On Sat, Jul 04, 2026 at 07:36:41PM +0200, Robin Gareus wrote: > I expect it's still the fallout from the days when it first became possible > to actually build a linear phase EQ, which is not possible in the analog > world where all EQs are "just short delays".
It IS possible in the analog world, but for audio (which spans 3 decades of frequency) it's not simple... When I worked in broadcasting (previous century) special telephone lines were used to connect remote locations to the studio. These provided 15 kHz of flat amplitude response and they were also delay-equalised which took quite an amount of analog hardware to do. 'Constant group delay' filtering is also essential in the analog RF parts of satellite transponders and similar equipment. But there the LP requirement is only over a relatively small bandwidth, so in most cases somewhat easier to achieve. But not for systems like e.g. Galileo where the required delay accuracy and stability is measured in picoseconds. Ciao, -- FA
