PC Player 1997 August

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AudioSim analogue synthesizer V1.90 --------------------------------------- AudioSim registers and usage...............................................I Oscillators...............................................................II Envelope generators......................................................III LFOs......................................................................IV Frequency modulation, mixing, synchronisation..............................V Multimode filter..........................................................VI Arpeggiator..............................................................VII Sequencer...............................................................VIII MIDI......................................................................IX Amplifier..................................................................X Menupoints................................................................XI Digital noises...........................................................XII Sample making...........................................................XIII Usage suggestions........................................................XIV Compatibility problems....................................................XV Known bugs...............................................................XVI AudioSim support........................................................XVII I. AudioSim registers and usage ---------------------------------------------------------------------------- AudioSim contains two oscillators, four envelope generators, two low-freq. oscillators and a self oscillating multimode filter. You can access the parameters of the different modules REAL-TIME via the graphical interface using your mouse. On/off switches are illustrated with LEDs which you can toggle on and off by clicking on them with the mouse pointer. Many parameters are represented with faders. You can adjust their value by holding the fader, and moving mouse up or down. There are knobs as well. Adjust them by holding down the mouse button, and moving the mouse left or right. We wanted to keep the structure of a classical analogue synthesizer, to make the usage of AudioSim clearer to those who have already used analogue styled synths before, and to show others what a real synthesizer looks like. See the programming of different modules in sections II. -> VIII. II. Oscillators ---------------------------------------------------------------------------- An oscillator generates a pure sound wave. Each oscillator in AudioSim is selectable between a sawtooth, pulse, noise or triangle wave. The first thing we have to do is to set which type of wave we want it to output by selecting the appropriate LED below the yellow graphics. We then have to adjust the envelope. This is how the volume of the wave changes over time. (see section III.) We can also detune the osciallator by using the TUNE and FINETUNE knobs. The TUNE knob has a range of two octaves. By turning KBDTRK off you can disconnect the oscillator from the keyboard so it always outputs the same tone no matter which key is pressed. This tone is specified using the TUNE and FINETUNE knobs (and the range of the TUNE knob changes to the whole frequency range that AudioSim can output). Using P. WIDTH you can change the impulse width of the pulse (square) wave. III. Envelope generators ---------------------------------------------------------------------------- The envelope generators are used to manipulate other parameters, for example the volume or pulse width of an oscillator or the filter. Their programming is based on the popular ADSR (Attack, Decay, Sustain, Release) method. (see diagram 1.) Lets say that we are programming the volume envelope of an oscillator. The attack parameter specifies how fast the note fades in (the lower the attack the faster the note fades in). The decay parameter then specifies how fast the volume falls until it reaches the level specified by the sustain parameter. When the key is released the sound fades out at the speed specified by the release parameter. Lets analyse the envelope of a piano. When the key is hit there is a loud bit at the beginning, then a quiter sustain and then it trails off. The loud bit at the beginning comes in quite fast, so the attack is set low. It then gets quiter quite fast so the decay is set quite low. It stays at a volume maybe half as loud as the initial volume, so the sustain is set to half, and then it decays quite slowly, so release is set quite high. III/B. Envelope generators ---------------------------------------------------------------------------- The gain parameter sets the maximum volume of the envelope. The generator envelope can be switched to control different parameters such as PWID1 (oscillator 1 pusle width), PWID2, FREQ1 (oscillator 1 frequency), FREQ2, FM MOD (frequency modulation), FLT RES (filter resonance). Some of the envelope generators are equipped with a sign control that allows you to vertically mirror the envelope. ____ / \ / \ / \_______________ / \ / \ / \ attack decay sustain release Diagram 1 - ADSR Envelope IV. LFOs ---------------------------------------------------------------------------- LFOs are oscillators that generate a wave at a low frequency which manipulates other parameters such as oscillator frequency (hence their full name - Low Frequency Oscillators). These oscillators have their own waveform SPEED (frequency) and RANGE (volume/amplitude). You can use the LEDs next to them to make them modulate the following parameters: 1: Oscillator 1 Frequency 2: Oscillator 2 Frequency P: Pulse width of both oscillators F: Filter Cutoff frequency X: The mixing of the two oscillators M: Frequency modulation The two LFOs are fully independent allowing them to be programmed seperately except that LFO2 has got the possibility to retrigger only when the key (on the keyboard) is pressed with maximum velocity. You can toggle this with the parameter T. V. Frequency modulation, mixing, synchronization ---------------------------------------------------------------------------- We have reached the mixing of the signals generated from the two oscillators. This is one of the main factors that shapes the sound of the output. AudioSim has the following 3 ways of connecting the oscillators: - Using the AMOUNT parameter you can set the frequency modulation amount. Frequency modulation is a very simple algorithm which modulates oscillator 2's frequency with the output of oscillator 1. The default value is 0. - Using the OSC1 MIX paramter you can mix the output of oscillator 1 with the output of oscillator 2 so you can hear them both. The default is full, so both oscillator 1 and 2 are output. - By turning SYNC (synchronization) on you can force oscillator 2 to retrigger when oscillator 1 is about to begin oscillating its period of the wave form. VI. Multimode filter (Lowpass, bandpass, highpass) ---------------------------------------------------------------------------- In AudioSim, there is a complex filtering architecture operating. The resulting cutoff steepness is 18dB/Octave. Usually, filters are used to reduce high frequencies made by different kind of modulations. This filter has got its own envelope generator which is connected to the cutoff frequency (with sign selection). Using the KBDTRK switch you can connect the cutoff frequency to the key that is pressed. This is used to so the filter can take into account the fact that deep notes and high notes consist of different frequencies. As the filter is resonant, it's possible to emphasize frequencies that are close to the cutoff frequency. You can alter the emphasis using the RESONANCE knob. High resonance with hard clippings enables you to get the TB303 type rave bass sound. You can select between lowpass, bandpass or highpass filter with LEDs. VII. Arpeggiator ---------------------------------------------------------------------------- The arpeggiator doesn't change the actual sound that AudioSim produces, but it is included because all decent analogue synths have one. As AudioSim can only produce one sound at a time (like most synthesizers), it is possible to play chords as an arpeggio, moving between the individual notes that make up the chord. Using the UP/DOWN switches you can select whether it moves up or down, using the SPEED you can choose the tempo and using the RANGE you can increase the range of the arpeggio to up to 4 octaves. Using the TOUCH switch you can tell the arpeggiator not to retrigger the notes. When using this make sure that they have a long decay time, and also don't forget, that the change of many parameters will be skipped. VIII. Sequencer ---------------------------------------------------------------------------- With the help of the sequencer you are able to make shorter sequences and loops, then sample those grooves into one sample. When the sequencer is used, the arpeggiator is switched off. With the TEMPO knob you can set the duration between the notes. By clicking on the sequencer area, you'll enter the sequence editor. In the first column, you can set the notes. Next to the notes are the velocity values, and the sliding parameters (pitch bend). Sliding values are -F to +F in hexadecimal. At the end of a pattern you have to set END or STOP (toggle with space). END means restart the pattern, STOP means stop the pattern. You should START/STOP playing your pattern with F1/F2. There is also a CUT command (on key '\'), which represents releasing the key. Other controls are similar to 'tracking' programs. IX. MIDI ---------------------------------------------------------------------------- As AudioSim is intended to generate wave files for further re-use, a MIDI keyboard is not necessary. However MIDI IN support has been provided which will allow you to use a MIDI keyboard to drive AudioSim. It will accept note messages and you can connect some paramteres to the MIDI modulation wheel and velocity. We don't suggest driving AudioSim with MIDI for Sound Blaster users. More information in chapter XIV/B from SB MIDI problems. XII. Amplifier ---------------------------------------------------------------------------- There is a small amplifier module which is used to amplify the output sound. It also has an LED meter and a MIDI activity display. The LED meter is useful to monitor how much of the 16bit range is used by the output. For optimal singal to noise ratio adjust the volume until the VU meter goes up to the last green/first red LED. Beware! Too much resonance on the filter can cause hard clipping! By using the CLIP parameter or by amplifying the sound to much you also can distort the sample, but CLIPPING causes extra Aliasing noises! XI/A. Menupoints ---------------------------------------------------------------------------- The menupoints can be found at the bottom of the screen, under the synth panel. You can choose between menus by clicking on them with the mouse. 'LOAD/SAVE SOUND' = Predefined instruments can be loaded, or self made sounds can be saved here in *.SND AudioSim File format. 'LOAD/SAVE BANK' = Predefined instrument banks can be loaded/saved here in *.BNK AudioSim File format. A soundbank includes the parameters of all the 99 instruments. 'RECORD WAVE' = Start sample recording. 'STOP RECORD' = Stop sample recording. 'PLAY DATA' = Playback the recorded sample. 'SAVE SAMPLE' = Save the recorded sample. (see more info on sample making in chapter XIII) XI/B. Menupoints ---------------------------------------------------------------------------- 'STORE SOUND' = Stores the finished sound in the memory. (Important to use to not loose an instrument while changing another.) The name of the sound can be changed by clicking on it. 'RESET KNOBS' = Sets the faders and switches to their default value. (Doesn't erase the name of the sound.) 'RESET SYNTH' = Resetting the synthesizer, in the case of any exciting. 'CREDITS' = The list of authors. 'QUIT SYNTH' = Back to DOS. (All menupoints are only available in the registered version!) XII. Digital noises ---------------------------------------------------------------------------- It is unavoidable to not mix some digital noise (while synthesizing) to the output voice. These digital noise are different to standard analog noise. In AudioSim most of digital noise is generated at the oscillator stage. This kind of digital noise is called Aliasing-noise, and this causes other (undesirable) bands to mix in to the sound. This is why AudioSim's oscillators are equipped with anti-aliasing filters. These filters are connected directly to the output of sawtooth and pulse oscillators, and dramatically reduces the volume of the Aliasing noise. The efficiency of Anti-aliasing should be selected by LEDs. You can choose between 32x, 16x or 8x filters. If you are using only a 8x Anti-aliasing filter, then a 486dx2/66 machine is far enough for the 44.1Khz sound. Use 16x for a 486dx2/80 or 32x for 486dx4/100 or better machines. WARNING! On slower machines it isn't suggested to set the anti-aliasing filter's speed to higher rates, because the program may crash (due to the inadequate performance of the processor). XIII. Sample making ---------------------------------------------------------------------------- You easily can sample any of your instrument. Choose 'RECORD WAVE', and press a key (trigger) on the keyboard for start recording. Now the program records all events (including tweeking) until you press the 'STOP RECORD'. With the 'PLAY WAVE' you can replay the captured data, with 'SAVE SAMPLE' you can save it to disk in *.WAV (Microsoft format), *.RAW (only the sample data) or *.IFF (Amiga soundfile) formats. AudioSim records and captures only 44.1Khz 16bit mono sounds. (AudioSim Demo doesn't feature the sample making option!) XIV. Usage suggestions ---------------------------------------------------------------------------- AudioSim (mainly) wasn't developed for windows based applications, but for DOS 'tracking' music. However, there is no limit in reusing output samples. You even can make patches (with patchmaker programs) and download the sounds into the memory of your soundcard, or using them like single effects, etc... Set your soundcard's bass and treble control to the middle as AudioSim does not need any tuning in the color of it's voice. The sounds of AudioSim are rich in all bands. Take care of your speakers, because AudioSim can damage them! We don't take the responsibility for any damage to your configuration, even don't take the responsibility of any damage to your sense of hearing! AudioSim's sounds are essential for making today's Techno-Acid-Rave styles. Mix them with Your existing samples, f.eg with strings, pads, etc... Simply OWN a unique analogue synthesizer!!! Use the keys of Your PC keyboard 'awsedftgyhujk..' to play AudioSim, keys '1-8' to select octave, and SPACE for cut voice. XV/A. Compatibility problems (Computer performance) ---------------------------------------------------------------------------- Unfortunately AudioSim has got some compatibility problems. We should first mention, that you will need at least a 486dx2/66 processor in your computer to run program. AudioSim uses its own synthesis algorithm, and not a kind of FM chip located on some soundcards. That's why we suggest a faster kind of machine for those who want to use AudioSim seriously. AudioSim isn't 100% compatible with any operation systems except for the MS-DOS, as other multitasking OS share the performance of the computer between whatever applications are loaded (including themselves). 'Virtual-analogue' modeling algorithms (as AudioSim uses) eat a lot of processor time. Hardware synthesizers use DSPs (Digital Signal Processors) to create the output, which are approximately 20/30 times faster for this operation than CPUs. Also AudioSim incorporates with lowest level BIOS routines and hardware ports/drivers which may cause it to be incompatible with multitasking operation systems, but makes it to be one of the most powerful software synthesizers. XV/B. Compatibility problems (Soundcards) ---------------------------------------------------------------------------- The AudioSim is compatible only with the Sound Blaster 16/32/AWE32/AWE64 (no clones or compatibles) and Gravis Ultrasound cards. Fully, working MIDI compatibility is available only on the Gravis Ultrasound cards, because the Sound Blaster family cannot support that kind of fast interrupting which AudioSim needs for continuous sound. It's now on average 20-24 times faster than an ordinary windows application, and may be even 64 times faster than a Hard Disk Recording/playback. In this case, MIDI interrupt is failing. The other problem is, that the MIDI interrupt line and the DMA (Device which forwards sound data to card) interrupt line is on the same on the Sound Blaster cards... However AudioSim enables to use MIDI with a Sound Blaster, we CAN NOT GUARANTEE THAT IT WILL WORK!!! Other way to forward data and get interrupt from the SB cards are also unstable, or incrementing 'dma-buffer' would cause AudioSim's reply time so long, that MIDI driving would loose its meaning. XVI. Known bugs ---------------------------------------------------------------------------- Because of we never met a bugfree program before, we don't feel ourselves ashamed for writing about AudioSim's bugs. It may happen, that some part of the graphics appear in different color than the original. It is beacuse some mouse driver may be incompatible with AudioSim's GUI, run program again and it will be ok. The keyboard buffer should overflow, and the PC speaker may beep awfully. Windows 95's mouse driver should leave rubbish on the screen. AudioSim could mess up the keyboard driver (ALT/CTRL/SHIFT flags). The program generates noise instead of analogic sound and does not work correctly anymore. This may be due to copy protection or by a virus. Registered users should have a backup and replace it, unregistered one may order it. XVII. AudioSim support ---------------------------------------------------------------------------- We hope that AudioSim will have a large amount of users in the next decade, so a lot of soundfiles (*.SND/*.BNK) will be available (of course for free) at our web-site and even at the users. Please send your soundfiles to us for appending to our bank. The new versions of AudioSim are also avaliable for free to registered users. Check our pages to keep you informed about everything related to AudioSim, such as technical documentation, tips and tricks, sounds, and more... Just send us a letter if you have got any question; Audio Simulation P.O.BOX 348 Budapest. 1616 Http://www.techno.org/audiosim/ HUNGARY E-mail:audiosim@techno.org