Link Drum Rev. 1.1

Rotten Appleswww.rottenapples.uk

Diodac Electronics Design

Manual rev. 0.1 26 September 2020

Content:

1. Module description

2. Specification

Link Drum Gold Edition!

50 microns thickness true gold finish.

Module Description

The Link Drum is an 8 bit monophonic instrument. The perfect drummer for D&B, Techno, Minimal, Trance or Acid.

It's a combination of a drum machine and sequence / pattern player. The Link Drum can be controlled in three ways by:

- MIDI (by any MIDI sequencer or any MIDI device)

- CV / Gate (by any CV / Gate step sequencer)

- Manual (by hand or feet ;)

You can also use CV OUT to control e.g. Pitch or Rhythm bank which gives unique and interesting effects. However, the

greatest pleasure of using the Link Drum coming with any CV / Gate step sequencer like our monster - ElecTriple 16

The Link Drum was inspired by instruments like the TR606 or CP5000 from the early 80s.

47 sound samples from the most iconic instruments such as TR606, TR808, TR909, Linn Drum and CP5000 are stored in

the memory of the Link Drum. The samples in PCM format have been arranged in a tone bank conforming to the

General Midi standard and are available in the range of 35 to 82 midi notes on channel 10 at “MIDI” mode or at “Normal”

mode 37 sounds are available for CV / Gate and voltage controlled from 0 to 5V range.

The range 0 to 5V CV Note corresponds to the range midi note 34 - 72, where 0 V is midi note 34. Gate is triggered by

high state 5 V at the "Gate In" input.

The samples have two-stage Velocity control. Level 63 (normal) or 127 (accent). Velocity level control is available under

the "Velocity In" input. The change is triggered by a high state 5 V or in MIDI mode by incoming midi note-on which also

contain information about the velocity level.

The samples also have a Pitch Bend control with 7-bit resolution. Pitch Bend changes can be made via midi messages in

MIDI mode or via CV or manual control. Please note that changes to the Pitch Bend will affect the playback time of the

sample. The lower the pitch - the sample need more time to play finish.

Link Drum has the ability to play drum sequences saved in the bank "Rhythm"

The Link Drum (silver panel) has a bank of 16 sequences.

The Link Drum Gold Edition has a bank of 34 drum sequences.

The select of sequences from the bank for playback can be made manually or by CV.

When playing a pattern, you can use the Gate function simultaneously and select a sound with the “Note” knob or via the

Note CV. Using Gate while playing a sequence, changes the sounds to the previously set sound with "Note" knob.

This possibility brings an interesting way of constructing transitions and new rhythms of the currently playing sequence.

The Fill function just like the above-described method, also can be used to make transitions to the rhythms, changes in the

arrangement of sounds in the rhythm, etc. The simultaneous and alternately use of the Gate and Fill functions during the

playback of a sequence gives plenty possibilities of transitions of the combination of the sequences from “Rhythm” bank!

This is a really unique way to play which is very intuitive and easy. With a little training, you can get powerful

possibilities to create unique rhythms.

Sequences can be played at speed ~ 60 - 180 BPM. Speed can be controlled by CV or manually.

The Link Drum cannot edit the sequences saved in the memory.

The Fill function is available during sequence playback and allows you to obtain 47 different rhythm variants for each

sequence stored in the “Rhythm” bank. Which gives at least 1598 transitions for all sequences!

Fill transitions can be made manually with the “Fill” switch and selected by "Instrument" knob or via the CV and fill

trigger input. The maximum number of transitions that can be obtained for the banked "Rhythm" sequences using Fill

when playing sequences is 1598 transitions, but you can additionally use the Gate function alternately with the Fill

function to obtain subsequent transitions, thanks to this method you can get even several thousand combinations of rhythm

transitions!

- Gate Out: represents triggering event. 5 V high state on the output when Gate or note is on.

- Time Out: is TTL level representation for Speed.

- CV Out: represents level 0 to 5 V or 1 V / Octave output depending on the actual note.

- Audio output format: Mono.

Link Drum was realised on two 8 bit MCUs, but still managed to achieve decent sound quality thanks to the use of a DAC

converter. The range 22 to 39kHz sampling frequency varies according to the type of sample.

Although Link Drum has 1 voice polyphony like most early 1980s instruments, it really does allow you to create complex

rhythms. The video presentations will be available on Dr.Diodac YT channel.

All inputs are buffered with a maximum input level of 5 V. The inputs also have over voltage protection.

The module is powered by a symmetrical power supply between 12 and 15V.

Specification

Front Panel

1. Switch to MIDI control mode.

2. Manual Gate control switch.

3. Switch for Play beat pattern / sequences.

4. Fill manual control switch.

5. V/Octave ON/OFF switch.

6. MIDI control mode LED indicator.

7. Gate control LED indicator.

8. Play sequence and speed/time LED indicator.

9. External Fill control input, high state 5 V for triggering.

10. V/Octave LED indicator.

11. MIDI input (channel 10) RTS type B

12. External Gate control input, high state 5 V for triggering.

13. External Play control input, low state 0 V for triggering.

14. External Velocity control input, high state 5 V for level 127, low state = velocity level 63.

15. Volume attenuator. Level 10 activate Overdrive effect.

16. MIDI output (channel 10) RTS type B.

17. Gate output.

18. Pattern play seed time output.

19. CV output.

20. Audio mono output.

21. Pitch Bend CV input control.

22. Note CV input control.

23. Sequence Speed CV input control.

24. CV input for selection and control Rhythm patterns.

25. CV input for selection and control Fill instruments

26. Pitch Bend control potentiometer.

27. Note control potentiometer.

28. Sequence/pattern speed control potentiometer.

29. Rhythm/pattern selector potentiometer.

30. Instrument selector potentiometer for Fill transitions.

CPU Board

31. Power supply input. + GND - 12 to 15 V dual supply.

32, 33 and 34. Factory diagnostic and programming ports, normally not for use.

35. Trimmer for adjusting V / Octave level.

Other modules by Rotten Apples available:

1. ElecTriple 16 Step Sequencer - with 3 independent CV and CV Portamento output sections.

2. Acid Wire - unique audio2midi/cv converter with midi looper and chromatic2 scales converter. 24 music scales bank!

3. WiFi / RTP Midi and Audio - Midi docking station for iPhone, iPad, Android and Windows devices. Station enables ultra fast and ultra simple plug&play MIDI wireless communication for almost all devices with any modular synth systems!

4. Amplitude - audio2CV/Gate converter.

5. ARP 4075 - clone legendary ARP VCF.

6. Dreamtime Synthesiser - compact monophonic synth with double DCO, ADSR, LFO, VCF, ENVELOPE,

7. FUZZLE - nice distortion effects on Russian germanium PNP transistors.

8. MatrixPin - an modern pin matrix.

9. AudioMixer - 4 input, EQ and UV meters included!

10. VCA+VCF - Polivoks inspired.

11. Ribbon - 500 mm ribbon controller with Z axis control and LED strip indicator position! Y,Z axis CV and Gate output.

12. PolyVCO - voltage and MIDI controlled 6 voice polyphony oscillator.