[jeenie67]

      Hola.   Here's one way us furniture makers (and model makers) do it.
      First you boil 20 or 30 gallons of water in any kind of container (a sawed off 55 gal. drum works great) on an outdoor fire. Suspend your work piece securely on center, with even lateral distribution, and with weights attached to the ends. Steam the wood. A fixture or template as to the exact curvature you desire should butt the work piece. Allow for retraction when cooled. Go slow, ease into this procedure the first time. With a little experience (the only way to learn this) you will be able to bend hardwoods, pine, balsa, or any other wood product including drywall which is done minus the fire and steam.....drywall is curved soaking it then allowing to air-dry over a form (another good use for a 55 gal. drum). One may try this on the kitchen stove with a pot o' water. I make vintage automobile fenders this way and roof struts. Hope I might have been some help, Jeenie.

[THWO]

After thinking again about my suggestion with the support board on top of the curved panel, I discovered a possible problem with the stability of the support when the cutout is being made by the router: when the circle is done, the inner plate will want to fall out, meaning loss of support for the ruler and drifting out of center. To avoid this, the circle ruler for the router must be large enough tu stretch out obove the inner circle and the center pick of the circle ruler must be deep enough to perforate not just the support board but to stick in the curved panel as well. Then it may work.

A completely different approach to build a curved panel may be to glue several thin layers together while being under heavy pressure (the boards, not me!) by a self-built press with a negative and positive profile. However, then the back side of the panel will be curved, too. By the way, also a nice way to produce curved side walls for a traditional floorstanding speaker cabinet.

Till

[AK]

also note that baffle is curved in two directions, say X and Y axis. I guess plywood needs to be tenderized quite a bit, because after first bend, resulting arc shape is very rigid, and it's much harder to make second bend.

[jeenie67]

Hola.    Thwo, your on the right track. You have to build a fixture to cut a perfect circle on a curved surface. Forget the circle compass guides and templates. First a router support board of sufficient size to accommodate the full base of the router from 1/2" plywood-MDF etc. Attach cleats of 3/4" pine that follow the curvature exactly. A circle cutting guide of 3/8" to 1/2" MDF-pine- Plexiglas etc. allowing for the diameter of the router base. Calculate this opening or eye it-adjust it to size. Attach this to the baffle from the backside with drywall screws. Cut slow. A bit of sufficient depth will be needed. The thicknesses of all these boards is up to your skill levels using power tools.
A sketch is in the Gallery...."router gd 1"  Jeenie.

[jeenie67]

[imJPEG imageg][/img].....???????  What am I missing?

[mcgsxr]

To post it, you have to get the full URL from the properties of the pic, in the gallery - <img>http://www.audiocircle.com/image.php?id=18920</img>

For the above, I changed the brackets to show you what you need to do.

[jeenie67]

O' TAY!!

[Rudolf]

what were the qts and xmax on the bass woofer pictured?

Angaria,
it is the XAW 310 HC by Mivoc:
http://www.mivoc.de/mivoc/PDF/XAW310HC-Datenblatt_WEB.pdf
Qts=0.3 and xmax= +/- 10 mm. I didn´t show that OB because of driver selection, but because of looks.
IMHO the driver selection is compromised because all drivers had to be sourced from the same distributor. The low end of the woofer response had to be equalized to keep the response from rising up to 200 Hz. Personally I would not put a driver with Qts below 0.5 on an OB. Xmax is much more appropriate.

[scorpion]

Rudolf,

I don't think it is about the Mivoc bass driver at all. The pictures you provide are for an all Micvoc drivers OB from the new HH.  Pictures are absolutely formidable but what about the rest. For me it might be very well all right. But closely looking at what is achieved, I think they are way behind what is for instance provided by the MJAO OB with similar German units.

/Erling

[Rudolf]

I don't think it is about the Mivoc bass driver at all. The pictures you provide are for an all Micvoc drivers OB from the new HH.  Pictures are absolutely formidable but what about the rest. For me it might be very well all right. But closely looking at what is achieved frequency wise, I think they are way behind what is for instance provided by the MJAO OB with similar German units.

Erling,

I am not sure where you want to point my attention to. But of course it was all about looks when I showed that picture. We have already discussed the drivers at the HiFi-forum: http://www.hifi-forum.de/index.php?action=browseT&forum_id=104&thread=16072&postID=1#1. And yes - most contributors thought that other drivers would have given better value for the same money. We would prefer the - mainly - Scandinavian solution: 2x Peerless SLS 12, 1x Peerless HDS 164 Nomex and 1x B&G 3" with opened back.

[scorpion]

Rudolf,

I support that unit choise, but go German with danish SLS and Monacor units. You won't go wrong. I am in fact much impressed by the Peerless units now when I have really simulated them. They would do really fine two by the side in H-dipoles and then fine tuning them to mid-treble combos active or passive.

I will be coming back with my Alphas supporting SLS134's and B&G Neo3 and some other options. For what it is worth I am becoming quite a testbed, I think

/Erling

[jeenie67]

...I should delineate the "X" axis as the curvature on the horizontal plane. "Y" would be the vertical plane. The horizontal plane "X" , would include surfaces to the sides of the baffle plate.  "Y" would include the top and bottom of the plate....or baffle.

[Angaria]

Thanks for the info Rudolf - always appreciate design inspiration, just was curious as to the specs.