My first build - Affordable Transmission Line spiralled Loud Speaker

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Sparrowlegs

Sparrowlegs

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Joined 2013
#1
Hi Guys,
This is my first post, and my first build. Please bare with me...

I am planning to build a Transmission Line spiralled Loud Speaker. Yes, this will resemble the Nautilus, but that wasn't intentional from the offset.

The build will be made from Baltic Birch Ply segments glued together. Has anyone else tried this kind of builder before.

Attached is picture of what it should like when finished.

Speaker Design White.jpg

Also, has anyone ever put ceiling speakers in a floor standing cabinet?
 
#2
I thought I should upload a few more pictures of my design, would be interested in any feedback.
 

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#7
Sparrowlegs,

Is the TL quarter-wave (open terminus) or half-wave (closed)?

From your sletches i see 2 immediate issues. 1/ you are not taking advantage of driver offset to reduce the 1st undersired harmonic (less of an issue with 1/2 wave), and 2/ it is likely that your line is starting out far too small. Are you modeling this with something like MJK?

dave
 
#8
There is one school of TLS design were the idea is to lose all back radiation from the driver in the line. What you have is then similar to a closed box with resistive losses.This is very different from the TLS that use the quarter wave resonance to agument bass output similar to the port of a bass reflex speaker. So do clarify the type of TLS that you want to build.
 
#9
Hi Planet10,

This is where the fun begins. I don't know what the difference is between half and quarter wave? Looking it up now, but a brief overview would be grateful.

With regard to the driver, my design actually isn't strictly correct. Once the spiral hits 12 o'clock, the line will continue to the vertical till the driver runs flush with the belly.

Though I am not a true audiophile, I am able to construct interesting shapes.

This particular project will be made from Baltic Birch Ply.
 
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#10
Notwithstanding the questions of the desirability / acoustic performance of such a design, do you have any idea as to the complexity and material yield of such a fabrication technique?

I'm not saying it shouldn't or can't be done in wood, but as a first build, it'd be a very ambitious undertaking
 
#11
With regards to the complexity of the build, this isn't hard when using a computer to model. I have done all the drawings and plotted it onto a CAD. It's now ready to be CNC Milled. I have to 3D mill, as it's the only way I can get a gradient on ply without ripping the veneers, (IE you can't plane ply.)

I will admit it will be time consuming piecing it all together, but the technical work wasn't the problem.

This is intended to be a closed unit, though I was planning to test as I go along, IE if there's any difference having a plug in the centre section.

Still trying to get my head around half and quarter wave TL. Any overview welcome.
 
#14
I am working out the volume now, though it may take me half hour. With regards to the driver, this is why I was asking at the very beginning what the opinion of using a ceiling speaker for a floor standing cabinet.

I have a pair of Bower & Wilkins CCM663 knocking around.

Cheers for the link, I found this earlier, still trying to understand what Martin is talking about.
 
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