Anyone reverse eng. 801 bass alignment filter?

[Michael Rothacher]

Looking to build a discrete, balanced bass alignment filter for 801's

Thanks for looking

Mike

[sreten]

The 801's use a Bessel 4th order alignment, basically
overdamped, but well suited to typical room gain.

The classic way of re-aligning is a 2nd order high pass filter
set at the port frequency with Q adjustable between 1 and 2.

For a non-vinyl system with no subsonic rubbish, its also
possible to use a low bass shelving circuit, which has
better transient response, this can be entirely passive
at line level, as maximum loss would be 6dB.

Design of either approach is fairly straighforward.

sreten.

[Michael Rothacher]

Thanks for the excellent info!

[jackinnj]

do you mean to say "all pass" filter for time alignment? Here's the design which Ballard used in his 1982 Speaker Builder Article with "virtual instruments" thrown in -- the output of the filter lags the input by 50uS.

[scottnixon]

I used this for several years. Same target as B&W's box.