Callback Freeverb vs QUARK Play
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
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.
QUARK Play
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QUARK Play easily transforms up to four iOS devices into a wireless, quadraphonic sound system. Place iPhones, iPads, and/or Macs around the space (or connect them to bluetooth speakers), hit play on the host device, and build a true, immersive surround sound environment anywhere. The Quadraphonic Universally Accessible Resource Kit (QUARK) is open source software used in Digital Audio Workstations (DAWs) and similar platforms to encode four channels of discrete audio into two channel (standard stereo) audio, then back to four channels again. This allows for the distribution of four-channel spatial recordings via widely accessible two-channel formats such as vinyl, cassette, and radio, as well as digital platforms such as YouTube, Spotify, and Qobuz. QUARK is made possible by dublab & the National Endowment for the Arts.
Screenshots
Verdict
Callback Freeverb and QUARK Play are too close to call on the numbers: across 5 compared parameters — price, ads, in-app purchases and device support among them — neither pulls far enough ahead to decide it. What separates them is feature set and interface, not measurable difference.
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. Neither carries in-app purchases, so what you see is what you pay.
| Parameter | Callback Freeverb | QUARK Play |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (1 ratings) — better | — |
| Number of ratings | 1 — better | — |
| Update frequency | — | Every 6 days |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | — |
| Devices | iPhone, iPad | iPhone, iPad |
| Requires iOS | 17.0 | 16.6 — better |
| Further details — not scored | ||
| Size | 7 MB | 25 MB |
| Age rating | 4+ | 4+ |
| Developer | Callback Audio, LLC | AKP Recordings LLC |
In-app purchases
Callback Freeverb
No in-app purchases
QUARK Play
No in-app purchases









