Black Rabbit Labs Presents
RACKSCOPE
Guitar Frequency Analyzer · Freeze it. Change it. Prove it.
Created by Garry G. PROFESSIONAL MUSICIAN, Lead Guitarist, Session and Touring Pro. CEO of SEO.
Live browser analyzer · Windows desktop app · No DAW · No account · Works with any audio interface
Meet RackScope Guitar Lab V1
The frequency bench built for guitar players
RackScope is a real-time guitar spectrum and reference-delta analyzer for players who want to see exactly where their tone changes. It is made for guitarists, modeler and amp users, pedal and IR builders, session and touring pros, engineers, teachers, and anyone dialing a rig into a full mix. RackScope measures your signal; it does not process or change your tone.
What it is
A focused guitar analyzer with a centered 0 dB reference, live spectrum, frozen baseline, measured Delta View, frequency tags, pink noise, and a hands-free lead recorder.
Who it is for
Use it with an amp, modeler, pedalboard, EQ, IR, audio interface, or full live rig. Compare before and after, verify a hardware knob, or find the frequency that disappears when the band starts.
What it helps solve
Inspect 80–250 Hz low-string blur and mud, 650 Hz–1.2 kHz honk, 2.5–4 kHz bite and mix cut with a highlighted 3.2 kHz target, and 5–7.5 kHz fizz or hard edge.
Why Black Rabbit Labs exists
Over the last few months, Garry searched for a metronome online and in apps with a very specific set of practice features. After checking what felt like every metronome under the sun, nothing did all of it. Ordinary metronomes are click, click, click: useful, but boring enough to drive a musician crazy after an hour. So he built the completely different BlackRabbit Metronome.
In The Matrix, they say to follow the White Rabbit. Black Rabbit is the musical, slightly evil brother. RackScope comes from the same idea: if the tool musicians actually need does not exist, build it.
Live RackScope Analyzer
See the analyzer before you read another word
The real RackScope is running below, with the frequency display moving immediately so you can see what it does. Click Start Engine when you are ready to connect your interface or microphone and analyze live audio.
Your audio is processed locally in your browser. It is not uploaded to SEO Inc.
The problem it kills
Stop guessing what your EQ is doing
You can hear that something’s harsh, but where is it? RackScope turns your rig into a measurement bench. Capture a reference curve with your EQ bypassed, engage it, and the Delta View draws exactly what changed: every boost, every cut, tagged live with its exact frequency and exact dB, right on the curve as you turn the knob. If your hardware says 800 Hz but the energy moves at 770, you’ll see it and compensate.
Live Frequency Tags
Every significant peak in your signal gets a floating tag pinned to it in real time: the exact Hz, right on top of the energy. Spot the boxy 300s, the harsh 3k spike, the ice-pick 6.4k fizz, by name.
Freeze & Delta
Freeze a reference with your EQ bypassed. Engage it. The delta trace shows the pure difference: your EQ’s actual curve, measured, not the one printed on the knobs.
Third-Octave Verification
Overlay the standard ISO third-octave centers, the same 31 frequencies as a classic Klark Teknik graphic, and see, in cents, how close your analog EQ really lands to its markings.
Pink Noise Generator
Full-spectrum pink noise, continuous or gated in 1.5-second pulses. It is the live-sound engineer’s trick for A/B-ing an EQ move by ear while the curve keeps drawing.
Lead Recorder
Record up to 90 seconds of your own playing, then loop it out through your hardware EQ and back. Dial in your actual guitar, hands free, held bends and all.
Measurement-Grade Engine
32,768-point FFT, 20 Hz–20 kHz log sweep, adjustable averaging from fast live response to slow measurement mode, peak hold, and a crosshair that reads Hz, dB, and the nearest musical note.
Sixty seconds to first measurement
How it works
Patch in
Run your EQ’s output into your audio interface. Open RackScope, hit Start Engine, pick the input. That’s the whole setup.
Freeze the reference
Bypass the EQ, run pink noise (or loop a recorded lead), let the curve settle, hit Freeze Ref. The amber baseline locks in.
Engage & read the delta
Turn the EQ on, open Delta View. The red trace is your EQ’s measured curve. Tags mark every band you move with exact Hz and dB.
Fix your tone
Loop your own lead, watch where the harshness lives, cut it at the exact frequency, and confirm the cut landed. Done guessing.
RANGE 20 Hz – 20 kHz LOG
GRID ISO 266 THIRD-OCTAVE
PRICE FREE
Built by a player, for players
From the Black Rabbit Labs workshop
RackScope comes from the same workshop as the BlackRabbit Metronome and RiffShead: practical tools born from real practice, studio, and touring problems. It is free to use in the browser, and the Windows build keeps the analyzer on your desktop. Your audio is processed locally; RackScope does not upload or track the sound you analyze.