Pentaholic Synth vs Callback Freeverb
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Pentaholic Synth
This app digitally recreates a classic polyphonic synthesizer, offering authentic sound design and songwriting inspiration. It features a 300-note sequencer, multiple oscillators per voice, and performance controls like a joystick and expression pedal inputs.
- Authentic 5-voice polyphony
- 3 oscillators per voice with 8 waveforms
- Component-level circuit modeling
- Dual ADSR envelopes
- 300-note polyphonic sequencer
- Joystick and expression pedal support
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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.
Callback Freeverb
This app offers a classic algorithmic reverb effect based on the Freeverb algorithm. It adds depth, space, and atmosphere to audio sources, creating lush, spacious ambience. Designed for mono use, it provides a smooth, musical reverb tail suitable for vocals and synthesizers.
- Classic Freeverb algorithm
- Schroeder/Moorer reverb topology
- Comb and allpass filters
- Mono operation
- Adds depth and space to audio
- Smooth, musical reverb tail
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A classic algorithmic reverb effect based on the Freeverb algorithm by Jezar at Dreampoint. A Freeverb-style Schroeder/Moorer reverb based on the classic 8-comb + 4-allpass topology, with simplified controls and no stereo spread. This reverb creates lush, spacious ambience through a network of comb and allpass filters. Freeverb is widely used in electronic music production, ambient music, and sound design to add depth, space, and atmosphere to audio sources. The algorithm provides a smooth, musical reverb tail that works well on everything from vocals to synthesizers. This reverb only functions in mono and provides no stereo imaging, and the user can expect the same behavior as a classic Freeverb implementation otherwise.
Screenshots
Verdict
The clearest difference is rating: Callback Freeverb at 5.0 against Pentaholic Synth's 3.8. Callback Freeverb also leads on in-app purchases (none vs 1). Pentaholic Synth's advantage is ratings volume (6 vs 1). On price, ads, monetization model and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Pentaholic Synth sells 1 one-off in-app purchase. Callback Freeverb asks for nothing beyond the download.
Callback Freeverb holds the better App Store score, 5.0 against 3.8. That said, the two scores are not equally well evidenced: Pentaholic Synth has 6 ratings behind it against 1, so its average is the more settled of the two.
| Parameter | Pentaholic Synth | Callback Freeverb |
|---|---|---|
| Price | Free | Free |
| Rating | 3.8 (6 ratings) | 5.0 (1 ratings) — better |
| Positive reviews | 57.1% of reviews | — |
| Number of ratings | 6 — better | 1 |
| Update frequency | Every 6 days | — |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | Free | Free |
| Devices | iPhone, iPad | iPhone, iPad |
| Requires iOS | 16.0 — better | 17.0 |
| Further details — not scored | ||
| Size | 21 MB | 7 MB |
| Age rating | 4+ | 4+ |
| Developer | Andrew Strickland | Callback Audio, LLC |
Customer experience
Pentaholic Synth
Callback Freeverb
In-app purchases
Pentaholic Synth
- Full Features$28.00
Callback Freeverb
No in-app purchases
Questions
Is Pentaholic Synth free?
Is Callback Freeverb free?
Which has better reviews, Pentaholic Synth or Callback Freeverb?
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