PLLXO with HP Attenuation

Member
Joined 2005
Paid Member
Hey all,

Looking to replace a somewhat noisy Active Crossover with a simple 2 way PLLXO. Did all the calcs and for my 100k input amp, came up with the value of resistors / capacitors for 1khz @ 2nd order. I would further like to have the ability to attenuate the High Pass as the Tweeter (compression driver) is quite a bit more efficient than the woofer on this open baffle (Selenium 220Ti - 2x Eminence 15A woofers). I could do an L Pad at tweeter, but would like to see if possible to do it at the line level.

First question is is it possible to just attenuate the HP with PLLXO?
Second question is before or after the tweeter PLLXO? (methinks before is best)
Third Question is what value pot should I use for the HP attenuation? (10k, 50k, and 100k Alps available)
 
frugal-phile™
Joined 2001
Paid Member
I usully adjust levekls with the gain controls on the amplifiers. Never had to attenuate the top. But for the bass amp i have, we added a 100k pot on the front so i suspect a series R would work.

That scheme would work with the top to, but since the input R on the Pre-amp is used as part of the PLLXO, the caps will likely need their value tweaked for different Rs.

Note that a 2nd order PLLXO is kinda “droopy”. I now try to design for first order PLLXO.

dave