Proposed Coiled TQWT Design

[Raphael Shaw]

Firstly, I am not too clued up about speakers, so please reply in understandable language if that is remotely possible.

I have been looking around on the weg for some nice speaker designs.

I am realy pleased with what I heard about TQWT's (Tapered Quater Wave Tube), but I always like to make things a little more personal, rather than just coppying designs.

I don't like the look of the straight pipes, they're too bulky.
But the folded pipes realy appeal to me, and I am going to build a pair anyway.

During my varios serches, I came accross B&W's TL (Transmission Line) design called The Nautilus, because it is coiled up in a spiral, like the Natural spiral of a Nautilus Shell.

This gave me the idea of making a coiled TQWT.
It would be similar to B&W's Nautilus, only I would put the driver, somewear along the middle of the tube, rather that in the opening at the end.

As I said I'm not exactly an accomplished speaker designer, and perhaps I'm missing some flaw in the design.

Also, to do a propper job, I am going to have to learn a bit of the theory behind the TQWT.

Can anyone give me any advice, or direct me as to where to find some. I think with some help, I could design some great speakers.

[Scottmoose]

Interesting idea you have there. Look at Martin King's website if you haven't already for everything you'll ever need to design a killer TL of any description, but particularly ML (Mass Loaded) TQWT from the man who cracked the mysteries of the transmission line. You'll find it here:
www.quarter-wave.com

Download MathCad Explorer 8 and Martin's TL worksheets, and play around. They look frightening, but thy're actually very easy -remember, Martin's done all the difficult Math. You just need to plug in the T/S driver parameters and then play around with the dimensions of the enclosure you want to build until you reach a satisfactory frequency response.
Also look at Bob Brines' site at http://www.geocities.com/rbrines1/
for some excellent articles on designing TLs using Martin's software.

Beware, or at least be deeply suspicious of most of the earlier works (as in pre-Martin) written about TLs -not that's there's much, because no-one really knew how they worked -it's all rule of thumb, trial and error tuning, and 99.99% of the theories are completely wrong. Lynn Olson's 2 way Ariel is one of the very few really good TLs that existed before Martin's work. For historical interest, generally the best that was possible using the old-fashioned way was that the line-length used to be tuned to the Fs of the driver, the driver being mounted 1/3 of the way along the line. It worked passably, with some hefty tweaking, but you can do a whole lot better now!
Best
Scott.

[Raphael Shaw]

wow that was quick
Thanks I'll check it out.

I only check in here once every couple of days, so don't worry if I don't respond to posts.

[inertial]

Hi Raphael, (sorry for my english)
Why not a clone of the Nautilus at all ?
Aura 1"
Aura 2"
Aura 4"
Hi-Vi 12" alu concave
If you are able to make the "cabinet"........

Regards,

[ShinOBIWAN]

There's a very good copy of the nautilus here:

http://www.pcpaudio.com/pcpfiles/pro...1/Odisea1.html

Gives a good idea to construction techniques required.

[inertial]

ShinOBIWAN,
IMO, This is FAR from the original Technical concept by L. Dickie.
Anyway it is very nice .
Cheers

[ShinOBIWAN]

Originally posted by inertial
ShinOBIWAN,
IMO, This is FAR from the original Technical concept by L. Dickie.
Anyway it is very nice .
Cheers

Agreed, I was talking from merely a construction point of view.

That design linked to has non of the internal labyrinths to cancel out rear wave dispertion from the mids and tweet, like in the B&W original.

Still its a looker.

[inertial]

I agree too

[Raphael Shaw]

I was realy looking for advice on the theory side of things.

Construction is never a problem for me.
For this particular project, I'm not too worried about how it looks, and I think I can get a good compact, aesthetic design, if I make the laberynth itself out of polystyrene, and cast concrete, or ceramic around it, and then disolve out the polystyrene with a suitable solvent.

However this idea could change when the time comes. But I'm not too worried about that sort of thing yet. Construction comes after design.

I was just not sure weather it would actualy work. perhaps the straight or folded tubes have an esential characteristic which a coil doesn't. Also I'm not too interested in TL, I want to make a Voigt Pipe, where the driver sits in the middle of the tube, not at the end.

What are the essential factors, for TQWT?
Total Volume?
Length?
Area of Cross Section?

How do I convert A Straight pipe into a coil with the same characteristics.

Another thaught I had, was to make the cross Section of the tuge Pentagonal, rather than round or rectangular. This would eliminate any parallel sides.

Thanks.

-Raphael

[Raphael Shaw]

-