TR-707 with ROM Expansion and Cymbals Board

video upload by Harry Axten

"Realised I haven't done a video showing the current version of the TR-707 ROM Expansion modification - it now allows switching kits at any time while the machine is running, done by holding down the enter button and pressing one of the first 8 step buttons. This TR-707 also has the optional cymbals board installed, which allows the last two sounds (crash & ride cymbal) to change as well. More information here - https://hkadesign.org.uk/tr707expansi..."

Korg KPR-77 MIDI Retrofit Kit

demo video upload by Harry Axten

"Updated version of my MIDI kit for the KPR-77. More info at https://hkadesign.org.uk/kpr77midi.html"

Modified TR707 with HKA Design ROM switcher

video upload by circuitbenders.co.uk

"A (far too long) demo of a modified Roland TR707 with a HKA ROM switcher installed to give 8 separate sound banks. Different banks are activated by holding down the 1 to 8 step keys as you turn it on.

This was mainly done as a proof of concept to work out if our standard TR7X7 glitching patchbay, individual pitch controls, DAC distortion and decay modifications would work on a HKA modified machine. It turns out everything works perfectly.

Further details on our mods can be found at: https://www.circuitbenders.co.uk/drum...

The HKA sound bank expansion can be found at: https://hkadesign.org.uk/tr707expansi..."

Classic Drum Machine sounds for the Sequential TOM | UPDATE

video upload by Espen Kraft

"The Sequential TOM drum machine, one of the coolest drum machines of the 80s and very advanced for its time. The cartridge port in the front made/makes it very easy to use 3 party drums. Today I check out the 8-in one classic cart from HKD.design. Linndrum, DMX and others all rolled into one."

See this post for an additional demo and link to the cart. You can find additional HKA Design posts here.

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

hka design digitizer (volca fm + vermona drm1)

studio snippets

See the HKA Design label below for more. They also made the pedal in black and they produced a Roland TR-707 ROM Expansion as well as TR-626 and TR-505 ROM Expansions.

Roland TR-707 ROM Expansion by HKA Design

autoy

"This is a small demo of some patterns with the expansion kits included in the HKA TR-707 Expansion mod. For more info and purchase:
https://hkadesign.org.uk/tr707expansi..."

One more:

Roland TR-808 vs CR-8000


"The famous Marvin Gaye beat in both machines, to show the different characters."

Roland TR-626 ROM Expansion - Oberheim DMX, LM-1, LinnDrum, TR-707 and TR-626 sounds

Published on Oct 29, 2019 midierror

"The ROM expansion from HKA Designs adds sounds form the Oberheim DMX, Roland TR 707, Linndrum and LM-1 Drum Machines - adding 60 sounds to the on board 626 sounds."

Available to buy as a kit here: https://hkadesign.org.uk/tr626expansi..."

HKA Design Digitizer Bitcrusher Pedal

Published on Jul 21, 2019 Harry Axten

"This is a digital sampling bitcrusher pedal I've been working on recently. It samples at 8/6/4 bit resolution and is based around an ATmega328P microcontroller.

The project is open hardware - all of the design files, code and construction details can be found on my website: https://hkadesign.org.uk/digitizer.html"

Demo with the Sequential Prophet-6.

CLICK FOR MORE »

HKA Design Roland TR-626 ROM expansion

Published on Jan 1, 2019 dothkoi

"refer to the following pages
http://harryaxten.altervista.org/tr62..."

Be sure to check out HKA Design's other DIY projects. HKA Design is run by Harry Axten whose work has been featured here on MATRIXSYNTH.

"My TR-505 ROM Expansion has proven itself to be a popular kit, but I was regularly asked if it would work with the TR-505’s big brother, the Roland TR-626. The answer was no, as even though the two machines look and sound quite similar, the electronics inside are incompatible. Eventually, somebody very generously offered to send me a TR-626 to keep if I could produce an expansion kit for it. Naturally I accepted.

Sample ROM address map / encoding

The TR-626, although it has more sounds than the TR-505, fundamentally works in exactly the same way. Samples are played back at 25.0 kHz, and once again some are stored in sequential order, while others are interleaved in pairs. Cymbals are stored in 8K blocks, with a byte being read from each block in cyclical order.

The TR-626 even uses a standard JEDEC-type ROM pinout for its sound ROM; unlike the 505’s which had a horrible custom pinout, requiring a complicated adapter board. The kit I designed for the TR-626 does still use a board, but this time it’s to allow for two ROM chips to be switched. The only real catch with the TR-626 sound ROM is that address lines 6 & 8 are swapped (in the data). It’s easy enough to swap them back using an EPROM pin swapper utility.

For the new sounds, I reused all of the classic sounds from my TR-505 version, although there’s also some TR-707 sounds in there as well, thanks to the TR-626’s larger ROM size. The new sounds are spread across two banks, with LM-1 and LinnDrum sounds in one, and DMX and TR-707 sounds in the other. There's also a socket to install the TR-626's original sound ROM, so you can keep using those sounds as well.

The TR-626 has several strange quirks. One is the way polyphony is assigned across the 8 drum voices. Despite the fact that some sounds share the same key, they don’t necessarily share the same voice. For this reason, some of the key assignments for my new sounds may seem a bit odd, but the reasoning is so that you can play certain sounds together - i.e. the LM-1 hi-hats and snare drum. A full list of the sounds can be found in the manual (see below). As the TR-626 lacks an individual output for claps, I duplicated these sounds into the china cymbal and cup memory locations, so they can come out of the crash / ride cymbal outputs."

See HKA Design for additional details.

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 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."

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."

PAiA Fatman Analogue Synthesizer Demo [Keyboard Version]

Published on Oct 11, 2015 Harry Axten

"A quick demonstration of some of the sounds the PAiA Fatman synth can produce. Although I housed mine in a custom built keyboard, it's a vanilla unmodified kit. Recorded with no effects."

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/"