Asteroid Mini Reference guide

Brand: Asteroid

Model: Mini

Type: Reference guide

Asteroid Mini Synthesizer Reference Manual.

Here is a picture of the module to make sure you got the right reference manual.

Asteroid Mini Synthesizer

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Format: Euro Doepfer compatible, 3U height (5.05")

Power Current Consumption: +108mA, -83mA

Depth: less then 45mm

Circuits involved: VCO, VCA, Envelope Generator, Sub Harmonic Generator, Noise Generator, and trigger

striking circuit.

Asteroid Mini Synthesizer Reference Manual.

Here is a block diagram of module:

What does this module do?

This module is a percussive synthesizer similar to the voice of a korg ER-1 drum machine. I used that

groove box as a model on how to internally connect the different sub modules found inside the Asteroid

Mini Synth. I was not shooting for a clone, it just helped me achieve an understanding of how to make a

great percussive mini synth. This module is 100% analog signal path, where as the korg ER-1 is a dsp

based simulation.

-The internal vco was taken from my Transistor Pyramid VCO. That uses a discrete transistor circuit to

create a nice triangle wave. The sine shaper is also transistor based and sounds fantastic.

-A booster circuit was added to achieve the ‘techno drum sound’ with ease.

-Part of the ER-1’s magic was the delay effect. On the Asteroid Mini Synth I used a PT2399 modern IC

chip to simulate bucket brigade effect (delay).

Asteroid Mini Synthesizer Reference Manual.

*Tune and Fine knobs: use these to adjust the vco pitch, the led’s to the right give you a visual of how

fast the vco is going.

*The toggle switch ‘1UF and 9U4’: these values determine the range of the Decay envelope generator.

The labels represent actual capacitor values. When it is set to the middle position you are using 0.47uf

capacitor. This is good for short drum sounds. 1UF is considered medium length. 9u4 will give you a long

decay range.

*To the left ‘VCA’ small black knob: this acts as a gate control. When it is turned fully counter clockwise

it is ‘closing’ the sound. You should not here sound at that position. As you slowly turn the knob

clockwise you give the vca a linear curve on how it will react when the red push button or trigger input is

used. The vca circuit will also overdrive creating nice over tones depending on the vca knob position and

the boost amount. There is only one Decay generator. The ‘Decay’ knob directly affects the vca knob.

Asteroid Mini Synthesizer Reference Manual.

*Mod VCA: to the right of the vca knob is an attenuated level for jack input ‘ModV’. Use this to add

more expternal control to the VCA.

*Lin small black knob: this is a linear fm input for the VCO. I set it up with a really strong range. To give

you more insight, the original value was 100k resistor, I installed a 1K resistor instead. What this mod

does is let you modulate the vco into hypersonic metallic sounds if the knob is turned fully clockwise. I

recommend when not in use to turn it back to ‘0’. At times it came fine move the pitch of the vco even

with nothing patched into the ‘Lin’ jack, that is normal behavior. Like mentioned just turn it to 0 when

not in use.

*Sub small black knob: this is the level for the internal subharmonic generator. It is mixing 2

subharmonic frequencies at once. It is best to use this when the vco is at medium or higher frequency.

*Boost small black knob: this is the internal booster circuit to give the VCA an overdrive overtone. This

circuit is not included when you use the output jack ‘SUM’. If you patch an external signal from another

module into the “Ext VCA” input jack the signal flow is: booster->vca->delay fx-> perc output, ¼” jack.

*Repeat and Time knob on the left: those are parameters for the delay fx. You will here no change if the

fx toggle switch is not engaged (set to FX), and the fx level knob is not turned clockwise.

*SYNC small black knob: This is variable sync circuit only found on the blue lantern triangle core design.

When not in use it is best to have this also set to zero, it is strong stuff. Use the ‘Sync’ input jack to

patch. Experiment with an external vco to create some bizarre synchronizations.

*MOD fm small black knob: this is an exponential 1v/per octave level in relation with the MOD input

jack.

*Toggle switch Triangle and Sine Waves: use this to select the vco output wave. You can also turn off the

triangle and sine wave from reaching the ‘Sum’ mixer when set in the middle position. The ‘Off’ can be

used for example when you only want to mix the Noise generator, square wave, or subharmonic square

waves.

*Pop knob: This is the internal striking spike hard wired to the vco. It creates a small punch sound when

turned clockwise. It is good for percussion sculpting.

*DEPTH + and – knob: this is a bipolar modulation knob for the internal vco. It is hardwired to the decay

knob. When it is in the + direction it will give the vco an impression of a kick or kraftwerk zap. When the

depth knob is used in the negative position it makes a wobble effect.

*Noise knob: this is the level knob for the internal noise generator. There is also a trimmer on the back

of the module near the bottom left. It determines the loudness of the noise generated. By default I set it

up low. If the 500k trimmer is set up too loud it can cause ‘bleed’ in the entire Asteroid Mini

Synthesizers output.

Asteroid Mini Synthesizer Reference Manual.

*HPWN and WN toggle switch: this toggle switch selects between ‘high pass white noise’ or ‘white

noise’. The difference is like bright and dark sound.

*Decay knob: this determines the length of the envelope generator. You will only here the effect of this

knob if you push the red button or have something patch into the trigger jack input. Use the top toggle

switch to setup the range.

*FX level knob, and the FX toggle switch: the FX level knob mixes in the wet fx signal with the dry signal.

The toggle switch will kill the fx.

*Noise and Square wave select toggle switch: this switch is in relation with the output jack right above it.

When Square wave is selected, you use the Square wave level knob to determine the ouput loudness of

the square wave. When you select the noise wave, it is outputting direct, meaning the noise level knob

does not effect the output level.

*Square wave use: this is not hard wired internally. If you want to use the square wave as a percussion

source you need to manually patch it into the ‘Mix’ input jack. You can also patch the square wave into

the PCV to create a saw wave.

Jack outputs and inputs

*PCV: this is the direct ‘PITCH CV’ input jack. Use these for 1v/octave control.

*MIX: this jack is used to mix an external signal with the internal vco, noise, and subharonic generator.

You can for example combine two Asteroid Mini Synthesizer modules, or a blue lantern TPC vco to

create a chord.

*RCV, TCV, LCV: these are cv inputs to control the delay fx parameters. Repeat CV, Time CV, Level CV.

*DRY and Perc output. Dry output does not have the delay fx in the chain. Perc output jack has the final

Delay FX in the chain. Both can be used simultaneous.

*1/4 Line level output jack: this also has the final delay fx in the chain.

Trigger input and thru jack

The Asteroid Mini Synthesizer is a percussive module. In order for the module to make such a snappy

response and return the pitch back to a reference point it must use a trigger input as oppose to using a

gate input. If it used a gate input as the internal circuit it would of remained high or low and the overall

perception would not have been the same (percussive). It would have been another mono synth.

What does this mean?

If you play a keyboard and use a midi to cv converter, for best playing style you are going to have to

trigger notes one at a time, not over lapping. If you are using another module like an LFO there is no

problem. The problem only lies when playing poly notes and they are over lapping.

Asteroid Mini Synthesizer Reference Manual.

The ‘thru’ jack will output the trigger that was inputted and can be used to trigger another module in

relation to using the onboard red push button.

Using the Asteroid Mini Synthesizer with an external filter module.

In order to process the sound generated inside the module with an analog filter use the ‘Sum’ jack

output. Patch that into a Blue Lantern Diode Operator Station VCF and then patch the output of that

back into the Asteroid Mini Synthesizer’s ‘EXT VCA’ input jack. This is similar to a send and return

configuration. You can also use the Asteroid Mini Synthesizers’ ENV output jack to control the cutoff.

Asteroid Mini Reference guide

Brand: Asteroid

Model: Mini

Type: Reference guide

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Asteroid Mini Reference guide

Asteroid Mini Reference guide

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