Project Wolfhorn - Page 4

Not if you're six and a half feet tall and have a 13.5 C shoe size

Got some good news. It seems I did something different when I pulled the panels off and started PL'ing. The big gap moved to the bottom, where I crammed excessive PL into it. I just passed my best saw guide over the length of the enclosure, and there's no gap greater than 4mm on any one panel now.

That means all the bracing is going in before the top goes on

After I go get some more PL of course...

There's nothing in the house straighter than that saw guide I'm afraid. I've got one low panel now - planning to use excessive PL in there and then maybe flip the box over while it cures. I won't be able to get at that panel anymore once the top goes on, so I'll just have to cross my fingers.

There's one panel that's ever so slightly too high - will plane that one down a bit by hand.

Last night, I killed all the lights and ran a bright flashlight up and down each joint. There is one leak, and one only - it's in the panel I was working on right after the thing fell on my foot. Didn't get enough PL in that joint as a result. Will fix that when the bracing goes on. Going to do that tomorrow - my foot is in a fair bit of pain right now. Need a day off.

I was pleased to find not one leak in the driver baffle - even where that big gap is.

After taking a day off to let my foot heal up and get some other stuff done, I went at it again today. As it stands right now, it's all over but the rumbling. The box is built, and will be ready for the woofers once the PL cures.

It didn't take long to finish off my initial can of PL - I got four of six braces installed with it. So frustrated was I with the CDX plywood I used for bracing, I decided not to install the side to side dowel bracing at all. Will have to see what effect that has, but this 3/4" shop birch is so stable I should be ok. Used the pocket screw idea to install the bracing - some of those screws didn't go where they were supposed to, and wouldn't come back out. So I PL'd over them... that'll show 'em.

The top panel was, as expected, the hardest part of the whole thing. I went nuts on the PL to insure all gaps were filled - I cut the spout on the new tube as far down as the gun would cut it. The tops of all the interior panels got so much of the stuff, the second tube is now almost empty. This resulted in making the top panel extra hard to line up, but I managed somehow. Used #10 screws to fasten the interior panels, and the rest of the #6's on the edges. No leaks that I can find.



This is when I had to stop to change PL tubes.



All bracing in, ready to start drilling the screw holes for the top panel. Measured very carefully to insure I was hitting the interior baffles in the middle for those #10's. Some didn't quite hit the middle, but they all found the baffles.



There is no bracing in the throat whatsoever - I wanted to keep compression ratio as low as possible. So, I PL'd and screwed in this mini brace on the other side of that panel.



The throat and the first two folds got a very thin layer of polyfill. The remaining folds have nothing.



All done. It took some doing to find the best alignment for the top panel, but I managed.

Thus concludes the most difficult subwoofer build I have ever attempted. I'm expecting this to rumble to life sometime on Saturday or Sunday - I want that PL cured before I fire it up.

Hmm... I thought it would be best to give it a day as it seemed like some of the PL drippings were still easy to peel off the day after the last big PL session, and somewhat wet. I will say the bond between the major panels seemed to be rock solid though.

I'm still a wee bit worried about the compression ratio, but I guess I'll find out soon enough that I'm probably worrying for nothing again. It's not like I'm mounting fifteens in there

The next horn I try will probably have to be smaller than this one. I'm surprised I managed one this big without help.


I just watched Fringe with this thing staring right at me. I thought it was going to try and eat me alive.

Eventually I'll have my brother in law help me move it outside where I'll paint it flat black - then it'll at least be hard to see once it goes behind the screen

3.25:1, or thereabouts. Considering they have the cone area of a 10" with an oval shape, I figured it was worth the gamble. Thanks for the reassurance

I originally thought that if I blew a cone in the front driver, I'd put its replacement behind the other driver and PL a panel over the hole in front. Now, though, that front mouth brace is in the way.

Drivers go in either tomorrow or Saturday. Got a full schedule this week, and my back is killing me right now from having to stoop over and PL the tops of every baffle within the 30 minute maximum strength window.

16Hz - due to path length errors, it's probably a bit above that now. But not by a lot, like half a Hz.

That's why I did it - I didn't think even a pair of THT's would make me as happy as having the lower corner of this thing. That, and I really really wanted to learn this stuff for myself.

Exterior dimensions are 74" x 42" x 17" - it takes up some 850 liters of room space. Power - it'll take 200W or so at 16Hz before Xmax. I'll have it wired at 8 ohms. The drivers look like they will exceed 12mm without too much trouble, so I may get over 120dB out of it in my magic corner, but that really wasn't the main goal. Main goal was to get reference to 16Hz with some room on top to spare.

Took about 3.5 sheets of plywood to build this. Except for some of the braces, it's all 3/4" stuff.

I've been trying to come up with one that does everything this horn does, only in less space with more SPL. It's slow going - I haven't found the right drivers yet. The closest I've come is a pair of Hifonics 10's. Problem is, they have a poly cone and need a higher compression ratio than this horn. Not a good mix methinks. The 12" versions of those woofers work even better, and like a low compression ratio, but then you get a massively huge horn again.

I'm going to start looking into multiple smaller woofers I think. Modeled a decent one with four Anarchys, but it's slightly light on the SPL compared to this design. Almost there, but not quite. The response is much flatter though, which may make it worth trying.

Sigh... ok, ok, I'll get the woofers in today. All my imaginary friends are pestering me about it too

Checked on the PL around the outside of the box - it's fully cured. I suspect some of the big beads inside aren't quite done yet though - the air is dry at my place lately. Should be good enough though.

Just have to make my way home from work first. Tonight is my usual movie night, so it would be cool to have this thing bringing up the low end. Not looking forward to dragging the IXL out of the corner, but at least this one's going to be on casters.

Edit - and I'm also looking forward to seeing what the Pioneer's standing wave correction filters look like after MCACC.

You're both wrong



Got it all up and running now. Before I let you in on my initial impressions, some more pics for you.



Me and my pet monster just before caster and driver installation.



Some of the goodies I used for wiring. Had to solder the wire to the small terminals on the TB's - they used a different size for negative than positive. That duct seal is fun to play with - it's like sticky putty.



Wolfhorn II in its temporary new home pointing at the magic corner. Eventually, it will point at it from the other way, behind the screen.

Ok... listening impressions. I strapped the beast to channel 1 of the RMX-1850HD, hooked up the DMM, and went to town. First thing I did was calibrate it for reference according to the SPL meter and the Pioneer test tones. Left the Reckhorn B-2 at its IXL gain level, removed the boost I was using on it, and plugged in my 10Hz test tone.

Already, things got interesting. Anytime the Pioneer went above -10dB, the horn started belting out the harmonics. One moment I would hear nothing at all, and then whammo... everything is shaking. I go over to the sub, and the woofers are barely moving. I then set the B-2's SSF to allow no more than 5V at 10Hz to avoid having things come off the walls.

After that, I ran some 15-20Hz test tones through it. As expected, the corner is juuuust over 16Hz. Didn't get much chance to turn it up good yet, but I can tell already this is going to be fun to listen to.

So what did I do next? War of the Worlds. Street cracking scene. Maybe it's just me not fine tuning the SSF enough, but I was expecting it to outdo the IXL here. SPL meter says it didn't. I saw the amp voltage hit 38V during this scene... max safe voltage as modeled is supposedly 36V. However, I didn't go over to the sub to check on the woofers - I need to do that yet. If they're not approaching Xmax, I'm ok. Given that the SSF is probably set too high to allow this thing to really open up on me, I'm inclined to think I need to do some tweakin' yet.

All that being said, this thing was brutal during that scene. At -24dB on the receiver, it was already coming close to the IXL for SPL. I'll dial it in this evening and run MCACC once there's nobody in the house. Then I'll probably go back and forth between test tones and get the SSF squared away. Then I get to watch Sherlock Holmes.

BTW - the sound is cleaner than the IXL by a fair bit. Good golly - if this is what a homebrew tapped horn sounds like, a Danley must be phenominal.

I'll report back later once things are set up properly.

I forgot to mention - the point in WotW where the amp hit 38V is the point it used to clip on the IXL. The wall paneling was rattling like mad right there... it sounded as loud as the IXL. Now that I think about it, I got to panicking over the 38V figure and forgot to go over and use the SPL meter to see what it was doing.

I ran some more low level test tones just now - couldn't help myself. 20-90Hz in 5Hz steps. That 50Hz dip is there, but not a big deal. The horn is louder the higher it goes, according to the SPL meter. It's actually quite smooth all the way to 90Hz - the 70Hz peak is not there. At all. 16-25Hz can be heard and felt even below the 90dB level at listening position - the IXL couldn't do that.

I'm really hoping that the 38V peak in WotW isn't an indication that's all the gas this thing has in the tank. I suspect it isn't, because I heard no untoward sounds from the drivers and the woofers just didn't move much with the 10Hz sine wave at much higher volume levels. Later, I'll hit it with 22Hz and see how loud it gets before the 24V mark, when excursion is supposed to be at max. Then I'll drop the SSF until things match up or I run fleeing in terror from the tidal wave of bass.

OKAY - I am officially glad I built this

After MCACC, the LFE channel is set 3dB cooler than the IXL and 5dB cooler than I had it set. Same input level at the amp, same level at the Reckhorn. SSF seems to be ok bottomed out, but I'll run it at 14Hz for now until I know the sub better.

I re-ran the street cracking scene in WotW and really let 'er rip. Normal listening level of -17dB. This thing easily hit 120dB at the mouth, and the woofers did fine. They maybe hit 9mm of throw. Voltage never even got close to 38V. Sitting there next to it, it was literally shaking my insides.

Not sure I have the headroom I wanted, but it looks like I have my reference level playback at last. For a first time tapped horn build, I'm quite pleased. Maybe I should build another one to stack on top of it... I do have some room between it and the ceiling...