Crossovers?

Read what "Mr. Active" says here:  https://sound.westhost.com/bi-amp.htm

The unit that you eventually decide to use will provide bandpass capability for the mids.  Before you go this route of using active through the entire range of freqs, ask yourself what it is about the mids-to-tweeter transition, using the provided passive, that you want to improve on.  The passive has an impedance correction and certain tonal characteristics that you will miss using an active filter.  That might be one of the things you heard that you should be cautious of.

...and that's about all I know about active filters.

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If you are going to bi-amp or tri-amp you can certainly use passive crossovers, but unless you are very skilled and experienced with passive network design I highly recommend using a good 3-way or 4-way active crossover instead.  This will give you the ability to fine-tune the system to match the driver's capabilities rather than guessing, building fixed passive networks and being stuck with whatever results you get.  You will also need to know the fs of each driver to choose your crossover points, and an RTA really helps getting the system response curve tweaked and the amplifiers gain matched to the drivers sensitivities (although a good SPL meter can be used for that if you know what you're doing.)  You may end up needing a good EQ to tame some harshness depending on a number of factors including driver location.  Setting up a good bi or tri amped system is a challenge but can result in some incredible SQ when done correctly.

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Thanks for the article. I understood a fair amount of it, but some of it was a little over my head. May be you can clarify a few things. He mentioned using a 20uF capacitor to prevent DC from reaching the tweeter voice coil (section 3.2 of article). So if I'm using a 3way Active Xover do I still have to worry about this?

He also talked about "padding" to help equalize each speaker's sensitivity (i.e. Low 90dB / W @ 1m, Mid 93dB / W @ 1m, High 92dB / W @ 1m from section 1.10). Pad the mid's 93dB by 3dB to equal the low. Is this something I have to worry about with an active crossover? I wouldn't think so, but I want to make sure.

Is there any electrical components that I'll need (i.e. capacitors, resistors, et cetera)? I wouldn't think so. I would think it would just be a matter of tweaking the crossover and amp gains.

Next question is choosing the appropriate amps for proper output to each range (low, mid, high). I had a basic understanding of the equations he gave (although I couldn't figure out where the button is on my TI-83+ to calculate the "antilog" for P2 = antilog (dB / 10) * P1 from section 4.2). Anyway, I have a Butler Tube amp (4x75 @ 4 ohm) and soon, hopefully, I'll be getting the Seas/Lotus Ref. tweets(89.5 dB, 6ohm) & 6.5 woofers(90 dB, 4ohm). I'm not sure of what sub and sub amp I want to run. Perhaps Dayton Titanic 10 or an Adire Shiva or Koda and not sure about the amp (I want solid sq in the lows, but don't want to break the bank). If I send two channels to the tweets @6ohm (56w?) and two to the mids @4ohm (75w) will they provide roughly equal output? If this is good, what kind of output should I look for from my sub amp? According to the article's formula it would call for 118w to the sub(for the Dayton with an approx. 88dB Sens.), but that seems a little light. Although, the article did say tri-amping was the eqivalent of doubling your amp output.

DYon said: "You will also need to know the fs of each driver to choose your crossover points..." Is "fs" the equivalent of "Free Air Resonance"? How do I use the fs to determine crossover frequency?

Please forgive the length. I do appreciate your help.