Plan B (aka, fun with virtual graph paper)

[grumpy]

May this thread go where it will...

2234 x2 in ~10ft3, ala 4435
2345HPL on 2352, expect Zilch has a near drop-on recipe buried here
somewhere xover somewhere between 700Hz and 1.2KHz...
(kidding about the drop-in, some real-good starts, perhaps).

Room for ST front & center or placed back in canyon on top (not shown)
if desired.

tune to suit (ports), maybe increase depth a smidge...

if you imagine the horn, viewing from above, you'll see an approximation of
the "rams horn" ... I'm assuming all of the hard looking corners would
be eased to 1/2" radius or more.

Attached pic breaks a few "rules". Oh well.

Might setting the "MF" 2234 outboard help with time alignment if you
set toe-in less than might be normal otherwise? (a lingering DD66000
question)

-grumpy

[Zilch]

2435HPL OR 2452H-SL, each takes a different filter.

Both require redrilling the horn throat flange for driver mounting.

Still gotta figure out how to deal with the horizontal offset alignment at crossing.

4435 had them (HF and primary LF) vertical in line.

MTM is "cumbersome," I like Everest better, if we can make it work....

[grumpy]

cut/pasted images of parts for better visualization.
Either compression driver suggested would fit.
2435's happen to be what I have to work with.
Trying to -not- sink the bass drivers back 6" or so, if I can avoid it.
I'm going to go with my hypothesis that the side offset can somewhat
compensate for a depth alignment issue, although I don't yet have to tools
to make observations to confirm or deny...

-grumpy

[Zilch]

I'm envisioning the compound tilt of the plane of time alignment.

Using toe-in and woofer delay, with the primary woofer stationed outboard, it's possible to get the planes to intersect at any point in the center 3-D space....

[I forget, now, if they said outboard or inboard for Everest II. I don't see inboard working, as the planes tilt away from the center....

[grumpy]

I forget, now, if they said outboard or inboard for Everest II. I don't see inboard working, as the planes tilt away from the center....

I don't recall that being stated either... just that you could change it with jumpers.

I'm envisioning the compound tilt of the plane of time alignment.

Thar' be a lotta long words in there missy. We be naught but humble (design) pirates.


but yeah... that's what I was getting at... seriously.

-grumpy

[Mr. Widget]

Why is the cabinet so shallow? I ask because in my experience deeper cabinets tend to have far less of a box sound.


Widget

[grumpy]

Fair question, reasonable concern (one I share)... also one of the broken "rules".

"Room intrusion" is at least a minor factor for me (depth of other furniture, or TV, or ...).

Width-min set by making the bass drivers adjacent and horizontal, ala 4435.
Height-min is set by adding a BF horn (that happens to meet my mental requirements
of not throwing away potential OA performance, attempting to minimize horn
depth, and shooting for a sub-KHz xover). I don't see a COTS horn that does this
and I don't have the resource to make one.
I don't really want to move the bass drivers closer to the floor, and the horn center
I'd like to have close to seated ear level.
I don't think I need more than 10ft3, hence the narrowish depth... BTW, add two more
inches & you've matched the DD66000 depth . Could push and pull here & there
a bit in the mock design without me popping a fuse (E.g., put a "butt" on it and
make the top modular)...

-grumpy

[Zilch]

Well, they got it wrong, is all....

[Mr. Widget]

... BTW, add two more
inches & you've matched the DD66000 depth .

JBL has, in my opinion, built their factory cabinets too shallow on the majority of their designs... their need to sell product can get in the way of performance. In the case of the DD66000... the curved rear panel is likely a big help in this regard... something you don't have.

You may be able to get away with the shallow cabinet if you use 3" Sonex... but I'd be inclined to avoid a design that is potentially compromised from the start.


Widget

[grumpy]

OK. Throw out that hypothesis... next! -grumpy

Widget, thanks for the feedback.

re cab depth... my first cut at this was deeper and taller... horn placement is more fixed
than is my determination to have a shallow design, but those woofers have to go somewhere,
need a certain amount of space, and perhaps have some benefit in proximity. Perhaps the
component choice is flawed (pushing compromised design choices), but I'll think on it.
I don't have a requirement for them to fit into an existing soffit location. I also don't particularly
have a need to show visual heritage, although it's a nice idea.

I do like the idea of continuing the general shape of the horn beyond it's boundaries... and that
takes some visual real-estate (perhaps a stick in the eye for some). One could consider a more
oval or ellipsoid shaped profile (looking down), in exchange for construction complexity.

Would be quite happy to see alternate "Plan B" considerations, whatever they may be.

-grumpy

[Zilch]

OK. Throw out that hypothesis... next! -grumpy

Naw. Zilch will watch for the errata adendum....

[grumpy]

OK... made me look. posted pics are 2" too thin from intent... not that it gets you into golden
rectangle proportions s/b ~3' x 4' x 1.33' ...still agree that panel resonances could be a
tough nut and intentional resonances (ported box) could be less than ideal.

FWIW, MTM -looking- version ends up being ~5ft tall with depth
depending on where you decide to put it: ~20" if a plain big box, assuming you go
for a "thin" front profile (22"). -grumpy

[Ian Mackenzie]

There are some fairly well defined rules for box building in the Vance Dickason publication "The Loudspeaker Design Cookbook".

[grumpy]

Hi Ian,

Indeed. Thanks and good point. I've made nice inert boxes... they are no longer a
challenge and they look like, well... boxes. Ran another design concept last night
for fun... looked like a mini-me dual El-Pipe-O with the horn between the verticals...
I and thought my posted pic at the start of this thread was aesthetically challenged...
-grumpy

[Ian Mackenzie]

Yes it was and it caught the attention of those so inclined.

Do you think it would be safe to let Me loose on your project.

Personally I think he would run rings around until we all got dizzy and it would be an embarrassment.