[Geardaddy]

I have been stewing over this issue recently.  A cursory, conceptual look at the subject leads one to believe that it is in some the way future.  Exotic material science is out and manipulation in the digital domain is in.  That being said, there is much cynicism amongst philes and less than stellar and non-analog fruit hanging on this tree.  Some companies are pushing the envelope and claiming good results.  Emerald Physics is one that comes to mind.  I wanted people's thoughts and experiences in this domain.

One conceptual problem I have with it is this:  are digital cross-overs in particular a source of jitter and thus perversion of the signal and corruption of that "analog sound" we all want???? 

[*Scotty*]

I'll express my concerns about the process. The amount money spent on the digital crossover is not sufficient to insure a that a top quality ADC is used. I am not overly concerned about added jitter from the internal digital processing but I will confess to ignorance about the potential problems that may exist. The DAC could also be a potential problem, you have to hope that a enough of the components budget is left to put a really good one on the end of the digital train. That leaves concerns about the analogue output stage and the power supply. There numerous reports on the web that a great deal of improvement can be had when the power supplies are beefed up and better op-amps used in the output stage. I believe there is also a mod that changes the DAC out for a better one. The reason for using a digital crossover in the first place is to do a better job than an analogue crossover commonly found in your loudspeaker as well as have room correction come along on the ride for free. In many cases the loudspeaker designer can do things with a digital crossover that cannot be done in the analogue domain. For example a designer can use a driver that has desirable characteristics but has undesirable behavior  such as ringing or cone breakup modes outside its passband. With a digital
crossover the driver can be rolled off steeply enough that problems it has outside its passband are not a factor. Phase coherency and perfect transient behavior are also possible.
The down side to this approach is that it requires two or more amplifiers for your system which can be a very expensive hurtle to overcome. The cabling required also has the potential to run the bill up substantially.  Speaking as a two channel purest for the moment I am not in favor of increasing the complexity of the signal path in my system anymore than is absolutely necessary for the signal to get from my source to the loudspeaker drivers. Every single gain stage in the system has the potential to lose information as the signal passes through it. At a minimum you have added at least one more op-amp to the signal path and the effects of the additional ADC and the DAC  are an unknown. Speaking for myself,I am not a candidate for one of these devices at this time,at the very least the cost of two more amplifiers is completely insupportable. Unobtainuim doesn't come cheap.
Scotty

[Geardaddy]

Thanks Scotty.  That is my bias as well.  According to Steve Nugent, whom I emailed earlier on the subject, Behringer units can be a major source of jitter.  At RMAF, he did use a DEQX active digital crossover followed by two Pace-Car reclockers and two Overdrive DACs.  That is a lot of extra fuss and potential expense even beyond bi-amplification and cabling.   .  It is vexing since it has so much promise. 

[*Scotty*]

It looks like jitter IS a major concern with these products and even after mods to the unit jitter probably remains to degrade the performance. It just keeps getting better. If the economy was stronger it looks like there might a place for a product that makes fewer cost related compromises and deals effectively with the jitter problems the units have.
Scotty

[Geardaddy]

Agreed....

[macrojack]

My dbx Drive Rack PA and matching mic cost $508 shipped from Amazon. I already had the cables I needed and you probably do too. For active bi-amping you need one more amp, not two and your woofer amp can cost as little as $200 with good results (Hafler, Adcom, others that are out of fashion). I have a Perreaux PMF 1850 reproducing frequencies below 450 hz. and I don't know nor care what kind of top end character it would exhibit since it won't be seeing any.

Jitter? Maybe it's there but my piano tuner friend was unable to detect it.

Scotty - In the dbx lineup you can find more professional Drive Racks already. Their audiophile caliber models go for as much as $4K.

I understand the thinking about audiophile purity but I'm here to tell you your fears are unfounded. Behringer may have problems; I can't speak about them, but the dbx stuff is really quite good. In fact, I think there are bargains to be had in the pro world that audiophiles would be wise to explore.