10 replies to this topic

[Paul Spencer]

My Synergy horns only go down to about 220 Hz so my bass modules will cover 40 - 220 Hz. The driver is an Eminence Magnum 18LF, an 18" pro woofer with a large phase plug and shorting ring. I've been running these in a 110L vented box, my prototype on which I was going to test vented vs sealed. In the end I decided on a sealed box, for a couple of reasons:

1. Smaller and lighter. When made solid, I will be able to work on it and lift it.
2. In it's intended spot, the in-room extension will be around 40 Hz with a sealed box.
3. I will have subs below.
4. Probably easier to integrate.

Pieces cut:



View from the back:



It has a spine and ribs. It's a basic rectangular box, 60L in volume with the back corners cut at an angle because this thing will sit inside a huge bass trap 1.2m wide. When finished it will have a 1m wide Synergy horn on top, all flush mounted like you would see in a studio control room, but instead of having a solid soffit this will be a bass trap. So of this box, only the front baffle will be seen.

Internal baffle added:



Not too many clamps used:



I prefer to use screws as clamps so I can keep on working. There is no waiting involved and I can get a lot done in a chunk of time.

You can see one of the rear corners that has been cut off.



One of those bits was the last to go on:



They look a bit rough assembled, but edges can be trimmed, it's something I've allowed for.



Driver cutouts have now been done and screw holes filled. All edges have now been planed and sanded flat, but no photo just yet.

Next up I will line the interior of the box with a composite similar to the one used by Terry on his Franks. Basically a mix of cornice adhesive and aggregate in a thick layer with steel mesh reo. Now you understand why I didn't want the box too big, because this thing will be like concrete!

I was working with limited time so to help speed things up I assembled some of the box with construction adhesive. This stuff made me more confident of a nicely sealed box and allowed a bit more fudge factor. I can make very accurate cuts when needed but it takes a lot longer to do it. These days if I can find a way to speed things up without causing problems I'll do it.

On the blog:
http://redspade-audi...nergy-bass.html
http://redspade-audi...-continued.html

They also need feet and will have a speakon connector.

More pics to come.

Edited by Paul Spencer, 16 December 2011 - 08:33 PM.

[CP_]

Looking good Paul. Are you only going to 40hz because of the driver, or the design of your cabinet?

[Paul Spencer]

I plan to build tapped horn subs covering around 15 - 80 Hz. Basically I'll let the woofer run as low as it can go without boost. The system that this will be part of will have very high efficiency and this part of it will be the part with the least efficiency - only 95 db! The rest of the system, including the subs will be 100 db +.

So the driver and cabinet and room put together will determine how low I can go without boost. Where this is going I will have to notch out a 15 dB broad room mode peak centred at 44 Hz. This mode actually acts like a vent in a way. Once that is notched out I'll see where that takes me. This driver in a sealed box rolls off 70 Hz anechoic.

[Peter the Greek]

Beasts! absolute beasts!

Cant wait to see the subs to match.

[Paul Spencer]

My plan is to turbo charge my Rythmik subs with tapped horn loading, under the floor, as big as they need to be, push pull driver mounting. Big, ugly and out of sight, seen only by termite inspectors!

[Peter the Greek]

Very cool! I'd thought about doing this in our ceiling, with a HVAC bar diffuser as the vent....

Sounds like this on a smaller scale

[Paul Spencer]

Yep the thought of a brick construction did come to mind, built insitu. But it will probably be something like formply.

[Paul Spencer]

More pics on the blog:
http://redspade-audi...ass-part-3.html

[Drizt]

Coming along nicely mate.

[St_Luke]

Looking solid! they ganna have some weight! near 40kg with speaker?

[Paul Spencer]

12kg for the driver
24kg for the MDF

36kg ... not a bad guess Luke but this is just the beginning. 30mm layer of composite will make it very heavy! Probably about another 20 - 30kg.