psNLr25kE-sub is an extract of 2sinNoiseLPFrLFO-sub-Ws, focusing on the synth part of the Max patch that animated the installation Wechselstrom. it is made up of 25 sine wave oscillators, a noise generator whose output passes through a low-pass filter, a random LFO, and an envelope follower.
click on the image below to download the Max collective and project folder. the text following it is a guide to psNLr25kE-sub.
the 25 sine wave oscillators are controlled with an onscreen keyboard. each key corresponds to a different oscillator, and each oscillator sounds 1.6 Hz above the other, ranging all together from 21.6 Hz to 60 Hz. the leftmost dial, “freq shift”, sets the value of a constant that is added to the frequency of each oscillator, shifting the keyboard either upward or downward and extending the range of the oscillators down to 1.6 Hz and up to 80 Hz.
note that the keyboard of psNLr25kE-sub is fixed to latch mode, and there is always at least one key that is pressed. when the patch is controlled with a MIDI keyboard, even after the keys are released they will continue to be played until new ones are played. clicking on an unpressed key on the onscreen keyboard will add the corresponding oscillator to the ones already sounding, and clicking on a pressed key will remove it. in that regard, the keyboard should be thought of more as a set of switches, as it has no influence on the volume and the articulation of the sound, but only on which oscillators are to be played.
the 3 dials to the right of “freq shift” control the low-pass filter through which the output of the noise generator passes. “noise mix” controls the mix between the sine waves and the filter’s output. “LPF cutoff” controls the filter’s cutoff (in MIDI notes, ranging from 12 to 72, that is, from C0 to C5). “LPF res” controls the filter’s resonance.
“rLFO rate” and “rLFO glide” control an LFO that produces a random signal of a controllable rate (“rLFO rate”) and smoothness (“rLFO glide”), which can be used to modulate all the parameters mentioned above (as well as its own). to modulate a parameter, set the blue number to the right of the parameter’s dial to a value other than 0. for example, set the one next to “freq shift” to 20 and the dial will start moving. the blue needle will still point to the stationary value before the modulation, but an additional gray needle will monitor the actual, constantly changing value. this value is equal to the blue number next to the modulated dial, multiplied by the signal produced by the random LFO, and added to the dial’s stationary value. note that the modulation can be either positive or negative (the random LFO produces a signal between -1 and 1). “rLFO rate” is the only exception, as the modulation is not added to the dial’s value but multiplied by it. for this reason, it cannot be negative and ranges from 0.1 to 10 (its zero-point is 1).
the rightmost dial in this panel (“volume”) controls the master volume. it cannot be modulated by the random LFO; instead, the number to its right provides an additional control over the gain, ranging from -18 to +18 dB. (note that even though psNLr25kE-sub is designed so that enough headroom will be available, clipping is still possible. this may be dangerous for amplifiers and loudspeakers, but could also be used safely and artistically to enrich the sometimes too “pure” sine waves.)
in the right part of the lower panel are 3 dials that control the envelope follower. an envelope follower detects the amplitude variations of an incoming signal to produce a control signal that resembles those variations. this control signal can then be used to modulate other signals (or parameters). psNLr25kE-sub’s envelope follower is set by default to modulate the master volume (to prevent feedback, it is designed to be particularly sensitive to frequencies above 2 kHz). the black needle of the “volume” dial sets the maximum volume and the gray needle shows the actual position based on the volume of the audio input. the louder the audio input, the louder the output of psNLr25kE-sub. note that the envelope follower can also be inverted: hold the Alt key and click on “volume” (the title of the dial, that is, the text above it), and the title’s color will change from purple, which indicates that the master volume is modulated by the envelope follower, to yellow, which indicates that the master volume is still modulated by the envelope follower, but inversely. this means that louder inputs will decrease the master volume rather than increase it.
other parameters can also be modulated by the envelope follower. click on a title of a dial and the title will become purple, indicating that the parameter is modulated by the envelope follower; hold the Alt key and click on a title of a dial and the title will become yellow, indicating that the modulation is inverted; hold the Shift key and click on a title of a dial and the dial will become purple, indicating that the degree to which the parameter is modulated by the random LFO is modulated by the envelope follower; hold both the Shift and the Alt keys and click on a title of a dial and the dial will become yellow, indicating that the degree to which the parameter is modulated by the random LFO is modulated by the envelope follower inversely; hold the Cmd key and click on a title of a dial and the title will be black again, indicating that the parameter is no longer modulated by the envelope follower; hold both the Shift and the Cmd keys and click on a title of a dial and the dial will be gray again, indicating that the degree to which the parameter is modulated by the random LFO is no longer modulated by the envelope follower.
note that it is also possible to control the degree to which the envelope follower modulates the different parameters. press “r” to reset the envelope follower, and all the titles and dials should be black/gray again except for the title of the “volume” dial, which should be purple. then, gradually turn “EF mod” anti-clockwise and the gray needle of the “volume” dial will rise until it merges with the black one. when “EF mod” is turned fully to the left, the master volume is completely independent of the envelope follower. if other parameters were also modulated by the envelope follower, however, “EF mod” would have also affected them. to control specifically the degree to which the envelope follower modulates the master volume, click on “EF mod” and a small window will appear, in which it is possible to set the degree to which the envelope follower modulates each of the parameters and the degree to which it influences the degree to which they are modulated by the random LFO (ranging from -1 to 1). this can also be done by holding the Ctrl key and clicking on a tile of a dial, which will increase the degree to which the envelope follower modulates the parameter by 0.25; holding both the Ctrl and the Alt keys and clicking on a title of a dial will decrease the degree to which the envelope follower modulates the parameter by 0.25; holding both the Ctrl and the Shift keys, or the Ctrl, the Shift, and the Alt keys and clicking on a title of a dial, will change the degree to which the envelope follower modulates the degree to which the parameter is modulated by the random LFO by 0.25.
in addition, the 2 dials to the right of “EF mod” determine how the envelope follower detects the amplitude variations of the audio input. “EF smth” determines the extent to which the envelope follower ignores small variations. “EF nrml” determines how normalized the input signal will be, making quiet inputs as effective as louder inputs.
setting the audio driver and the input and output devices, as well as the MIDI input, is to be done by clicking on “extras” and selecting the desired driver, inputs, and outputs from the drop-down menus. clicking on the texts to the left of the menus will refresh their content. (the keyboard is mapped by default to AKAI LPK25 and the dials to novation LAUNCHCONTROL.)
it is also possible to make a mono recording of the output of psNLr25kE-sub. to do so, double-click on “recMONO” in the “extras” window, click on “open” to save the file, and turn on the toggle to start recording (do not forget to turn it off when you are done).
finally, placing different objects on the speaker cone of the loudspeaker (ideally, a subwoofer) with which psNLR25kE-sub is played, can create various rattling sounds. experiment with slinkies, plastic boxes, broken plastic cups, plastic bottles, disposable (and nondisposable) cutlery, aluminum foil, coins, etc.