Commercial crossover or DIY?

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Hello,
I want to biamp my speakers (Wharfedale Diamond 10.1) and I need a crossover.
My amp is a Marantz 4230 (quadradial) and it has 4 separate amplifiers inside, as well as 4 inputs for each.
So I was thinking of either diy-ing a Linkwitz-Riley 4th order active crossover that I can set the crossover frequency like my speakers passive crossover did, or buying a commercial one like a Behringer CX2300 (not cx2310!).
I don't have a lot of cash and I can get the CX2300 for 50$. It's upgradeable as well, all through hole components. Has more features than the diy route, and also a case. That's what bothers me the most at diy, cases. Expensive to buy separate.
Diy route I can try and get the pcb done locally for 5$ or so, or order from FusionPCB 10 pieces for 20$ and have a double sided pcb. Then there's the cost of the capacitors. Can't get away with less than 10-12$ only for them. Then power supply / transformer etc.
Even if I replace some parts in the cx2300 I still have a case/knobs/leds 🙂
Behringer CX2310 is a joke inside, lunchbox:
http://dcx2496.caraudiotechnique.com/files/includes/images/cx2300-cx2310.jpg
Behringer CX2300 is something else:
http://84.255.203.119/cx2300/IMG_0001.JPG
I can also upgrade it with output transformers from a Behringer DI4000 if I find a cheap one (has 4 Behringer OT-1 transformers inside that fit on the crossover board). If that would make any improvement to the crossover. Can experiment though.
Also the CX2300 is claimed to have a Linkwitz-Riley 24 dB/octave inside.
I also found the complete schematics for it.
I already diy-ied a Linkwitz-Riley crossover pcb about one year ago but for 2.1 output. That is not useful in this situation as I need 2x2 channels output.
I would also get the nice XLR connectors with the CX2300 (not that they are useful at the moment, maybe later when I have a balanced source).
Being knob adjusted I'd have at first to check the crossover point on oscilloscope but then it's fixed.
Also with the CX2300 I can adjust each channel gain as there's a 5db difference between the SPL of tweeter/midbass drivers. At least that's what the passive speaker crossover tells me.
Crossover frequency with level offset for the tweeter works out at about 1.85KHz.
I attached the difference between speaker passive/low level active crossover. There's no contest, and phase is great with active.
 

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Well, the Behringer design is actually a State Variable Crossover that is also presented on Rod Elliott's site. Project 148 to be more exact. What I wanted to build is Project 09.
I see that Rod Elliott himself said he used the state variable design until he upgraded it to the project 9 design.
Also weirdly enough I see that he presents the state variable crossover as 12db/octave while Behringer says it's 24db/octave. I had a look at the datasheet and it looks very close to the Rod Elliot's design.
I'm not sure if the overall result would be better (sq wise) by building myself project 9 or upgrading the cx2300. I would have all the extra features (like a case for starters 🙂 )
 
I didn't think of that actually 😱

I presume this would be a good start?

An externally hosted image should be here but it was not working when we last tested it.

Hi,

Could be built into the active x/o, but like RE's site electrical
L/R 4th order is nearly always wrong due to the drivers.
Proper acoustic 4th order x/o's are nothing like electrical.
Look at Zaphs site : zaphaudio.com

rgds, sreten.
 
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