3D Spiral Horns Anyone?

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Ok, so nobody has tried them - that doesn't usually stop people having an opinion, lol

Has anybody tired something similar? Would this idea work as a good quality transmission Line - any technical reasons against this?

I'm new to speaker building & have a pair of Jordan JX92S drives & wanted something that had the bass level of a GM MLTL but was less intrusive!
jkeny said:

...that doesn't usually stop people having an opinion...

Absolutely true - I have two of them (opinions). One is that I love the way the cursor works on that site ;) ; the other is that they look fascinating, especially the plexiglass version. I have a pair of the JX92Ss I'm still thinking about a home for - let me know if you think of trying these, perhaps we can share experiences*.

I must say I find the site a bit confusing to navigate - there's no easy way to differentiate the more recent designs from the older ones, and (worse), as far as I can see, there's no indication of which variation is - in the opinion of the originator - better or worse than any of the others. What is your take on this?



*Only if you are very patient, though - I am a slooow builder.
Panomaniac, Why has no one built them? - is the design flawed in some way? Can you give me a link to previous discussions (I can't find anything in search)

Aengus, I agree about the site - hard to tell which is best but I emailed the guy & this is what he replied:
Thank you for your interest to a 3D spiral speaker.

I have no experience of Jordan JX92S, which is too expensive for me.
The best matching design for JX92S may be AG180M.

Best regards,
Masaaki Takenaka

What do you think - is it worth a go? I need some opinions from experienced speaker builders as to the chances of success! Glad to share experiences if you wish to go ahead!
Joined 2004
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"Why has no one built them?" Good question!

Maybe too labor intensive for an unknown technology?
I've looked at the site for years, but never built. As the site grows, it gets harder and harder to figure things out. (as noted above)

I have heard some amazing little speakers that had way more bass than they should have. Used a "proprietary waveguide" inside the box. Port was too small for the spiral stuff, tho.

So it is possible.

Guess you have to decide if you want to take the plunge and find out if you're going to start a new trend here on diyAudio. :)
looks interesting, Yes.

However, remember good/bad, right/wrong. The Japanese tend to prefer a different type of bass to the average American.

One of the Fostex designs detailed on his site I theik with an fe 166, HE labeled his best yet then lined it out?

There is a thread over on the Lansing forum where a DIY'er built an ersatz Altec with some old woofers, and new compression driver for an old horn, he built a spiral horn with help from this gent.

I'm sorry I don't remember the title to the thread, ( may have been "ersatz Altec"?).

I'm trying to design a box and keep hitting results from the various and available box design prog's that I don't understand, too bad I studied business instead of physics....

Ok, I think I'll go for a 3D spiral version of the MLTL cabinets recommended for the JX92S drivers. WoodturnerFran is doing all the hard stuff for me i.e. the cabinet build, otherwise I wouldn't attempt to take this on.

As this is new ground & I have no idea about speaker building I need some experts to help in guiding me towards the most likely design to succeed with the Jordans.

My reason for going this route is to try to minimise the profile of the MLTL (mainly baffle width & height) while preserving the good bass response of this design, so I thought something like the Helix-AG150 cabinets shown here (about half way down page) http://www3.ocn.ne.jp/~hanbei/eng-angular.html

These are for the Fostex's 12 cm FE126E with low Qts (0.25) with a front port. Here's the spec
Full-range FE126E (Fostex)
Height 800 mm (except base)
Width 150 mm (except base)
Depth 180 mm (except base)
Air chamber volume; V 2.9 liters
Rotation number of spiral; n 5
Rotation number of sonic fins 6
Max length of sound passage; L 280 cm
Cross sectional area of throat; S 37 sq. cm

Now I know the JX92S are 14.4cm and total Q (is this Qts?) of 0.4 but and here are some measures for other designs including MLTL:
GM's original MLTL CSA = 30.0407 with a total volume = 932.46332

This trapezoidial version has a CSA = 30.04187 and a total volume = 932.4996

The CSA is cross sectional area, I presume. What is the significance of the rest? How should I optimise these figures for the JX92S?

Consider this a new DIYA speaker project which I will detail along the way with pics & the end result will be tested against Fran's Fonkens & Fonken tuned Towers & his Quad ESLs
One other thing I'd like members opinion on is something I brought up on another thread about some other non-standard ideas:
- screwing on the back of the cabinets rather than glue & screw.
- using thin walls for the cabinets

I know this mightn't be the widely agreed build method but the Rogers LS3/5As cabinets with screwed backs were the ones favoured by the BBC research dept and are considered to sound the best in a major shootout of all the flavours of LS3/5As. It's offered now by Sterling Reference as the thin walled reference cabinets so as well as screwed backs they have thinner cabinet walls than usual http://www.stoneaudio.co.uk/

The theory being, IIRC, that it acts as some sort of lossy baffle, helping to reduce some resonances. I'll look for the reference & post the link here.

Does this have any applicability here?
Joined 2004
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The Helix-AG150 seems like a good choice. Guess you'll have to try it and see.

As for screwed on backs, I've seen that mostly on pro gear, where you need to get inside the case from time to time.

And for thin walls, ask Planet 10, he knows all about them.
- screwing on the back of the cabinets rather than glue & screw.
- using thin walls for the cabinets

If you are building the spiral horn cabinets as described, IMO you wouldn't want the back to be removable, you would not be able to get to anything back there except the binding posts.

Seems more reasonable to me to screw on the front, then if stuffing is required you'll be able to get in.

I think you''ll still want to gasket the removable panel, regardless, to seal it when closed.

As to using thinwall material on the balance of the cabinet, just how thin? seems to me that where you'd use 3/4" front, back , top, and bottom. You could get away with 1/2" on the sides where all the spiral parts are glued as these would stiffen them up considerably.

That said, I am a noob, and IMHO advice is usually worth just exactly what you pay for it.

oops, I didn't go look at the referenced cabinet until after I put my foot in my mouth.

He shows 15mm ( that's pretty close to 5/8" in imperial, which right or wrong is how I'm wired to think....)

I think I'd stay with that as a minimum.

If I was to build that cabinet, I believe I would use 3/4" anyway ( maintaining inner dimensions ).

Thin wall cabinets

I wouldn't mix the classic BBC thin-wall cabinet technique with something like a horn or TL. The technique seems to work best on sealed and reflex enclosures. There's also some good info on this technique on the Harbeth site. They continue to use this technique in their modern, post-BBC designs.

PMC use heavier wall techniques in their studio and broadcast TLs.

FWIW, I'd have thought the 31" MLTL designed by GM would lend itself quite well to a folded, compact TL.
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