Voxengo SPAN

Overview

Voxengo SPAN is a free real-time FFT spectrum-analysis plugin for professional audio and music-production hosts. It is best suited to producers, engineers, and mastering users who want configurable spectral views alongside loudness and level meters. Its broad analysis toolkit costs nothing, but it is not the choice for track-to-track spectrum exchange without SPAN Plus.

Key features

SPAN handles stereo, mono, mid-side, and surround analysis, including 5.1 and 7.1. Showing spectra for two channels or channel groups at once is useful when assessing relationships in a multichannel session. The trade-off is that these views live inside a plugin workflow, so users need a compatible host.

Its meters cover EBU R128 and K-system standards, RMS and true-peak levels, clipping, and stereo correlation. This makes SPAN more useful than a spectrum display alone when checking level and stereo behavior in a mix. FFT block size, window overlap, visual slope, smoothing, and a secondary spectrum display give users meaningful control over the presentation, though they do not provide the separate spectrum-import and export workflow reserved for SPAN Plus.

Channel routing and grouping, output signal power statistics, presets, undo and redo, A/B comparisons, and a resizable interface round out the workflow. The plugin supports VST, VST3, AudioUnit, and AAX, but the downloads vary by operating system: Mac offers AU, AAX, and VST3; Windows offers VST, VST3, and AAX. Listed compatible hosts include Ableton Live, Cubase, Logic Pro, REAPER, Pro Tools, FL Studio, Studio One, OBS, Bitwig Studio, Nuendo, and Adobe Audition.

Pricing

Voxengo SPAN — free. The free plan provides the real-time FFT analyzer, analysis views, and metering described above. It is a strong fit for users who need spectral and level checks in a host and do not need SPAN Plus's spectrum importing and exporting. Voxengo says a workaround using the free plugin works only in some hosts, such as Ableton Live, so that route is not dependable for every setup. There is no free trial to weigh against a paid plan; SPAN itself is free.

Platforms

SPAN is available for macOS 10.12 and later and Windows XP, Vista, 7, 8, 10 and later. The stated minimum hardware is a 2.5 GHz dual-core or faster processor and at least 4 GB of RAM. Its plugin formats are AAX, AudioUnit, VST, and VST3, subject to the OS-specific download choices above.

Who it's for

Choose SPAN if you work in a supported audio host and want one free plugin for frequency analysis, loudness and level checks, and stereo correlation. Its multichannel views also suit sessions where comparing channel groups matters. Look elsewhere if importing and exporting spectra between tracks is central to your workflow, or if you need analysis outside a compatible plugin host.

Pros and cons

• Pros: Stereo, mono, mid-side, and surround analysis—including 5.1 and 7.1—cover varied session layouts.
• Pros: EBU R128, K-system, RMS, true peak, clipping, and correlation meters give users several complementary checks in the same plugin.
• Pros: Adjustable FFT and display controls let users tailor how spectral information is presented.
• Cons: Spectrum importing and exporting for easy track comparisons is a SPAN Plus feature.
• Cons: The free-plugin comparison workaround works only in some hosts, limiting its usefulness across setups.
• Cons: Supported plugin formats differ between Mac and Windows downloads.

Alternatives

For a different free mastering or audio-analysis option, browse Audio Mastering Software and Audio Analysis Software.

• Matchering is a free, open-source option for readers looking for software available on Linux, macOS, Windows, the web, or self-hosted.
• IK Multimedia ReSing fits readers seeking a voice and instrument tool: its free tier includes 2 voices, 2 instruments, and 1 RVC import, while model generation is excluded; the paid plan is $129.99 as a one-time payment and raises the limits to 10 voices.
• Tunr is another free option for macOS and Windows, with a free key by email counted per machine and a three-master allowance before the key.
• StudioZIO Mastering Suite is a free macOS alternative for users who want AU, VST3, AAX, or standalone availability without a licence key or account; it requires macOS 11 or later.
• TDR Limiter 6 GE may suit readers looking for a limiter rather than a spectrum-analysis plugin: its personal/small business license costs €60 as a one-time payment and covers one user on up to five computers.
• Acustica Audio Erin Studio is a paid macOS and Windows alternative.
• DSP-Quattro is a macOS freemium alternative with a free trial.
• oXygen Mastering Suite is a free option for Linux, macOS, and Windows.

Verdict

SPAN is an easy recommendation for audio producers and engineers who want detailed spectrum, level, and stereo analysis in a free plugin, especially when multichannel views are useful. Its main reason to choose it is the breadth of analysis and metering at no cost; its main reason to look elsewhere is the lack of general track-to-track spectrum importing and exporting in the free plugin.