Comparison

FET Acoustic Compressor vs SL Prism

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

Head to head
About

FET Acoustic Compressor

This app emulates the warm, musical character of classic FET compressors for acoustic instruments and more. It offers intuitive controls for punch, presence, and glue, with a special "All-In" mode for aggressive sounds. Designed for mobile studios and live performance.

Highlights
  • Classic FET compression emulation
  • Voiced for acoustic guitar, versatile for other instruments
  • Intuitive controls: IN, ATTACK, RELEASE, RATIO, OUT, DRY, SC HPF
  • Special "All-In" mode for aggressive sounds
  • AUv3 plugin support for popular DAWs
  • Low latency for live performance
  • Factory presets included
Read full description

FET Acoustic Compressor brings the warm, musical character of classic FET compression — voiced in the tradition of the Cali76 by Origin Effects and the vintage 1176 circuit it's based on — to your iPhone and iPad. Dialed in for acoustic guitar, but equally at home on electric guitar, bass, vocals, keys, or any source that benefits from that signature FET feel. Whether you're tracking at home, mixing in a DAW, or running signal live through Loopy Pro or AUM, FET Acoustic Compressor gives your sound the punch, presence, and glue it needs. Voiced for feel The compression curve, soft knee, and gentle FET saturation are tuned for the transients and dynamics of acoustic strings — but that voicing translates beautifully to any instrument that needs a compressor with character. It sits, it glues, it breathes. Full control, intuitive layout - IN — Drive the input and push into compression - ATTACK / RELEASE — Fast enough to catch a pick attack; slow enough to let the body bloom - RATIO — 2:1 to 20:1 for everything from gentle leveling to heavy squash - OUT — Trim your output level - DRY — Blend in parallel compression for the best of both worlds - SC HPF — High-pass the sidechain so low-end doesn't trick the detector - Gain Reduction Meter — See exactly what's happening in real time All-In mode Tap the RATIO label to activate All-In — the infamous "all buttons simultaneously" trick from vintage 1176-style compressors. Ratio jumps to 100:1, the knee tightens, and asymmetric FET saturation adds the gritty, pumping character that's made this mode a go-to for aggressive sounds. A secret weapon hiding in plain sight. Factory presets to get you started - Compressed Fingerstyle - Dynamic Fingerstyle - Pop Strumming Built for the mobile studio and stage - AUv3 plugin — use in GarageBand, AUM, Loopy Pro, Cubasis, and any AUv3 host - Low latency — optimized for live performance and real-time processing - 4x oversampled processing for clean, artifact-free compression - Designed for iPhone and iPad *Cali76 is a trademark of Origin Effects Ltd. 1176 and UREI are trademarks of their respective owners. GarageBand is a trademark of Apple Inc. AUM is a product of Kymatica AB. Loopy Pro is a product of A Tasty Pixel. FET Acoustic Compressor is not affiliated with, endorsed by, or sponsored by any of the above companies.*

About

SL Prism

Read full description

SL Prism is a precise, fast, touch-ready equalizer for corrective mixing and creative sound shaping. Create a band directly on the spectrum. Move it to set frequency and gain, then refine Q, filter shape, channel routing, dynamics, threshold, attack, and release. Every enabled response stays visible while you work. Use dynamic EQ to control frequencies only when they become a problem. Enable spectral processing for more focused reactions. Switch between Zero Latency, Natural Phase, and Linear Phase modes to match recording, mixing, and phase-sensitive work. Features: • 24 independent EQ bands • Nine filter types • Dynamic and five-slice spectral processing • Stereo, Left, Right, Mid, and Side routing • External sidechain support in compatible hosts • Realtime input, output, masking, and combined analyzers • EQ Match and resonance suggestions • A/B comparison, Undo, Redo, Auto Gain, Pan, Phase Invert, and Mix • Factory effects including Underwater, Telephone, Airy Vocal, Warm Vintage, and Lo-Fi Radio • AUv3 plugin and standalone app • Scalable interface for iPad Audio is processed locally on the device. Core EQ processing does not upload project audio.

Screenshots

FET Acoustic Compressor1 screens
SL Prism3 screens

Verdict

The call

The clearest difference is price: FET Acoustic Compressor at $5.99 against SL Prism's $19.99. FET Acoustic Compressor also leads on iOS requirement (13.0 vs 15.0). SL Prism's advantage is update cadence (every 10 days vs every 2 months). On ads, in-app purchases 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

FET Acoustic Compressor costs $5.99 and SL Prism $19.99 up front. Neither carries in-app purchases, so what you see is what you pay.

UpkeepUpdate frequency

FET Acoustic Compressor ships an update every 2 months, SL Prism every 10 days. Both last shipped on October 31, 2026.

Scorecard3 real differences · 7 level
FET Acoustic Compressor versus SL Prism: the parameters behind the verdict, then further details
ParameterFET Acoustic CompressorSL Prism
Price$5.99 — better$19.99
Rating5.0 (2 ratings) — better—
Positive reviews100.0% of reviews—
Number of ratings2 — better—
Update frequencyEvery 2 monthsEvery 10 days — better
AdsNoNo
In-app purchasesNoNo
MonetizationPaid—
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS13.0 — better15.0
Further details — not scored
Size9 MB18 MB
Age rating4+4+
DeveloperShelbybark LLCVIACHESLAV ZHILTSOV

In-app purchases

None

FET Acoustic Compressor

No in-app purchases

None

SL Prism

No in-app purchases

Questions

Is FET Acoustic Compressor free?
FET Acoustic Compressor costs $5.99, with no in-app purchases.
Is SL Prism free?
SL Prism costs $19.99, with no in-app purchases.
Do FET Acoustic Compressor or SL Prism have ads?
Neither FET Acoustic Compressor nor SL Prism shows ads.
Which is updated more often, FET Acoustic Compressor or SL Prism?
FET Acoustic Compressor ships an update every 2 months, and SL Prism every 10 days. Most recently, FET Acoustic Compressor was updated on October 31, 2026 and SL Prism on October 31, 2026.

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