Someone's selling a bunch of the "No Steeinkin' Badges" 269-469 drivers on the Trading Post section. I think I was the first person to offer to buy them.
So, what do I do with 18 of them? They seem to have a F/S of about 120hz, and are pretty flat from 130hz to about 16khz.
Tempting as a line aray is, I don't have a very large room. (I'm about 5-6' tops from each of my speakers.) Something that runs off of a T-amp is ideal, of course.
As a side note, I have access to a CNC router (WOOT!), and a place to sell speakers, so long as they're technically "art". If I were to make a speaker that was constructed primarily out of PVC pipe, and easily duplicated, I could make a very large profit, and as a student, profit is a good thing.
Someone said that the 269-469 works very well when coupled together in opposite directions, with one driver firing back and the other forwards. (They're wired in opposite phase). Although I'd probbably screw up trying to attach the drivers together, just placing them in opposite directions seems to work pretty well.
http://www.t-linespeakers.org/FALL/bipolar/index.html
So, what should I build? PVC pipe has been successfully used with TLs, although baffle step loss (which I don't entirely understand) seems to be a problem. And the bass is lacking horribly; how should I add more bass? (A single subwoofer for both speakers?)
So, what do I do with 18 of them? They seem to have a F/S of about 120hz, and are pretty flat from 130hz to about 16khz.
Tempting as a line aray is, I don't have a very large room. (I'm about 5-6' tops from each of my speakers.) Something that runs off of a T-amp is ideal, of course.
As a side note, I have access to a CNC router (WOOT!), and a place to sell speakers, so long as they're technically "art". If I were to make a speaker that was constructed primarily out of PVC pipe, and easily duplicated, I could make a very large profit, and as a student, profit is a good thing.
Someone said that the 269-469 works very well when coupled together in opposite directions, with one driver firing back and the other forwards. (They're wired in opposite phase). Although I'd probbably screw up trying to attach the drivers together, just placing them in opposite directions seems to work pretty well.
http://www.t-linespeakers.org/FALL/bipolar/index.html
So, what should I build? PVC pipe has been successfully used with TLs, although baffle step loss (which I don't entirely understand) seems to be a problem. And the bass is lacking horribly; how should I add more bass? (A single subwoofer for both speakers?)
I tried the PCV pipe with some of the NSB's. Was OK sounding at low volumes in the TL as background music. Sealed? Well, it made some noise. Wasn't great but wasn't bad. The reason I'm selling my remaining NSB's is to buy some proper full range speakers, or atleast as proper as they can get. Some Fostex or the Seas T18RE coaxials are in my next project. My wife never fully appreciated the concept of a line array on either side of the television. Go figure!
I resized the diyAudio reference project monopole TL (outside dims, using 3/4in MDF: 6.5in wide * 9in deep * 18in tall) and used the NSB in it. These turned out fantastic, everyone that hears them loves them!
Tom.
Tom.
renfrow said:
Sweet! Got any pictures?
(Now, to persuade the owners of the CNC machine to let me use it!)
Just checking - the inside dimensions are 5" (vs. 6" for the originals), 16.5" tall (vs. 16 and 3/8" for the originals), and 7.5" deep (vs. 8.75" for the originals). What about the L-shaped bit on the inside? Is it scaled directly?
http://www.partsexpress.com/projectshowcase/nsb/nsb2.htm
Everything from a single driver system to a line array.
Everything from a single driver system to a line array.
What I would do:
Nine-per-side line arrays using something like 2/3/4 power tapering. Required reading:
http://www.audiodiycentral.com/resource/pdf/nflawp.pdf
Because CTC distance is 4", it is recommended not to operate the array above 3.39 kHz. So cross over to a single tweeter at 3kHz or so.
Put the arrays in sealed enclosures. Buy a cheap pair of powered subwoofers. Run the arrays full-range, and blend in the subwoofers.
IIRC line arrays partially mitigate the need for baffle-step correction. (Is this true?) Don't worry about baffle step for now.
Nine-per-side line arrays using something like 2/3/4 power tapering. Required reading:
http://www.audiodiycentral.com/resource/pdf/nflawp.pdf
Because CTC distance is 4", it is recommended not to operate the array above 3.39 kHz. So cross over to a single tweeter at 3kHz or so.
Put the arrays in sealed enclosures. Buy a cheap pair of powered subwoofers. Run the arrays full-range, and blend in the subwoofers.
IIRC line arrays partially mitigate the need for baffle-step correction. (Is this true?) Don't worry about baffle step for now.
Spasticteapot said:
I only took 2 pictures during construction of this set (I'm building three more sets, with RS 40-1197, that I'm taking pictures as I go along.). The originals were 16-7/8in tall on the inside, and these 16-1/2. I made the dimensions of the inner divider such that the vertical piece was centered from front to back, and in length such that the distance to the top, from the top of the divider was the same as from the back side of the front to the divider, and the bottom of the horizontal section was that same distance. I then used a 2in section of 2in pvc as the port. It was inlet into the backpiece about 3/8in, glued, then the inner part was routed flush, and a 1/2in roundover was done on the outside of the port to make it a flared port. (I hope that all made sense
. I put 2 coats of damar varnish on each driver.This picture I just took, something funky going on with the flash, these look a LOT better in real life
.Tom.
Attachments
Array length would be 8 x 4in = 32in = 0.81m. At 1,500 Hz, near- to far-field transition would therefore be about 1.5 meters, seems like you are still getting advantages from array even if technically outside of "cylindrical" wave area.Scottmoose said:
"And massive Eq." Not if crossed over to tweet at or below roughly 3,400 Hz. Or maybe I'm not grasping something?
Although it wouldn't technically be a nearfield array, you would still get the power handling/excursion advantages of using multiple drivers, at the very least.
I have 10 NSB drivers sitting at home... 50 cents each is a great deal!
http://www.zillaspeak.com/50Cent.asp
Scroll down to see what i did with mine... cardboard box provided by HP toner cartridge.
http://www.zillaspeak.com/50Cent.asp
Scroll down to see what i did with mine... cardboard box provided by HP toner cartridge.
I'm not suggesting that the listener would need to be that close, but that the SPL drop-off will be a combination of nearfield (-3dB for each doubling of distance) and far-field (-6dB).Scottmoose said:
That is, even though the line array will not be true nearfield over all freqs, it will be still have a pattern different from point-source. The popularity of other "mini-arrays" (Jordan, Bandor, Seventh Veil) suggests to me that there still are virtues in line arrays that aren't 100% nearfield.
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