DSP vs. active analog crossover vs. passive analog crossover. What is your take?

@russbutton wrote:

Now when you add in mid and bass drivers, with high and low pass filters there... It's a real mess. But we're not done there yet. Nope. Many of your extreme hi-end loudspeakers add in equalization to their crossover designs, which makes that impedance curve even worse. This is very hard for an amp to properly manage. That's why people drop many, many thousands of dollars on things like Krell, Threshhold, Bryston, or Rowland Research solid state power amps.

Now when you use an active crossover, an amp channel only has to manage a single driver. There's no passive, reactive component in between the amp and the loudspeaker driver. Then you don't need a megabuck amp to deal with it.

...

Another major benefit is that you can use much, much lower powered amps when you use active crossovers. A lot of power is wasted having to push through a passive crossover. You really don't need to push many watts into a tweeter or mid-range driver to get a lot of level out. You could even run a single ended tube amp on your tweeter, and a mid-level tube power amp on your mid-range driver, and a solid state amp for the bass driver. You have a lot of options.

So instead of dropping $7,000 on that Threshold Stasis 8.0 power amp. You could spend much less on an active crossover and the various much more modestly priced amps of your choice.

Unapologetically concise, to-the-point - one that actually gets it. Thank you, @russbutton. 

Yes, active crossovers are theoretically better than passive ones as russbutton points out.  You can read Nelson Pass's take on them in the Pass Labs XVR-1 manual on the PL site which includes many of the same observations and more.

There are downsides to active crossovers. Every commercially available analog one that I've owned (3 of them) has it's own sound. The Pro sound ones noted in the thread don't use very quality parts and probably sound like  sh@!. Heaven knows what the digital ones are built with.  I have a fairly nice DSP unit, and it too was far from neutral.  It did sound a little better when I upgraded it's power supply.

There are a few challenges to implementing an active XO in place of a passive one.  It's not "plug and play" . The results may be worse if you don't know what you're doing.  Read the chapter in Jim Smith's "Get Better Sound" if you want to know more.

My experience is based on 30+ years of using and modifying both active and passive crossovers in various systems including my current one.    

@russbutton Wrote:

Here's WHY active crossovers are so very much better than passive. A single loudspeaker driver is an inductor, and provides a frequency dependent, reactive load to an amplifier. Looking at the image here, the blue line on the bottom is the frequency dependent impedance curve for an SB Acoustics SB29RDAC Ring Dome Tweeter, and it typical of any dynamic tweeter. As you can see, it is anything but flat, yet it is listed as having a 4 ohm impedance. It's 4 ohms at about 1200 hz, but at 600 hz, has an impedance of nearly 10 ohms.

Now if you put a passive crossover circuit in front of it, you add capacitors, resistors and inductors, which then give you a frequency dependent impedance curve which looks like a Coney Island roller coaster. And that's just for a tweeter high-pass circuit

Now when you add in mid and bass drivers, with high and low pass filters there... It's a real mess. But we're not done there yet. Nope. Many of your extreme hi-end loudspeakers add in equalization to their crossover designs, which makes that impedance curve even worse. This is very hard for an amp to properly manage. That's why people drop many, many thousands of dollars on things like Krell, Threshhold, Bryston, or Rowland Research solid state power amps.

Now when you use an active crossover, an amp channel only has to manage a single driver. There's no passive, reactive component in between the amp and the loudspeaker driver. Then you don't need amegabuck amp to deal with it.

All of the Linkwitz loudspeaker designs use active crossovers. Earlier designs used analog crossovers, but his last designs were all digital crossovers. There are some digital crossovers that offer DSP EQ, which allows you to tailor the total system response for the room you are in. Then you're not just limited to whatever sound your speakers give you in the room you're stuck with.   

The lowest cost active crossovers are typically pro grade, from manufacturers like Behringer, dbx, Rane or even Nady. There are many manufacturers. Some of the best known home audio digital crossovers are from miniDSP.Another major benefit is that you can use much, much lower powered amps when you use active crossovers. A lot of power is wasted having to push through a passive crossover. You really don't need to push many watts into a tweeter or mid-range driver to get a lot of level out. You could even run a single ended tube amp on your tweeter, and a mid-level tube power amp on your mid-range driver, and a solid state amp for the bass driver. You have a lot of options. 

So instead of dropping $7,000 on that Threshold Stasis 8.0 power amp. You could spend much less on an active crossover and the various much more modestly priced amps of your choice.

Bravo!! Well said. Thank you, @russbutton 

Mike

Currently most AVR's offer passive biamping.  If AVR's can have another another adjustable crossover between 2k and 4k Hz similar to LFE crossover.  The users can implementing active biamping with either AVR's internal amp or external amps.  Then most loudspeakers do not need internal passive crossovers.  AVR manufactures will eat the speakers manufactures lunch.