Re: FIR filters
The delay is fixed, but you select what time or “alignment delay” you want e.g. 1.25, 2.5, 5, 10, 15 or 20 ms. The compromise is the lowest frequency you can achieve and the slope. You can also configure one LM26 as a mono 4 way crossover. In this case I think they combine the FIR modules and you can obtain crossover slopes that are twice as steep. E.g. (from the manual pg 94 - ish)
3 way mode
- 1.25ms = 13 dB/oct at 500Hz, up to 93dB/oct at higher frequencies
- 40ms = 14 dB/oct at 32Hz
4 way mode
- 3.15ms = 13 dB / oct at 220Hz, up to 180dB/oct at higher frequencies
- 25.17ms = 24dB /oct at 62 Hz.
http://www.reflechi-son.fr/paris/manuel-utilisateur/Dolby-Lake-Controller-Manual.pdf
