Welcome to the all new SimSynth 2.x! SimSynth is Copyright© 1999 by David Billen. All rights reserved.

The new SimSynth can load old presets, but they do not sound exactly the same. Here are some of the differences:

This is an overview of the controls on the SimSynth panel. Consult the online help window for a reference.

To program SimSynth 2.x, change settings to get the sound you want, and click "TEST" to hear it û or û click the "loop" switch next to "TEST". This causes the playback to loop continuously, and most settings are changed in real-time. A few, (such as TEMPO) are not real-time. Changing one of those while looping causes the sound to immediately remake and play over from the start.

After you have the sound you want, click "EXPORT" to create a .WAV file.

You can right-click any knob in order to set it in detail.

Select the "HELP" button above the envelope window. From there, you can get an online parameter reference to help you with settings that are unfamiliar. The following is just an introduction.

OSC SECTION

There are 3 oscillators. Each can be a triangle, sawtooth, pulse, noise, or pure sine.

The ADJ knob has a different effect depending on the shape. For a triangle, 50% is normal, adjusting towards 100% converts it gradually into a pure sine wave, and 1% is a triangle with sine added to it, (or not a sine wave). For sawtooths, ADJ works kind of stupid, and might get changed in a later version. Anything less than 50% is a reverse sawtooth. 50% or greater isa a normal sawtooth. For pulse, ADJ is pulse width just as in real analog synthesizers. ADJ has no affect on other shapes.

The amplitude at which the output from all three oscillators is sent to the filters is always the same. For this reason, the MIX knob works slightly different than some people expect. It is not a straightforward amplitude control for an oscillator. It controls the amplitude relative to the other oscillators. It controls the degree to which an oscillator is mixed into the output. For example, if there is only one oscillator that is "on", changing the MIX knob doesnÆt have any affect.

You can also select "+1", "+2", and "warm". +1 adds an octave. +2 adds a second octave. "Warm" adds a second frequency, which is detuned, (sharp). If the shape is "noise", +1, +2 make it whiter. "Warm" makes it very white.

If the shape is "sine", you can click the "Edità" button, and access a harmonic synthesizer. This is an array of 16 sliders that lets you set the harmonic ratios for the first 16 harmonics of the tone. There are only about zero people on the planet that are handy with harmonic synthesis, so itÆs doubtful that youÆre included. Just mess with the sliders and you will catch on quickly to what theyÆre doing.

The rest of the settings are familiar to people who have programmed an analog synthesizer. "FRQ" sets the relative frequency in cents, (1/100 of a semitone). "LFO" and "ENV" adjust the amount that the LFO and envelope modulate the oscillator frequency respectively. (If the OSC envelope is on it is used. Otherwise the AMP envelope is used).

LFO SECTION

This section lets you program the LFO (Low Frequency Oscillator). LFOÆs havenÆt been in a lot of synthesizers since the æ80Æs, so; a lot of people arenÆt familiar with them. An LFO is simply a really slow oscillator that can be used to modulate normal (fast) oscillators or the filter cutoff level.

The shape buttons work exactly as in the OSC SECTION described in the oscillator section overview.

The "Rate" button sets the rate for one cycle in CLOCKS.

The "Noise ramp" switch causes noise shape to glide from one random value to another. The default is to use "sample and hold", which means that the LFO just instantly changes to a random value every cycle.

SVF SECTION

SVF stands for "State Variable Filter". That is a type of filter that was used on many Oberheim synthesizers. ItÆs most distinguishing characteristic is itÆs soft slope, (i.e. itÆs low pass output lets a lot of high frequencies bust past it). Also, it produces low pass, band pass, and high pass all at the same time. You can select the mix of each type of output you want with the LP, BP, and HP knobs.

The "x2" switch makes the (characteristically soft) SVF filter twice as hard.

The "1.x style" switch causes the filter to be compatible with SimSynth 1.x versions. A sine function is applied to the filter output when any amount of "preamp" is used. This was a cheap way for SimSynth 1.x to deal with clipping, and is available for 1.x compatibility, (and because it can have a cool effect on some presets). Also when "1.x style" is selected, the filter response is different than normal, especially when using EMPH, BP, and/or LP.

The "post" switch adds a little low pass filtering after the normal filtering. This can be useful if you want to use mostly highpass but donÆt want the very top frequencies, or to clean up some noise produced by the filters or something.

The "preamp" knob boosts the level of the oscillators before feeding it into the filters. This is mostly used to better simulate a MiniMoog, which would overdrive its filters with three fat oscillators. You can also use it to compensate for phase cancellation in the oscillators, (when "detune" and other oscillators cancel each other out and they get quiet). Once in a while, depending on what youÆre doing, itÆs kind of cool to crank it for an intentionally distorted sound.

OUT, LP, BP, and HP make up a little mixer for the filter output. OUT is like a master for LP, BP, and HP. This type of filter (SVF) produces low-pass, band-pass and high-pass output all at the same time using the same cutoff. You can adjust LP, BP, and HP to get the amount of output you want of each. Normally, you would have only one of the three set to anything other than zero, depending on which type of filter you want. Some uses for mixing and matching the levels are:

EFX SECTION

The EFX consist of a delay, a "modulator", (choruser/flange), and optional band pass or notch EQ.

The MIX knob sets how much "dry" or "wet" output is in the sound, ("dry" means unprocessed and wet means the output from the EFX). The SEP knob determines the amount of stereo separation between dry and wet. All the way down is mono. All the way up pans the dry mix completely to the left, and the wet mix completely to the right.

The DELAY knob sets the amount of delay in clocks; (there are 500 clocks per beat). The RATE knob sets the choruser rate in clocks per cycle, and is also used to control the FMOD rate described later.

The BEND knob controls the amount that the sound is "bent", which means modulated in pitch up and down at a speed determined by the RATE knob. (Combining this with the dry and some delay produces a chorusing effect. Tiny amounts of delay and BEND produce more of a flanging effect).

REFEED controls how much of the effect signal is mixed back into itself every DELAY period.

BAND controls the amount if any that the EFX are passed through a bandwidth filter. FRQ is the frequency of the filter, and Q is tightness of the filter, (same as EMPH in the filters). FMOD stands for "frequency modulation", and controls the amount that the FRQ level is modulated up and down at a speed determined by the RATE setting times 8. The NOTCH switch inverts the whole thing and makes it a notch filter instead of a bandpass filter.

The PING-PONG switch causes the dry output to center, and the wet output to shift from left to right stereo at the DELAY rate. Note that the amount of shift is still controlled by the SEP knob. BOUNCE causes both wet and dry to fade from left to right under control of the RATE setting. The maximum pan for each is still controlled by the SEP knob.

INVERT inverts the wet signal before mixing it with the dry signal. This can be used to help reduce phase cancellation caused by some settings. Put in less technical terms: If the EFX settings seem to cause the sound to lose substance, especially in the low end, the INVERT switch might fix it.

ENVELOPES

There are three envelopes, AMP, OSC, and FILT, which control the amplitude, the oscillators, and the SVF filter respectively. The OSC and FILT envelopes can be turned off and on with the power switch above the envelope window. If either of them is off, it tracks the AMP envelope. For example, if you turn off the OSC envelope, yet add some ENV value to an oscillator in the OSC section, the AMP envelope controls it. If you turn the OSC envelope back on, control of the oscillator is transferred to it.

The envelopes are graphic edited. They appear as lines in the envelope window with little red squares on the points where they change direction or slope. To edit an envelope, either drag a handle to a new position with the left mouse button, or click at some point where there is not a handle in order to create one. To delete a handle, drag it right on top of another.

The VIEW knob located to the right of the envelope window changes the view size. This is useful for zooming in on an attack or for changing the size of an envelope when used together with the FIT button, (which is located beneath the envelope window). The FIT button scales the envelope to exactly fit the window.

The GRID knob located to the right of the envelope window changes the grid size. The grid can be seen as vertical bars in the envelope window. The grid can be used to perfectly align envelope handles to a specific clock value, when used with the SNAP button. The SNAP button aligns all handles on the envelope in the envelope window with the grid.

RIFFS

SimSynth includes a step sequencer, which allows you to create short riffs. Riffs are useful for testing a sound or for creating short techno or bass-line sequences for export to other audio apps.

In general, left click anything in the riff window to turn it on. Right click to turn it off.

Turning on an accent causes the note to be played with a filter level boosted by the amount shown in the red SVF slider at the right. (You can adjust that too by just clicking in it). The note is also played with its amplitude boosted by the amount shown in the red AMP slider at the right.

Left click a note to turn it on, and drag the mouse up and down to change it. After clicking a note, the border around it changes color to show that it is now the "current note". You can also change the current note value by clicking in the little orange keyboard near the OUTPUT section.

Left click a slide position once. It becomes yellow, and the next note will not cause the envelopes to trigger. Left click it again. It becomes green, and the next note will not cause the envelopes to trigger û plus û the pitch will glide from the selected note to the next.

Clicking a sequence number lets you edit that sequence, (or bar). Sequences that have notes in them are hilighted. The full length of the riff is always an even number of bars, starting with the first, and ending with the last bar that has any notes in it.

From the keyboard, you can clear a bar by pressing "C", or copy the previous bar by pressing "P". You can transpose it up by pressing æUÆ, or down by pressing æDÆ. You can shift it left by pressing æ<Æ, and right by pressing æ>Æ.

The orange tracking switches allow you to select whether or not the oscillators, filter envelopes, or amp envelopes play along with the riff. If an oscillator tracks, it plays the notes in the riff; otherwise it always plays the same note, (using the BASE FRQ value). If an envelope tracks, it starts over when a note in the riff is played, otherwise, it repeats in a loop without regard to whatÆs playing in the riff.

The responsiveness of SimSynth to MIDI input, (latency), depends on the buffer size in the OUTPUT OPTIONS. The lower the setting, the more responsive SimSynth is. You should set it as low as possible without hearing pops. Pops are not present when writing a wave file, and neither is the latency. These are only side-effects which may be experienced during realtime playing and recording.

MIDI is active, (and the MIDI device is open), only when the MIDI window is "ON". When SimSynth is started, the MIDI window is always off. (This is to prevent SimSynth from failing to start when there are problems with the selected MIDI input device).

You can play SimSynth with a MIDI controller. You can record what you play, play it back, and then render the recording to a wave file when satisfied. You can also convert a recording into a RIFF.

The sustain level for a note is determined by the second to the last envelope point, (which has "sus" next to it in tiny letters).

Many presets which work nicely with riffs do not work very well when played via MIDI. You may need to adjust the envelope in order to correct it. You may also need to lower the filter CUTOFF level, if you intend to use velocity over filter, (see below).

In the MIDI window, click switches to toggle them on and off. Left click "spinners", (things that have the little up/down arrow next to them), and drag up and down to change them, (like a knob). Clicking a mod target rotates through the available options.

If you convert a sequence to riff, then you are amazingly skilled if you can get the timing right and some of the notes are not in the wrong slot. There is a feature in the RIFF window where you can drag notes in the riff right and left. You can often use that to fix it.

After you mess up a preset with controllers, you can click MAKE/SYNC to straighten it out.

Here are the controls in the MIDI window and a description of what each one does.

SimSynth is based on an instrument called an analog synthesizer. Analog synthesizers date from a time when there were no personal digital computers. The name comes from the use of vibrating electronic circuits to simulate the vibration of sound waves.

While it was virtually impossible to store recordings of acoustic instruments, it was easy to build circuits that produced simple repeating waves. Three different waves were chosen for their harmonic content.

These waves allowed a sound design approach called "subtractive synthesis". You start with a lot of harmonics and then get rid of the ones you don't want. (Of course if you have a way of controlling the harmonics generated and adding them together you have "additive synthesis"- which was done in a very primitive way with the drawbars on the Hammond Organ.)

The way you get rid of harmonics is by using a filter. A low pass filter passes all of the signal below it's frequency setting. A high pass filter passes all of the signal above it's frequency setting, and a band pass filter passes only the part of the signal that is within the band. The width of the band is called "Q" or "Resonance". The higher this number, the more narrow the pass band. The filter becomes "sharper". There is an opposite filter called a "band reject" or "notch" filter. It passes everything except for the selected band.

These electronic circuits had been around for a long time, but they required manual control - somebody had to move a knob for each of the controls. A revolution occurred when Bob Moog built an instrument that used a voltage to change the setting of a control. It meant that it was possible to control several controls at one time. This instrument had two other innovations. One was a "Voltage Controlled Amplifier" (VCA) and the other was an "Envelope Generator".

When you pluck the string on a guitar, the sound starts up instantly and then fades down to zero. If you were to draw a chart of the volume of the string starting some time before you plucked it, and going until the string faded away, you would have a graph of the "envelope" of the sound. An envelope generator is an electronic circuit that allows you to create an envelope for a sound. The VCA takes the output from an envelope generator and uses it to control how loud a sound is in time.

You can also use an envelope generator to control the harmonic content over time if you use a "voltage controlled filter" (VCF).

When you look at an analog synthesizer, you can separate the parts into three types: signal sources, modifiers, and controllers.

Signal Sources:

In the OSC section are the signal sources for the SimSynth. Each Oscillator has the waveforms for subtractive synthesis, Triangle, Sawtooth, Pulse, Sine as well as a noise generator. There is also an Edit button that allows you to create a waveform with very specific harmonics.

Modifiers:

For control and modification of harmonics you have an SVF (State Variable Filter). On SimSynth this combines a couple of design ideas from two famous synthesizers. It gives you all four types of filter, LP (Low Pass), BP (Band Pass), HP (High Pass), and by turning up both LP & HP you have a Notch filter (Band Reject). The SimSynth SVF also gives you a PRE control which allows you to overdrive (distort) the filter, think of it as another way of changing the harmonics.

There is also a way of modifying the signal amplitude just like a VCA on an analog synth. It is how you get notes to start and stop. If you press the Amp button in the ENV section, you will see the envelope generator for this function. Since all it does is control the loudness of the signal in response to a control signal from an envelope generator, there are no other knobs and buttons associated with this function.

Controllers:

For controllers, you have three envelope generators, an LFO (Low Frequency Oscillator), and a sequencer. As mentioned in Modifiers, the first envelope generator controls the Amplitude of the note. This is how loud it is at each point in time. The second envelope generator controls the SVF. The third envelope generator can be used to modulate the frequency of an oscillator, including the LFO.

The LFO is another oscillator, but one whose frequency is below what we hear as a tone. It can be used to add vibrato to a sound by modulating the pitch of an oscillator. It can also be used for tremolo effects by modulating the SVF. The LFO can be controlled in turn by envelope generator 3 (the OSC ENV Generator).

To create a patch on SimSynth, break the sound down into the three types and start building.

First, what kind of amplitude envelope do you need. Ask yourself questions about the envelope. Does the sound start instantly like a struck drum or a plucked string? Or does it happen a bit slower, like a woodwind instrument? Or is it very slow, like a synthesizer fading in from zero over several seconds? Does it stay at the same volume until it is time for the note to stop? Or does it start to decay at once?

Next think about how the sound evolves in time. Does it start very bright, a lot of harmonics, and become dull over time? This will help you decide which filter type to use and how to set the envelope generator controlling the SVF.

Finally figure out the raw source material you need. If it is a pitched sound, then use the waveforms on the oscillators. If the sound is un-pitched, then use the Noise generators. And above all: Register SimSynth so you can save your presets and work on refining your patches!