[pixelgrease]

Center channel? We don't need no stinking center channel! The sweet spot is slightly wider than my sofa. The toe-in design increases volume for the opposing speaker; as I move more to the right I am moving more on-axis to the left speaker and off-axis from the closer, right speaker. Since the waveguide for the compression driver forces the dispersion pattern to conform to the woofer's dispersion pattern, vocal and instruments continue to sound natural as I move to the side of the listening area. Even when I sit past the center axis of the opposite speaker; it always sounds like dialog is centered on the screen.

These are large speakers, but in my listening room they go below 25Hz before beginning to roll off. Using an SPL correction table, they are flat to 25Hz, -2db at 20Hz and -6db at 16Hz in my 15'x21'x8' media room. The room is deep enough that I can place the Prismas wider than the screen and have the wide sweet spot effect at the optimal viewing position. The sweet spot at the viewing position is as wide as the speakers are far apart, which allows me to sit in a dinner chair next to the sofa and still hear dialog centered on the screen.

Duke is like a brother to me... but in reality he's just a half-brother. I've listened to his speaker designs for over 30 years. The Rhythm Prisms were the first speakers he made that came into my price range but I got an early adopter/half-brother discount on the Prismas so I went for them. They are incredible. I was expecting 30Hz bottom and 20 lbs lighter. I love them. At the end of the first day of listening to them, I kept thinking, "I'm done. I've got as good speakers as I will ever hear."

The consensus among friends is that I have the best sound system. For demos, I start with movie scenes that show off the projector and sub, then switch to a music video and finally play just audio tracks. It really hammers home the fact that between "good for movies" and "good for music", "good for movies" is a cheap compromise.

[Randy]

Awesome. What's the rest of your system?  (not too interested in the video stuff)

[unclexray]

I just got a new pair of prismas and love em. I'm thinking of grills and I like the look of yours. Did you do them yourself or did you order them that way.

[pixelgrease]

System components:

• Pioneer Elite BDP-31FD Blu-ray player
• Western Digital TV Live Plus Media Player
• Epson Home Cinema 8700 UB
• FAVI HD-120 Motorized Screen
• Logitech Harmony 650 Remote
• Denon AVR-3311ci Receiver*
• Walnut Prismas with grills as mains/pantom channel center
• Anthony Gallo Acoustics Micro Ti side and rear channels
• Custom Corner Subwoofer with 10" Driver and Bash 300S Plate Amp. I designed the cabinet with Duke's assistance and he determined the driver/amp/port length requirements.

I wanted the Gallo Acoustics Adiva Ti's for the satellite speakers but I already had the Micro Ti's from a TV speaker upgrade. The Micro Ti's go down to 100Hz in-wall whereas the Adiva's go down to 80Hz on in-wall installations, but it's the same driver just with a little more internal volume.

The corner sub is at the rear of the listening area, closer to sofa than the mains. Planned expansion includes dual subs under the rear seating platform to replace the corner sub.

The speaker grills are optional and expensive. I had Duke install them before delivering the speakers. Ask Duke about grill options. He prefers his speaks sans grill, but I have children who still believe in Santa Claus and that speaker grills don't come off and I'll ride out that fantasy as long as I can.

* Edit 12/10/2011 - I replaced the Denon AVR-884 with an AVR-3311ci.

[tesseract]

What a wonderful place to relax, gorgeous room! The Prismas look right at home in there.

Have you tried throwing a blanket over the leather seating? It might help knock down reflections.

[unclexray]

Duke tells me that parts express offers a speaker grill kit. Has anybody tried the kit?

[pixelgrease]

I have no experience with this grill kit, but I did grill covers once the old-fashioned way. Actually, I probably just did them wrong. The horror of the experience was enough for me to pay Duke to make grills for me. I looked over the parts express kit and it looks easy enough to do.

It looks like you can make two Prisma grills for about $60:

• #260-346, Speaker Grill Kit, $18
• #260-348, Speaker Grill Frame Corner Kit 4 Pcs, $11
• #260-349, Speaker Grill Frame T-Joint Kit 2 Pcs, $5
• #260-332, Mellotone Premium Black Speaker Grill Cloth Yard 64" Wide, $25

Factory Prisma grill dimensions: 15.5" X 28.5"

Run the crossbrace 18.5" from the bottom of the grill between the compression driver and the bass driver. Cuts:

• (4) 16.25" lower side rails
• (4) 7.75" upper side rails
• (4) 12.25" top and bottom rails
• (2) 13.625" crossbraces

You might tape the sides to a straight edge when gluing to avoid an odd angle coming off the crossbrace t-joint. Aside from that it should be easy to keep the grill squared.

Note: If you buy the kit, be sure to verify my calculations before making any cuts. I only measure once and cut twice half the time.

[Duke]

Great photo, thanks for the information and details on DIYing the grille.   Yeah I hate doing grilles, but will if necessary.   Must admit they do look pretty good.

And really great shot for showing off phantom center channel mode... in case anyone missed it, that screenshot is from Phantom of the Opera.

Earlier today I spoke with one of my other Prisma customers, and since getting his pair, he has put his subwoofer and his center channel speaker up for sale.   He says neither are needed with the Prismas; he likes phantom center mode with the Prismas better than normal mode with his $1200 center channel.   Kinda cool.

Duke

[pixelgrease]

I made a few mistakes when I wrote "flat to 25Hz, -2db at 20Hz and -6db at 16Hz". My biggest error comes from only using compensated values from 25Hz down. Since posting, I went back over my readings and sound level is up at 25Hz after compensating. Here are corrected values:

• 16Hz    74.5db
• 20Hz    78.5db
• 25Hz    80.0db  <- room?
• 31.5Hz  73.0db  <- room?
• 40Hz    77.5db
• 50Hz    72.5db  <- room?
• 63Hz    79.5db
• 80Hz    77.5db

The median reading is 77.5 and variations are due to the reflective nature of my room. This looks more like "up 2.5db at 25Hz, up 1.5db at 20Hz and down 3db at 16Hz". I attribute the increase to room reinforcement. I was expecting around 50db at 16Hz -- 74.5db is far, far better, although I can't hear a thing at that frequency but get a really creepy vibe for 20 seconds while the tone is playing.

I did not expect the Prismas to have better bass extension than my subwoofer and I'm working on accepting that.