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New Cheap Quasi Line Array [message #22854] Tue, 29 November 2005 08:42 Go to next message
FredT is currently offline  FredT
Messages: 704
Registered: May 2009
Illuminati (1st Degree)
No new messages in more than 20 days, so I'll break the silence with some info on the new quasi line array I'm building. Each sealed enclosure will have sixteen 3.5" Bravox woofers ($3.99ea from Parts Express) and a single tweeter in the middle (probably a Vifa DX25 if it's sensitive enough). This one will definitely require a subwoofer.

Re: New Cheap Quasi Line Array [message #22855 is a reply to message #22854] Tue, 29 November 2005 09:01 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18786
Registered: January 2001
Illuminati (33rd Degree)

I'm anxious to see that speaker. I was real impressed with your last array, so I'm eager to hear this one too.


Re: New Cheap Quasi Line Array [message #22856 is a reply to message #22854] Tue, 29 November 2005 10:44 Go to previous messageGo to next message
Mike T. is currently offline  Mike T.
Messages: 4
Registered: May 2009
Esquire
Looks like another great build Fred- would love to hear some of your many designs/projects. When is the next get together of the audio club? I am working on a set of the Axon 8-12's at the moment as I have for many many "moments". You are a building machine!

Re: New Cheap Quasi Line Array [message #22857 is a reply to message #22854] Tue, 29 November 2005 12:21 Go to previous messageGo to next message
Tom R. is currently offline  Tom R.
Messages: 51
Registered: May 2009
Baron
I am new to the forum, but have been reviewing posts, and researching line arrays for a few months, and am looking for a inexpensive project to start with. I have the sub to go with the array, so now just waiting on more input from you on the project. Please post more information when possible.

Tom R.

My Advice About DIY Line Arrays [message #22858 is a reply to message #22854] Tue, 29 November 2005 14:31 Go to previous messageGo to next message
FredT is currently offline  FredT
Messages: 704
Registered: May 2009
Illuminati (1st Degree)
People often express interest in my diy line arrays because they are really kewl looking, inexpensive to build, and sometimes they don't sound too bad either. But I don't want anyone to get the impression that a $250 line array will provide anything approaching "high end" sound. Folks who know me are aware that I'm retired and build speakers for fun because after 30 years working for big oil I found I can't just watch TV all day. The speakers fall into two categories: 1) Budget speakers (under $500 total) I build as fun projects and then sell to friends to cover my costs and finance the next project, and 2) Serious speakers I build to keep.

If you are looking for a project in the first category and they aren't going to be your main speakers a quasi line array (woofer array with a single tweeter) can be a rewarding project, and the final product, even with $4 buyout drivers, will provide sensitivity, dynamics and a soundstage you can't get with most smaller two or three way point source speakers. But almost any speaker built around cheap drivers will display some serious compromises in its octave-to-octave tonal balance (there will be some clearly audible peaks and nulls) and detail resolution. They definitely will not be high end speakers.

If you are looking for a pair of speakers in the second category (serious, high end "keepers") a budget line array is not the best choice. My guideline minimum expenditure is $1,000 because that's about the least you will spend for 16 to 20 quality woofers, two ribbon tweeters, and all the other parts plus enclosure construction and finishing costs. If your budget is less than $1K I believe you will get much better sound from a conventional point source two or three way pair using good quality $30-$60 drivers like GR Reserach M130 woofers, Dayton Audio RS series drivers, and many others. Also, if you don't have testing equipment it's impossible to design and tweak a crossover that will provide the sound a good quality set of drivers is capable of achieving, and it's best to get a speaker "kit" from one of the non mainstream companies who offer them, like Selah Audio, GR Reserach, RAW Acoustics, Pi Speakers, etc. With their designs the drivers have been selected by knowledgable people and the crossovers have been competently designed and tested.

Re: My Advice About DIY Line Arrays [message #22859 is a reply to message #22858] Wed, 30 November 2005 09:54 Go to previous messageGo to next message
Tom R. is currently offline  Tom R.
Messages: 51
Registered: May 2009
Baron
Thanks for the candid advise. Question: While looking at different line arrays or quasi arrays, it would seam like a line array with high quality full range drivers covering 100Hz to 12-15k, topped with a super tweeter may sound better than a woofer/Ribbon line array with a high order crossover in the 2.5 to 3K range, as the full range drivers would cover the most important frequency ranges, and keep
the crossover out of the midrange area. Please advise
Then again, if the crossover is well implamented, it may be a wash?

Tom R.




Woofer Array Crossover Frequency Limitations [message #22860 is a reply to message #22859] Wed, 30 November 2005 11:22 Go to previous messageGo to next message
FredT is currently offline  FredT
Messages: 704
Registered: May 2009
Illuminati (1st Degree)
Woofer arrays must be crossed over a fairly low frequencies because of the comb effect above the frequency where the driver starts beaming. I'll refer you to Jim Griffin's nearfield line array white paper for an explanation. See the section on center-to-center driver separation for circular drivers starting on page eleven.


Re: My Advice About DIY Line Arrays [message #22861 is a reply to message #22858] Wed, 30 November 2005 11:43 Go to previous messageGo to next message
Anonymous
To add;

I built a NSB/PT2 line array last summer. 49 cent midwoofers that
were modified, 16 per tower and 10 Dayton PT2 planars per tower
{$25 ea.)

While I consider this a budget line array, the plan was to make
'high end' sound and I think I achieved this as I auditioned high end store speakers and I wasn't too thrilled. The point is, while
the system is using 49 cent midwoofers and $25 tweeters, what really
gets you cost-wise is all the misc. costs that add up.

I itemized about 95% of the project on a spreadsheet counting every
screw, rags, gloves, nails, tools, glue, stain, magnets, plywood,
mdf, solid oak pieces, sandpaper, terminals, wire, solder,
chemicals, Acousta-stuf, poly batting, turntable, skidpads,
rope caulk, sanding sealer, liquid nails, bondo, etc., and the
project cost about $2k to make from scratch taking into account all
the stuff needed.

While DIY is cool, driver cost alone will not be a good judge on
project cost. Driver cost for this project was;

midwoofer = 32 * 49 cents {plus $1 shipping per driver} = $47.68
tweeter = 20 * ~$25 = $500

Driver cost = ~$547.58
Materials = ~ $1450

If I went 'cheap' on material costs, then the sound I get out of
the system would not be as good. 'Sum of all parts' is what makes it sound good including construction method and materials used.




Re: Woofer Array Crossover Frequency Limitations [message #22862 is a reply to message #22860] Wed, 30 November 2005 12:11 Go to previous messageGo to next message
Tom R. is currently offline  Tom R.
Messages: 51
Registered: May 2009
Baron
I down loaded the white paper the other day, but have only read
the first few pages. When I read the entire paper, I may have a few more questions - Thanks again.

Tom R

NSB/PT2 Line Array [message #22863 is a reply to message #22861] Wed, 30 November 2005 12:34 Go to previous messageGo to previous message
FredT is currently offline  FredT
Messages: 704
Registered: May 2009
Illuminati (1st Degree)
You are not the only one who disagrees with me, and maybe I should listen to some more arrays using "budget" speakers. I am familiar with the PT2 and it's a good sounding tweeter, easily the equivalent of dome tweeters selling in the same price range or possibly a bit more, and a much better choice than an array of 25 cent domes for use in a line array. But as you indicated, 20 of them will set you back $500. I haven't heard the NSB's so I can't comment about them.

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