The DR912a Line Array Speaker System

[FredT]

Just completed, my latest project: The core element in this "system" is two 92"H, 14"W, 14"D ported towers, each housing nine BG Neo 8 PDR tweeters and twelve Dayton Audio RS180-8 midwoofers. The tweeter array is wired for four ohms nominal impedance. The woofer array is wired for 12 ohms. This results in almost equal sensitivity. The drivers are connected directly to each tower's dedicated stereo amplifier.

The active crossover is a dbx DriveRack PA+ crossover and signal processor. It is configured for three-way operation, with the summed suwoofer output connected to the LFE input of a Dayton Audio SPA500 plate amp. The subwoofer driver is a TC Sounds Epic 12 in a two cubic ft sealed enclosure. The sub is low-passed at 80hz with a 24dB LR. The midwoofer array is high-passed at 80hz with a 12dB LR, and low-passed at 1khz with a 24dB LR. The tweeter arrays is high passed at 1khz with a 24dB LR.

Everything except the mdf was obtained from Parts Express.

http://fredt300b.smugmug.com/Hobbies...0568&k=BM9HXw2

[Steve Henry]

I don't suppose yo will be bringing those to LSAF next year? Great job - wish I could hear them.

[Mayhem13]

Wow!

[bungelow_ed]

Wow! Simply wow! I'd sure like to hear those babies! That's some fine workmanship!

[FredT]

I don't suppose yo will be bringing those to LSAF next year? Great job - wish I could hear them.

Not a chance! They're taller than the doors and ceiling fans and weight quite a bit.

If you want to hear them you should organize a group of Dallas Audio Club friends to come to the July 14th Houston Audio Society meeting at my house. The DR912a's are the meeting topic.

I plan to have the Omni Mic system set up, and I'll demonstrate how different settings on the dsp effect the measured response: How I used several of the parametric equalizers in the DriveRack dsp to smooth out some peaks in the response, especially that notorious 12khz peak in the Neo 8 tweeter response. I'll also demonstrate the subjective-listening difference between ruler-flat response versus the response I finally selected for day-to-day listening (down about 3dB at 10khz).

[aarond]

Fred,
Nice work. I wish I weren't tied up in July so I could make your demo. Couple of questions:

1) Cost of the DriveRack you used on this? Advantages over DEX2490? I was planning on using the DEX if I ever get my LA project off the ground.

2) With the use of those NEO8's did you consider going open back on them (or the whole thing? It looks like you have enough room for an OB system to work, no?

[aarond]

Fred,
Nice work. I wish I weren't tied up in July so I could make your demo. Couple of questions:

1) Cost of the DriveRack you used on this? Advantages over DEX2490? I was planning on using the DEX if I ever get my LA project off the ground.

2) With the use of those NEO8's did you consider going open back on them (or the whole thing? It looks like you have enough room for an OB system to work, no?

[FredT]

Fred,
Nice work. I wish I weren't tied up in July so I could make your demo. Couple of questions:

1) Cost of the DriveRack you used on this? Advantages over DEX2490? I was planning on using the DEX if I ever get my LA project off the ground.

2) With the use of those NEO8's did you consider going open back on them (or the whole thing? It looks like you have enough room for an OB system to work, no?

I'm not familiar with the DEX2490. The DriveRack is $500. My first choice would be a DEQX brand unit, which I may add later.

With open back speakers you introduce another variable, which is the peaks and nulls created by the back wave reflected off the back wall and interfering with the front wave. This can be managed if you are able to position the speakers at least five to six feet out, but I don't have this capability in the room. I did have Maggie 3.6's in the room at one time and was able to get good sound, but only by pulling them out so far they were on the carpet in the picture, which blocked access to the master bedroom. It was easy to pull the maggies out to listen and push them back to sleep, but not these monsters.

[howard]

Fred,
Do you plan to keep these or will you be liquidating them in a few month? I would be interested in being considered if you decide to sell them.
PS: did you ever finish your second set of the ART array speakers with Pete
S' crossover? If yes, what did you think?

Howard

[FredT]

Fred,
Do you plan to keep these or will you be liquidating them in a few month? I would be interested in being considered if you decide to sell them.
Howard

These are keepers.

[greywarden]

Wow, nice, those are sexy.

[brokencrank]

Love it! Very happy to see others posting about arrays.
I have a few questions for those more experienced and am going to start a new thread so as to not clutter FredT's up.

[r-carpenter]

very nice build!
where did you cross BGs to Daytons?

[FredT]

very nice build!
where did you cross BGs to Daytons?

Both the low-pass and the high-pass are set to 1khz with a 24dB/octave LR. No science was used in this decision. I just set it there initially, and measurements indicated a smooth transition, so I haven't changed it. When the drivers have 100 hours or so of playing time I'll experiment with different crossover points and slopes, and measure & listen for any audible change.