Request: Unlock Frequency Limit Beyond 20kHz in Graphs and Filter Definitions

[YKH]

YKH

25 July 2025 at 1:27 am #1097

Dear Eclipse Audio Team,

First of all, thank you for your continued work on FIR Designer (M) and the powerful tools you provide to the pro audio and loudspeaker engineering community.

I’d like to kindly request a feature enhancement: Please allow the upper frequency limit (currently capped at 20 kHz) to be configurable in all graph windows and in FIR/IIR filter definitions.

While 20 kHz aligns with the upper limit of typical human hearing, there are several practical and technical reasons why extending this range would be useful:
Why Higher Frequency Support Matters

1) HF Driver Behavior & Ultrasonic Content
Many modern compression drivers and tweeters exhibit mechanical resonances or phase anomalies above 20 kHz. Even if inaudible directly, these behaviors can affect the audible band through phase shift, intermodulation, and nonlinear distortion. Being able to view and shape filter responses slightly beyond 20 kHz helps us manage those effects more accurately.
2) Measurement and Modeling Accuracy
Measurement systems often capture data well beyond 20 kHz (e.g., 40-48 kHz with 96 kHz sample rate), and many users operate at 96 or 192 kHz. Visualizing the full available response can help spot aliasing, truncation artifacts, or FIR ripple that might otherwise go unnoticed when limited to a 20 kHz view.
3) Export for Hardware Filters
Some hardware DSPs (especially in PA and measurement gear) allow filter coefficients affecting behavior beyond 20 kHz. Allowing design and export of filters that extend beyond this range – especially for use with oversampled systems – can increase compatibility and transparency.

Suggested Implementation
Add a user-configurable max frequency setting (e.g., up to 48 kHz or Nyquist) for graphs and filter plots.
Allow FIR and IIR filters to define and view their responses beyond 20 kHz, if the sample rate supports it.
This feature wouldn’t affect workflows for most users but would significantly help those working on high-performance systems, diagnostics, or R&D.
Also low and up frequency bounds may be configurable in graph like level min and max to comfortably zoom band limited channels.

Thank you for considering this request – and for your dedication to creating truly excellent DSP design tools.