Home » Audio » Speaker » New Project - The DR912a Line Arrays
New Project - The DR912a Line Arrays [message #70061] Tue, 08 November 2011 06:24 Go to next message
AudioFred is currently offline  AudioFred
Messages: 377
Registered: May 2009
Location: Houston
Illuminati (1st Degree)
The 42 drivers arrived last week, and I'll soon be headed to Home Depot to pick up five sheets of mdf, and to the woodworkers supply store to pick up the just-sharpened blades for the table saw. My friend John, who was the amp testing guy at this year's LSAF, will help me saw the panels. I've tried pushing full sized 4X8 sheets of 3/4" mdf through a table saw solo, which convinced me this is a two-person job if you hope to saw just the mdf, and not risk the amputation of your important and highly valued body parts too.

The DR912a is so named because each 7-1/2' tower will house nine BG Neo 8 PDR planar tweeters and twelve 7" Dayton Audio Reference Series RS180-8 woofers, actively crossed over using a dbx DriveRack PA+ loudspeaker management system. Each speaker will have its own dedicated 125w/ch stereo amp. Two downsides to this choice of drivers are that the woofer array will be more sensitive than the tweeter array, and the Neo 8's have a problematic frequency response curve and are normally used as midrange speakers, extending only to about 15khz. Neither should be a problem with this project, since the speakers will be bi-amped, with each section having its own level control and dsp equalization, and at my age I can't hear much above 15khz anyway.
http://www.parts-express.com/pdf/264-713.pdf
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-355
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=246-171


The towers will be fairly complicated, with a separate 4" deep internal tweeter chamber extending the full vertical height of the enclosures, plus extensive internal bracing that will effectively divide each tower into six two-woofer ported sections. I expect this to be a months-long project. I'll post updates.
Re: New Project - The DR912a Line Arrays [message #71186 is a reply to message #70061] Thu, 02 February 2012 06:04 Go to previous messageGo to next message
AudioFred is currently offline  AudioFred
Messages: 377
Registered: May 2009
Location: Houston
Illuminati (1st Degree)
Progress report. Click on a picture to enlarge: http://fredt300b.smugmug.com/Hobbies/The-DR912a-Line-Array-Speakers/21201321_b8FFDH#!i=1589877607&k=f7rFd45
Re: New Project - The DR912a Line Arrays [message #72940 is a reply to message #71186] Wed, 06 June 2012 08:23 Go to previous messageGo to next message
AudioFred is currently offline  AudioFred
Messages: 377
Registered: May 2009
Location: Houston
Illuminati (1st Degree)
Completed! http://fredt300b.smugmug.com/Hobbies/The-DR912a-Line-Array-Speakers/21201321_b8FFDH#!i=1885200568&k=BM9HXw2

index.php?t=getfile&id=791&private=0
  • Attachment: DR912a.jpg
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Re: New Project - The DR912a Line Arrays [message #72942 is a reply to message #72940] Wed, 06 June 2012 10:02 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18670
Registered: January 2001
Illuminati (33rd Degree)

Wow, those are awesome! Very impressive, Fred!

Re: New Project - The DR912a Line Arrays [message #72944 is a reply to message #72942] Wed, 06 June 2012 18:22 Go to previous messageGo to next message
AudioFred is currently offline  AudioFred
Messages: 377
Registered: May 2009
Location: Houston
Illuminati (1st Degree)
I need to replace the outside feet with some that are slightly taller so the speakers will tilt inward and, like the pillars of the Parthenon, appear to be straight up and down to a ground level observer. Laughing
Re: New Project - The DR912a Line Arrays [message #73187 is a reply to message #72944] Mon, 02 July 2012 15:21 Go to previous messageGo to next message
Ka7niq is currently offline  Ka7niq
Messages: 43
Registered: May 2009
Baron
Nice work Fred!
I saw you have had some old line arrays for sale, do you still have them ?
How far is Houston from what I do for a living in Tampa Florida ?

I was thinking on building a line array using all full range drivers, floor to roof, like Murphy does.
They say it gives a really clean sound, that images well ?

Re: New Project - The DR912a Line Arrays [message #73291 is a reply to message #70061] Mon, 16 July 2012 06:13 Go to previous message
rb132333 is currently offline  rb132333
Messages: 3
Registered: August 2011
Location: Pensylvania
Esquire
Ok Fred, you have to elaborate more on the results. You can't leave us hanging Smile How do these compare to like the XT-8 that you built in the past or the LS series or ?? Where did you cross? How is the bass response (need sub assistance)? Can you provide more 'meat' on the end result? Thanks.
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