Ever think of building a Cornu Spiral horn? Now you can!

[xrk971]

Originally Posted by mondogenerator

I fancy trying the micro version as i have a couple of types of 2 inch drivers. Is there a preferred range of Qts that will work best in the micro cornu?

Mondo,

I am having a blast listening to the Micro's yesterday and today - about 8 hours total now. They sound amazing considering that the sound is coming from a tiny 2 inch driver that I pulled from cheap PC speakers. There is a lot of nice bass down to about 120 Hz I would guess based on the songs that sounded nice. The Micro has the big advantage of being very easy to build as the channels are 2 in tall, the facers are relatively small, and I did the whole thing in hot melt so I did not have to wait for the front face to dry with PVA glue.

Your question of Qts for the 2 in driver: I am using what appears to be a high Qts driver (as most cheap drivers are) that resembles a Visaton FRS5. I thik Qts is of order 0.9. It works great. I think it would work well with a wide range of Qts. If you wanted to get technical, use hornresp to model a long horn, then use some math to divide that and curl it up and come up with your own design. Or just try it - the amount of effort needed to expend to actually build it is very little compared to how much effort might be required to sim and design from scratch. Do you have TS params for your 2 in drivers?

Good luck and have fun!

[xrk971]

Originally Posted by jacco vermeulen

Cal,

(maybe because it's not a folded horn, not a single horn exit opening/location, Hey ! And so flat)

The multiple horn openings on the edges combined with the flatness which permits wall mounting makes the sound unique - and special. The sound, for the lack of a better word, feels roomy - like it is coming from a much bigger speaker. This probably has to do with the reflected sound from multiple walls ceiling/floor reflections combined with the mids and highs which come from single point source which just anchors the spatial imaging right on. So you get the feeling that it is a roomy concert venue, but you are sitting in the front row because you can localize the lead vocals from the singer or the instrument players.

[Cal Weldon]

I am thinking of going up to a 5.25" driver. The ever popular RS-1354. Already with planet10 treatment(s). I wonder how big that would be if we kept it at 4.5" walls and did the Pentagon box?

[mondogenerator]

thanks XRK that answered my query perfectly. I have FRS5X (Qts 0.7), TB W2-800SL (Qts 0.25) and some random 2.25" drivers from a JVC surround box of unknown Qts. I was merely concerned that high Qts may not be a good thing, as with other horns. Glad to hear youve tried the 'less hifi' FRS5, results with the X version should be great! Thanks again.

[Bare]

Omar Bose would be proud .. Or might seek legal action
Hey! notice that each Christmas season brings out the Full Page Newspaper adverts for the Bose Wave Radio.

[xrk971]

Originally Posted by Bare

Omar Bose would be proud .. Or might seek legal action
Hey! notice that each Christmas season brings out the Full Page Newspaper adverts for the Bose Wave Radio.

Amar did not invent this, Daniel Ciesinger did - German patent, Planet10 posted It on the foam core thread. The Bose Wave radio patent is very different, as it is not a spiral. Bose does have a spiral horn patent but it is a single horn wrapped like a snail with driver located 1/3 from closed end.

[xrk971]

Originally Posted by Cal Weldon

I am thinking of going up to a 5.25" driver. The ever popular RS-1354. Already with planet10 treatment(s). I wonder how big that would be if we kept it at 4.5" walls and did the Pentagon box?

Sounds like fun and it will make some deep sounds like the devil you are still on this pentagon thing.... You should try your daisy and see which sound better.

Is there enough room in the standard cavity to fit the 5.25 driver? You might need to increase channel depth to 5 inches and then glue strips of foam core braces between the channel walls (parallel to face) every 3 inches or so to keep the radial stiffness. Otherwise, maybe build a double faced spiral for 8 horns like original, more time but lots of breathing room for drivers and you can even flip the handedness of one spiral vs the other side so each speaker contains both clockwise and counterclockwise spirals.

This thing would be only slightly bigger than your current one but take twice the work. However, you are experienced and it goes twice as fast

[xrk971]

On Post 720 of the foam core thread I placed sound clips of the output of the mini Cornucopya from the combined direct and horns vs horns only. If you are interested in checking out the sound, go here: Foam Core Board Speaker Enclosures?

[xrk971]

Cal,
When are you gonna start on speaker set #34 with your 5.25 in drivers? My fingers are starting to get restless after not handling a hot melt glue gun or xacto in a while...
Xrk971

[endia]

Hi,
i made these drawings to ease scaling and printing.. first one is sebastian's original drawing and the other has more spiral shape. but i don't know if it has any advantages over the original, does it?
i have a pair of 3" full-ranges, may i use them for 70 cm panel or should i scale-down the layout to (3/4) 52.5 cm?
i also hope these pdfs helps to further builders..
xrk971, thanks for the bring us this project..