[Tyson]

I built the stock V2 a while back from GR Research.  I had the passive crossover for a bit, but ultimately bought a DCX 2496 and went active, with a tube amp for the tweeters, a 2nd identical tube amp for the mids, and a Crest CA9 for the woofers.  For a long time I mirrored the 1khz crossover point that the passive crossover used. 

I liked it a lot.  And I felt that going active definitely was an overall improvement compared to the passive crossover.  But as is my nature, I had to inquire and experiment further.  So I recently measured each of the drivers in isolation to see how their response curves looked without any crossover points applied.  The cool thing about the DCX is you can mute (for example) the bass drivers and the midrange drivers, and then measure ONLY the tweeters.  And not only that, you can go further and measure the tweeters running full range (ie, no crossover), or you can measure them with a crossover point of 1khz with a butterworth 6db slope, or a LR12 slope, or a LR24 slope, or a LR48 slope, etc.. and you can iterate that out to 1.5khz, 2khz, 3khz, whatever.....

The same applies to the midrange driver - you can measure it running full out, with no crossover slopes applied at all, to see how it measures "raw" in your baffle.  But you can also apply slopes at 1khz, 1.5khz, 2khz, 3khz, etc.... And different slopes - 6db, 12db, 24db, 48db, etc....

What I found in my setup was very interesting indeed.  First off, I found the tweeter sounds best if you keep it at 1.5khz or higher.  But here's the rub - I found that the midrange driver has a roll off starting at 900hz.  So you have a gap between the resposne of the midrange and the optimal range of the tweeter.  What to do?

Well, if you are passive, you pretty much have to cross in the tweeter at 1khz, where IMO it's not at it's best.  BUT, if you are active you can simply boost the 900hz-1.5khz response of the mids to allow it to transition to the tweeter seamlessly.  This is what I have done, and it sounds fabulous. 

More goodness - you can also easily try out different slopes.  For example, I set up the V2's to measure very well using a 48db/octave filter, and then reset everything and then got them to measure just as well using 6db/octave filtering.  Since I could "save" both in the DCX, I am now able to compare them directly.  Frequency response is identical between the 2, and I can switch in less than a second to compare them.  Only difference is the crossover slope.  I gotta say, the 6db setting just kills the 48db setting.  The 48db setting just sounds thin and pinched, while the 6db setting sounds big and full, like life.

But there's a caveat - full range measurement of the midrange by itself reveals a bad peak at 3.5khz, and a 2nd peak at 4.4khz.  A 6db/octave crossover will NOT deal with these peaks very well at all.  But, since the DCX has built in EQ, I'm able to set notch filters at each of these points to null them out, and still keep the benefits of the 6db/octave crossover.

Did I mention that I love using an active crossover

[Pez]

Active: the single most ignored improvement that makes one of the biggest change for the best.

[Tyson]

Of course, only those people already convinced re: active will listen to us.... Cause, you know, crossovers are magic.  Better to focus on cables and isolation feet.

[Pez]

  Tyson you elitist.

I think people in general know it's a huge improvement I just think maybe it's a bit daunting to start experimenting. Even more than cabling or room treatment etc. For me the biggest obstacle is the fact that you need multiple amplifiers.

[Tyson]

Hey, what can I say?  People spend big bucks on a cable, but won't buy an earthworks mic and mobile-pre USB mic-preamp?  That's kinda dumb.  Dive in and get your hands dirty!  You'll discover that you are just as smart as any designer out there (well, maybe not quite).  But I can guarantee this - you know your own preferences better than any designer out there!  And having the knowledge, experience, and control to dial in your speakers to your specific preferences is.... (wait for it)..... priceless!

[Bob in St. Louis]

I used a DCX for not only two channel but home theater for a couple years, something like four or five amps in all.
The ability to change slopes, XO points, and hell, even temperature compensation (!?!?!) with a couple mouse clicks via remote PC control was one of the most fun I've ever had in this hobby.

Storing "files" for whatever kind of mood I was in is nothing short of amazing.

But the DCX is a cheap cheesy piece of crap that sounds like **** for the main channels (I've sinced started using it for sub channels only), plus it's hard to mod due to the ultra thin PCB. The folks I've talked to that have modded these give plenty of warnings about that fact.

The machine is great for it's inteded use, just not for "audiophiles", in main channel duty.... In my humble opinion.

Bob

[macrojack]

Try an XTA speaker management system. Made in Britain - good as it gets.

[JoshK]

I thought you were using a DEQX for some reason.  Did Mike G mod your DCX for you?

[Tyson]

I've had the DEQX, the mgalusha super-modded DCX, and now a plain stock DCX.  IMO, going active is a bigger step up over passive than any of the mods.  Of course the mods take you further, but the stock DCX is pretty darn good, if you know how to optimize it.  That said, I do have my eye on the newer miniDSP 2x8....

[studiotech]

Hey, what can I say?  People spend big bucks on a cable, but won't buy an earthworks mic and mobile-pre USB mic-preamp?  That's kinda dumb.  Dive in and get your hands dirty!  You'll discover that you are just as smart as any designer out there (well, maybe not quite).  But I can guarantee this - you know your own preferences better than any designer out there!  And having the knowledge, experience, and control to dial in your speakers to your specific preferences is.... (wait for it)..... priceless!

Preach it brother!  Stop with the voodoo y'all and get familiar with science.  My project is all active 4 way.  DSP on 3 of the 4 ways.  Active crossovers and effective room treatments is where it's at. 

Greg

[studiotech]

I've had the DEQX, the mgalusha super-modded DCX, and now a plain stock DCX.  IMO, going active is a bigger step up over passive than any of the mods.  Of course the mods take you further, but the stock DCX is pretty darn good, if you know how to optimize it.  That said, I do have my eye on the newer miniDSP 2x8....

I am curious about the miniDSP too.  I have to say that in direct comparison btw the stock DCX and a BSS Omnidrive with the same settings, the BSS sounded like the proverbial veil had been lifted.  DCX was not bad by any stretch and its benefits probably outweigh its negatives, but looking for the ultimate solution, the DCX is not it.  It also runs out of processing power much faster than better processors.  Steep slopes and a few bands of EQ on each output and WHAM, it's 100% maxed out.

Greg

[Tyson]

The weakest link in my system used to be the passive crossover, now I'm sure it's the DCX.  The mgalusha modded unit and the DEQX were both better sounding.  But, ALL of them kick butt over passive...

[JohnR]

Nice post Tyson Hey, if you're preaching to the converted, count me in 

With that said, I'm likely to continue to play with other options like fullrange drivers and two-ways with simple passive crossovers. But with active I have gotten so much further with my main (OB) system than I ever thought I would.

I found that I preferred the 48 dB/octave crossover to the 6dB/octave one. To my ears and with my drivers/baffle, while the first-order xover initlally sounded more natural, in the end I decided that the steeper slope sounded cleaner and more dynamic. However, this is so dependent on the drivers and the specific crossover settings. I'll have another shot with the lower-order slopes again at some point. Which is I suppose your point - you can experiment with all of these without spending any more 

[jtwrace]

Hey, what can I say?  People spend big bucks on a cable, but won't buy an earthworks mic and mobile-pre USB mic-preamp?  That's kinda dumb.  Dive in and get your hands dirty!  You'll discover that you are just as smart as any designer out there (well, maybe not quite).  But I can guarantee this - you know your own preferences better than any designer out there!  And having the knowledge, experience, and control to dial in your speakers to your specific preferences is.... (wait for it)..... priceless!

Amen!

[Badwater]

Tyson, what measurement software are you using?  I am ready to go active, just need to pull the trigger on a mic, preamp and software.

Bill

[Pez]

Holm impulse is the way to go. Free and effective.

[Tyson]

Nice post Tyson Hey, if you're preaching to the converted, count me in 

With that said, I'm likely to continue to play with other options like fullrange drivers and two-ways with simple passive crossovers. But with active I have gotten so much further with my main (OB) system than I ever thought I would.

I found that I preferred the 48 dB/octave crossover to the 6dB/octave one. To my ears and with my drivers/baffle, while the first-order xover initlally sounded more natural, in the end I decided that the steeper slope sounded cleaner and more dynamic. However, this is so dependent on the drivers and the specific crossover settings. I'll have another shot with the lower-order slopes again at some point. Which is I suppose your point - you can experiment with all of these without spending any more 

Agreed on the slopes - on my speakers, a 6db/octave at the top of my mids actually gives me a very sharp roll off, acoustically, so a steep electrical filter is not needed.  For a wider band transducer, I might use a sharper filter.  It really does come down to the individual driver and your baffle. 

Tyson, what measurement software are you using?  I am ready to go active, just need to pull the trigger on a mic, preamp and software.

Bill

I use HOLM Impulse - it's excellent, and free.  I also recommend getting an Earthworks M23 measurement mic.  And I also like the M Audio Mobile Pre for the mic preamp.

You can get something like one of the Dayton or Behringer mic, but they need to be calibrated for flat frequency response, but their phase response is off, and no calibration can fix that. 

[brj]

You can get something like one of the Dayton or Behringer mic, but they need to be calibrated for flat frequency response, but their phase response is off, and no calibration can fix that.

I'm not at home to check, but I seem to recall phase as one of the 3 columns in the Kim Girardin generated calibration file for my Nady CM100.

[Bob in St. Louis]

You can get something like one of the Dayton or Behringer mic, but they need to be calibrated for flat frequency response, but their phase response is off, and no calibration can fix that.

Huh!?!?!? 
news to me. How do you fix that?

Bob

[jtwrace]

You can get something like one of the Dayton or Behringer mic, but they need to be calibrated for flat frequency response, but their phase response is off, and no calibration can fix that.

http://www.hometheatershack.com/forums/spl-meters-mics-calibration-sound-cards/31380-ecm8000-phase-response.html