BackgroundI built the V2's a while back, having gotten tired of "box" sound and wanting a good OB solution that also used coax drivers. Enter the V2's. Of course, my previous box speakers used a DEQX active crossover and 3 amps, while the V2's used passive crossovers with active OB subs.
Honestly, I was never quite happy with the V2 sound in passive mode. I guess I have just been spoiled with the sound of an active system, and the control it affords you.
I won't touch on the passive crossover much here, since I have gone active and want to focus on that. I will say that if you want to keep it simple and have an overall good sounding system, the passive crossover is all you will ever need.
Man, I've wanted to post this for so long and couldn't, at least not until tonight. My V2's are custom because I am running them with the V1 tweeters (with the rear chamber opened up to make them OB like the rest of the speaker). This was important to me because using the stock V2 tweeters resulted in a disparity between the total energy radiated into the room by the OB mids and the direct radiating tweeters.
I thought that this would be an advantage in a poor acoustic room like mine, but I was mistaken. The lack of consistency of radiating patterns between the mids and tweets was a far bigger deal than the acoustics of my room. Or, rather, the difference in radiating patterns seemed to make my room problems worse!
Danny of course is the most awesome person to deal with that I've come across, so an OB tweeter was sent to me in relatively short order (the OB V1 tweeter, to be precise). Since I am running fully active, he didn't need to design a whole new passive crossover for me. On the other hand, I was "on my own" with regarding integrating it properly into my speakers.
Going ActiveSo, the passive crossovers are kicked to the curb, and an active crossover in the form of a DCX2496 is put in it's place. You might think (as I did), oh this will be a snap, just dial in LR24db crossovers at 100hz and 1khz, then level match the drivers, and done. WRONG! There is WAY more to it than you think. First, you need a good mic. And I don't mean a crappy Behringer mic (or other sub-$100 cheapie). Earthworks is your friend. Spring for an M23, it's completely worth it. For software, there's nothing I've seen that's really better than the HOLM Impulse program (plus it's free!).
After you have those tools, it's time to figure them out - both the DCX and the HOLM software have steep learning curves - it's time to measure, measure, measure, make adjustments, and measure some more! Your efforts will sound terrible most of the time. ESPECIALLY with OB speakers, which add a level of complexity you don't have with box speakers (reverberant field and total power/room response, plus wrap-around cancellations/reinforcements). But keep at it. Eventually you will get there.
What I've Learned with the V2'sMisc - The first thing you must do - measure the midrange driver by itself, run full range. This is the heart of your speaker and it pays to get a good look at it's natural behavior without any EQ or crossover slopes applied to it. After that, measure your tweeter by itself from about 500hz on up, for the same reason - to see it's native behavior. BTW, I measure them at 6 inches, 1ft, and 2ft, and they all came out identical, so pick whichever distance you prefer it won't matter in the end.
Update 4/3/2011 - Save yourself a lot of time and heartache by focusing on the mid/tweeter crossover transition first. Mute the bass output and keep it muted. Select your mid/tweeter crossover point and slope, measure, dial in the EQ, and get it measuring and sounding excellent before you even begin to mess with the bass. In other words, treat the V2 like a 2 way speaker first! Only after it's sounding great as a 2 way are you ready to do anything with the bass. This also has the advantage of letting you focus your efforts - if you have your V2's up and running full range and they sound bad, it's almost certainly a bass issue (which you can verify by muting the bass output at anytime and just listening to the V2's mids/highs). If the V2's sound slow, veiled, or wooly, it's likely the bass that is the culprit.BassSome tips from my learning experience with the V2's (with V1 tweeters) - The low end dies below 50hz. You will need to dial in a 12db/octave boost (about 10db) to compensate. This is just a result of OB bass. Don't worry, you have the pure woofer power to deal with it, just do it. 2nd, response on these tweeters drops off a lot above 10khz. A 6db/octave boost (about 6db) fixes it nicely.
Update 4/3/2011 - Actually I've learned a bit more here that I wanted to update - first, OB bass measures and sounds different than traditional bass. And the bass boost you use in the very low end WILL affect/color the lower mids. Even though the bass "seems" to drop below 50hz, it doesn't, really. My initial attempt to bring it up w/a low pass boost of 10db was way too much. Somewhere between 3db and 6db actually sounds much better and more correct. If you are using the standard SA-1 amp, you don't actually have to worry about this, because it has the boost already built in. Finally, I used a 48db/octave Butterworth on the bass upper end, and the 48db/octave LR filter on the mirange driver's low end. This gave the smoothest transition between drivers. I also moved the crossover point to 220 hz, which I chose by ear, more or less.MidsThe tweeter has a bit of a resonance at 1.4khz, which is easily dealt with by shifting your crossover point to 1.3khz and using a 2nd order LR filter. BUT (and this is a big but), you must use an 8th order Butter worth filter on the mids. This is because the midrange driver droops a bit from 900hz otherwise. Using a LR12 on the tweeter and a Butterworth 8th on the mids keeps the transition nice and smooth, without the need for EQ to boost the upper range of the mid unit.
Update 4/3/2011 - I changed my mid/tweeter crossover point to 2khz, I just like the sound of the midrange driver a bit more extended. About 750hz is a peak that needs to be tamed (about -5db), and there's a drop off at 900hz (to 2khz) that needs to be boosted (about 5db). Same thing on the low end - there's a droop below 360hz that a low pass boost addresses nicely (about 3db). I ended up with a 48db/octave LR filter on the mids and on the highs, which worked nicely since I had boosted the upper end of the midrange driver. If you decide to use a shallow slope like Butterworth 1st or LR 2nd, the mid driver has a nasty resonant peak at 3.5khz, so make sure to notch it out. There's another peak around 4.5khz too, so I notch that one out too. The V2's sound MUCH better if you do this. Of course, if you are using a higher order 4th or 8th order slope, it's not really necessary.Tweeters - They have a bit of a peak at 3.5khz, and a bit of a dip at 2.2khz. These are VERY critical and must be addressed or the speakers will sound too sibilant. The top end also droops starting at 12khz, and a high pass boost of 6db fixes it.
Update 4/3/2011 - I've learned that the range from about 500hz to 3khz is by far the most critical of all. You must be absolutely anal about getting a smooth transition here, as even small problems will be magnified by our high level of sensitivity in our hearing in this range. Also, if you are using LR48 crossover slopes, you must invert the output of the tweeter or you will get a deep null at the crossover point. Besides having a smooth FR transition, running the tweeter with inverted phase has no affect on the sound (on the other hand, if you invert the mids, it does have an affect on the sound). Finally, the drop off at 12khz is very, very low in audibility. If you boost it 6db, it measures fine, but it affects the sibilance range and makes the speaker sound bright. A boost of 3db still gets you the correct level of sparkle and ambiance without the issue of sibilance raising it's ugly head.Yeah, but how do they sound?OK, I've wasted enough time with technical rambling. The sound? As close to real as I've heard. Still not "real", but then again, nothing in hifi is all that close. This gets you closer. I'm not a soundstage or imaging guy so I won't talk about that. But I am a tone/dynamics/transparency guy, and these are just beautiful in those areas. One of my previous speakers was the VMPS RM40's and the detail here is at least as good as them in my room. Bass is far better, and dynamics are similar. Not bad for a speaker literally half the size
For me (sitting nearfield) coherency is far better with the v2's. Probably due to the Coax nature of the mids/highs.
Hmm, I sense that you want more detail on the sound. OK, here it is - Brahms. If his second piano concerto moves me to tears, then it's a good system. If not, then not. The V2's allow me that experience. Enough said.
Update 4/21 - Try, try, try to get these puppies more than 3 feet into the room. Read up on the AudioKinesis site about why this is important. In summary, it's due to the rear signal not being delayed long enough, which causes two bad problems - 1st, image smear, things tend to run together more than they should, optimally. 2nd, it causes tonal shifts that make it necessary to use more EQ than you would otherwise. By pulling them out to about 4 feet (measured from the front baffle, so not as far as you might imagine), you get a much smoother tonal balance and better imaging by default, so less messing around in the DCX. Always a good thing.
Since my upper mids are less re-inforced by the room now, I can also lower the point that I bring the bottom woofers in. I went from 200hz, to 150, to 120, to 100, finally to 80. Since the midrange driver goes down to 90 hz strong, I can use the bottom woofers at 80hz w/a shallow slope of 6db and get VERY strong mid/low bass now without it touching the midrange at all. The subjective result is that the presentation has change from a "lower midrange centered" presentation, a bit laid back, to one that is not mountain-stream clear, with tensile strength, jackhammer dynamics, and center-of-the-earth explosive bass. D@mn, and I thought it couldn't get any better!
**EDIT**
As requested, as screenshot of the response I've been able to dial in -
