Simply curved TMW design concept

[alexcd]

Here's the concept

Northcreek D28 (http://www.northcreekmusic.com/Drivers/NorthD28-06S.PDF)
Seas W18NX (http://www.madisound.com/catalog/pro...oducts_id=1596)
Dayton RSS315HF (http://www.parts-express.com/pe/psho...number=295-464)

I am very happy with my currently-built 2-way North D28/Seas W18NX design but want to make a statement by building them into a 3-way. The design would include a side-firing sub. For this reason it's duties will only be up to 120-150hz as to avoid being faced the wrong way. I think this will greatly help the existing configuration. My plan is to built the cab with curved sides and recess the woofer into the curve... details of the build will follow.

My question is what woofer to use. I have done a quick search and found the Dayton RSS315HF to offer good performance at a significant value. I want -3dB around 30hz (better to be lower) without a port. My amp is 350Wpc and I plan to run an active XO channel to the woofer. I believe going with a 12" instead of a 10" could get me a significant difference in low end.

[DancesWithBeers]

I'm curious how you're going to build the flat baffle for the sub into the side of the curved cabinet. Are you doing a stacked lamination, or are you bending wood around a form?

-DWB

[alexcd]

I'm curious how you're going to build the flat baffle for the sub into the side of the curved cabinet. Are you doing a stacked lamination, or are you bending wood around a form?

-DWB

My thought is to create a skeleton form in which to bend thin wood (maybe high density board) around but with a baffle cutout on the side. The side will look curved from the front but have a hole in the side. I am thinking about a 1/8" thick panel, then leaving 1/2" for sand, and then 3/4" more wood. This should provide enough strength to hold the sand filled walls. Everything will be braced but I would like a very very dead cabinet.

[brianpowers27]

That is an interesting concept. I like the idea. Eactly how big is that cabinet going to be?

.707 sealed = 45l f3 40hz
.8 sealed = 30l f37.5 hz
vented (24hz) 45l = f3 28hz

By the time you add bracing and fill you may end up with a real behemoth!

[alexcd]

45l is no problem. I was thinking up to 2.5cuft before you are right... it would be a behemoth. So you're saying that a 45l (Q=0.707 ?) sealed should get me F3=40hz? That's sort of weak. I get 50Hz out of my (ported 180mm/tweeter) combo now. I want to get rid of the port and go with a larger woofer. I just thought I would get lower extension than that.

[ThomasW]

I want to get rid of the port and go with a larger woofer. I just thought I would get lower extension than that.

You'll need a much bigger box to get lower extension, or you'll need to use a LT circuit.

Sand?

Come on, sand filled chambers went out of style in the early 1960's.... unless you keep a powered forklift handy to move the speakers around the house.... :B

[brianpowers27]

45l is no problem. I was thinking up to 2.5cuft before you are right... it would be a behemoth. So you're saying that a 45l (Q=0.707 ?) sealed should get me F3=40hz? That's sort of weak. I get 50Hz out of my (ported 180mm/tweeter) combo now. I want to get rid of the port and go with a larger woofer. I just thought I would get lower extension than that.

Consider modeling this in Unibox. It could be that the woofer is too large and you could get better extension by altering the ratio of woofer to available chamber space.

I am sure that you would be able to get better extension in the same size by either doing one of these

--Use the HO instead of the HF (Ported)
--Try the 10" version of the reference HF.

[alexcd]

Consider modeling this in Unibox. It could be that the woofer is too large and you could get better extension by altering the ratio of woofer to available chamber space.

I am sure that you would be able to get better extension in the same size by either doing one of these

--Use the HO instead of the HF (Ported)
--Try the 10" version of the reference HF.

The sand is OPTIONAL... I just hate spending a ton on expensive padding.

I used WinISD and got the "best" response from a 12" in a 2.5cuft enclosure. F3 was in the mid 30's and that's a BIG box. I'm willing to do dual 10"s.

I considered the LT circuit but still don't want to be -11dB at 20Hz and go from there. I have a 350W amp, not going to have any gas left at 100hz if I want +11dB at 20hz without clipping.

[brianpowers27]

I used WinISD and got the "best" response from a 12" in a 2.5cuft enclosure. F3 was in the mid 30's and that's a BIG box. I'm willing to do dual 10"s.

I assume that you mean 2 per box? I don't know what kind of room you have but I can only imagine that 2 10" woofers (1/box) is more than adequate. If that isn't enough, try adding a 3rd woofer as a seperate sub.

I can't imagine what sand would do for you. The goal of lining/stuffing is different than the benefits that sand would provide. Don't skip lining the cabinet walls. Consider using 1" carpet pad, if the budget it tight.

[alexcd]

My approach at this point may be to buy the Dayton HF woofer and go with a simple design. The Dayton 10 HF only requires a 1cuft box. The Dayton 12 HF needs at least 2cuft. Opinions?? I think I really need to account for room adding more gain than I can model. I have a small room now, 10x15, but plan to keep these for a while.

[brianpowers27]

If it can mount to the box...

Buy 2 dayton reference HO drivers. One per box. Give them 40l, tuned to 30hz. It would be very hard to go wrong....

f3 27

But I think you want sealed. If you must go sealed then my recommendation doesn't stand.

[alexcd]

I really don't want to go ported. I think sealed is much cleaner.

[brianpowers27]

Consider putting the 10" reference hfs in the box sealed at a qtc of .707 (40l) or lower. THis will still require a sub for the deepest bass since the f3 will be 44hz. The rolloff is gradual - f10 is 24.9. Should sound very clean. Use a room gain calculator to approximate the effect of modes....

[alexcd]

I hate to throw another option out there but I just came across the Shiva-X 12 (http://www.diycable.com/main/product...roducts_id=653) I want to focus on saying I want a musical sub. I have no experience with this sub. Would it be ok to integrate with an active design? (120hz and lower) or does the Dayton 12 still win in most people's opinion?

[brianpowers27]

I have no experience with that driver. Try throwing it in unibox/winisd and gettin a volume for a .707 alignment and an f3/f10.

[alexcd]

Both the Shiva-X and Dayton 12hf require a 2.6cuft cab for a 0.707 alignment. The responses overlap almost exactly. The Shiva-X is more efficient by 0.3dB but everything else is the same.

[brianpowers27]

Both the Shiva-X and Dayton 12hf require a 2.6cuft cab for a 0.707 alignment. The responses overlap almost exactly. The Shiva-X is more efficient by 0.3dB but everything else is the same.

2.6cf is pretty big. How much airspace do you need for the regular woofer?