Building our own speakers....

[maxg]

A friend of mine has decided to build his own speakers. The target is to build a set of bookshelf speakers on a par with the Heresy 2's I have (or better - so much optimism) with more bass (27 Hz cut off).

Anyway he is off building boxes and whatnot and talking unintelligibly about drivers, crossovers and the like. Who knows what it will sound like in the end but it keeps him happy in the meantime.

During the process I asked a question which has been on my mind for a while. Why are most speakers box shaped? I cannot imagine this is the optimum shape for a speaker (presumably Norh agrees with me).

Anyway my idea was to take a single tree stump about 50 cm (19.5") in diameter and 1 metre (39") high.

Cut the thing in half for 2 speakers and hollow out in each 3 separate comparments as follows:

Thickness of wood to be retained 2cm (3/4") all round.

Section 1 : For tweeter (horn of course) 15 litres volume required, therefore 10 cm high.

Section 2 : For Midrange horn - 15 litres volume, therefore again 10 cm high.

Section 3 : 24 cm remaining space for the woofer, or, about 39 litres of air. This should be enough for a 12 inch woofer in a sealed (not base reflex) setup.

This leaves a 2 cm top and bottom with similar between each section to ensure proper isolation.

Internally there will be no corners as each space is cylindrical (and curved up to the sidewalls if I can).

Questions:

1. Anyone care to guess what this would sound like?

2. Would I need any further insulation between tweeter / mid / woofer?

3. Would I need any sound absorbing materials inside at all?

4. How come no-one else is doing this?

5. Am I barking mad?

6. Presumably no 2 speakers would sound exactly the same and all would be influenced by the choice of wood. Do you think that could be a marketing angle?

7. Do I have too much time on my hands?

[Guest BobG]

Of course if the mid and tweeter are horn loaded, the space in the enclosure (trunk space? lol) is not needed.

If the speakers don't sound good, the enclosures could always be used for small fishing boats.

While you may, as you say, have too much time on your hands, there are even crazier ideas that have made it into production. Saw a rocket speaker at a hi-fi show in China one time. Fins and all. Think I saved the literature. It was a two-stage design. Anybody knows the added complexity of a three-stage rocket speaker is not worth the increase in cost.

[HornEd]

Ahh, MaxG, thought provoking as usual!

Glad to see your nOrh reference... I thought of you when I reviewed their drum speaker designs in solid wood and marble.

Cylindrical designs fascinate me as well. The concept of a room full of cylindrical column speakers holding objects d'art atop them is something that would make a Hurst Castle aficionado stop and take notice!

In subwoofers, cylindrical designs appear to provide an even pressure on all interior surfaces... negating the need to build a heavier box. Standing waves, while no problem for subs, can be real performance killers inside full-range towers.

Some higher end speakers use internal pipes but keep the outsides essentially rectangular. Rectangles seem to be easier to produce and more in tune with the buying patterns of consumers in the mass market. And that produces a corporate stability and growth potential that keeps stockholders happy.

I am afraid, MaxG, that those of us who find swimming against the tide a reasonable exercise of our time and resources may not constitute a prudent market base.

I think some of the secret of Klipsch success comes from finding the right blend of innovation, quality and market-segment attractiveness. I hope the new Reference 7 additions will be so successful that they bite the backsides of all the authorized Klipsch dealers that could not find room in the showroom. Could it be that these new speakers are so dynamic and so cherry... that retailers are afraid they will make their other brand offerings pale by comparison? I hope so.

Meanwhile, I will keep looking for an IPO for a "Midas Touch" speaker manufacturing company with MaxG at the helm... after all, once you hear sold gold chambered nautilus speaker cabinets... No, just a minute, didn't I read something about Stradivarius beating fine grains of gold into the wood that would become the world's finest violins... how about gold laced MDF cylinders?

The wilder it gets... the more I respect the acoustic engineers and the job they have done in Hope. HornEd

[djk]

>>The target is to build a set of bookshelf speakers on a par with the Heresy 2's I have (or better - so much optimism) with more bass (27 Hz cut off).<< Two points here.If the box size is held constant a 27Hz cut off will be 8dB less efficent than the 50hz Heresy cut off.If the box is not on the floor it won't go lower than 40hz anyway(PWK wrote an article about this in the JAES about 50 years ago).

>> Am I barking mad?<< Probably.But so are most of us.

[CRAZEDLUNI]

Here is a cool site to check out. Alot of reference's for do it yourself box making. Somewhat deal's with your nature based form's of boxes. Nautilus to be exact. Also no standing wave's. Just one speaker full range design. www.carfrae.com

Also this site is good for DIY selfer's. http://hornet.hi-fi.hr/HedStart.htm

Hope this help's?

------------------

Denon 48oo

Klipsch

4 - KLF-20's

C-7 center

[Dale A B]

That photo reminded of the small company in South Carolina that produces a HORN speaker using "one" 4" driver. If you are not familiar with it, check them out at WWW.THEHORNSHOPPE.COM.