New Project Critique Please

[Ugg10]

I am about to launch into a new 3 way project and would like to hear views/comments etc. form the forum members before I commit to the driver buy.

• 3 Way initially active with Minidsp (Nanodigi + 4xKardas Toneboard + Rotel RMB1066) then maybe passive later.
• Box size - Re-use Akai SW125 with extra bracing and sound deadening panels (bitumen) plus 25mm MDF baffle level with box edge - external 350 x 560 x 295mm (13-7/8" x 21" x 11-5/8") - approx 40litres net volume. If all goes well I may remake at a later stage but bout for pocket money and they are the size and volume I would have made anyway, I like the Monkey Coffin style.
• Drivers - SB WO24P-4 + Morel EM1308 + Morel ET448.
• Crossovers - doing some modelling in Boxsin 2.0, Vituixcad and Jeff Bagby's PCD I get good consistent result with the published data (obviously will measure and re-do) with very good phase tracking with all LR2 electrical at 700hz and 3600hz plus a tank/notch on the woofer at 3500hz and a notch on the tweeter at 4500. Mid out of phase. The crossover point are also fairly consistent with the couple of papers that Jeff Bagby produced on the EM1308 and ET448 (on DIY Loudspeaker project Pad on Facebook) which gave me some confidence I was on the right track.
• Alignment - for the WO24P-4 40l is pretty much spot on for a sealed box and also can be used as a BR tuned to 28hz giving a very slight lift at 75hz, F3/6/10 are 52/38/28.5hz and 38/28.5/24hz respectively according to WinISD.

Any thoughts on whether there is a decent chance of success before I commit. Thanks in advance.

(P.S. Also posted on DIY audio so sorry for those that are reading this twice).

[tktran]

Nice choices,

I wonder why you chose a 12” wide baffle for a 9.5” woofer?

[Chris Roemer]

JMO, but I'd be sad if I had a 10" 3-way that couldn't do full (rock) bass guitar range (low 40s).
Guess I'd vent it. A 3" PrecisionPort (17" long) might be okay.
(A pair of 2"ers should work too - can you vent out the back?)

Your PXO doesn't look bad either (IF you factored in BSC - if needed).

[mattsk8]

JMO, but I'd be sad if I had a 10" 3-way that couldn't do full (rock) bass guitar range (low 40s).
Guess I'd vent it. A 3" PrecisionPort (17" long) might be okay.
(A pair of 2"ers should work too - can you vent out the back?)

Your PXO doesn't look bad either (IF you factored in BSC - if needed).

In a 40L cabinet (1.4 cf), that should cover the low end well. If he used a 3" x 9" long port, F3 should be around 35 Hz. For that woofer a slightly larger cabinet would be better, but then he can't repurpose what he already has.

[Ugg10]

Thanks all for the comments, very useful. The Winisd model is using two 5cm ports which are quite long (38cm) but tune to 28hz and give f10 of 24hz but will have to have a 90 degree bend in them as per the rough cad model. The reason for the 40l box is that is is about perfect for a Sealed enclosure which I would like to try but also can be made to work ported or even with a SB29NRX passive radiator (similar to the Helios by Bagby/Shadzi).

I prefer front ported as I have an odd shaped room and would like to reduce any rear sound as much as possible so may start with sealed and see how I get on or even make it ported and some bungs so I can try both.

[mattsk8]

Thanks all for the comments, very useful. The Winisd model is using two 5cm ports which are quite long (38cm) but tune to 28hz and give f10 of 24hz but will have to have a 90 degree bend in them as per the rough cad model. The reason for the 40l box is that is is about perfect for a Sealed enclosure which I would like to try but also can be made to work ported or even with a SB29NRX passive radiator (similar to the Helios by Bagby/Shadzi).

I prefer front ported as I have an odd shaped room and would like to reduce any rear sound as much as possible so may start with sealed and see how I get on or even make it ported and some bungs so I can try both.

I personally wouldn't tune that woofer that low in a cabinet that small. In my opinion, stick with tuning above 30 Hz. But you can obviously play with port length if you decide to go ported later. I've used this woofer in 1.5 cubic feet ported and it's very good. My port was 3" x (IIRC) around 9" long. Good luck! I love your choice of drivers too, wish I could hear this when you're done

[Ugg10]

mattsk8 thanks for the comment, nice to hear that the Woofer should work well (1.5 cuft is 42l so not too different), will look into the slightly higher tuning, 3” diameter has the same area as 2x2” (edited) give or take so again looks promising. One option I have is to offset the mid and tweeter which will allow a 3” port on the front baffle but will have to see what edge diffraction does if I move them plus will have to keep telling myself to mirror the baffles three times a day until I start cutting :-)

[Chris Roemer]

Uh, Ugg ...
a PAIR of 1.5"id ports do NOT have the same area as a single 3" port. They only have HALF the area of a 3".
Doubling the dia. makes the area go up by 2 SQUARED (4x).

[Ugg10]

Doh, sorry typo, should be 2x2” ports, conversion form metric to imperial went a bit squiffy, 75mm or 2x50mm should have similar cross sectional areas.

[Ugg10]

Well, I have taken the plunge!

Ordered the following today -
SB Acoustics WO24P-4 9.5” woofer
Morel EM1308 2.25” mid dome driver
Morel ET448 28mm Soft dome tweeter
39uF and 12uF Claritycap PX protection capacitors
18mm and 25mm MDF sheets
40m of Kabeldirekt 1.5sq.mm speaker wire
12 Jantzen speaker binding posts

I’ve got a week off work in a few weeks time so once the garden has had a tidy up I am hoping to get a couple of days on these. I will look for some tubing for ports in the meantime and may order some banana plugs and need some connecting crimps but will need to measure up the driver connectors first. In the mean time if I get chance I can cut out the baffles and rip the MDF to size.

[donradick]

Dude, That looks like a tremendous build! I loved my build with a Morel dome mid.

[Ugg10]

Stuff has started to arrive 😁👏

Now have everything to start cutting wood and making a noise.

[Billet]

Looks like a great project. I hope you at least try the sealed box alignment, you might be very happy with it...

[Ugg10]

Billet Thanks, I think I will try sealed box first with the usual 1lb of Stuffing per cuft and see how that goes. Position in my fairly lively room has always been an issue in the past so sealed may help.

Now just need to name them - the obvious would be the "Satorels" or may be the "Capuchin Cabinets" (i.e. small monkey box?) - any thoughts welcome.

[djg]

Monkeybox? (Monkeypox)

[Ugg10]

Quick update, baffles now cut and will order hardware next week. Note, I used the Bituix diffraction model to find the best compromise for teweeter and mid position, this is what it came out with.

Untitled by A H, on Flickr

[randyohoh]

Should you decide to go ported, here is accurate pvc pipe data