[motosapien]

Are the adustable cross over and phase something you can create?  Maybe just an analog mini dsp would do the trick?  It does not take long to collect extra amps not to mention speakers in this hobby.  Appreciate some learned opinions.

[mikeeastman]

I don't know about learned  But I use a Dodd built classD amp to power my bedroom sub and I use a DESpeaker 8033-s as the x-over, works fine.

[motosapien]

Now that is a trick bit of kit.  Some what above my price range though (300 euros).

[JRace]

yes, a sub amp is just an amp with xover, phase eq...etc.

If you have a home theater AVR with sub preout then you don't need xover of EQ.

Phase may not be needed depending on the room, main speakers and location.

[*Scotty*]

You might want to look at the Behringer NU3000 iNuke Ultra-Lightweight, High-Density 3000-Watt Power Amplifie. If you buy the one with the built in DSP you have the crossover and digital delay you need to optimally set up your subs. This model or the next one up are on my short list to use with my rear subs.
It looks like a near perfect solution which puts digital delay and variable crossover points in one box.
http://www.amazon.com/Behringer-NU3000DSP-Ultra-Lightweight-High-Density-3000-Watt/dp/B005EHINAS/ref=sr_1_1?ie=UTF8&qid=1411181285&sr=8-1&keywords=Amazon.com+Behringer+NU3000+iNuke+Ultra-Lightweight%2C+High-Density+3000-Watt+Power+Amplifier
Scotty

[motosapien]

I'm a 2 channel hold out.  Don't watch the tele.

[*Scotty*]

I am also a two channel Luddite. I run the subs on the rear wall of my living room to help achieve flat bass response. I have two 12in. woofers per side in the floorstanding loudspeakers in my system and being flat to 18Hz. they load the room pretty hard.  The out of phase subs(180degress) in the rear tighten the bass up and reduce any room resonances. Strangely, they also improve the imaging. When you do nothing more than turn off the rear subs, the imaging becomes more 2 dimensional and stuck in the front half of the room.
Scotty

[randytsuch]

Hey Scotty
I was looking at those DSP Behringers
http://www.amazon.com/Behringer-NU1000DSP-iNuke-Power-Amplifier/dp/B005EHIN3A

And year, I agree, seems perfect for a sub.  A minidsp would work too, but for the price the Behringer looks really nice.

Randy

[*Scotty*]

It appears perfect for implementing the Controlled Acoustically Bass System (CABS). The linch pin is digital delay of the correct duration which
the Behringer iNuke amp appears to have.
Scotty

[richidoo]

Or the Crown XTi 1002. Similar function, much better reliability for $180 more.
http://www.amazon.com/Crown-XTI1002-U-US-XTi-1002/dp/B004ZGBLJO

You can DIY analog sub controls per your OP with plans and PCBs from here:
http://sound.westhost.com/projects-0.htm#xvr
Project 09 for the XO and Project 103 for phase. Also need power supply for the opamps.  Also some good articles linked on those project pages about subs. If you can position the sub at same distance to your ear as the main speakers then you don't need the phase.

If you have low output impedance on your preamp/source and high input impedance on your class D amp then you might get away with a passive, line-level crossover filter. It's only good for 12dB octave slope. A 24dB/oct slope will require a current buffer, like project 09 circuit above.  But it's worth a try, super cheep.
http://www.t-linespeakers.org/tech/filters/passiveHLxo.html

[motosapien]

Thank you for all the suggestions.  My initial application is to run woofers from 90 on down in a bi amped set up.  If I did not already have the class d amp I surely would have used a plate amp.  I may still considering the costs involved with these pro amps.

[Bob in St. Louis]

If you're looking for the controls, but not the amp, this might be what you want:
http://www.reckhorn.net/pages/active-x-over.php

Hope that helps!
Bob