Feature spec
Goal: Send a clear invoice after finishing a job.
- Add a client, line items, a due date, and payment instructions.
- Preview the total before exporting a PDF.
- Keep an editable draft if export fails.
App Overview
Classic FX
Classic FX is a complete sound effects processor and a mono-to-stereo enhancer with equalizer, effects and reverb, based on specially designed high-quality processing algorithms and suitable for any kind of audio sources
$6.99 · In-app purchases
PRICE
$6.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.6
22 ratings · Top 15%
Evidence scope: No current overall US chart position is available. Category-chart positions shown in discovery are a separate scope. Revenue is a directional model estimate, not verified earnings.
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Build Kit
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A product spec, screen plans, and build steps for your coding agent.
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What's included18 files
A product spec, phased build plan, differentiation notes, and screen references.
- START_HERE
- AGENTS
- EVIDENCE
- SPEC
- BUILD_PLAN
- DIFFERENTIATION
- skills/
- screens/
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Illustrative example: an invoice app for independent contractors. Your kit is tailored to the app you choose; this is not its generated content.
Screen plan
Invoice editor: Client at the top, editable line items in the middle, total and preview action at the bottom.
States: Empty draft, validation errors beside each field, exporting, and a retry action that preserves the draft.
Differentiate and validate
Hypothesis: Contractors need faster repeat invoices more than more templates.
First experiment: Test duplicating a previous job with five contractors. Watch where they hesitate before expanding the feature set.
The full kit adds a phased build plan, evidence notes, tool prompts, and implementation guidance. It is a plan for your coding agent, not a finished app.
Usage: Mechanics are fair game; never reuse the original name, branding, assets, or verbatim copy.
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Free quick prompt For a smaller starting point
Quick prompt
Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
// RORK SYSTEM PROMPT
Rork plan preview for Classic FX: map the core Music workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
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Opportunities
AI-GENERATED OPPORTUNITY HYPOTHESES
These are generated suggestions, not verified review quotations. Check current App Store reviews and speak with users before treating a possible gap as a requirement.
Hypothesis 1
Expand the range of audio effects and filters.
Assumption to check: Limited effects compared to competitors.
Validate with people who use this workflow before building.
Hypothesis 2
Implement features for sharing effects with friends.
Assumption to check: No social sharing options.
Validate with people who use this workflow before building.
Hypothesis 3
Introduce a subscription model with a free trial.
Assumption to check: High one-time purchase cost.
Validate with people who use this workflow before building.
Hypothesis 4
Allow users to create and save custom effects.
Assumption to check: Lack of user customization for effects.
Validate with people who use this workflow before building.
App evidence
Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.
App Store description
Classic FX is a complete sound effects processor and a mono-to-stereo enhancer with equalizer, effects and reverb, based on specially designed high-quality processing algorithms and suitable for any kind of audio sources. This application will add brightness and expand the sound space of any musical instruments, synthesizers, drums or voice. Unique and diverse effects with unified control parameters provide convenience and ease of customization, while at the same time plenty of room for individual expression and experimentation. Another unique feature of Classic FX is the Morphing option, based on complex effects matrix transformations, which allows you to control the dynamic transition between any two presets. While this can produce stunning effects, it's a breeze to control - you just need to move a fader or push a button. For more morph experimentation, this app has three LFOs to create more complex waveforms for changing morphs. Each LFO has different ranges, waveforms and can sync to the external BPM. Some of the other features of Classic FX: - Classic FX has 22 unique processing algorithms and 40 different presets. - Two slots in which you can use different effects and smoothly morph between them. - Three band equalizer with high / low shelving filters and middle peaking filter. - Easy to use algorithmic reverb, suitable for any sound source. - Limiter on output prevents any possible clipping. - Envelope follower for dynamic control of each effect. - Sequencer for rhythmic control of each effect. - Three special LFO in series to automate morphing. - Hot buttons to change the active effect slot. - Changing a group of parameters at the same time. - Echo module, Sequencer, and Auto morphing synced with the main BPM source. - The effect algorithm and its parameters can be saved as a preset. - Detailed application description and description of algorithms. - Quick info and description of each algorithm used in presets. Classic FX is a universal application for iOS and macOS. It can work on iPhone and iPad as well as Mac / MacBook with M1 chip (and later). Classic FX works on iPhone and iPad standalone, as an Audio Unit or Inter-App Audio module, and supports Audiobus and Ableton Link. On MacOS, Classic FX can works both as a standalone application and as an Audio unit (AUv3) with DAWs and audio unit hosts like Ableton Live, Logic Pro, GarageBand, MainStage, Cockos Reaper, Plogue Bidule, Hosting AU, and other hosts that support AUv3 plugins. All application features are available on iOS and macOS. Presets demo: https://www.youtube.com/watch?v=qyiKOAM7pjQ https://www.youtube.com/watch?v=6h6Or3OTCsY https://www.youtube.com/watch?v=qXoxGmrXJVk You can find more information on Classic FX and other experimental audio processing apps at: https://motion-soundscape.blogspot.com
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Screenshots
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Build scope
Plan a focused first version with your coding agent. These are planning assumptions, not a delivery guarantee.
Define the first version
Choose one audience and one core workflow. Use the kit to agree on its screens, data, and acceptance criteria before building.
Set boundaries
Decide which secondary features, integrations, and platform support can wait. Your version does not need to reproduce everything in the original.
Check the hard parts
Validate external services, specialist technology, data access, and ongoing costs for your chosen scope.
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BUILD KIT DIFFICULTY
Advanced
From the Build Kit assessment.
A reliable timeline needs an agreed scope and a technical check. Ask your agent to estimate the phases in BUILD_PLAN.md after that review.
