Best way to Crossover JL Audio F110 into system

The excellent First Watt B4 retails for $1500, but Reno Hi-Fi sells it discounted. It provides a lot of flexibility: 1st/2nd/3rd/4th order filters in 25Hz increments from 25Hz to 3200Hz. All discrete components, no Opamps or IC’s.

But if a 6dB/octave filter will suffice, the "cap-on-the-amps-input-jacks" method is the most transparent way to go.

"I know that JL has a crossover for 3k, but was looking for "better and possibly more economical" way to achieve this."

I wouldn't use the sub. Your SF's completely outclass it. You should get better results running the SF's full range.

hambon---When a capacitor is attached to the input jack of a power amp (typically soldered to the back side of the jack, on the inside of the amp), it creates a high-pass filter which rolls off the signal the amp sees at a rate of 6dB per octave, starting at a corner frequency determined by 1- the value of the cap, and 2- the power amps input impedance. The formula for determining the cap value needed for a particular desired x/o frequency and with a particular amp input impedance can be found via a Google search. The value of the cap, the amps input impedance, and the desired x/o frequency are inter-related.

This method of high-pass filtering has a couple of sonic advantages over any and all active cross-overs, and one disadvantage. That disadvantage is that the slope of the filter is very shallow, only 6dB/octave. That is a 1st order filter, and active x/o’s commonly provide steeper slopes (2nd-3rd-4th order, 12dB-18dB-24dB/octave), removing more of the bass from the signal sent to the amp and then speakers.

The advantages are: 1- There are no active electronics added to the system; 2- An additional interconnect is not required (an active x/o does); and 3- It’s cheap! Just the cost of the caps (one per channel), plus the cost to have them installed if one can’t solder. Purists having been filtering this way for a long time.