My new Dipole Line Arrays speakers

[m.parigi]

Ok, I admit it: I've spent the last month or so totally ravished by how wondefully my new speakers sound.

I'm a long-time addict to dipole and ribbon speakers, over the years I've owned Maggies MGIII, Apogee Duetta Signatures and I'm currently the proud owner of a pair of Ambience ribbon hybrids (Super Slim 1800).
The last speakers have convinced me that the matching of ribbons with conventional cones is feasible, albeit difficult. The only area in which my Ambience fall short of perfection is the "punch" of very low basses and the sound pressure.
So, after having read Mr. Linkwitz material on the Phoenix and Dr. Griffin white paper on line arrays, I've decided to byte the bullet and to build "The Ultimate" pair of speakers.

I have to apologize because I haven't found out a way to attach more than one image to the post, so I'll have to make several posts...
Anyway, I'm going to give you only a few elements, because I don't know if my project might interest anybody. Should there be some interest, I'll be glad to give more information.

Here are the most important specs of the speakers (all numbers are referred to a single speaker):

Woofer section: Two Adire DPL-12 in a Phoenix-like (courtesy of Mr. Linkwitz) enclosure

Midrange: Twelve Peerless HDS series (the ones tested by Mr. Linkwitz) power tapered according to Dr. Griffin model

Tweeter: B&G RD50. Simply superb! It might lack a little bit of very high frequecies (above 16KHz, I mean), but I'm 46 and I don't miss them much anyway ;-)

Midrange and tweeters are mounted on a dipole MDF baffle, with cherrywood sides (they've costed me a fortune).

I haven't even tried to match the various drivers' efficiency with a traditional crossover, it would have been impossible in my opinion. In addition to that, I wanted to have a no-compromise speaker, so I've resorted to an electronic crossover and speaker management system like the Driverack 260. This drives 3 power amps, so that I'm tri-amping the speakers.

I've measured the speaker in anechoic conditions in my backyard, where I have no reflections whatsoever (I live in the country) and I've optimized the crossovers (100 Hz and 1100Hz), phase and linerity of the speakers by using "Speaker Workshop".
Then I've gone through several rounds of room optimization by using a couple of RTA softwares and Speaker Workshop in gated measuring mode.

The sound is simply beyond what words can describe. The cost too, unfortunately.

Should anybody be interested I'll be glad to post more information.

[m.parigi]

Close up of side

[m.parigi]

Back...

[m.parigi]

Assembly details

[mazeroth]

Very, very, very, very, very nice!!! I'm envious!

[Tim Moorman]

That is quite a massive undertaking. Most excellent. I like the crossover points above and below most of the voice region, except for harmonics.

You must be driving the DPL-12s quite hard to keep up?

Tim

[Jim Griffin]

Quite an impressive project with great looking results. I'm glad to hear that you are pleased with the sound.

Jim

[jdybnis]

Beautiful work.

I don't have any experience with these drivers, but couldn't you have crossed over the RD50 an octave lower? Did you try this? Also do you plan on experimenting with eq. You can boost the high end of the RD50 flat up to 20k.

[rcavictim]

Boy, you sure did spend some dough on drivers! That project sure is fine. Glad you are pleased with the results. I'd love to hear them.

You might get a slight improvement if you line the inside facing surfaces of the sides with 1" thick Rockwool or some fiberous sound absorber. Since the needle dust from rockwooll is nasty put some grille cloth over it to make it look and behave better.

[m.parigi]

Thank you all for your kind words, I really do appreciate. Should anybody happen to come close to Turin (northern Italy), you've got an open invitation to a listening session (and some nice wine or beer as well, of course)!

To Jim Griffin: your work and the speakers you've built, even if I never had a chance to listen to them, have been one of deciding factors for me to embark in this project. Thanks again, I wish I could meet you in person and have a nice listening session

To Tim Moorman: You must be driving the DPL-12s quite hard to keep up?
Actually, the DPL-12s hardly move even during the loudest passages. I've tried with some REALLY loud symphonic and pop music and I have to say that there's no hint of distortion or overload coming from the woofers. They're pretty efficient on their own and they're driven by a Classe C200

To jdybnis: re. Xover frequencies
I didn't cut the ribbons below 1100Hz because I was concerned about their ability to handle large amounts of power. The rational for this is that with the curent configuration the woofers handle approx. 3 octaves, the midrange approx. 3.5 octaves and the ribbons 4 (the Xover filters and slopes are Linkwitz-Riley, 24db/oct.). I didn' feel comfortable in increasing even more the power handled by the ribbons.

To jdybnis: re. boosting the RD50 flat to 20KHz
I thought about it, but something I read on Mr. Linkwitz site convinced me against doing it. By compensating the roll-off of the driver you're actually increasing the power (again!) handled by it. Since the RD 50 natural response has the 20KHz at -10dB approx., this would mean multiplying by 10 the power applied in that range (my understanding is that you have to double the power every 3 dB). Even assuming that the driver can take it all, I am concerned about the level of distortion that this would induce.
My preference lies in having the cleanest sound I can get and if the price is the 16 to 20 KHz range roll-off, so be it. What do you think about it?

To rcavictim: re. lining the inside surfaces.
Very good suggestion, I like it. What I don't like is the material you propose, it is messy and unhealthy (at least the kind I can get over here). What about felt? Do you think it would do the trick?