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Preamp Detector (PRNV)
The new Serge preamps and envelope detectors provide an exceptionally responsive link between external audio signals and the Serge synthesizer modules. The key to this responsivity comes from the fact that our detector was designed to respond to the POWER rather than to the AMPLITUDE of a sound. No other synthesizer system offers this sophisticated capability. Human perception of loudness is proportional to the POWER content of a wave, rather than to its AMPLITUDE. Detecting the AMPLITUDE of a signal produces an inaccurate envelope, sometimes too soft, and most of the time too loud. The new Serge detectors are exceptionally accurate, responsive devices which output a control voltage envelope that is directly proportional to the perceived loudness of an input signal. It operates over a very wide dynamic range, in excess of 70 db (or the difference between a whisper and a subway train at 15 feet!). The output is accurately log-linear at 12.5 dB per volt, a taper which mates perfectly with the control characteristics of our newest VCAs. Thus it is possible, for example, to control the loudness of a synthesizer sound by the sound envelope of a locomotive, a dog barking, or a voice going from a whisper to a shout. The effect is especially remarkable [since] because of the accuracy of the responses, the whisper is really a whisper, and the shout a shout.

The PREAMP DETECTOR (PRNV) allies a Serge detector with a multi-purpose preamp suitable for a wide variety of inputs. The HI-Z input accepts transducers such as guitar pick-ups and contact microphones. It is also suited for amplifying low level signals from tape machines, tuners, etc. Detector and Preamp can be switched to work separately or coupled. Sensitivity for the various microphones and audio sources can be adjusted over a very wide range using the Preamp's gain control. Please note that it will not cut the gain to zero, however.

Precision Oscillator (PCO)
The Precision VCO is a versatile, voltage controlled oscillator offering three high quality waveform outputs (sine, triangle, and sawtooth) and both linear and exponential frequency modulation capabilities. A front panel switch conveniently extends the range of the PCO from the audio range (16 to 16,000 Hz) to a sub-audio range (.1 to 200 Hz) for use as a Low Frequency Oscillator.
  • EXCELLENT RESPONSE, TRACKING AND STABILITY - Featuring the identical exponential response, exceptional tracking characteristics, and perfect temperature stability as the NTO, the PCO is especially suited for use with the NTO as a modulation source for dynamic depth linear FM. 
  • MANY FEATURES - Two calibrated one volt per octave inputs as well as a variable processing input are provided for complex frequency control. FM depth can be varied with the front panel adjustment. All output levels are "hot", greater than +4 db to insure maximum signal to noise ratio when used with subsequent processing. A Sync input is also available for locking the PCO to another oscillator's fundamental, harmonic, or sub-harmonic frequency. 

Ring Modulator (RING)
Our new RING MODULATOR (RING) is a brand new design which incorporates greatly improved specifications. Features include the following:
  • A VERY CLEAN SOUND down to very low signal levels (unlike conventional modulators where distortion increases at low levels). 
  • 80 DDS OF CARRIER SIGNAL REJECTION. 
  • INAUDIBLE NOISE OUTPUT. 
  • NO SQUELCH CIRCUIT IS REQUIRED due to the low noise characteristics, therefore annoying signal dropouts and “pumping” effects are totally absent. 
  • INTERNAL WAVESHAPING OF CARRIER to add to modulation effects 
The sum total of these design improvements is a Ring Modulator capable of treating the most subtle acoustical signals, without the coloration typically associated with even the best previously available ring modulators. The versatility of the Serge Ring Modulator is enhanced by the added feature of voltage and manual control of the entire spectrum of modulation possible: from zero modulation (i.e. the original, untreated input signal) through amplitude modulation to full ring modulation. This allows many shadings of effect, manual or automatic with voltage controls. The ability to control the Carrier level manually and through voltage control allows the output to be level controlled as well. Through the use of an internal signal processor for the Carrier, additional effects can be produced by waveform modification of the carrier signal. When the module is set to full Ring Modulation from the lower knob or voltage control the output signal contains the sum and difference frequencies of the Signal Input and the Carrier Input. If both signals are pure sine waves (only one frequency component), the output will be a composite signal consisting of two frequency components: the sum and the difference frequency of the Signal and Carrier. If the Carrier level is increased beyond the mid-position, then the carrier waveform will become slightly rounded, and new frequency components will be produced. Each of these new components will also modulate with the Signal input to produce a sum and difference frequency, and the output signal will become richer in harmonics. This effect is unique to the Serge Ring Modulator, and allows another dimension in timbral modification. Although this module may be one of the most sophisticated in the SERGE system, it only takes up one inch of Panel space. (Recommended as companion modules placed near the RING MODULATOR are the various Preamps and VC Oscillators.)

÷ N Comparator (NCOM)
The ÷ N COMPARATOR (NCOM) consists of two sections: a comparator and a voltage-controlled pulse divider. The divider section outputs a pulse once every “N” comparator pulse, where “N” is a number from 1 to 31, settable with a control voltage at the divider's VC input (or manually via the divider's control knob). Additionally, the Divider outputs a staircase wave with “N” steps. This will produce whole-tone steps when plugged into the 1 V/Oct input of a VCO.

This module has two distinct areas of use (in addition to the normal functions of the comparator):
  • For audio frequencies, the divider can be set to output sub-divided frequencies with digital precision. Output frequency depends on “N”. If “N”=2,3,4, etc., the output frequencies will be an octave, an octave and a fifth, or two octaves below the input, respectively. Because “N” is voltage controllable, arpeggios and various melodies can easily be programmed. The nature of this type of division (integer division) results in frequencies that fall along the sub-harmonic series, a series that has great tonal charm. 
  • For sub-audio frequencies, the divider acts like a counter, outputting a pulse only after “N” number of input pulses. Input pulses can be fairly random, or regular. This capability is especially powerful for determining tempos and rhythmic patterns when using several sequencers (especially if the “N” VC input is taken from one of a sequencer's rows of controls). In a more random situation, using a microphone preamp/detector as input, the divider might be set to count how many times a sound of a certain loudness will have occurred, and be set to trigger an event upon reaching the count. Since the count can be made variable (from 1 to 31), fairly complex and subtle interactions can be generated. 

Wave Multipliers (VCM)
For generating and modifying sound, the typical synthesizer patch is VCO-VCF-VCA, linked in series, with suitable control from keyboard, sequencer, or computer. The VCO generates the raw sound, the VCF dynamically varies the timbre (sound quality). and the VCA controls the amplitude and produces the envelope on the sound event. The Serge Modular WAVE MULTIPLIERS (VCM) provide a new link in this chain, representing an advance in synthesizer technology. In this typical patch, the Wave Multiplier could be placed just before the VCF. Like the VCF. the Wave Multiplier affects the timbre. Unlike the VCF, whose action is a subtractive process of filtering frequencies from the input waveform, the Wave Multipliers are able to dynamically process the input waveform to produce new harmonically-related overtones. This function should not be confused with Ring Modulation, since it is a non-linear process using a single audio input. Although it is possible to describe the effect of a VCF by saying the sound gets “bass-heavy”, makes a “wah-wah” effect, or sounds “thin”, describing the sound of a Wave Multiplier is much more difficult. The input sound comes out richer in harmonics, somewhat similar to pulse-width modulation and to linear frequency modulation, but with a new characteristic timbre. The nearest we can come to describing the unique sound qualities (there are three different sections) is to say that they alter the timbre in exciting new ways, producing interesting alternative forms of signal processing which are unique in the Serge Modular Music System. Since there are three entirely separate and different types of Wave Multipliers in this module, an enormously varied palette of new effects can be synthesized.
  • The uppermost section is the simplest of the three multiplier sections. but it has two switchable effects. With the switch set at the “HI” position, the module functions to “square-up” an incoming signal. This is not the same as a simple comparator squaring function, though, since there is a rounded flattening of the signal peaks: an effect somewhat similar to overdriving a tube amplifier (except that in this version the process is voltage controllable!). With the switch in the “LO” position, the module is a linear gain controlled VCA. This is useful for various functions such as amplitude modulation and for gating signals into the other sections. 
  • The middle Wave Multiplier provides a sweep of the odd harmonics (1,3,5,7,9,11, and 13th) when a sine wave is applied to its input and the knob is turned up or a control voltage is swept from low to high. This effect is similar to overblowing a wind pipe closed at one end, and thus the module can be used to produce the sounds of various wind instruments. A second input is included to allow two signals to be mixed before processing, a technique that we have found to be very usable. This module can be used to explore timbral areas beyond the range of ring modulation because there are more varied harmonics than the sum and difference tones. 
  • The bottom Wave Multiplier performs non-linear wavehaping known as full-wave rectification, but with sophisticated level-compensating conditioning as well. Actually the circuit uses three full-wave rectifier sections linked in a very refined controllable format. Each section can double the frequency of a sine or triangle wave applied to its input. Thus sweeping the VC input over its range will produce a smooth timbral transition using the even harmonics (second, fourth, and eighth). Many other partials are present in this basic sound, however, and the sonorities are very rich and varied. A notable feature of this multiplier is that the full-wave rectification is not accompanied by a reduction in the output amplitude. There is no alteration of the essential level of the sound. There are two inputs to provide mixing before processing, and two outputs. One output is a “squared up” version of the other. This output resembles voltage controlled pulse width modulation (only much more interesting). 

The Wave Multipliers are among the most powerful timbral modifiers available on any analog music synthesizer. The rich varieties of inter-patch possibilities are nearly inexhaustible, and these possibilities combined with the flexibility of other Serge modules will provide unique synthesis tools for the person who is eager to experiment with entirely new classes of sounds. The Wave Multipliers provide what has too often been lacking in electric musics: a means of generating sounds as complex and dynamically variable as those found in acoustic sound sources. Yet these are also precision modules which respond accurately to control voltages, so they may be used to give repeatable results in the most exacting analog or digital applications.

Triple Waveshaper (TWS)
The TRIPLE WAVESHAPER (TWS) is a non-linear modifier which can transform a sawtooth wave into a sine wave. This module incorporates three independent waveshapers for modifying synthesizer waveforms or for processing signals from preamplified instruments. Although originally designed as a waveshaper for our early oscillators, this module has been found to be an excellent modifier of electronic and acoustic sounds, and is highly recommended for subtle timbral modifications beyond the range of simple oscillator/filter patches.

Variable Bandwidth VC Filter (VCF2)
The VARIABLE BANDWIDTH FILTER (VCF2) has a band-pass output which can be varied manually or with voltage control. This is a standard response synthesizer VCF, typical to filters used in many studio systems. In the VCF2, two state-variable VCF's are connected in series to produce a total of five outputs. High pass, low pass, two fixed bandwidth outputs, and one variable bandwidth output are available. The outputs are all flat-response (no resonance) so the VCF2 is suitable for processing concrete sounds without introducing resonant coloration to the timbres. Under voltage or manual control, cut-off frequency of the high and low-pass outputs are affected, as well as the center frequency of the two band-pass outputs. Both center frequency and bandwidth are independently controllable on the variable bandwidth output.

Dual Audio Mixer w/ phase switch (2-3x1) (MIX2)
The Serge Dual Audio Mixer (MIX2) contains two independent mixers for audio signals. [Each section has three inputs with level control knobs]. [The top section is a three-in/one-out manual mixer with a phase switch on input 3]. [The bottom] section is a four-in/one-out manual mixer [with an additional] unity gain (non-attenuated) input. The main output of one section can be connected to the unity gain input of the other section to create larger mixing units. This module can be used as two audio mixers with three variable inputs, or as one mixer with six variable inputs. Used in combination with other mixers and VCA modules, various mixing functions can be patched.

Cross-Fader (XFAD)
The CROSS-FADER (XFAD) is an equal-power cross fade unit. The module has two signal inputs. As one signal increases in level at the output under manual or voltage control, the other signal decreases in level at the output. This effect is used to accurately fade one sound in while fading another out. Cross-fading with voltage control permits a smooth transformation between two different timbres. If a sound and its reverberated image (available with the Wilson Analog Delay) are sent through the cross-fader, the reverb mix can be voltage controlled. This effect can be used to modify the spatial characteristics of a sound event, from immediate presence to distant ambience. In addition to the cross-fade function, a VCA controls the output amplitude.

Dual Channel Stereo Mixer (2x2) (DCSM)
The DUAL CHANNEL STEREO MIXER (DCSM) is an alternative output VCA/MIXER/PANNER for two and three-panel systems. The other choice for small systems is the UNIVERSAL AUDIO PROCESSOR (UAP). The UAP can be used for a number of voltage controlled mixing functions, but the DUAL CHANNEL STEREO MIXER is used for the standard output level control (or enveloping) and for voltage controlled panning. The DCSM has two independent channels for stereo panning, whereas the UAP can pan only a single channel when used as a stereo panner. Each channel in the DCSM has two VC inputs, one for amplitude control and one for panning. The panning controls are opposite for the two channels, so that if a single control voltage is used, the output signals will pan in opposite directions. Auxiliary inputs are used to mix other signals into the outputs of the module. Signals applied here will not be affected by knobs or control voltages applied to the module. These are mainly useful for linking other mixers (either manual or voltage controlled) to the output bus. The output is available at a pair of banana jacks (for routing the signals to other modules within the synthesizer), and at mini-jacks (for connecting to external amplifiers, tape decks, and other equipment).

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