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Read from two schematicsAll synths

Monophonic Netlist Bass Synthesizer

Profundus

The sound of a chainsaw ripping through a dollhouse.

One voice of low end, written out part by part: three oscillators that sweep from sine to pulse, a ladder filter from the schematic of a 1970s bass pedal, a folder for its ring, and a wobble that keeps time with your song.

Hear itTour the panel

VST®3 instrument · Windows 64-bit No activationmacOS VST3 and Audio Unit are in development.

The Profundus panel on its SOUND page, the circuit drawn as a signal path of cream blocks on brick red with a black scope in each, in four numbered columns. 01 OSCILLATORS: MAIN on a saw, SUB 1 locked to MAIN on a triangle, SUB 2 a free core on a pulse, each with WAVE, PW and LEVEL in the same three columns. 02 WRAP · MIX: the WRAPPER; the MIXER, its four inputs as bars, and DRIVE; FEEDBACK, the VCA's output back into the mix. 03 LADDER · RING: the LADDER, four poles, its FULL scope over CUTOFF, EMPHASIS, KBD and CONTOUR; the RING, full less the twin ladder drawn dashed inside it, drawing the burst at each edge. 04 VCA · FOLDER: the VCA with its OUT scope and AMP, and the RES FOLDER, PARALLEL or IN-LOOP. Along the bottom, 05 CONTROL: ENV 1 and ENV 2, and MOTION with two pins in, WOBBLE to CUTOFF and VELOCITY to VCA, and the wobble drawn small. Across the top: PROFUNDUS, the SOUND and MOTION tabs, BOUNCE with 3 NETLIST, GLIDE, TUNE, the octave keys and OUT.
  • 3 oscillators
  • 4 poles
  • 147 pins
  • 11 blocks to bounce

Two 1970s American circuits, read part by part from their schematics and joined into one voice of bass. Then patched into itself.

THE CORE

Each of the three oscillators is the saw core of a 1974 American expander module, with its designators, the core the Overtime Eight-Tone is built from.

THE LADDER

The filter is the four-pole ladder of a 1970s American bass-pedal synthesizer, and it lands on the voltages its schematic prints.

OUR OWN

A wave wrapper, a folder for the ladder's ring alone, and FEEDBACK, the output back into the mix. Written out the same way, part by part.

Listen

Six takes. Hear it.

Six takes from Profundus, thirty-two seconds each, in stereo. They were raised together to sit with our other synths' takes, so their balance is as it was made; nothing else was done to them on the way here.

  1. TAKE 10:00 / 0:32
  2. TAKE 20:00 / 0:32
  3. TAKE 30:00 / 0:32
  4. TAKE 40:00 / 0:32
  5. TAKE 50:00 / 0:32
  6. TAKE 60:00 / 0:32
The SOUND page of the Profundus panel, which the camera moves across block by block: the header with BOUNCE, GLIDE, TUNE, the octave keys and OUT; MAIN, SUB 1 and SUB 2; the WRAPPER and the MIXER with DRIVE; the LADDER; the RING with the twin ladder inside it, and the RES FOLDER; the VCA; FEEDBACK; and ENV 1 and ENV 2.

THE SOUND PAGE

The circuit, drawn as it runs.

Every block on the SOUND page is a stage of the circuit, wired the way the signal flows, with a black scope at each tap drawing what the engine is doing there. MOTION, the second page, is everything that moves it.

LADDER · four poles

A ladder from a bass pedal.

The filter is a four-pole transistor ladder transcribed from the schematic of a 1970s American bass-pedal synthesizer, its designators kept. The schematic prints its own DC voltages, and the netlist lands on them with nothing tuned. That is how we know it was read right.

THE SCHEMATIC'S PRINTED VOLTAGES AGAINST THE NETLIST
NODEPRINTEDNETLIST
Q502, Q503 emitters10 V10.06 V
Q504, Q505 emitters8.5 V8.53 V
Q506, Q507 emitters6.9 V6.93 V
Q508, Q509 emitters5.3 V5.33 V
Q510, Q511 bases4.2 V4.30 V
Q512 collector3.6 V3.60 V
Q513 emitter-1.7 V-1.57 V

CUTOFF runs the ladder's pole from 51 Hz to 28 kHz, and CONTOUR sweeps it 5.4 octaves either way on ENV 2. KBD makes it follow the key. DRIVE sets how hard the mixer pushes into it: warm with one oscillator, well into the ladder's own saturation with three.

EMPHASIS is the regeneration, a reverse-audio pot as on the original, so most of the knob is spent on the top tenth. Past the blue tick on the panel the filter sings on its own, a clean sine.

FEEDBACK · the VCA's output, back into the mix

Patched into itself.

The old trick of patching a bass synth's output back into its own mixer, built as a circuit. TONE darkens the return from 16 kHz down to 161 Hz, and AMOUNT is centre-tapped: positive one way, negative the other, nothing at the middle. Its own gain cell rounds the loop off, so it growls rather than running away.

The Profundus SOUND page with FEEDBACK at AMOUNT +60 % and TONE 475 Hz: its RETURN scope draws the slow wave coming back, the return wire runs solid from the VCA's output round the panel's edge and up into the mixer, whose RETURN bar reads +60%, and the OUT, RING and FOLDED scopes are reshaped by it.
AMOUNT ON THE DEFAULT NOTE: THE NETLIST AND THE LIVE ENGINE
AMOUNTNETLISTLIVEWHAT IT DOES
+40 %+4.8 dB+5.0 dBlouder
+100 %+10.8 dB+10.9 dB31 to 250 Hz up 8 to 13 dB, the pitch held
-40 %-3.6 dB-3.4 dBthe bass thins
-100 %-1.4 dB-1.5 dBthe bass down, a peak near the cutoff

Turned all the way up with TONE dark, the loop halves the period and growls an octave under the note; all the way down with TONE open, it screeches near 9 kHz; with the oscillators off, it sings by itself. The loop closes through the VCA, so it dies with ENV 1.

MOTION · LFOs · PINS · WOBBLE

Pins, and a wobble on the beat.

The second page of the panel is everything that moves. 7 sources reach 21 destinations through a pin matrix where every pin is a resistor, 100 kΩ over its amount: PUT A PIN IN, set its amount either way, PULL THE PIN.

The Profundus MOTION page on brick red. LFO 1 on a triangle at 2.97 Hz and LFO 2 on a sine at 0.72 Hz in one frame, each with KEY; LFO 3 below them, which bends their rates, with TO LFO 1 and TO LFO 2. On the right the PINS, 2 of 147, drawn as the matrix itself: seven rows from LFO 1 to WHEEL, each with its source's meter, by twenty-one columns from PITCH to FEEDBACK, with pins in at WOBBLE to CUTOFF, +0.50, and VELOCITY to VCA, and PULL THE PIN beneath. Along the bottom, the WOBBLE lane over two bars of sixteen steps, each step's cycles above and its shape below, the pattern drawn in phosphor green, and the STEP 13 inspector: CYCLES IN THE STEP, SHAPE, DEPTH, LEVEL, GLIDE, TIE and RANDOMIZE ALL.

LFO 1 · LFO 2 · LFO 3

Three analog LFOs in the circuit: SIN, TRI or SQR, from 0.04 to 55 Hz, each with KEY to restart at a note. LFO 3 does nothing but bend the rates of the other two.

WOBBLE

One to four BARS of sixteen steps. Each step holds its CYCLES IN THE STEP, from H to 8, a SHAPE, DEPTH, LEVEL, GLIDE and TIE. RANDOMIZE ALL writes all of them anew; SMOOTH rounds the edges.

ON THE BEAT

The wobble reads its place from your song's position, so seeking, looping and bouncing all land on the same value. With the transport stopped it runs from the last note; RETRIG restarts it at every note.

FROM

  • LFO 1
  • LFO 2
  • WOBBLE
  • ENV 1
  • ENV 2
  • VELOCITY
  • WHEEL

TO

  • PITCH
  • SUB 2 PITCH
  • MAIN WAVE
  • SUB 1 WAVE
  • SUB 2 WAVE
  • MAIN PW
  • SUB 1 PW
  • SUB 2 PW
  • MAIN LEVEL
  • SUB 1 LEVEL
  • SUB 2 LEVEL
  • WRAP DRIVE
  • WRAP SYM
  • CUTOFF
  • EMPHASIS
  • FOLD
  • VCA
  • LFO 1 RATE
  • LFO 2 RATE
  • LFO 3 RATE
  • FEEDBACK

Playback and bounce

Play the equations. Bounce the parts.

While you play, Profundus runs the same parts as equations, every block worked from the netlist's own resistors. When your DAW renders offline it solves the circuit for the blocks the BOUNCE menu names, and the live engine plays the rest. Both have the same latency, 29 samples at 48 kHz, so a bounce lines up with playback to the sample.

The BOUNCE menu open over the Profundus panel, headed what an offline render solves, block by block: eleven rows from OSCILLATORS to PIN MATRIX, each with what it holds and a LIVE or NETLIST pair; WAVE WRAPPER, FILTER and RESONANCE FOLDER lit on NETLIST, the rest on LIVE; ALL LIVE, DEFAULT and ALL NETLIST beneath.
  1. OSCILLATORSthe glide, core 1 and SUB 1, core 2, the three shapersLIVE
  2. WAVE WRAPPERthe drive cell and the six pairsNETLIST
  3. MIXERthe three level cells, the mixer, DRIVELIVE
  4. FILTERthe ladder and its twin, the ring, the regenerationNETLIST
  5. RESONANCE FOLDERthe fold cell and the four fold stagesNETLIST
  6. VCAthe AMP cell and the VCALIVE
  7. FEEDBACKTONE, the return cell, AMOUNTLIVE
  8. ENV 1loudness: attack, decay, sustainLIVE
  9. ENV 2contour: attack, decay, sustainLIVE
  10. LFOSLFO 1, LFO 2, LFO 3 and its bendLIVE
  11. PIN MATRIXthe rows, the 21 columns, the wobble's lagLIVE
  12. DEFAULT: 3 NETLIST, THE REST LIVE

1.88 s

for each second of audio with the default blocks, on one thread

9.74 s

with all eleven blocks solved

-0.54 to +0.61 dB

the default bounce against the live engine on a bass line, within 0.1 dB on 10 of 13 patches

Those times are the default patch; a busy one costs far more. If the circuit ever faults, the panel says so and the fault is logged.

What it is, and what it is not

Solved, read, and not yet.

SOLVED

On a bounce, the blocks you choose, down to every part; with ALL NETLIST, the whole instrument. The wobble is digital, worked out in song time as a step sequencer's would be; everything it moves is the circuit.

READ, AND KEPT

Three values the schematic's scan cannot confirm are kept as read. The core's ramp is slightly bowed, as the original's is, so the sine carries a little second harmonic. IN-LOOP folding is chaotic, and there the live engine and the bounce differ most. The live engine is a model of the circuit.

NOT YET

The Mac: Profundus is Windows only for now, with the Mac VST3 and Audio Unit in development. Nothing on this page is for sale yet.

Profundus

The sound of a chainsaw ripping through a dollhouse.

Hear itAll synths

VST®3 instrument · Windows 64-bit No activationmacOS VST3 and Audio Unit are in development.

At a glance

Profundus specifications

Technical specifications for Profundus, Monophonic Netlist Bass Synthesizer
FormatVST®3 instrument · Windows 64-bit
In developmentmacOS VST3 and Audio Unit
Requires64-bit Windows 11, in any version Microsoft still supports. When the Mac version ships: macOS 15 or later, on Apple silicon or Intel.
VoiceMonophonic · last, low or high note priority · legato · glide
OscillatorsMAIN, SUB 1 locked one or two octaves down, SUB 2 free · WAVE sine to triangle to saw to pulse · PW
FilterA four-pole transistor ladder from a 1970s bass-pedal synthesizer's schematic · CUTOFF · EMPHASIS · KBD · CONTOUR
Wrapper and folderWAVE WRAPPER on the main · RES FOLDER on the ladder's ring, PARALLEL or IN-LOOP
FeedbackThe VCA's output into the mixer · AMOUNT positive or negative · TONE 161 Hz to 16 kHz
ModulationThree analog LFOs, LFO 3 bending the other two · two envelopes · a pin matrix, 7 sources by 21 destinations
Wobble1 to 4 bars of 16 steps · cycles, shape, depth, level, glide and tie a step · read from the song's position
PlaybackThe same parts as equations
BounceEleven blocks, each LIVE or NETLIST · the wrapper, the filter and the folder solved by default
Bounce timeAbout two times slower than real time with the default blocks · about ten with all eleven (the default patch, one thread)
Latency29 samples at 48 kHz, the same in playback and the bounce
The panel1200 by 800 · SOUND and MOTION
Validation47 of 47 validator tests · host-tested
ActivationNone. No license server, no phone-home
Security updatesUntil November 2031
LicenseLicense agreement · Facts sheet
VST Compatible

VST is a registered trademark of Steinberg Media Technologies GmbH.