Hi Jim
My 2 cents ( okay there's more than that ) on this topic is;
I'd be more concerned with maintaining correct phase relationships than "time-aligning" those two components.. I realize that's an obscure / meaningless statement so I'll give you an example of a present dilemma I'm trying to work out a solution to . It all goes back to my playing around with DC blocking capacitors ( hence the title of my injoke - Ian should appreciate this ) & listening to the sonic signature of different dielectrics .
Some background; I use a 24 db/octave, LR slope type , active crossover ( 1st generation Behringer ). My only HF EQ is a simple RC network that depresses the mids and effectively adds a 6db per octave "boost" that fights against the 9 or 10 db/octave roll-off of my big 2441 drivers. This isn't a "flat" curve but the net result sure does sound musically correct to me. This setup on a small round-mouthed horn gives stellar results, like pin-point imaging and great depth of sound-stage. No synching up of the woofer & compression driver is involved or is a contributing factor in my musical enjoyment. The voice coils have about a 4" offset .
BUT - add in those damn DC blocking caps and my great soundstage collapses or compresses. For a couple of weeks I thought I was listening to a particular quality of the caps themselves until I twigged that this problem happens with all my types of DC blocking caps. The lurching-trail of logic has become that I am now reacting in a very negative fashion to an LR circuit that has been tragically mucked with giving the Hi-pass secton a 450° phase shift. This is easy to do with active components . For two years I've listened ( more or less ) to music with no DC blocking caps in place. So, the 90° phase-shift added onto that of the 360° hipass section has created something quite distracting to my ears. I can time-align the 2 sections but my ears tell me its far from the same. And I think the analog "bucket-brigade" delay section of the Behringer is a linear-phase type that begins correct in the crossover area and then just keeps adding increasing delay ( and phase offsets ) into the low pass section. In a couple of weeks , when work patterns permit, I'm going to turn my DC blocking caps into a 12 LR style network ( gloomed ontop of the choosen active frequency ) - then flip the drivers polarity and see if this does the trick for my ears by restoring the lost LR phase relationships . Going all passive may be a better option .
Obviously the domino effect of one change can be quite staggering .
Can I ask why you are concerned with time-aligning? It's mostly relevant ( to vertically alligned transducers ) within a single horizontal plane ( while these pesky phase anamolies will exist over a much broader listening area ).
If you go digital; I'd suggest a CD player with a digital out allowing you to keep it digital until you get to the best sounding DAs in your setup . This could also mean buying Apogee DACS and using them after the crossover if it has a couple of AES digital outs - which I can't remember if it does .
regards <. Earl K :)
