Wolfhorn SDX Design Finished - Page 10

Found a leak. A small one. Leak fixed, and here's the re-measured impedance graph:

I've been meaning to do an X months later update on this build, so I might as well do it now. lilmike's comments about bracing in the F-20 thread reminded me I'm a bit late in doing this.

I am currently at 18 months with the sub, give or take a few days. Learned a few things since the build about what to do and not do when it comes to building these, and I wanted to share my thoughts about it.

First, I am upgrading this unit from "bracing optional" to "bracing strongly recommended." I have not had any problems with this bad boy due to the lack of bracing (and I've not heard of the other builders having any problems), but I do know it is not the sub it could be were it completely braced. The driver baffle does flex ever so slightly at high SPL. We don't want that if we are running this box at full blast consistently, thus my change in the recommendation. You can get by without it, mine is proof of that, but it's something I'd like potential builders to start considering. It won't give you its full potential without bracing.

Second, before you build one of these, take the factory gaskets off the SDX drivers first. Those gaskets promote leaks, as I found out the hard way. We don't want that. Best to use the duct seal putty alone.

That's it for now. It's still a low end monster in my home theater... I've lost a few more pieces of stone off the wall by the fireplace since I first fired it up

To date, best SPL with both horns in use is still 124dB at listening position. I won't let them exceed that. I like having the ceiling above my head, thank you very much.
Edited by Oklahoma Wolf - 12/6/12 at 10:00pm

Yeah, it's really sad the way it turned out for him

Just wanted to do a quick update with some bracing suggestions. If you do brace this horn, here's how I would currently do it:



Light colored wood is the vertical bracing, green is the horizontal bracing. Blue is removable horizontal bracing in the mouth... this will allow you to pull the brace out so you can install the drivers. I'd window the horizontal braces the same way the vertical ones are.

You don't have to do it exactly as I have... you can make it stronger as desired (like adding a removable vertical brace right at the mouth in front of the drivers, or corner bracing), but I wouldn't make it weaker. If you brace nothing else, get the mouth and throat segment done... in other words the areas on either side of the drivers. Don't add too much of it, or the response will deviate too much from the model. 1/2" plywood should be enough... that's all I used in my Tang Band horn IIRC.

Attached is the revised Sketchup file.

SDX 3L.zip 39k .zip file

Psst! Looks like Bob's put the SDX10 on sale for $139 for the holiday season: http://creativesound.ca/details.php?model=SDX10

I've had a couple more people asking me about it, but nothing yet.

That reminds me - it's looking like the ACI SV10 is another alternate that will work. It's not the best match for the design, but it's not bad. The biggest issue with that one is that it has a low-ish Xmax figure and I have no idea where Xmech is. It may give up some top end SPL to the SDX drivers. Models show those drivers hitting Xmax at around 150W or so... should have the box doing around 117dB at a meter in room.

As always, workability of those drivers is entirely dependent on how accurate the specs are. I haven't measured them, so I don't know for sure. Anybody trying one of the alternates does so at his own risk. The only one I can speak for firsthand is the SDX10

Let's put it this way - I have no need of any more bass. I could hit 125dB at listening position with these beasts if I wanted to, but they break other objects in the room at that level. Not to mention flapping the projector screen around to the point it gets distracting.

I do have another tapped horn design planned for this year if I can get around to it, but no promises. Money's tight.

Basically, I'm looking to get 120dB at a meter half space to 30Hz from four 5" drivers. In a cabinet less than 8" deep.

Figured if I don't need anything more for movies, I might as well do a nice loud one for music.

There is a highpass via my Reckhorn B2 centered at about 12Hz or so. Took a lot of trial and error adjustments to do that because the B-2 is rather imprecise to set up. I did want a MiniDSP at one point, but decided it was hard to justify the cost when I was already pretty flat at LP using the B-2. There's not much EQ beyond the standing wave correction applied by MCACC in the receiver and a slight 17-18Hz boost by the B-2.

As is the case with any other design, the room really determines the best placement for these - that's why I usually suggest building one first and then experimenting with placement options to find the best way to fire the mouths before doing anything permanent with them as risers. In FUN4ME's case, he has the mouths coupled together and placed nearfield... two of these would get insanely loud at LP like that because listening position is right there on top of the mouths. You likely could also use traditional subs to sort of get an idea how it would turn out... just put them where you figure the horn mouths would end up, and see what it sounds like at your planned listening position.

In other words, I really can't say for sure how well that placement would work in your room without actually trying it. In my case, I already knew where the best placement would be, because I'd already had subs there before. I call it the magic corner

Cutlist diagram is in post 125. I probably still have the file on the computer somewhere. Otherwise, you can get all the dimensions you need out of the Sketchup file in the first post. The tape measure tool and a little math is all you need. Uses 18mm thick (3/4") wood.

Metric's just easier to deal with. I'd rather deal with millimeters just so I can be as exact as possible. Exactness with the saw matters with this build... that one sheet of ply had very little scrap left over.

I bought a couple plastic sawhorses to build it on. That helped a whole lot, being able to get underneath and go to town with the drill. I started with the innermost panels first, and just kind of worked my way outwards. I would measure where the panels were supposed to be on each end, mark their positions, then screw them in from underneath. Never used any clamps because I don't really have any big enough.

At any rate, I mostly figured things out as I went. As long as you're careful and patient with the measuring and don't spare the PL Premium, it's not too hard to put it together right. You might want a helper to put that last side panel in place though. I did it by myself, and thought my back was going to go out.

Edit - cutlist has been added to the zip file in the first post.
Edited by Oklahoma Wolf - 2/9/13 at 8:56pm

Missed that part. Yeah, it's best to do the cuts yourself.

My longer two piece saw guide was cheap (Home Hardware probably still carries them), and when I learned to use it properly I was making cuts with it that were only about a millimeter off. The trick with it is to use a clamped perpendicular piece of scrap wood in the middle to keep it from bowing as you cut.
Edited by Oklahoma Wolf - 2/10/13 at 10:03am

Added my list of alternate drivers to the first post. Remember... try these at your own risk. I have not verified their parameters, and I have no way to do so, so it's a gamble.

The most recent addition to that list is the TC Epic 10, which is actually the best one I've seen for this design if the published parameters are valid. The stronger motor does a lot to control reactance. I don't know why I didn't model it in here before... I've modeled designs with that driver before. Probably the price... these drivers aren't that cheap.

Will add more drivers as I find them.

If the SDX12 were a bit more affordable, I'd have already gotten started

Otherwise, check out the AlpineGeist instead. I personally love that one. I could do one based on the newer Alpine Type R's, but I tend to be more interested in stuff nobody's done yet.

Like maybe a design with a pair of Sundown 15" Zv3's... can we say huge SPL? Sure we can.
Edited by Oklahoma Wolf - 2/21/13 at 10:29am

That it does, and I still make a 4 figure yearly income. Bills come first. Often, they come last too

By the time I get the cash for any dual 15" design, the drivers may be off the market.