Stone Echo vs PO
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Stone Echo
This app creates a unique echo effect with adjustable frequency modulation, inspired by Mayan pyramid acoustics. It offers musical and experimental soundscapes, functioning as a standalone application or an AUV3 plugin.
- Frequency changing echo effect
- Phase modulated frequency
- Standalone app and AUV3 plugin
- Adjustable time, feedback, and level
- UFO mode for experimental sounds
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Echo effect Audio Unit V3 inspired by the mayan pyramids acoustic echo. I come up with a complex phase modulated frequency of the echo so you can change it’s frequency signature. It is kind of changing the material of the reflective surface and I called it “Stone F”. I have made the echo to sound more music friendly to me but there is button called “UFO” and if you press it the effect is more close to the mayan just shifting the frequency backwards (I liked that better). You can also control the feedback of the phase modulation. The effect can work as a stand alone app and as an audio unit AUV3 plug-in. Stone Echo is an effect that is heavy on the CPU Controls: - Time - time offset of the echo - Stone F - frequency response of the echo - Feedback - echo feedback - Level - the volume of the echo - UFO - heavy modulated echo
PO
Design and edit drum sounds, kits, and patterns for Teenage Engineering's PO-32 Tonic. Transfer your creations to the device via audio. Back up and edit existing sounds, and import/export patches from Microtonic.
- Shape 16 sounds with 21 synth parameters
- Program 16-step patterns with accents
- Send kits, sounds, or patterns via audio
- Back up and decode PO-32 data dumps
- Import/export Microtonic patches
- Local library with tags and favorites
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PO-PatchStudio designs drum sounds, kits and patterns for Teenage Engineering's PO-32 Tonic, then sends them to your Pocket Operator over sound. Free, with no ads and no account. The PO-32 has no USB data connection. It loads new sounds the way an old modem does, by listening through its microphone. So this app does the fiddly part on a proper screen: build a kit, hold your phone next to the PO-32 and press play. WHAT YOU CAN DO - Shape all 16 sounds with the full set of 21 synth parameters, plus both ends of the morph - Program 16-step patterns on the pads, with accents, and hear them before you send - Send a whole kit, a single sound or a pattern to the PO-32 over audio - Back up your PO-32: record its data dump through the microphone and the app decodes it into a kit you can edit - Import Microtonic .mtdrum and .mtpreset patches, including files from older versions of Microtonic, and export your sounds back out - Keep kits, sounds and patterns in a local library with tags and favourites WORKS WITH - PO-32 Tonic - Also sends drum sounds to the PO-35 Speak's built-in Tonic channel HOW TRANSFER WORKS Put the PO-32 in receive mode (press acc + sound), turn your phone's volume up and play the transfer into the PO-32's mic. To back up, start recording in the app, then hold write and press sound on the PO-32. Previews come from an open-source recreation of the PO-32's synth, so they sound close to the hardware but not identical. Once a sound is on the PO-32, it plays through the device's own engine. A NOTE FROM ME I'm a solo developer and a PO-32 owner. PO-PatchStudio stands on the open-source libpo32 library by Eric Lewis and years of reverse-engineering by the Pocket Operator community, which is why it's free. If something is missing or broken, tell me. Not affiliated with or endorsed by Teenage Engineering AB or NuEdge Development AB. Pocket Operator, PO-32 and Tonic are trademarks of Teenage Engineering AB. Microtonic is a trademark of NuEdge Development AB.
Screenshots
Verdict
The clearest difference is review sentiment: PO at 100% against Stone Echo's 50%. PO also leads on price (Free vs $2.99) and rating (5.0 vs 2.8). Stone Echo's advantage is in-app purchases (none vs 3) and ratings volume (4 vs 1). On ads 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
PO is free to download; Stone Echo costs $2.99 up front. PO sells 3 one-off in-app purchases. Stone Echo asks for nothing beyond the download.
PO holds the better App Store score, 5.0 against 2.8. Both are backed by a comparable volume of ratings — 4 and 1 respectively. Written reviews point the same way: 50% of Stone Echo's written reviews are positive against 100% of PO's.
Stone Echo ships an update every 38 months, PO every 2 days. The most recent releases landed on October 24, 2026 and October 25, 2026 respectively.
| Parameter | Stone Echo | PO |
|---|---|---|
| Price | $2.99 | Free — better |
| Rating | 2.8 (4 ratings) | 5.0 (1 ratings) — better |
| Positive reviews | 50.0% of reviews | 100.0% of reviews — better |
| Number of ratings | 4 — better | 1 |
| Update frequency | Every 38 months | Every 2 days — better |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Paid | Free — better |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 10.0 — better | 15.0 |
| Further details — not scored | ||
| Size | 9 MB | 14 MB |
| Age rating | 4+ | 4+ |
| Developer | Aleksandar Mlazev | Photon Consulting Limited |
Customer experience
Stone Echo
PO
In-app purchases
Stone Echo
No in-app purchases
PO
- Tip: Thanks$5.00
- Tip: Big Thanks$10.00
- Tip: Huge Thanks$20.00









