[gitarretyp]

Images of construction and the finished speakers are linked in my gallery below.

History:

I commissioned Rick to design a dipole for me using Accuton c82 mids, BG Neo 3pdr tweeters and Seas Excel w22 woofers in February, and i finished them April 15. I decided to have these designed after hearing Rick's Tanzanites. After discussing what i thought were some shortcomings of the Tanzanites compared to another open baffle speaker I'd auditioned, Rick mentioned that he'd been interested in doing a dipole for a while and suggested using higher quality drivers than those in the other design I'd heard. Well, I couldn't pass-up the offer of a custom design with top quality drivers, all for a very reasonable price.

A few notes on the construction/design:

Since these were custom, the overall cabinet design was my idea. The woofers are in a 1 cu ft enclosure and roll-off below ~80Hz. They are meant to be augmented with a subwoofer. Since I don't have access to good shop equipment, a fellow Austinite and AC'er Hank cut the flats for me. I handled all of the assembly, veneering, and finishing. The only special thing I added to the cabinet was lining the walls with 3/4” Sonic Barrier. A bit of poly-fill stuffing was added to smooth out the bass. Binding posts are  Cardas Patented posts. Wiring to the woofers and mids are 24 gauge magnet wire in a 4 wire per pole Litz braid (aggregate 17 gauge). The tweeters are wired with 22 gauge fine silver from handmade electronics. The external wiring was made chew proof (one of my cats is wont to chew on cables) with cotton and techflex. The veneer is figured cherry, and the finish is three coats of danish oil sanding during and after each coat and five coats of poly sanding after every other coat. Spikes are Viablue HS.

Aside from my subwoofer, these were my first DIY speaker project. Overall, I'm pretty happy with the way they turned out cosmetically.

The crossovers are primarily Sonicap Gen Is with Solens on the woofer and one in parallel with the mids, Mills resistors, and a mix of Solen and Madisound air core and Goertz foil inductors.

Quickie review:

First, see the link below for my current system. They are setup firing straight ahead in an 8' equilateral triangle. They are ~50” from the rear and 25” from the side measured to the front center of the baffle, I haven't experimented a lot with placement yet. Previous speakers I've had in the same room are Eminent Technology LFT-VIIIA and Usher CP-6311s.

My one word description of these speakers is fantastic . The only faults I can find are: the low'ish sensitivity (85 db) means they like slightly loud volumes to really come alive (not that they sound bad at lower volumes), the treble is rolled-off above 15k (I only know from the response curves, not audibility), and the bass is too fast for my sub to keep up . I don't consider it a fault, but these do make bad recordings sounds bad (as I think accurate speakers should).

On to the details:

My musical tastes are pretty eclectic. To give you an idea, my regular test material includes: Eva Cassidy Live at Blues Alley, Diana Krall Girl in the Other Room, Norah Jones' albums, Ray Charles Genius Love Company, Kind of Blue, Pink Martini both cds, Tori Amos Tales of a Librarian, Westminster Choir Like as a Hart, Metallica Black Album, Nine Inch Nails Downward Spiral, Mapleshade Sampler Disc, Gladiator Soundtrack, Dark Side of the Moon (mofi), Allison Krauss Live, Blue Rider Trio Harp, Steel, & Guts, David Elias The Window, Tool Aenima, Neko Case Blacklisted, Death Cab for Cutie Plans, and Rebecca Pidgeon The Raven.

The overall sound of the speakers is very clean, neutral, and fast. Voices are the most natural I've heard. I hear no emphasis placed in any part of the spectrum, and the driver integration is spot-on. In fact, I have to be either very close to the speaker or near the floor for the integration to break-up. Lateral imaging extends past the speakers and is accurate but very spacious. The image sizes are a little bigger than life, but that's something typical to dipole imaging in my experience. The depth is the best I've heard in my smallish room. Partly because of the imaging, choral music sounds fantastic and makes the walls of my room melt away. The speakers handle micro and macro dynamics with aplomb. Somewhat surprising given the mtm design, the sweet spot is actually pretty big (anyplace on my listening couch sounds good), and the sound is reasonably good seated or standing. The speed of the bass and mids is excellent and captures the attack in percussion instruments, piano, and guitar very well. As noted above, my sub noticeably blurs some of the upper bass near its hand-off to the dipoles because it can't keep up.

Compared to my most recent speakers, the Usher CP-6311s, these simply trounce them. The Usher's bass is much slower and looser, the mids are colored and lack detail, and the highs lack considerable detail and air. Their imaging is less spacious laterally and in depth. They're up for sale on audiogon, if anyone is interested .

In summary, these speakers exceed my expectations. My girlfriend tacked a no new speakers for five years clause on my purchasing and building new speakers (I've been through three sets prior to these in the past four years), and I highly doubt I'll have to violate her conditions .

If you're in the Austin area and want to check these out, let me know.

I'd also like to add that working with Rick has been great. He's very accommodating and helpful .

[lonewolfny42]

They look great....nice job !!

[/list:u]

My one word description of these speakers is fantastic !!!

[/list:u]Happy listening !!!

I'd also like to add that working with Rick has been great. He's very accommodating and helpful

[/list:u]

One of the good guy's in audio..... [/list:u]
Chris[/list:u]

[Hank]

Hi, I'm Hank In Austin - I did cut the flats, veneer the front baffle slab from two pieces of 3/4" MDF and routed the recesses, through-holes and rear basket compression reliefs.  Jason did a great job assembling and veneering the speakers.  I really like the subtle, elegant look of the figured cherry.  

Sound:  Neutral comes to mind.  Voices are very natural sounding, and as Jason noted, apparent "speed" throughout the spectrum is fast.  I played an excellent recording of a percussion ensemble and the upper voices (xylophones, cymbals, etc) were THERE in Jason's living room.  I listened early on before break-in and didn't hear the wide, walls melting away soundstage that Jason mentions, so, I need to go back for a second listen.
Good job, Jason!  And Craig!

[Rick Craig]

Kudos to both of you guys for the excellent cabinet work  

I really enjoyed this project and plan to do more dipole designs. For those of you who don't have subwoofers I'm working on a 10" 3-way  

[OBF]

Rick,

Since you've played around with the DEQX, do you happen to know how a device like that (the room correction part, not the driver correction), or more specifically a TacT preamp would respond to dipole radiation?

I intend to use my TacT to integrate a pair of subs once I get them, and since they will be able to play fairly high (100-200hz), I find the open baffle idea very interesting but don't know if that would confuse the software.

[Rick Craig]

Rick,

Since you've played around with the DEQX, do you happen to know how a device like that (the room correction part, not the driver correction), or more specifically a TacT preamp would respond to dipole radiation?

I intend to use my TacT to integrate a pair of subs once I get them, and since they will be able to play fairly high (100-200hz), I find the open baffle idea very interesting but don't know if that would confuse the software.

That's a good question. I've not used the DEQX with any dipole designs but plan to do that in the near future. I have a friend using one with a dipole array and he's pretty content with the sound.

With the room correction aspect of the TacT or DEQX both of them keep this information proprietary. How they process the room response is a mystery and we don't know how they correct for the different formats (dipole, monopole, etc.). Fortunately I have a measurement system where I can go back and verify the results. With the DEQX you can do this but not with the TacT because of the way its' software works.

Rick

[Rocket]

Hi Rick,

I can only imagine how good this speaker sounds.  The accuton mids are my all time favourite drivers.  

Regards

Rod

[Rick Craig]

Hi Rick,

I can only imagine how good this speaker sounds.  The accuton mids are my all time favourite drivers.  

Regards

Rod

The midrange is exceptionally open and detailed, probably the best I've ever heard.

[Brucemck]

Rick, do you attribute that midrange to the open baffle design or to the drivers?

I've owned several open baffles, and they all had an "airy holographic" midrange, particularly on solo voices, that was really different than box designs.

[Rick Craig]

Rick, do you attribute that midrange to the open baffle design or to the drivers?

I've owned several open baffles, and they all had an "airy holographic" midrange, particularly on solo voices, that was really different than box designs.

Both the design and driver contribute to the results. I recently did a custom 3-way design using the Accuton but with a sealed subenclosure for the midbass. In this system the attributes of the Accuton were obvious but I believe the open baffle takes it to another level.

The rear radiation and side nulls have some real advantages over a sealed midbass. The depth is increased giving a more spacious and realistic soundstage. The side nulls also reduce the reflections from nearby walls that can degrade imaging. There's also some evidence that the absence of the backwave being re-transmitted through the cone makes a difference.

With the new 10" 3-way you can have a kit for $1,100 to $1,200 / pair. The pair with the MTM and W22 is $1,400 to $1,500 / pair. Both will easily compete with commercial speakers at $6K or more. Just take a look at what speakers using the Accuton drivers usually cost  

[OBF]

With the new 10" 3-way you can have a kit for $1,100 to $1,200 / pair. The pair with the MTM and W22 is $1,400 to $1,500 / pair. Both will easily compete with commercial speakers at $6K or more. Just take a look at what speakers using the Accuton drivers usually cost  ...

Two more questions.  What would be an estimate of cost for just the upper MTM section?

And 2ndly, if I was using a pair of sealed subs that could be crossed as high as needed via the TacT, do you think the dipole could be effective without the box portion so that it would be just an open baffle MTM?  I'm asking because I have no idea what the effective cutoff would be for the Accutons.

[Rick Craig]

Two more questions.  What would be an estimate of cost for just the upper MTM section?

And 2ndly, if I was using a pair of sealed subs that could be crossed as high as needed via the TacT, do you think the dipole could be effective without the box portion so that it would be just an open baffle MTM?  I'm asking because I have no idea what the effective cutoff would be for the Accutons.

About $1,000 - $1,050 for the MTM section. With the TacT you can apply EQ to cross them over to a subwoofer. Depending on how low you want to cross a 12-14" wide baffle is possible.

[OBF]

Thanks Rick.  Because I'm tenatively planning to go with a pair of small subs using the Adire 6.8s, I'll have a huge range of crossover options since it's designed as a midwoofer (however I assume corner loading them could cause a problem going up too high with localization).  That probably sounds like very wimpy subs to most people, but since I'm currently just using Ellis 1801 2-ways and the 6.8 is a little larger than the W18 and also has like double the linear excursion I'm hoping it takes the strain off the 1801s at loud volumes while also increasing the bass output by a decent margin.

I'm very interested in all the positive attributes of open baffle systems, just not sure if they're compatible with room correction.  I certainly like the idea of a narrow baffle if the subs were crossed high enough.

While it wouldn't shake the house, I wonder how good that might sound with a narrow MTM using the Accutons and BG planars + Extremis 6.8s for clean bass and integration/crossover via a TacT 2.2x.

[Rick Craig]

Thanks Rick.  Because I'm tenatively planning to go with a pair of small subs using the Adire 6.8s, I'll have a huge range of crossover options since it's designed as a midwoofer (however I assume corner loading them could cause a problem going up too high with localization).  That probably sounds like very wimpy subs to most people, but since I'm currently just using Ellis 1801 2-ways and the 6.8 is a little larger than the W18 and also has like double the linear excursion I'm hoping it takes the strain of ...

Having listened to the TacT with a line array I think it will handle a dipole without any problem.