Features & Capabilities

Pentaholic Sketchpad Synth - The First Digital Emulation of the Gleeman Pentaphonic - 5 Voice Polyphony - Analog Modeled CEM 3320 24dB Filter - 300 Note Sequencer - MPE

Pentaholic is the first digital recreation of the Gleeman Pentaphonic. It's audio signal path is traced at the component level and built specifically for Apple Silicon devices utilizing native Metal 3D graphics featuring classic and clear UI.

In 1982, the Gleeman Pentaphonic was released as a "sketchpad synth" with a 300-note polyphonic sequencer boasting 5 voices, 3 digitally controlled oscillators per voice, and 8 waveforms per oscillator, all from an 8-bit microprocessor. After DAC, a trio of CEM chips per voice passes the audio: a 3310 envelope generator, 3320 configured as a 24dB low-pass resonant filter, and a 3360 as dual voltage-controlled amplifiers. Each subsequent stage of audio is summed out to a LM348 op amp, stacking saturation through to output. Add performance controls like expression pedal inputs and a joystick for modulation and pitch bend for a performance powerhouse synth.

Pentaholic brings the circuit to life in the digital realm for the first time ever on any platform. The concept of a sketchpad synth was the main inspiration for this - getting back to the fundamentals of songwriting and sound design. Pentaholic is meant to inspire ideas faster and prevent Producer Paralysis induced by too many options on the piano roll. Record your idea to the sequencer and play over it - the keyboard takes precedence over the sequencer notes so you can nail down your melody or adjust your groove with the rate and delay of the sequencer.

• Authentic 5-Voice Polyphony: True chorusing detune of OSC 2/3 relative to OSC 1's pitch (not BBD!) - oldest note first voice stealing. • 3 Oscillators Per Voice: 8 waveforms CMP 1 CMP 2 3% PULSE 12% Pulse SQR SAW TRI SIN per OSC and a HIGH or LOW octave mode. • One octave of chromatic pitch: transposing progressions or leads just like you put a capo on a guitar. • Component-Level Modeling: The soul of the synth - a 24dB resonant low-pass filter - self-oscillation, and nonlinear harmonic drive of the legendary CEM 3320 filter chip for a distinct bite with each subsequent gain stage pushing into saturation through a LM348 op amp. • Dual ADSR Envelopes: Precise, vintage-snappy envelope generators for exacting control over amplifier and filter contours. Subtle noise and quick snap attacks from resistor-capacitor networks the envelopes pass through. • The Polyphonic Sketchpad Sequencer: A massive 300-note sequencer honoring the original hardware workflow. Recording polyphonic chords in real time and yielding to performance on the keyboard in playback. • Joystick and expression pedal hookups: +/- 5 step pitch bend, modulation of depth of the LFO destination and cutoff expression all from the joystick even more control with expression pedals.

Pentaholic honors the original but Gotham Paradise recognizes the value and convenience of advances for performance available from soft-synths, MIDI 2.0 and Bluetooth.

• *MIDI Polyphonic Expression - *MIDI Learn - *6 Octave Pitch Change - *Master Volume - *Re-assignable joystick 0 to 5 steps - *Sync'd parameters for glide, sequencer rate/delay, LFO rate - *Game controller performance using scales to the directional pad and ABXY buttons, stick click sequencer recording and playback - Bluetooth MIDI controller Connectivity

*Pentaholic is fully functional from download but the following features are accessible with in-app purchase *Sequencer Volume *Keyboard Volume *Master Volume *6 Octave Pitch *Unison *Sync'd Parameters *Recall or Automation of parameters when hosted in a DAW such as Logic for iPad or Garageband *User Preset Saving *MIDI Learn/MIDI CC Parameter Assignment *M.P.E. *Sequencer records and plays back but resets when stopped *MIDI export of recorded Sequences *Game Controller Performance Mode *Reassignable Joystick Pitch bend

Keeping Pentaholic's core functionality free for young and new producers who can't afford the full version is important to Gotham Paradise, purchasing the full featured synth helps pay it forward.

User Growth & Download Statistics

App
By:
Andrew Strickland
Rating:
2.50
(2)
Version:
1.4.1 Last updated: 2026-05-18
Version code:
885740222
Creation date:
2026-05-09
Compatible devices:
Size:
20.78MB
URLs:
Privacy policy
Full description:
See detailed description
Source:
Apple Apps Store
Data ingested on:
2026-06-07
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Contact the developer

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Developed by:
Andrew Strickland
Apple Apps Store
https://apps.apple.com/us/app/pentaholic-synth/id6762106586

User Reviews

Terrible workflow. Just a bunch of ‘stuff’ poorly arranged. And $28 for an app not smart enough to have note hold.
by Er*****, 2026-05-23

The UI is kind of not user friendly. Maybe it’s not made for iPhone but it works fine so not really sure but the scalability of the knobs for the effects and modulation board doesn’t fit so it has to be scrolled along as you work on the surface face. The keys are large but maybe too large, esp if using an external midi and not on screen keys, then would provide more space for the knobs. Other than that, it sounds okay, and does what it does.
by Oi*****, 2026-05-18
View all user reviews ›

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