback board to plug into his lightly-modified DW-6000. The initial model used stripboard, but naturally a decent PCB was created. That might be everything, but of course some means of working with those samples was required. Enter a Windows wavetable editor and organiser to create new ROM images, for the complete DW-6000 upgrade kit.

This project took several years, proving that persistence can pay off. If you’re not used to the way microcontrollers did their interfacing back in the 1980s then it’s definitely worth a read even if old synths aren’t your thing.

This isn’t the first bit of Korg reverse engineering we’ve brought you, either.

Thirty Six Frets For A 3D Printed Guitar

April 19, 2019 by Brian Benchoff 5 Comments

Only 80s kids will remember actual hair metal with the meedley-mees way up high on the fret board, and in the 80s, fret boards got longer. Twenty one or twenty two frets on a guitar weren’t good enough, and you needed the full two octaves of twenty four frets. As with anything, more is better, so [Said Too Much] decided to add frets to his guitar. Yes, you can do that, and it actually doesn’t sound too bad, all things considering.

A few things to cover before going over this build. This did not start out as an experiment to extend the fretboard of a guitar. This started out as a soprano guitar build; this would be the inverse of a baritone guitar — instead of an extended scale length and heavier strings to play a fourth or fifth below a regular guitar, this soprano guitar would have a shorter scale length and lighter gauge strings to play a fourth or fifth above a regular guitar. After a few calculations and some calls to companies that make very, very thin guitar strings, this project morphed into a 3/4 scale guitar (a 23″ scale length, although I question that scale length being actually 3/4 scale) and a set of strings that used 0.07″ strings.

Since a soprano guitar is pretty much just like a normal guitar with more frets, this project also got an extended, 3D printed fretboard. Why? Because. The stock pick guard was modeled and printed out in PLA, removing the neck and middle pickups. Then, an ‘extended fret board adapter’ of sorts was slotted in behind the strings. This gives the guitar 38 frets, a full third of them being printed in PLA.

The burning question: does a 3D printed fret board work? Yes, kind of. If you can get your fingers in between the frets, you can absolutely play the 36th fret on this guitar. It’s not for everybody, obviously, and PLA printed frets will never be as good as polished metal frets. But it is an interesting experimental technique for stringed instruments we haven’t seen before. Check out the video below.

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A Mostly 3D Printed Speaker

April 17, 2019 by Lewin Day 2 Comments

The common magnetic loudspeaker is, fundamentally, a fairly simple machine. A static magnetic field is generated by a permanent magnet, and a membrane is mechanically connected to a coil. When a varying electrical current is passed through the coil, this causes the coil to move due to the magnetic field, vibrating the membrane and producing sound. [Mattosx] put this theory into practice with a simple 3D-printed speaker.

It’s not the first 3D-printed speaker we’ve ever seen, but it’s one of the cutest. The main body of the speaker is rectangular, and has a cavity in which three neodymium magnets are placed. The vibrating membrane is then printed separately, including an integrated spindle upon which the coil is wound. The assembly is held together with some socket-head cap screws which complement the pleasantly modern look.

The device does a good job delivering the bleeps when hooked up to an Arduino, and we could see this basic design serving well in all manner of charming 3D-printed builds. Video after the break.

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Giving MIDI Organs MIDI Drawbars

April 15, 2019 by Brian Benchoff 10 Comments

This goes back to Bach: if you want to change the sound an organ makes, you have to pull on some drawbars. This design didn’t change for 300 years, and in the 20th century with the advent of ‘tonewheel’ organs, you still had small bars to pull to change what sounds came out of the organ. While this was a simple solution for air-powered organs of the 1700s, when it comes to MIDI, rotary pots are a lot less expensive than linear pots. Given the lack of drawbar MIDI controllers, [Stefano] decided to build his own. It has nine drawbars and eight buttons, all connected to MIDI.

The interesting electromechanical part of this build, the drawbars themselves, are ripped from a Hammond organ. Don’t worry, plenty of these were made and only a handful actually sound good. To that, [Stefano] added a few pushbuttons soldered onto a piece of perfboard, and everything is wired up to a Teensy LC, the microcontroller platform that’s becoming the standard for everything from MIDI controllers to computer keyboards. MIDI over DIN and MIDI over USB are supported, and all the buttons and drawbars are individually programmable. You can even do that through SysEx messages, because that’s how things were done back in the day.

While there are a few MIDI-controlled organs that still use drawbars — the double manual Nord comes to mind imminently — this is a great solution to putting drawbars into anything that speaks MIDI, VSTs included.

Building Your Own Guitar Pickup From Scrap

April 14, 2019 by Lewin Day 13 Comments

Pickups are a key part of an electric guitar’s sound. You can spend a king’s ransom on tracking down just the right Vintage American Original 1950s Whatevers (TM) to put in your Spudocaster, but it’s not the only way. [Keith Decent] decided to make a pickup from scratch, using only materials found lying around the workshop. (Youtube, embedded below).

To build a pickup, you’ll want some magnet wire. In this case, [Keith] harvests this from an old transformer. A pickup body is then constructed from an old wooden ruler and some machine screws. A drill is used to spin the pickup body while the wire is roughly wound on, and everything is then held together with lashings of hot glue.

It’s a grungy build with a very Mad Max vibe – with the perfect aesthetic to suit [Keith]’s junkbox guitar build. The sound is good, but difficult to rate accurately when used on a guitar with slightly imperfect intonation. We’d love to hear it installed on a well-tuned body to get a better comparison.

It goes to show you don’t need to spend money on new parts and tools to get a build started. Sometimes you can make something perfectly functional with stuff you have lying around at home. Video after the break.

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It’s (Almost) Two Keytars In One!

April 13, 2019 by Jenny List 4 Comments

All the best retro-1980s chiptune acts should possess a keytar. It’s the Law, or something. [Theremin Hero] has reminded us of this with a new video we’ve shown below featuring an instrument he had a part in creating alongside [Sam Wray] and [Siddharth Vadgama] a few years ago. The Blade is a 3D-printed keytar featuring two Guitar Hero necks and an integrated pair of Game Boys to provide the sound from the authentic silicon.

To describe it in those terms though is to miss a wealth of other components and featured. The keyboard itself is from a Rock Band keytar which feeds MIDI to a Raspberry Pi running PD Extended that handles all the button press mappings. An Arduino Mega performs the same task for the two Guitar Hero necks. Midi from the various sources is processed by an Arduino Boy which then feeds the Game Boys that make the sounds. Oh – and there’s a Leap Motion 3D motion controller in the mix as well, though that doesn’t seem to be used directly in the chiptune synth functionality.

We’ve had a few keytars here over the years, but this one makes us think of the Commodore 64 instrument created by [Jeri Ellsworth].

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This Is The Delay Pedal You Can Build Yourself

April 10, 2019 by Brian Benchoff 33 Comments

If you’re looking to make money in electronics, there’s no better market than guitar pedals and modular synths. The margins are high, and all the consumers are otakus who will spend outrageous amounts of money chasing the next big thing. The products are just one step above audiophile wank with zero oxygen cables, and if your opamp sounds ‘more transparent’, you’re going to make a fortune, never mind how something can sound more transparent, whatever that is to begin with.

If you want to do something really cool, build a delay, because everyone needs another delay. If you want to build the latest in delay technology, just grab a PT2399 chip. That’s what ElectroSmash did with their Open Source Time Manipulator delay. Everything’s right there, all the parts of the circuits are described, and you too can become an effects pedal engineer.

This pedal is based on the PT2399 chip from Princeton Technology, a digital delay chip that can be used with something that sounds like an old-school bucket brigade chip or something resembling a tape echo. As a digital chip, you’ve also got the clean, clear sounds of a digital delay, with just a few tweaks of the circuit. We’ve taken a look at the PT2399 before, but surprisingly not many people are sharing their secrets.

The circuit for the ElectroSmash Time Manipulator is built around the ATMega328, the same chip in the Arduino Uno, with two PT2399s that can be configured to operate in serial or parallel for everything from a slapback echo to a 600ms digital delay. If you set everything right, you can get choruses, reverbs, or some psychobilly flange-ish sounds.

The entire circuit is open, with a board designed in KiCad, the code is right there written in C, and the only hard-to-replicate tech is the PT2399 chip itself, which can be had from the usual vendors for less than a dollar a piece. It’s a great pedal, and be sure to check out the video below.

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