That one time that MXR made a Drum Machine

video upload by Alex Ball

"In 1983, effects giants MXR made a drum machine.

Huge thanks to Harry Axten for the loan.
https://hkadesign.org.uk/

0:00 Intro Jam
1:05 The MXR Drum Computer
1:37 Face Review
2:08 What is it +Harry Axten Midi
3:47 Demo 1: Know what I mean 'arry?
4:46 The tuning problem
6:04 Demo 2: Drum Computer
7:00 A later success
7:47 Sample Pack
8:27 Outro Jam"

VS1103b DIY MIDI Synthesizer

Published on Jul 17, 2013 Harry Axten·1 video

"Yet another rebuild of my VS1103b MIDI synthesizer. It now has nice robust aluminium panels and a working soft-reset button. The tunes are from the game 'The Incredible Machine 2'. Build details, schematics, etc. can be found at:
http://harryaxten.webs.com/vs1103bmid..."

See the VS1103b label below for previous posts. Note Harry changed his YouTube channel and chances are the videos in the old posts will move to it. Currently only the video above is on the new channel though so I provided the link to the channel in the older posts should the old embedded videos disappear.

Roland TR-707 ROM Expansion Kit

Harry Axten

"Coming soon for the Roland TR-707 and TR-727..."

via https://hkadesign.org.uk

"You asked for it, now here it is – a ROM expansion kit for the Roland TR-707 and TR-727. It gives the machine 8 banks of sounds you can select, including the stock sounds from both the TR-707 and TR-727, so you can turn one into the other (to an extent – more on this later).

Changing between 8 banks would be a bit cumbersome using toggle switches, and I didn’t want to spoil the machine’s futuristic looks either, so this time the bank switching is done by holding down one of the first 8 step keys while turning the machine on. The setting is remembered and will be recalled the next time it’s turned on. There are no modifications to the outside of the machine, and the installation is easily reversible.

Apart from having different sounds, a modified TR-707 / TR-727 behaves exactly the same as a stock unit, no functions are lost. The machine should also be compatible with any other modifications or circuit bends you may have fitted, such as voice tuning, hi-hat decay mods etc.

I’d like to extend a huge thank you to Sunshine Jones, who donated the TR-727 which I used to develop the modification, and who also provided the excellent TR-808 and TR-909 samples which were used in the expansion banks.

The 8 banks included are :

TR-707
TR-727
TR-808
TR-909
LinnDrum
LM-1
DMX

TR-707 + TR-727 mix (handy for those who don’t own both machines)
The ROM expansion kit will switch out all of the sounds (referred to as a bank) apart from the last two sounds (crash + ride / quijada + chime), which will remain the same across banks, as they are stored on their own ROMs in a different part of the machine. I may produce an optional add-on board that can switch these as well if there’s sufficient interest."

CLICK FOR MORE »

Crumar Bit One MIDI Upgrade demo

Published on Dec 29, 2019 Harry Axten

"This is a modification I developed for the Crumar Bit One, a fairly rare Italian-made polysynth from the mid 1980's, that improves its MIDI capability. The upgrade takes the form of a small daughterboard that installs neatly inside the synth. More information can be found at https://hkadesign.org.uk/bitonemidi.html"

Korg 03R/W ROM Demos

YouTube Uploaded by HarryMatic on May 28, 2011
Channel moved to Harry Axten

Wild West demo in there.
"The three built in demo songs of the Korg 03R/W Sound Module from 1992. To be honest, they're not very good. The demo songs of the Korg M3R were much better in my opinion and what's more, the M3R was released three years earlier."

DIY MIDI Keyboard Encoder

YouTube Published on Jul 13, 2012 by HarryMatic
Channel moved to Harry Axten

"This is going to be part of a project which will add a full size keyboard to a Korg Monotron, along with other modifications. It is a two octave keyboard (which was liberated from a well and truly ruined keyboard controller). The control circuitry was built by me on stripboard, and uses a pre-programmed PIC microcontroller bought from http://picsynth.000space.com/midi.html

Although it does not use velocity sensitive keys, the fixed velocity can be set using a potentiometer. I had to assemble a new circuit board which was attached under the keys, on which were 24 tactile switches. As a key is pressed, it closes the switch. The keys are arranged in a 2 * 12 matrix, although the PIC software supports up to a 4 * 12 matrix.

The sounds in the video are generated from some of the softsynths that come with GarageBand."

Roland TR-505 EEPROM Adapter / New Sounds

Published on Aug 16, 2015 Harry Axten

"The PCBs for my EEPROM adapter finally arrived so here's a demo of the two new kits, based on the LinnDrum and Oberheim DMX. The board installs directly in place of the original sound ROM.
http://harryaxten.altervista.org/tr50..."

VS1103b MIDI Synthesizer v3

Published on Oct 8, 2012 by HarryMatic
Channel moved to Harry Axten

"The last version of my VS1103b MIDI synthesizer. I have designed nice front and back panels which are made of laser-cut plastic. I have also gotten rid of the noisy volume control and the MIDI thru, instead adding separate left and right audio outputs. Schematics, stripboard layout, more photos and a full writeup can be found at : http://www.instructables.com/id/E82VEK1GXUZ7YJA/"

Follow-up to this post.

"The VS1103b, manufactured by VSLI Technology, is a single-chip MIDI/ADPCM/WAV audio decoder and ADPCM encoder that can handle upto three simultaneous audio streams. It can also act as a MIDI synthesizer.

It is this MIDI synthesizer capability that we are interested in. Make no mistake - the quality of the MIDI voices isn't stunning, but it has a charm to it that reminds me of the FM synthesis found on old Soundblaster cards of yesteryear. The VS1103b MIDI synthesizer mode conforms to the General MIDI standard - 15 melodic channels and 1 percussion channel.

The only problem with this chip however is that it is a very small 48 pin surface-mount package. Fortunately, SparkFun make a break-out board for this chip that has a 20 pin DIP package - much more suitable for DIY electronics."

Sequential Circuits TOM custom cartridges

Published on May 13, 2018 Harry Axten

"Showing off some sounds and famous patterns demo for these bare-bones cartridges for the Sequential Circuits TOM drum machine."

VS1103 MIDI Synthesizer

YouTube Uploaded by HarryMatic on Jul 17, 2011
Channel moved to Harry Axten

"A small MIDI module made using a VS1103b Breakout Board and some extra circuitry. It has a very warm and synthy sound - a lot like the OPL chips found on SoundBlaster cards of yesteryear.

If you want to make your own - http://www.instructables.com/id/VS1103-MIDI-Synthesizer/"

E-mu Planet Phatt G-Funk track

Published on Aug 7, 2013 Harry Axten

"I've been looking for a Planet Phatt for quite a long time and I finally got one for a good price. Here is a quick demo track I put together, using Cakewalk Pro Audio 9 to sequence the different parts. All sounds are coming from the Planet Phatt, with some outboard compression and reverb."

E-mu E-drum demo

video by Harry Axten

"Couldn't resist pulling the trigger when I found one of these for sale online. It plays back 8-bit samples stored on cartridges, with velocity routed to amplitude and optionally pitch. Mine only came with the 'ROTOTOM1' cartridge, but I was able to scan in and copy the cartridge PCB to produce my own; which in this case have the TR-909 cymbals on them.

It's basically a rebadged Clavia unit, with a different paint job. I think the cartridges are also compatible with the original Clavia DDrum rack system (but not the later 'Sound Pac' ones)."

E-mu Audity 2000 ROM Demos

Published on Jul 19, 2013 Harry Axten

Dancin' with Dr. Who!

Super modified Korg Monotron keyboard demo

Published on May 28, 2018 Harry Axten

"This synth was a work in progress from mid-2012 until last year when I finally got around to finishing it. It's based on a heavily modified Korg Monotron; giving it a full-size two octave keyboard with mod wheel, a sub-oscillator, a variable pulse wave and more. The digital side is running on Arduino code and supports MIDI, although that functionality isn't shown here. The case is laser-cut MDF with an aluminium panel and the keyboard mechanism was re-purposed from a dead M-Audio MIDI controller.

Photos, code and schematics can be found here:
http://harryaxten.altervista.org/mono..."

Sequential Circuits TOM 'Classics Cart'

Harry Axten

"Replacing my previous set of 3 mini cartridges for the TOM. This multi catridge has 8 banks, full of classic EPROM drum machine sounds, which are cycled through with the button. Housed in a proper case this time too! Coming soon."

Update: now available here: https://hkadesign.org.uk/tomclassicscart.html

MPC Electronics MPC-1 with Tubbutec uniPulse MIDI retrofit

video upload by Harry Axten

"Pretty rare British-made drum machine from 1981, originally intended to interface with the Sinclair ZX81 computer. I’ve installed Tubbutec’s excellent uniPulse MIDI retrofit in this, using the existing sync socket for the MIDI input. The drum voices are very responsive to playing dynamics, which I was pleased to find works great with the uniPulse’s velocity-sensitive outputs.

The sequencer board in this one was wrecked by a battery leak, which is sadly very common in these. The leakage also got onto the main analogue board, although fortunately not as badly. It ate up three of the potentiometers for the Tom 4 voice, and I haven't yet located suitable replacements, hence those controls being missing and blanked off; but everything else is now working as it should, having cleaned up corroded board traces and replaced a number of damaged components."

Roland TR-505 ROM Expansion demo (new LM-1, DMX & LinnDrum kits)

Published on Aug 28, 2016 Harry Axten

"The latest version of my Roland TR-505 custom ROM project. Now uses a 512K EEPROM so it can store 4 kits, including the original stock sounds. Kits will be for sale shortly."

E-mu Audity 2000 ROM Demos

Published on Jul 19, 2013 Harry Axten·3 videos

"This is a really cool 19" sound module. Unlike every other 1U rack synth I've owned, programming it 'through the letterbox' is actually fun, rather than a tedious, confusing mess."

mCKENIC Linn DMX 505 rom

Published on Sep 28, 2015 mCKENIC

"Quick play after installing Harry Axten's WONDERFUL Linn/DMX rom for the Roland 505... makes the 505 a whole new beast :-)

http://harryaxten.altervista.org/"

KORG KPR-77 Retrofit MIDI Interface (work in progress)

Published on Jul 24, 2016 Harry Axten

"This is a project I'm currently working on. It adds MIDI to the KORG KPR-77 analogue drum machine from 1983. It installs internally; requiring no case mods to fit it, as it fits in the battery compartment and re-uses the DINSYNC connector for the MIDI input.

There are still things to be done, such as redesign the printed circuit board and add the final feature set to the firmware, but I aim to have a kit for sale this year."