if you want an SAE stack let me know I know someone with enough SAE kit to make about three of them.
I diverge there sorry i'm in a humorous mood. but its true if you want.....
Luxman made a quality Eq in the mid 80's that had tone controls with cut off frequency adjustment. I had a similar option in a Luxman L560 and it was fantastic for what you need a tone control for. having the ability to tailor the frequency range is much better then a blanket adjustment. you may find something from them similar in a newer version the Japanese don't have the hang up of tone controls like we do here in NA.