Project Wolfhorn

Ok, I think I'm ready to start my thread now. Don't have the woofers ordered yet, and that's partly because I'm now trying to decide between two designs.

As the title suggests, I'm trying my hand at a horn. But not just any horn - my brain wanted to jump right into the deep end. I have two tapped horn designs I've come up with, and I want to see which one's more worthy of my time and money. Not to mention see if I got any of this stuff right

For want of a better name I'm calling them Wolfhorn I and Wolfhorn II. The build itself is planned for spring/summer 2010... I can't do it in winter due to health issues, and that gives me time to iron the wrinkles out and fold the horns.

Some details - WH I is a 20Hz horn and uses the Tang Band 6x9" W69-1042M. These things can be found on eBay for cheaper than dirt right now, and are the reason I wanted to take a stab at tapped horns. They modeled surprisingly well in a TH, and with the price so cheap why not give it a try. As an alternate driver, the W8-1747 and W8-1747A appear to work as well, and get louder, but the response isn't as smooth. Haven't checked on the compression ratio for them yet. W69-1042J does not work, however. The general idea is that I would be building two of these designs, each housing two woofers. The design is about 420L as it is right now. Each one can exceed reference, so I'm not going nuts over getting that magical 120dB at 20Hz number in eighth space I was so obsessed over last night.

Now, Wolfhorn II is much the same as I, only with a 16Hz corner, a 600L design, and two much bigger Tang Band woofers - the 8x12" W8Q-1071F. This one gets MUCH louder than Wolfhorn I. The problem is, I'm still so new to this I don't 100% know if the design will work. It models well, as pictured below. Risk factor to the wallet is high as these woofers would need to be bought from Solen for about $104 Canadian each. I would only be building one of these. I may try it anyway, and just do Wolfhorn I in the meantime for practice.

Attached is a zip file of both designs. Any advice about the design is most welcome, if you spot something I need to address.

These shots are all modeled eighth space. That's how these would be run in my room. The room in question tends to fall off a cliff below 22Hz if the LLT is any indication, so keep that in mind.

WH1 SPL:



WH1 Parameters:



WH2 SPL:



WH2 Parameters:



These are with as much power in as the woofers can take without bottoming out. II might need some active EQ to pull down that big peak around 60Hz. Not sure about the compression ratio on WH2... is 3.12:1 possibly too much for those woofers? I get 2.66:1 if I up S1 to 300, which adds another 20L to the size, but maybe that's the way to go there. 123dB in eighth space at 15.5Hz... that's going to get me committed to an asylum if I run it full out in here.

Edit - I'm adding the Sketchup plans and Hornresp sim for the final built version of Wolfhorn II to this post.

 

Wolfhorn 2.zip 24.0263671875k . file

I couldn't help myself - went back to the drawing board and polished up Wolfhorn II a bit for lower compression (2.66:1). Needs a little bigger box (618L), won't quite do as much SPL, corner is now about a half Hz higher, and the 130+ dB spike of doom at 60Hz is still there, but will still manage over 115dB in half space. Attaching the revision to this post.

It's a real struggle to keep from skipping over Wolfhorn I to try this thing instead. But, I don't have the money for the woofers, and I can't really justify buying them until after summer vacation. I is already enough of a financial risk.

Then again, looks like one II will beat the stuffing out of two I's, and that means less wood needed. Decisions, decisions

I also played with a 20Hz version of this that will do 130dB in eighth space at 20Hz. Not crazy enough to try that one, and I kind of want the extra extension more than extra volume.

Parameters:



Eighth space SPL:



Impulse Response (I have no idea what I'm looking at here, as yet):



Wonder if I have enough room gain to bring the low end up towards that 60Hz spike...

MCM isn't an option for me, being across the border. A friend of mine got burned bad by them not long ago, and even though I ordered from them all the time back in the early 90's I decided that was it for my relationship with those guys.

I still have two of their 30W 8" woofers on a shelf here waiting for a project. They're old though, and probably useless for a tapped horn. Folded horn, maybe.


lol - I wouldn't say I have the space more than I'd say I don't have the WAF issue to deal with. 36 and single, and still happy with that


Aha - gotcha. I thought it might be something like that... I was assuming damping on the folds would be necessary, with reflectors along some of the longer stretches.

I think I've decided - someone else can try Wolfhorn I. The woofers work, one just has to get them off eBay because the J version won't work. I'm going ahead and prioritizing II. Now to try and get those woofers...

The only real space requirement I have is that II must fit down the stairs, it must preferably be no taller than 48," and the shorter the length the better, though length will be the most adjustable factor. Depth should ideally be less than 20," but I can be flexible there too. I think I'll build it up with 1/2" C2 Birch from Windsor Plywood - same stuff I used for the LLT only thinner. Might make it 3/4" yet so I can go less nuts with bracing... my box making skills aren't that great.

Any comments on the compression ratio on Wolfhorn II revisions 1 and 2? If I can get away with version 1, I will. I expect though not much but trial and error will help me find out what's safe for the woofers. Surely 2.66:1 is safe enough though.

Edit - impulse response on Wolfhorn I is really clean. Now I'm back to the indecision.

I'm not quite sure how yet. I'm still using an older version of Hornresp - I should update that.


The 8x12" came right from Tang Band's site, but the 6x9" had to come off the eBay listing. Couldn't find it anywhere else.

I'll tweak it some more yet and see if I can get impulse response and phasing cleaned up.

I've been comparing eighth with half space each time I tweak to see what the differences are. I wanted to get something that looks good in both.

Hornresp updated. Now attaching a TXT of the Wolfhorn II revision 2 design... rev. 3 now under development

Right - keep forgetting that. It would be awesome if it was smooth up to 100Hz.

 

wh2r2.txt 0.4228515625k . file

Folks, say hello to Wolfhorn II revision 3. Still 600L. Impulse response has been cleaned up, but it's not quite as good as Wolfhorn I looks. I'm attaching text files for both designs.

This is in half space. SPL graph is with 2.83V in, IR graph is still at full power.







Forgot to put it back to half space on this one... it's inside 90 degrees up to 80Hz in half space.



I'm having way too much fun doing this

 

wh1r3.txt 0.4033203125k . file

 

wh2r3.txt 0.416015625k . file

Muahahaha!

I got started on a revision 4 of Wolfhorn II, but it seems that I've gotten it as good as it'll get for now. Can't seem to get impulse response any cleaner.

Double checked Wolfhorn I r3 and it needs work yet. Will fiddle with that one some more in case someone ever wants to go ahead and try it. Those W69-1042M woofers seem to come up a lot on eBay - there's an auction right now for four of them with no bids for around $60.

Edit - but not much work. Attaching Hornresp record now...

Edit 2 - how did I miss this?

I think I like that one enough to keep it. Maybe... I plugged the new L12 into rev. 3 and liked what I saw. Now attaching revision 4

I really should get away from the computer soon...

 

wh2r4.txt 0.4228515625k . file

 

wh1r4.txt 0.408203125k . file

I'm not sure these oval TB's do too well with one per horn, but I didn't really try modeling them very hard that way.

I like that the TB 8x12" has significantly more excursion than the 6x9" I was looking at, yet still works in a tapped horn. I probably wouldn't have been happy with just one Wolfhorn I... I was going to grab that set of four woofers off eBay and do two. I also like that the 8x12" can actually be found for sale off eBay - Parts Express and Solen both have it, and there's currently an eBay seller with them too. A little pricey, but one look at my SPL graph made me forget the price. Maybe I should post the 20Hz version - the eighth space graph on that one is almost scary

Edit - one W69-1042M models just fine in a TH. I managed to put together a very nice looking 150L 23Hz design with just one of those drivers. Hits about 100dB in half space with 10V in. A little tweaking to raise the corner and it might come in at close to 100L. The 8x12 however resisted all attempts at a solo TH. If there's a way to make it work, I couldn't find it in the time I had.

Well, this is it. Unless you all can give me reasons I shouldn't do it like this, Wolfhorn II revision 5 is going to be what gets built. Used Paint Shop Pro and Volvotreter's double folding guide to come up with this.

The main design jpeg is to 100% scale, a pixel per millimeter, so I can figure out exactly how to cut the wood from it. Assumes 18mm stock, but no bracing or reflectors... I presume I need to compensate for that somehow?

Final design is about 74" x 42" x 16.5." I fiddled with the design a bit more after discovering I couldn't fold it easily if I left it as is. Calculations show that there is a 30cm error in path length, but I'm betting the error is smaller than I think it is, and even if it isn't modeling shows it's not going to make a whit of difference except raise the corner a wee bit (like half a Hz).

I'm attaching the final design to this. Here are all the visual goodies. This is in quarter space, 36V in.

Scaled down version of the fold drawing:



Driver displacement:



Impulse response:



Parameters:



Phase:



SPL graph:



Schematic:



Unless y'all send me back to the drawing board again, I'll be building this come springtime. Until then, I have a 102" projection screen to mount and a projector to buy.

Thanks to everyone who has helped me out thus far - I'm sure I'd be in the loony bin by now if I'd tried to puzzle all this out by myself. Then again, how do I know I'm not there now...

 

wh2r5.txt 0.4228515625k . file

Heh - only if the wallet cooperates - still, $210 for woofers, $50 for misc hardware and 1" dowells for bracing, and maybe $100 for C2 shop birch and this project should beat the cost of the IXL build pretty easily. Then if I get the LLT sold, I'll come out ahead... sort of.

I'm still working on getting a cheap SPL meter for measuring the outcome.

At 74" long it's going to be a huge box, but now that the screen is here I can see that it will fit my planned corner easily. Helps a lot that the box is only going to be 16.5" deep. The mouth will fire right into that corner. I hope I don't see the cops the first night I test it

No problem - got into electronics repair when I was 14, and electronics in general a fair bit sooner than that

This might be the way I end up going. The soldering iron still gets a weekly workout even though I'm not fixing stuff for people anymore.

Basically, the green line up there is right between where the two drivers will be, with the magnet side being visible from the mouth. They'll be oriented with one woofer in front of the other looking in from the mouth.

It'll be the only way the woofers will fit. With them side to side, they'd be wider than the width of the horn itself.

It's pretty much a scaled up version of Volvotreter's 30Hz Tang Band horn here. Just picture two woofers, one above the other, and the mouth firing down instead of sideways. And a much bigger box, of course. I'll try and get lots of pics when the build starts.