Big speakers... NaO 2-piece *PIC*

**tktran** · 10-09-2007, 07:05 AM

Provided Link: NaO

Hi Roman,

Here's the first 2-cabinet speaker that I built, from gorgeous MDF...

It's been years in the making, and I've got an 8x12' paper-backed Quilted Bubinga ready, but with all these open panels, there may be a lot of scrap leftover. :-(

regards,
Thanh.

**johnl** · 10-09-2007, 07:49 AM

> Hi Roman,

> Here's the first 2-cabinet speaker that I
> built, from gorgeous MDF...

> It's been years in the making, and I've got
> an 8x12' paper-backed Quilted Bubinga ready,
> but with all these open panels, there may be
> a lot of scrap leftover. :-(

> regards,
> Thanh.

what do you plan to use as fill-in for the holes in the back, and sides?

**tktran** · 10-09-2007, 10:10 AM

> what do you plan to use as fill-in for the
> holes in the back, and sides?

Grill cloth!

**johnl** · 10-09-2007, 11:42 AM

> Grill cloth!

An open aire enclosure? Have you tried this before? I ask because I have serious doubts about the system living up to it's optimum, being open this way.

**dickwest** · 10-09-2007, 12:42 PM

> An open aire enclosure? Have you tried this
> before? I ask because I have serious doubts
> about the system living up to it's optimum,
> being open this way.

Are you familiar with the great work done by John K?

<A HREF="http://www.musicanddesign.com/">http://www.musicanddesign.com/</A>

**tktran** · 10-09-2007, 12:44 PM

Provided Link: NaO

> An open aire enclosure? Have you tried this
> before? I ask because I have serious doubts
> about the system living up to it's optimum,
> being open this way.

This is my interpretation of the NaO loudspeaker system.

The original cabinet design was an open backed (dipole) baffle for the MTM section, joined to a U-frame woofer or sealed box woofer system. You can click on the link for details.

I wanted to strengthen the bracing, and increase the weight of the open-backed dipole MTM panel section. A secondary goal was to create a 2-piece cabinet, which can fixed together during listening, or taken apart, for easy transportation.

I will be adding roundovers to the side/top/back panels, and hope to preserve the natural dipole radiation pattern of the midwoofers and tweeters.

**johnl** · 10-09-2007, 01:09 PM

> Are you familiar with the great work done by
> John K?

> <A HREF="http://www.musicanddesign.com/">http://www.musicanddesign.com/</A>

Ok, I see what you mean. I forgot to note that the enclosure on the bottom was entirely seperate from the mids and highs. I assumed that All the drivers were going to be in the open mode. sorry about that.

I'll slink off now, and hide for awhile.

**johnk** · 10-09-2007, 05:04 PM

Provided Link: Music and Design

> Hi Roman,

> Here's the first 2-cabinet speaker that I
> built, from gorgeous MDF...

> It's been years in the making, and I've got
> an 8x12' paper-backed Quilted Bubinga ready,
> but with all these open panels, there may be
> a lot of scrap leftover. :-(

> regards,
> Thanh.

Interesting variant Thanh. It's been a long time in the works, hasn't it. Obviously you are going with the woofer in sealed box only format, as I recall we discussed. Keep me informed and I'd love some pics when you have it done. I'll copy the one from you post if you don't mind.

**Andy_G** · 10-09-2007, 05:28 PM

You have taken a speaker that had an interesting side profile, and turned it back into a BOX.

How could you ;-))))

nice way of doing it though, if it really had to be done for some obscure reason.

**Pete Schumacher ®** · 10-09-2007, 06:48 PM

> You have taken a speaker that had an
> interesting side profile, and turned it back
> into a BOX.

> How could you ;-))))

> nice way of doing it though, if it really
> had to be done for some obscure reason.

A plain baffle without any additional stiffening members would be far more prone to flexing with nothing to damp the resonances. And while I know you loath the rectangular prism as a design form, the same result could easily be accomplished with a different shaped truss-work. I'd think a single spine running the length top to bottom directly behind the drivers (with cutouts for each driver) would be a great alternative.

;-)

**Andy_G** · 10-09-2007, 11:00 PM

what I meant was that the reason that anyone would intentionally change TO a rectangular cabinet is obscure to me. !!

**johnk** · 10-10-2007, 06:28 AM

> A plain baffle without any additional
> stiffening members would be far more prone
> to flexing with nothing to damp the
> resonances. And while I know you loath the
> rectangular prism as a design form, the same
> result could easily be accomplished with a
> different shaped truss-work. I'd think a
> single spine running the length top to
> bottom directly behind the drivers (with
> cutouts for each driver) would be a great
> alternative.

> ;-)

I use a full length, centered, rear spine on the NaO Mini. The plans for the NaO II call for two sets of baffle braces angled from the base to the baffle. Once set of braces attaches to the (outer sides) of the baffle at the center lower midrange and the other pair at the center of the upper mid. Thus they triangulate between the base and the baffle at the point of the force vector from the driver motors making the baffle effectively very stiff. The position of the braces and the dimensions tend to prevent standing wave in the baffle. In the system picture I posted (Mike Hunt's system) the baffle was made of thicker material than specified and he reported that the result was more than satisfactory.

**tktran** · 10-10-2007, 07:29 AM

> Interesting variant Thanh. It's been a long
> time in the works, hasn't it. Obviously you
> are going with the woofer in sealed box only
> format, as I recall we discussed. Keep me
> informed and I'd love some pics when you
> have it done. I'll copy the one from you
> post if you don't mind.

Hi John,
Yes it's been a very slow moving project.
I have a lot of my plate at the moment, with
full-time university and part-time work.
It's take time to build a cost-no-object multi-
driver active speaker system on a college food,
book & beer budget, but it WILL be done! :-)

I thought long and hard about how to strengthen
the braces, without using trusses, which I
thought may be damaged during transport.
Also several people commented that they didn't
like the "board-on-a-box" look of dipole
speakers, so I wanted to increase the aesthetic
appeal by adding some curves.

Originally I had curved trusses, and even
considered using aluminium (my cousin owns a
fencing company) but the speaker still looked
bottom heavy. At the end, after many prototype
sketches on paper, the braces turned out to be
full length curved side, back and top braces.

After assembly, it looks like conventional boxed
speaker, except with big holes cut into it. :-)
That's ok, because the side effect of that is
that now I've got a great 2-piece "box" speaker
system, which can be taken apart for easy
lifting and transport. During listening they
can be locked together, or separated (with the
woofer section placed anywhere in the room for
optimal bass performance (ala NaO mini style)).

The side, top and back open panels will all be
integrated with black grill cloth. Pictured
below is an Audio Physic speaker with integrated
grill cloth on the side panel, and gives an idea
of what I am hoping to achieve in my NaO.

best regards,
Thanh.

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