Spectro vs. Fabl: Which Is Better for Detecting Fake Lossless Audio?

If you've been researching how to detect fake lossless audio files, you've probably come across two tools: Spectro and Fabl. Both do spectral analysis and return a verdict. Both work without requiring you to read spectrograms manually. But they're built for different situations, and the differences matter depending on how many files you're checking, whether you care about privacy, and what platform you're on.

This is a direct comparison of both tools — what each does well, where each falls short, and which one fits which use case.

What Fabl is

Fabl is a free, browser-based audio quality checker. You upload a file through the web interface, and it performs FFT spectral analysis to detect frequency cutoffs. It returns a verdict indicating whether the file appears to be lossless or transcoded.

Fabl's main advantage is accessibility: no download, no installation, no payment required. If someone sends you a single file and asks whether it's genuine lossless, Fabl answers the question in about 30 seconds.

What Spectro is

Spectro is a native macOS application for batch spectral analysis. You drag a folder of files, and Spectro analyzes all of them simultaneously, displaying a verdict for each — LOSSLESS, FAKE, or MEDIUM — alongside a spectrogram. Results are filterable: you can show only FAKE files and delete them directly from within the app.

Spectro is a $39 one-time purchase with a 10-file free trial. It runs locally on your Mac — your audio files never leave your machine.

The core differences

Privacy

This is the most fundamental difference between the two tools.

Fabl is browser-based. To analyze a file, you upload it to Fabl's servers. The analysis happens remotely, and your audio data transits the network. Fabl's privacy policy governs what happens to that data, and it may vary.

Spectro is offline. The audio never leaves your computer. For DJs with unreleased music, upcoming sets they haven't announced, or files under NDA, local processing isn't optional — it's a requirement.

If you're checking publicly available commercial releases and privacy isn't a concern, this distinction doesn't matter. If you're working with any audio you wouldn't want uploaded to a third-party server, Spectro is the only option.

Batch processing

Fabl processes one file at a time. You upload, wait for the result, then upload the next file.

Spectro processes entire folders at once. Drop 200 files in, and you have results for all 200 within a few minutes. The interface shows all results simultaneously, sortable by verdict, so you can see at a glance how many files in a folder are FAKE and which ones they are.

For a pre-gig check on a 20-track set: Fabl takes 20 uploads and 20 waits. Spectro takes one drag and approximately 90 seconds.

For a library audit of 500 tracks: Fabl is not practical. Spectro processes the entire library and lets you filter to the problem files.

Native experience and integration

Fabl works in a browser tab. You navigate to the site, use the web interface, and get results in the browser.

Spectro is a native macOS app built for Apple Silicon, notarized and signed by Apple. It integrates with macOS conventions: drag and drop from Finder works natively, the app respects system dark mode and accessibility settings, and file operations (including deleting flagged files) happen through macOS's standard file handling.

If you work on a Mac and want the tool to feel like part of your computer rather than a web service, Spectro behaves accordingly.

Deleting fake files

Fabl tells you whether a file is fake. It doesn't do anything with that information.

Spectro lets you select FAKE files and delete them directly from the interface, or move them to Trash. For a library cleanup workflow — find fakes, remove them, replace with genuine versions — this means staying in one application rather than switching between the analysis tool and Finder.

The MEDIUM verdict

Both tools return a binary or near-binary verdict for clear cases. The distinction is in ambiguous ones.

Spectro uses a three-tier verdict system: LOSSLESS, FAKE, and MEDIUM. MEDIUM captures files where the spectral evidence doesn't cleanly indicate genuine lossless or obvious transcode — high-bitrate MP3 sources (320kbps), heavily mastered tracks with natural high-frequency rolloff, or vinyl transfers. This prevents false positives while still flagging clearly fake files.

Fabl's output is more binary. In cases where the spectral evidence is ambiguous, a binary verdict either over-flags (calling lossless tracks fake) or under-flags (missing questionable files). The MEDIUM tier exists to handle the real-world messiness that a binary system doesn't capture well.

Cost

Fabl is free.

Spectro is $39 one-time, with a 10-file trial that requires no account or payment information. The trial is enough to verify a full pre-gig set.

Platform support

Fabl works on any platform with a browser — Windows, macOS, Linux, iOS, Android.

Spectro is macOS only (Apple Silicon and Intel, macOS 12+).

If you're on Windows or Linux, Spectro is not an option. For cross-platform teams or non-Mac workflows, Fabl covers the use case at no cost.

Comparison table

	Spectro	Fabl
Platform	macOS only	Browser (any OS)
Privacy	Fully local	Files uploaded to server
Batch processing	✓ Entire folders	✗ One file at a time
Verdict tiers	LOSSLESS / FAKE / MEDIUM	Pass / Fail
Delete fake files	✓ Built-in	✗ Manual
Native Mac app	✓ Apple Silicon native	✗ Web interface
Spectrogram view	✓ Per file	✓ Per file
Price	$39 one-time	Free
Trial	25 files, no account	Unlimited
Internet required	✗ Fully offline	✓ Required

Which one to use

Use Fabl if:

• You're on Windows or Linux
• You need to check one or two files quickly and don't want to install anything
• You're verifying publicly available commercial tracks and privacy isn't a concern
• You want a free tool for occasional use

Use Spectro if:

• You have more than a handful of files to check
• You're on macOS and want a native experience
• Privacy matters — you're working with unreleased music, DJ sets not yet announced, or any audio you wouldn't upload to a third-party server
• You want to delete fake files directly from the analysis interface
• You're doing a full library audit and need batch results sorted by verdict

For most DJs on Mac who take audio quality seriously, Spectro and Fabl are not really competing for the same workflow. Fabl is for quick spot checks when you don't have Spectro available. Spectro is for systematic library management.

To understand more about how the detection works under the hood, see our guide on how to detect fake lossless audio files.

Try Spectro free — 25 files, no account needed →