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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. 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.

[The PRNV includes the following mod for this panel:

"There is an on-board Comparator with a variable 'Threshold' control, now included in the Preamp with the input available to any audio signal OR CV control signal for creating gates, triggers or square wave signals from any source in the system."]

New Timbral Oscillator (NTO)

The Serge Modular Systems NEW TIMBRAL OSCILLATOR (NTO) is the state-of-the-art VCO, featuring exceptional range, superb temperature stability, and accurate tracking. Dynamic depth frequency modulation and voltage control of waveform allow unprecedented control over a wide range of sound qualities.

• EXPONENTIAL 1 VOLT/OCTAVE RESPONSE - Exponential response parallels the response of human hearing perception as well as musical pitch structure. With multiple oscillators, each must respond exponentially to control voltages to allow transposition from key to key and to produce alternative equal-tempered tunings such as quarter and third tones. In addition, the one-volt-per-octave response assures that the New Timbral Oscillator is compatible with most keyboard and computer controllers. 
• ACCURATE TRACKING - When two or more oscillators are tuned, it is expected that they will remain in tune throughout their entire range (in other words, that they track). Even two oscillators which track within a fraction of a semitone will be out of tune at the extremities of their range. Therefore, the New Timbral Oscillators have been designed so that any two will track within one cycle/second throughout their entire musical range. 
• TEMPERATURE STABILITY - Instability of pitch with changes in temperature is the criticism of most synthesizer VCO's. Performers are aware of the disastrous effects of temperature when they must desperately retune oscillators that have drifted during a live performance. The temperature sensitive components are kept at an even 120 degrees by a solid-state "oven". Thus temperature stability is guaranteed from 50 degrees to 100 degrees F. 
• WIDE FREQUENCY RANGE - The frequency range covers from below 16 to 16Khz. With control voltages, the range can be further extended from less than .1 Hz (10 sec/cycle) to greater than 100,000 Hz. 
• VARIETY OF WAVEFORM OUTPUTS - In addition to three standard waveforms (sine, triangle and sawtooth) of exceptional purity, the New Timbral Oscillator offers a variable waveform output providing an amazingly varied range of sounds, unavailable on any other synthesizer. This waveform is voltage controllable, allowing dynamic control of sound quality. 
• DYNAMIC DEPTH LINEAR FREQUENCY MODULATION - Dynamic depth frequency modulation is now available to the analog synthesist. Frequency modulation (FM), the modulation of one oscillator by another, generates both harmonic overtones (found in most acoustic instrument sounds) and non-harmonic overtones (bells, percussive, and electronic timbres). By varying the amplitude of the modulating oscillator, the richness or complexity of the sound can be varied. However, with conventional FM, an annoying pitch shift occurs. With the New Timbral Oscillator, Linear FM avoids this pitch shift, making it possible to maintain accurate pitch control while changing the quality of sound. A built-in VCA assures accuracy and provides dynamic voltage control of Linear FM Depth. Of course, conventional exponential FM is also available on the New Timbral Oscillator. The New Timbral Oscillator offers two voltage control inputs calibrated to one volt per octave and one variable voltage control input. One of the calibrated inputs incorporates a variable Portamento. This allows gliding from pitch to pitch at a voltage-controllable rate, set at each oscillator rather than from the controller (such as a keyboard), and therefore independently variable at each New Timbral Oscillator. All of the output levels are "hot", greater than +4 db to ensure maximum signal-to-noise ratio. A Sync input is provided for locking the NTO to another oscillator's fundamental, harmonic, or sub-harmonic frequency. 

[The NTO includes the following mod for this panel:

"The NTO has a 'HI -LO' frequency range switch allowing a powerful set of vari-waveform outputs, featuring voltage control of both exponential and linear frequency modulation, operating as a stable complex LFO or as the typical NTO."]

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.

Audio Mixer w/ phase switch (3x1) (AMX)
[The Audio Mixer is a three-in/one-out manual mixer with a phase switch on input 3].

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.

Wilson Analog Delay (WAD)
The Wilson Analog Delay was specifically designed to allow internal functions such as filtering, feedback, and delay to be determined by the user as a patch programmable function. Features of the Wilson Analog Delay include the following:

• VOLTAGE VARIABLE DELAY OVER A VERY WIDE RANGE, from a minimum of .0005 sec. to greater than one half second ** 
• VOLTAGE CONTROLLED PROGRAMMING OF THE FILTERS WHICH CONDITION THE INPUT AND OUTPUT SIGNALS. 
• Availability of the TWO DELAYED OUTPUTS (A & B), one which is twice the delay of the other. 
• A FLANGING OUTPUT with a control to set its depth 
• A 1 VOLT PER OCTAVE (V/OCT) OUTPUT to permit controlling external VC filters easily. 
• THREE INPUTS, each with its own gain control and specific function. IN-1 is the main audio input for internal or external signals. IN-2 is suitable for audio, but also for the input of control voltages to be delayed. IN-3 is connected via a switch to provide feedback selectively from either the "A" or "B" delay outputs, or from the AUX jack. This channel features a processing-type control to scale and invert either the feedback from "A" or "B" or the AUX signal. 
• An INNOVATIVE NOISE-CANCELLATION CIRCUIT which produces a very clean sound, as opposed to the "muffled" quality of more conventional analog delays. 

These features provide an amazingly varied palette of effects. Here are some of the possible ways to use this module:

• VC FLANGER 
• "GLIDING" FREQUENCY SHIFT effects (the frequency shift effect is never steady, but is a function of envelopes varying the delay rate). 
• STRAIGHT DELAY (perceived as fast repeats as in the delay between two tape recorder heads). 
• ECHO CHAMBER EFFECTS, where the delayed signal is fed back into the Analog Delay's input. (The switchable AUX input is particularly valuable for this type effect, especially if an external VCA is inserted into the feedback loop, allowing voltage control of the number of echoes as well as their rate of occurrence). 
• CHORUS EFFECTS 
• VIBRATO EFFECTS 
• DELAY AND ECHO OF CONTROL VOLTAGE ENVELOPES (via IN-2). Though the maximum guaranteed delay is .5 second, in practice the delay will go to more than 5 seconds for low frequency signals such as control voltages. 
• MODULATION EFFECTS resulting from the modulation of the input signal by the clock internal to the Analog Delay. 

** The first question often asked about the Analog Delay is how long a delay can it do? The answer to this question is fairly complex. Quite a long delay can be performed by the module. However, as delay becomes longer, the bandwidth of the signal which can be processed by the Analog Delay becomes more restricted. As an example, if it is desired to delay a signal consisting of a sine wave at 440 Hz (concert "A"), then better than a half second can be gotten quite cleanly. The same note with a lot of harmonics, say a square wave at 440 Hz, if delayed at a half second, will produce a very modulated output (if the Analog Delay's built-in filters are opened wide) full of extraneous signals, or will lose its overtones because the filters will remove them. (This is why many other delay modules have a dulling effect at long delays). The moral to this story is that one function which the Wilson Analog Delay will not do, is to reproduce the full effects of tape delay (i.e. "echo-plexing") without appreciably changing the signal being delayed. But tape delay is a stock effect, usually available to most synthesists (but which can be used with other voltage-controlled functions such as filtering, phasing, frequency shifting, etc., for more sophisticated effects). The forte of this module is its ability to transform signals and control voltages in an incredible number of ways.

Dual Universal Slope Generator (DSG)
The DUAL UNIVERSAL SLOPE Generator (DSG) is the ultimate patch-programmable control voltage generator in the Serge system. At least one (DSG) is recommended for almost every Serge system. and in most cases, a number of these are desirable. People familiar with our previous series of “slewing” modules know about the importance of this kind of function in a large patchable synthesizer system. For those unfamiliar, it is advised that the various applications as outlined here and in the Serge Owner's Manual are studied. The uses of this module are numerous, some duplicating functions found on other synthesizers, some totally unique to the Serge system. Most systems require a number of control voltage generators to control the various signal processors and modifiers. Sources of trigger, pulses (clocks), control voltage processors (portamento's), regular repeating voltages (LFO's) are standard synthesizer requirements. The Dual Slope Generator is the main module providing these functions in the Serge system.

The Universal Slope Generators are unity gain voltage followers with voltage controllable slopes. The range of control is exponential, extremely wide, and the Rise and Fall times can be controlled independently. The range of the Slope Generator is from sub-sonic to high audio frequency. Trigger inputs and trigger outputs allows each section of this dual module to function as a transient (envelope) generator, pulse delay, or in a “cycling mode” (to produce an LFO or clock). Since the Rise and Fall times are voltage controllable, this adds another dimension to the above functions. Two VC inputs are available, one is calibrated at 1 volt per octave (within about 3%), and the other is fully adjustable in the negative and positive direction. This VC input can control either the positive slope (rise), negative slope (fall), or both. The linearity and accuracy of the slewing amplifiers allows them to be used in the most exacting applications, such as processing the output of a keyboard or sequencer to produce portamento functions. Note that this portamento function has a separate rate control for rising notes and falling notes... An interesting portamento effect. Among the functions which one Slope Generator can be patch-programmed to perform are the following:

• VC Transient Envelope Generator. The envelope is simply started with a trigger, or may be used with a gate input to obtain a steady-state sustain level on the envelope. This envelope will repeat if the END trigger output is connected to the TRIG IN input. 
• VC LFO. Patched as mentioned above, a wide-range, low-cost, space-efficient Low Frequency Oscillator can be patched when needed. The Slope Generator is often used as an LFO since it is more cost effective than a regular oscillator switched to a low frequency range. it has a built-in LED to show its current output level, and it has a synchronized trigger output. The waveform can be set from saw to triangle, and the rising ramp can be voltage controlled independently of the falling ramp. 
• VC Portamento device. The accuracy of these devices makes this portamento function useful with keyboards and for generating control voltages of arbitrary shapes and times with computer control. Analog control of slopes allows the computer to do less “number crunching”, and frees the processor from time-consuming routines that are more easily handled in this low-cost multifunctional hardware. 
• Envelope Follower (Detector). The decay rate is voltage controllable with the unique function that under voltage control, the response may be moved from positive peak detection to negative peak detection. 
• VC Pulse Delay (Monostable). When the unit is triggered, it will produce an envelope set by its Rise and Fall knobs (and VC's) and then the END pulse will go high. This may be used to trigger another Slope Generator, ADSR, or advance a sequencer. 
• Sub-Harmonic Series Generator (Divider). If a series of triggers are applied to the TRIG IN jack that are faster than the total rise plus fall time, then the unit will divide the incoming triggers by a whole number. This allows the user to program synchronized rhythmic relationships (such as 2 against 3, 13 against 11, and so on). If the Slope Generators are set to audio frequencies, and the incoming triggers are in the audio range, then the output will be the sub-harmonic series. This is similar to the “hard sync” sound found in other synthesizers (and is the main reason that it is not included on Serge VCO’s). 
• Audio Oscillator. The range reaches 4000 Hz, and the waveform has variable symmetry (saw to triangle). 
• Non-Linear Audio Processor. The slew limiting is voltage controllable, so a sawtooth wave input will progressively be transformed into a triangle wave. This aspect allows the unit to be used as a low-fidelity VCF! 

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.