Build Thread K-Slot Rear Loaded Horn for Tangband W8-1772

[zobsky]

This is a build thread for a horn loaded enclosure for the Tangband W8-1772 8" full range driver.

Driver Detail: Parts-Express.com:Tang Band W8-1772 8" Neodymium Full Range Driver | Tang Band W8-1772 8" Full Range Driver full range tb speakers neodymium driver line array point source midrange home theater computer speaker center channel set tube amplifier
Driver Spec sheet: http://www.parts-express.com/pdf/264-893s.pdf

When researching designs for this driver, I looked at
1. the Sachiko horn : The Spawn Family of Double Horns
and
2. the RCA-Fan K-Slot Horn : Acoustic Horn - Backload K-Horn

Both have their own approaches to horn loading, and with little to go on as far as real life A-B comparisons , I've decided to build the K-Slot design. Both have been tested succesfully with a variety of drivers, but never (to my knowledge) with this tangband. Bill Woods of Acoustic Horn feels that his design will work with my drivers, .. and Martin King feels likewise about the Sachiko, so go figure.

Basically, I'd like to get
1. honest response into the 40 Hz region, without the driver crapping out,
2. tuneful bass ie. the design must not sound like a one note boom box.
3. minimal to no bass suckout, which some designs have i.e. low bass present but bass impact missing

I'm not new to high efficiency designs or horns, so I know what to expect from a good sounding design.


This thread will chronicle the build and results, for better or worse.

[zobsky]

I've had two sheets of Arauco ply (3/4" x 4' x 8') cut up from Lowes. This should get me about enough plywood to make some progress. Baltic birch is too rich for my blood, and I've almost never liked anything I ever built with MDF over the past 9 years. The quality of veneered ply available at home centers has taken a sharp dip over the past few years which is why I use 7 ply Arauco ACX nowadays


My rough cut plan (in order to get everything to fit inside my car)
Sheet 1: Four 2 ' x 4 '
Sheet 2: One 2' x 4' and Four 1' x 6 '

[Greg B]

Kinda OT, but what exactly is Arauco plywood? Brand name?

Sounds like a cool project. I don't know if anyone's built one of the Woods back horns yet.

[freddi]

I believe there been several builds of Woods blh for a few years - how much "strength" in plywood is really needed for typical fullrange blh?

from one article

"Arauco is the name of the company in South America that makes
a plywood from radiata pine trees You’ll see that Arauco plywood
has seven plies. It’s stronger than domestic birch and less expensive
than domestic or Baltic birch. The downside is its face veneers are
less attractive and may contain some defects or patches."

[Greg B]

Pinus Radiata? aka plantation grown Monterey Pine. Hilarious since I grew up in Monterey. We always saw it as firewood, but some of the old buildings used it for timber.

I'd guess it's just a bit less dense than fir ply. Strength isn't really an issue, since a speaker box is unlikely to break. MOE and damping and mass play some sort of role.

Any write ups on the Woods horn? Does everyone use the ever-popular FE206e?

PS

Pinus radiata are very resonant when hammered on by woodpeckers...

[zobsky]

At least its void free unlike the other abberations the folks at Home Despot market as plywood

Re. driver choice, there's some information at AA. For example see http://www.audioasylum.com/forums/hu...s/7/72315.html

[freddi]

do you think 1772 would play subjectively well in K12?

[zobsky]

Managed to trace out one side last night. Going to be a "fair" sized cabinet. the raw ply you see is 2 ' x 4'

[freddi]

lookin' good and makes nice use of 2'x4' dims - how do the plies, etc. look on edge with your Arauco?

[zobsky]

Originally Posted by freddi

lookin' good and makes nice use of 2'x4' dims - how do the plies, etc. look on edge with your Arauco?

Plies are void free. I'll add a photo soon.

No veneer, though one side looks better than the other (worse side pictured in my last post). Either way, some sort of veneer or paint will be needed, if anything made of arauco is to be domestically acceptable.