Comparison

Stone Echo vs PO

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

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.

Highlights
  • Frequency changing echo effect
  • Phase modulated frequency
  • Standalone app and AUV3 plugin
  • Adjustable time, feedback, and level
  • UFO mode for experimental sounds
Features
Read full description

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

About

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.

Highlights
  • 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
Features
Read full description

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

Stone Echo2 screens
PO4 screens

Verdict

The call

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

CostPrice · In-app purchases · Ads · Monetization

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.

ReceptionRating · Positive reviews · Number of ratings

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.

UpkeepUpdate frequency

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.

Scorecard8 real differences · 2 level
Stone Echo versus PO: the parameters behind the verdict, then further details
ParameterStone EchoPO
Price$2.99Free — better
Rating2.8 (4 ratings)5.0 (1 ratings) — better
Positive reviews50.0% of reviews100.0% of reviews — better
Number of ratings4 — better1
Update frequencyEvery 38 monthsEvery 2 days — better
AdsNoNo
In-app purchasesNo — betterYes
MonetizationPaidFree — better
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS10.0 — better15.0
Further details — not scored
Size9 MB14 MB
Age rating4+4+
DeveloperAleksandar MlazevPhoton Consulting Limited

Customer experience

Stone Echo

All ratings4 ratings
Positive50.0%
Neutral0.0%
Negative50.0%
Written reviews2 reviews
Positive50.0%
Neutral0.0%
Negative50.0%

PO

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews1 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

None

Stone Echo

No in-app purchases

3 purchases

PO

One-time3
  • Tip: Thanks$5.00
  • Tip: Big Thanks$10.00
  • Tip: Huge Thanks$20.00

Questions

Is Stone Echo free?
Stone Echo costs $2.99, with no in-app purchases.
Is PO free?
PO is free to download, with in-app purchases available.
Which has better reviews, Stone Echo or PO?
PO is rated higher. Stone Echo averages 2.8 out of 5 from 4 ratings, while PO averages 5.0 from 1 ratings.
Do Stone Echo or PO have ads?
Neither Stone Echo nor PO shows ads.
Which is updated more often, Stone Echo or PO?
Stone Echo ships an update every 38 months, and PO every 2 days. Most recently, Stone Echo was updated on October 24, 2026 and PO on October 25, 2026.

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