REW Beta Release REW API beta releases

John Mulcahy · Mar 9, 2026

sm52 said:
John, after the second impedance calibration step, the level value becomes -3.01 dB. Although before that I set -9.7 dB in the measurement window, and took the first calibration step.

I guess the level was -3 before you changed it to -9.7? I have fixed it for the next build.

sm52 · Mar 9, 2026

John Mulcahy said:
I guess the level was -3 before you changed it to -9.7?

The level in the Measure window and in the Preferences window was -9.7. I installed them before calibration. Just in case, there is a video.

John Mulcahy · Mar 9, 2026

No need for a video, problem has already been fixed.

sm52 · Tuesday at 11:39 AM

There was once an issue that the measurement window took a long time to load due to the FSAF setting, even if the FSAF tab was not used. In the latest versions, the measurement window does not allow me to do anything for 10 seconds after opening. Similar to what it was before.

John Mulcahy · Tuesday at 12:34 PM

Doesn't give me much to work with. Every time you open the Measure dialog or only the first time? What are your Measure dialog settings for SPL, FSAF and Impedance? Anything else you can say about when this happens?

sm52 · Tuesday at 1:12 PM

This only happens the first time after running REW. All subsequent openings of the slowdown window are not present. Should I take screenshots of the settings of the three tabs?

John Mulcahy · Tuesday at 1:15 PM

Yes, please.

sm52 · Tuesday at 1:23 PM

Settings for three tabs.

John Mulcahy · Tuesday at 1:27 PM

How long is the FSAF file? Does the Measure dialog open in FSAF mode when you get the delay or is it in SPL mode? Is there a Busy indicator shown during the delay?

sm52 · Tuesday at 1:42 PM

FSAF file length is 35 MB. The delay appears with all three tabs with which REW was closed. But on the SPL and Impedance tab there is no delay indicator; a small window appears and disappears very quickly, the text of which is not visible. There is a delay indicator on the FSAF tab; it starts to 'spin', freezes almost immediately, and remains like that until the end of the 'Measurement' tab freezing.

John Mulcahy · 2026-03-15T08:03:50-0500

Builds updated today (beta 119) with these changes:

Added: German translations of the interface courtesy of Andreas Lartz
Added: The RTA has an option to show the hearing threshold when the Y axis is SPL
Added: The RTA distortion settings have a "Show note name" option to label the fundamental with the corresponding musical note
Added: prefboxlabels.properties and prefhints.properties have new entries for the RTA hearing threshold and RTA note name options
Added: API RTAAppearanceConfiguration has an entry for showing the hearing threshold
Added: API RTADistortionConfiguration has an entry for showing the note name
Added: The main window title bar shows when the API server is running
Changed: Revised FSAF file handling to reduce delays when opening the Measure dialog
Changed: Implemented a faster resampler for FSAF files
Fixed: Audio inputs and outputs with Cyrillic characters were displayed incorrectly
Fixed: Sweep level may not be properly saved and restored when making impedance calibration measurements

dcibel · 2026-03-15T10:32:16-0500

John Mulcahy said:
Changed: Revised FSAF file handling to reduce delays when opening the Measure dialog

Changed: Implemented a faster resampler for FSAF files

Thank you John, it's much faster now, maybe 5x.

REW Beta Release REW API beta releases

John Mulcahy

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sm52

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John Mulcahy

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sm52

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John Mulcahy

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sm52

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sm52

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