USER MANUAL April 30th 2021 We always value feedback and ideas, so feel free to reach out. Please check the website for the latest firmware! THANK-YOU! Thank-you for adopting MEGAfm, the product of several years of work & play. We are particularly fond of the YM2612 as they offer a unique gritty texture that is uncommon in the FM word, plus hands-on FM experience that is unprecedented in the hardware FM synthesiser world.
YM2612 Overview “The Yamaha 2612 Frequency Modulation (FM) sound synthesis IC resembles the Yamaha 2151 (used in Sega’s coin-op machines) and the chips used in Yamaha’s synthesisers. It is famously known as the Sega Megadrive’s voice. An FM channel is capable of expressing, with a high degree of realism, a single note in almost any instrument’s voice. Chords are generally created by using multiple FM channels.
Operators There are four dedicated operators per voice which may be arranged in eight different configurations, called “algorithms”. Following is a diagram of the algorithms. Slots are indicated by shading.
The sound starts when the key is depressed, a process called ‘key on’. The sound has an attack, a strong primary decay, followed by a slow secondary decay. The sound continues this secondary decay until the key is released, a process called ‘key off’. The sound then begins a rapid final decay, representing for example a piano note after the key has been released and the damper has come down on the strings.
Voicing MEGAfm offers up to 12 voice polyphony. The 12 voices are spread across two YM2612 chips. In all modes you can use the fat knob to detune the voices. Hold voicing mode button and the fat knob becomes glide. Glide knob determines the time it takes for each voice to change pitch when a new note is played. Mono Mode: When a single TS 6.35mm jack is plugged into output1, both chips are summed to output1. Stereo Mode: When a second TS 6.
Dual ch3 YM2612 offers a special mode where the 4 operators of channel3 can be individually detuned to arbitrary frequencies as described above in the YM2612 Overview. Recommended for experimental / percussive sounds. Unison All voices are played at once in unison and detuned using the fat knob. Turn the fat knob clockwise to gradually detune all 12 voices. At maximum fat, the 12 voices are arranged in a chord. Fat Use the fat knob to detune the 12 voices in any voice mode.
Algorithms & Feedback Use the algorithm knob to select any of the 8 algorithms and the feedback knob to set the amount of operator1 feedback. Note: both parameters can be modulated by LFO! Vibrato Use the depth knob to add vibrato to the overall pitch of MEGAfm. Use the vibrato rate knob to set the vibrato’s speed. The vibrato can be configured to sync to incoming MIDI clock at 8 different speeds, please refer to SETUP instructions for more details.
Arpeggiator and Sequencer When unison voice mode is active the arpeggiator can be used. The arpeggiator has 7 modes: Up (shown as “UP” on the numeric display) Down (shown as “dn” on the numeric display) Up/Down aka pendulum (shown as “Ud” on the numeric display) Random1 (shown as “r1” on the numeric display) The arpeggiator chooses and plays any of the held keys at random. Random2 (shown as “r2” on the numeric display) The arpeggiator chooses and plays any notes at random.
Recording a sequence To record a sequence press rec to activate recording mode. The rec LED will flash. Now play up to 16 notes via MIDI. Each preset can store up to 16 notes. Every time you input a note, the step recorder will advance and the numeric display will show the current step. You can use the preset up button to skip a step. No note will be played. You can also go back a step with the preset down button if you wish to correct a note.
Modulators ( Lfo 1 to 3) Any knob or fader can be modulated by up to 3 lfo modulators at once. To link a knob or fader to an lfo move a knob or fader and press a chain link button. Click the chain button a second time to unlink a knob or fader from an lfo. The LED above the chain button indicates whether the modulator is linked or not. Each knob or fader can link to up to 3 LFOs at once.
Selecting an lfo waveform To select any of the 3 LFOs simply move one of the LFO rate or depth knobs. Use the 4 waveform buttons to select a waveform. Selecting an already lit waveform will put the LFO in manual mode. Now you can adjust the value of the LFO at any time with its depth knob LFO depth Set the depth of an LFO with its depth knob. This defines the amount of effect the lfo will have on the associated knobs or faders. LFO rate Set the rate of an LFO with its rate knob.
Presets MEGAfm has 600 a preset memory capacity arranged in six banks of 100 presets. MEGAfm currently ships with 50 factory presets (0-49) organised according to the following chart. Misc 0-9 Bass 10-19 Lead 20-29 Pads 30-38 Rhythmic 39-44 SFX 45-49 Each preset can be edited and stored and preset banks can be transferred to and from a computer via MIDI SYSEX. Loading a Preset Simply press the preset up and down buttons to load a preset.
Saving a preset You can save the current preset to any of the 100 slots, first press preset up + preset down simultaneously to enter save mode. The numeric display will flash the current slot number. This starts a 3 second countdown before automatically saving the preset at the same slot. But you can change the destination slot by pressing the preset up or down buttons. Each time you select a new slot the 3 second timer is reset.
Setup Mode Hold voicing at startup or anytime for 3 seconds to enter setup mode. “SE” appears on the numeric display LED Brightness Turn the vibrato depth knob to adjust brightness LFO1 to 3 sync to incoming MIDI clock Turn the respective LFO rate knob to choose whether to link LFO1,2 or 3 to the MIDI clock. Above 12 o clock the setting is on, below the setting is off.
Velocity controls LFO1 Turn the vibrato depth knob to choose whether to control lfo1 with MIDI velocity. With this option activated, the MIDI velocity will control the depth of lfo1 when the rate of lfo1 is above zero. When the rate is zero (stopped lfo) MIDI velocity will override the lfo and directly modulate all parameters associated to the lfo. Use the depth knob to adjust the amount of effect. Above 12 o clock the setting is on, below the setting is off.
Arp sync to incoming MIDI clock Turn the arp rate knob to choose whether to link the arp to the MIDI clock. Preset Volume on/off Turn the volume knob to turn preset volume loading on or off. When set to off, the preset volume will be ignored when changing preset. Above 12 o clock the setting is on, below the setting is off. The setting is indicated by ON/OF on the numeric display MIDI THRU Press the LFO1 link button to toggle MIDI THRU on/off. When on, all incoming MIDI is sent to the MIDI output.
Fat mode range (in all modes but unison) When you are in all voice modes but unison, the fat knob will detune the 12 voices in 2 possible ways: by 1 semitone (set the fat/glide knob below 51%) or by 1 octave (set the fat/glide knob above 50%). The LED display will indicated 1S (1 semi) or 1o (1 octave) as you adjust the setting.
MIDI Implementation MEGAfm responds to the following MIDI controls. You can also control it with the Plugin (available for free download on the website) which uses the following MIDI parameters.
Parameter MIDI CC Range Op2 Detune 20 0-127 Op2 Multiplier 24 0-127 Op2 Total Level 16 0-127 Op2 Attack Rate 49 0-127 Op2 Decay Rate 50 0-127 Op2 Sustain Level 51 0-127 Op2 Sustain Rate 45 0-127 Op2 Release Rate 37 0-127 Op4 Detune 47 0-127 Op4 Multiplier 39 0-127 Op4 Total Level 38 0-127 Op4 Attack Rate 46 0-127 Op4 Decay Rate 33 0-127 Op4 Sustain Level 41 0-127 Op4 Sustain Rate 43 0-127 Op4 Release Rate 35 0-127 LFO1 Rate 15 0-127 LFO1 Depth 12 0-127
Parameter MIDI CC Range Arp Rate 48 0-127 Arp Depth 13 0-127 VIBRATO Preset Upload/Download (SYSEX DUMP) MEGAfm holds 600 presets in its memory. The presets are divided into 6 banks of 100 presets. You can transfer 50 presets at a time (or half a bank) to and from MEGAfm via MIDI SYSEX. To download a half bank from MEGAfm to a computer hold preset DOWN at startup. Then choose a BANK using the 6 LFO waveform buttons.
a MIDI interface. The LEDS will blink during the transfer, and MEGAfm will reboot when complete. For SYSEX transfers we recommend SYEX LIBRARIAN for MAC and MIDIOX for Windows. Note: the firmware version is displayed as X.X for a half second at startup for revisions 1.1 and onwards. Firmware files are independent. You can safely install any version on to any other, earlier or later. Factory Reset If you wish to restore the device to factory state, hold reset at startup.
