In this tutorial, we explain how to use the ‘Gain/Polarity/Delay’ tab in FIR Designer M, the third step in the workflow for designing custom DSP and FIR filters for loudspeakers and audio systems.
The GPD tab is used to adjust gain, polarity, and alignment delay that will be used in the target proccessor, particularly for multi-way designs. For this reason, this video is based on FIR Designer M (ie. FIR Designer “Multi-way”) rather than the single-channel FIR Designer. The GPD tab in less relevant for single-channel DSP designs, although the GPD tab in FIR Designer is still useful for mulit-way projects built from several separate single-channel projects across multiple independent channels.
This video demonstrates how to:
- Align low-frequency and high-frequency loudspeaker drivers using gain, polarity & delay parameters
- Compare driver phase and phase slope through the crossover region
- Use the ‘Second View’ window to monitor filtered responses while working in the GPD tab
- Optimize crossover summation and reduce excess phase rotation between drivers
This video is the third in a new-for-2026 tutorial series, with each video focused on a single FIR Designer workflow tab. These new tutorials will gradually replace several older tutorial videos, ensuring coverage of the full feature set available in current FIR Designer versions.
