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Discussion Starter · #1 · (Edited)
I've got four Dayton RS 100-4's. I want to use them in a pair of bipole/dipole transmission lines tuned to 80hz. Im also going to attempt to laminate plywood to achieve a curved line. I have some questions:

Can two drivers occupy the same t-line?

Should they be wired bipole, dipole, or switchable?

Does the second driver's Sd affect the line length or cross section area?

Would curving the line be superior to the traditional folded line?

Attached is an un-proportional sketch... In the picture you can see a brace incorporated into one of the laminates to lock in the drivers.

I'm still in the brainstorming stage, any input is appreciated. The goal is to have them done by Christmas... We'll see

Specifications: * Power handling: 30 watts RMS/45 watts max * VCdia: 1" * Le: .67 mH * Impedance: 4 ohms * Re: 3.0 ohms * Frequency range: 80-20,000 Hz * Fs: 80 Hz * SPL: 87.2 dB 2.83V/1m, 84.2 dB 1W/1m * Vas: .07 cu. ft. * Qms: 3.10 * Qes: .57 * Qts: .48 * Xmax: 4mm * Sd: 37.4 cm2
 

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Elite Shackster , HTS Moderator Emeritus
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Sadly, I am not even close to a transmission line expert. But as a woodworker, I am really intrigued by this idea. I hope you get some design answers, because I'd really like to see pics of these completed! :)

The only place I know of that has transmission line info is quarter-wave.com
 

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Discussion Starter · #3 ·
yea, I've checked out quarter-wave and also Frugal-horn.com. Laminating the plywood will enable me to construct a very thick and dead enclosure. But, its really the concept of eliminating the crossover that is most appealing to me.
 

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Interesting concept. You are second one I come across planning on to do speaker cabinets from laminated plywood. Me being the first. :whistling: I will follow you progress.

I'm trying to build Nosov's Ortho cabinets for my small full range elements. Still working on it. At the moment I'm trying to figure out how to make reliable gluing between plywood and acryl sides. Unfortunately only information I have on cabinet is from this finnish site.


More pictures in my gallery at DVD-plaza (finnish forum) I hope it motivates you to continue on your project.
 

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Elite Shackster , HTS Moderator Emeritus
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My first thought would be clear epoxy and metal pins. The pins would do most of the work and the epoxy would seal it without gunking things up.
 

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Discussion Starter · #6 ·
interesting interpretation. Maybe I described it wrong. The plan is to cut out six patterns of the shape in the picture and stack each 3/4" plywood shapes side-by-side.
 

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Misunderstanding might be my bad. Anyways, nice curved transmission lines or horns can be made like I do mines. Making bending mold is only hard thing.

PS. I might try metal pins along with epoxy. First thing that came to my mind too. One friend just insists that epoxy won't stick to acryl. He couldn't give any reason for that, though.
 

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if you have two speakers in different points in the transmission line 'line', I would presume you could model the speaker as 3 individual transmission lines, or maybe 2 transmission lines and a passive radiator, so there would be the interaction between the speaker at the 'typical transmission line spot', then there is the interaction between the second speaker and the open end, then there is also the interaction between the second speaker and the other speaker... I would think the sum of these responses would be your actual output... it is going to be a bit hairy to model :) especially if you are not crossing over the speakers... if you do cross them over (and ones plays lower and the other higher) I would think, for the most part (except at the crossover frequency) the 'other speaker' could be seen as a passive radiator...
 

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Discussion Starter · #9 ·
Maybe I'll just build them and have a driver one fifth from the closed end, the other one third from the closed end, and vary the amount of fill at the ends and in between, trial and error?
 

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Discussion Starter · #11 ·
Made some headway on the speakers over the past two days. The New York snow storm gave me the push I needed to get started. Ive got them assembled and running, just need to finish them. My first impression was "WOW, There is acutally some bass coming out of these." After the initial shock, I was dissapointed with the upper frequency range. I havent tuned the line yet. I imagine some dampening will clear that up some. Attached are some pictures of the construction process.
 

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Elite Shackster , HTS Moderator Emeritus
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Great work. I love the look of them. Depending on what you don't like about the drivers, you may need to apply a shaping filter on them to knock down a cone breakup mode (scratchy shrill static-y sound), tame a resonance peak, baffle step compensation, etc.. Not a crossover, but it might tune in your response more if you can't get it all from port tuning. The nice thing is that these filters are usually only 2 or 3 parts.

Keep us posted!
 

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First, I hate you.. anoyone that can pull off that design deserves to be hated. :doh:
Second, I have no idea how the design works, but I like the way it looks. :nerd:
Third, have you tried placing the speaker in different places? For example, I would have thought a di-pole like that would need more space behind it. :huh:
Fourth, where are the REW graphs? :paddle:
 

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Elite Shackster , HTS Moderator Emeritus
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Easiest would be Room EQ Wizard on this site (REW for short). Go to the REW forums and there are a lot of recommendations. A $50 microphone, $50 mixer board, and some cables and the computer you already have. A bit more for nicer or calibrated mics, and if you use a laptop, you may need an external soundcard. Lots of good info in those forums.
 

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As as been mentioned by Anthony, testing equipment isn't too expensive
A common microphone is the ECM8000 which can be found for $50 all over the web. The only caveat is that it needs a microphone cable connection (XLR) on the sound card to attach it to.
REW is free for the download
And then find a sound card (external for laptops) that has a microphone connection (XLR). M-audio has a several that get good reviews.
 
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