[sdiy] filter help

[mark s]

greetings everyone,

i am trying to build an active, tunable HPF (2 pole is fine) using no more 
than one opamp stage and one section of a pot (i.e. not a dual-ganged pot). 
also, it should have good phase characteristics and a small parts count.

it seems to me, from my limited perspective, that a Bessell requires a 
dual-ganged pot for changing the frequency, so i have ruled it out. can 
anyone enlighten me or point me in a direction ?

thanks!

mark scetta