Capturing is a short loop: route audio through the device under test, watch the transfer-function view while you align the two signals, freeze, refine the fit, and save.
Routing
Probe listens in two places: its main input reads the device’s output, and its sidechain reads the device’s input, so it can compare the two. Insert Probe right after the device under test, and route the signal feeding the device to Probe’s sidechain.
The routing, using Ableton Live as the example:
- Generate a test tone.
- Place an External Audio Effect after the test tone. It sends audio out to the hardware’s input and brings the hardware’s output back into the DAW.
- Place Black Diamond Probe after the external effect.
- Route Probe’s sidechain input from before the effect (the channel’s Pre-FX signal), so Probe can compare input against output.
For a software device under test, skip the external effect and insert the plugin in its place. The same routing works in other DAWs with slightly different steps - and Probe shows a routing reminder whenever its sidechain isn’t connected.
The test signal
A sine wave that spans the device’s full input range - say a 0 dB sine - is the best default. It sweeps the device through every input level, and because it’s a single frequency, phase shift from filters before the distortion just looks like a static delay, which the lag controls below can compensate. Bypass any EQ or filters in the device if you can - they break the clean 1:1 mapping a capture needs. If a filter after the distortion won’t bypass, pick a test frequency far from its cutoff - 500 Hz clears a DC blocker comfortably.
Aligning with X Lag and Y Lag
Any latency between the two signal paths smears the transfer plot into a loop. X Lag delays the sidechain and Y Lag delays the main input, each from 0 to 512 samples in 0.01-sample steps - drag the value, or click it to type. Only the difference between them matters, so in practice you leave one at zero and raise the other until the loop collapses into a single curve. Alignment happens while the plot is live; both boxes are disabled once frozen, so get the loop collapsed first.
Freeze
Freeze (the pause icon) stops the live plot and fits a transfer curve to the audio Probe has recorded, on a background thread. If you freeze before enough audio has accumulated for the selected capture length, Probe finishes the capture automatically as soon as it has heard enough. The display switches to the fitted curve. Play resumes live plotting; Save is only available while frozen, so save the curve before you resume.
Size and Algo
While frozen, the control bar swaps its live controls for two capture settings.
Size is how much of the most recent audio the fit uses - 16k, 32k, 64k, or 128k
samples. More samples take longer to capture but consider more context. Probe always
keeps the full 128k history, so changing Size while frozen re-fits instantly without
recapturing. Algo chooses the fitting strategy: Mean (the default) averages the
samples that land at each input level, and ODR uses a locally weighted fit that
tracks steep sections of the curve more faithfully. If a capture looks ragged with
one, try the other.
Smoothing
Smoothing tames noisy captures by running a smoothing window over the fitted curve, from 1 (off) to 100, default 50. It’s available only while frozen and re-applies as you drag, so you can watch the curve settle. Smoothing reshapes the stored capture, not just the display - what you see is what saves.
Save
Save (the disk icon, or Cmd+S / Ctrl+S) exports the frozen curve as a
.tfunc file. The first time you save, Probe asks for an artist name to embed in the
file’s metadata - you can set or change it later from the
menu. The save dialog opens in your
transfer-function folder:
- macOS:
~/Library/Audio/Presets/Aspen Instruments/Transfer Functions - Windows:
%APPDATA%\Aspen Instruments\Transfer Functions - Linux:
~/.config/Aspen Instruments/Transfer Functions
The saved curve is shape-only: the capture peak-normalizes both signals, so input level and Scale settings don’t change the result - only the shape of the distortion does. Saved files load directly into Black Diamond Distortion’s curve browser.