Recommendation for two-way active crossover?

[MAP]

Greetings,

My first post here. I'm looking for a two-way active crossover, kit or finished-product unit, to accomplish a 2-way 4th-order LR filter with adjustable delay on the LP section, so I can keep group delay constant through the crossover region. This is for stereo, so a minimum of four channels of output.

I believe a miniDSP 2x4 HD or a Dayton DSP-408 would get the job done, but I've read reviews of these units that don't give me complete confidence that their distortion and noise would be negligible. I haven't heard any of these units, so I'm only going by hearsay regarding this...

I'm generally aiming for very high audio performance. And how do I define that? If I compare the potential active solution to an equivalent passive crossover network thoroughly within each filter section’s passband, the active solution shouldn’t sound in any way inferior to the passive one.

Is this a reasonable request? Do I have to use DSP and the requisite A-D and then D-A conversions, or can I go analog active? I’m looking at potentially 1ms delay in the LP section (1kHz target crossover frequency), which I know is sizeable.

My sincerest appreciation for any and all advice!

 

[xrk971]

I used MiniDSP 2x4 (non HD) measurements with and without.

The Nautaloss Ref Monitor

 

[MAP]

Thanks, xrk971. Can you confirm performance beyond matching of frequency response? Distortion, noise, and "transparency", for example?

Thanks again,
MAP

 

[MAP]

Hi Folks,

I dug around at Linkwitzlab.com and found the circuitry to execute this. Here's the block for the delay correction, for example:

http://www.linkwitzlab.com/images/graphics/allpass2.gif

The whole circuit is resistors, capacitors, and op-amps, plus a clean, stiff power supply. Since this isn't my area of expertise by any means, I'd be most grateful for any pointers here. It all comes down to low noise and good distortion performance, which I know may begin, but certainly doesn't end, with low HD. And it's the things other than HD that give me pause, and explain why I use arm-waving expressions like "good transparency."

Again, I'd be most grateful for any pointers. But if you still think I'd achieve the highest performance by buying an off-the-shelf solution (provided absolute max cost <$1k,) I'd be open to that.

Many thanks again!

Best,
MAP

 

[xrk971]

The MiniDSP sounded great - I had no complaints. It was my main rig for years and really let’s you play with the crossover settings on the fly. I use passive crossovers now so that I can test various amps against same speaker.

I think one would be hard pressed to tell that the miniDSP was altering the signature of the sound if it was just a digital pass through.

 

[MAP]

I appreciate your reply, but I remain unconvinced about the MiniDSP based on your qualification of using a digital input.

This online review of the HD version of the unit wasn't particularly flattering:

Review and Measurements and miniDSP 2x4 HD DSP and DAC | Audio Science Review (ASR) Forum

Provided I can get my 1ms or so of LP delay to happen without resorting to DSP, I'd very much prefer that, in order to avoid redundant A/D and D/A conversions.

Best,
MAP

 

[xrk971]

Not digital input, basic 2x4 miniDSP only accepts analog input and does ADC on board. I was not using it like digital audio interface but merely as a line level active crossover. You should just try it and return it if it doesn’t live up.

 

[MAP]

Hi Xrk971 - definitely good advice and I may well take you up on it. Thanks.

In the meantime, I sent an email to Phil Marchand at marchandelec.com and he replied he has modules for both the two-way filter I'm looking for, as well as delay blocks (I meant on the HP side, not the LP - editing oversight on my part.)

Best,
MAP