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Discussion Starter #41 (Edited)
That's a possibility. I have them both strapped to the QSC right now getting 10V @ 10Hz... want to see how they hold up over a couple hour span or so.

Edit - 10:30pm and they're still fine and dandy. That's over 6 hours and counting. Shutting it down for the night now.
 

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Discussion Starter #42 (Edited)
Minor update - after taking a long break for the blizzard of the century and its frequent power failures, I've now done enough testing of the woofers that I think I'm just going to keep the "bad" one. The electronics tech in me is insisting I caught the problem and fixed it early enough, and it beats waiting on Solen to get these back in stock. I may buy a spare just in case, but I think they're both going to be fine now.

New video:


I barely get enough gain using only the Reckhorn as a pre-amp with an SSF at the frequency of the test tone I'm using, but it works. Burned a 50 minute long 10Hz test tone to CD and set it on repeat. The drivers are sitting on a brace for another project with the vents exposed about two inches off the floor.
 

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after playing 10Hz tones even for a few seconds with a chunk like that I'd want a replacement but I don't want to wait to see how this performs either cut some wood!
at the end of the 50 minutes when the CD repeats, does anything happen at the changeover... like a pop? I use a tone generator off my PC to be safe. I've always wondered/worried.
 

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Discussion Starter #44
A little bit of a pop, but nothing major. Solen's told me that they'll honor the 1 year warranty on the driver should I ever need it, so I'm determined not to worry about it. Next time, I'll inspect suspicious drivers before they ever go on the amp. I should have caught it sooner.

While testing, it looked to me like the two woofers needed 16V to hit Xmax, so I'll be using that figure to set up my subsonic filter once the thing goes together. The idea is to set it up initially with a 20Hz SSF, let the Pioneer 919 calibrate the level for reference, run the 10Hz CD, and then slowly run the thing up to +5dB or so while watching the voltage at the amp and running back and forth between amp and sub to make double sure that as I reduce the SSF, the woofers never see that 16V at 10Hz.

I can't tell you how much I want to get this built yesterday, but sadly there's still snow on the ground and I have no heated shop to work in :(
 

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Heats for wusses!

I grew up in Manitoba. We scoff at minus 25. But then again glue doesn't like it!

Mark
 

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Funny it seems every major build I do ends up being during the coldest time of year... due to waiting on finances, it may warm up first this time for me!
 

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Discussion Starter #47
We scoff at minus 25. But then again glue doesn't like it!
Asthma doesn't like it either :(

And I have a double whammy to deal with in my allergies as well. Allergic to everything, which is why you will never see me work with MDF. I have to be very careful with when and where I do my woodworking. I still haven't figured out where to leave the project while the PL Premium cures and (possibly) the paint dries.
 

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Hi Jeremy,

Well done on finding and fixing the problem with the rubbing woofer. Did you measure the Thiel-Small parameters for these drivers, and are they close to the published specs?

Regards,
 

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Discussion Starter #50
Thanks :)

I have no way to measure them right now - no money for a woofer tester, and no time to fiddle with doing it the hard way.

My car recently blew its second fuel pump in 4 months... this has put me significantly behind on this project :(
 

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Discussion Starter #52 (Edited)
I got it fixed - that's why I'm broke :(

Fortunately, I was able to do the work myself with some help from a couple nice guys with a heated shop.

A cheap SPL meter arrived off the boat from Hong Kong last week, so I had some fun this morning measuring my 11Hz tuned IXL 18.2.2 for eventual comparison to the horn. With my Pioneer VSX-919 set to -17dB, which is the hottest I usually run it, I popped in War of the Worlds, went straight for the "something's coming up through the street" scene, and flipped over to the DTS track.

Meter said I was getting 112dB peaks at the couch, my RMX-1850HD showed me the blinking red light on channel one a couple times, and I said to myself, "That's it? That's all the room gain I'm getting in here?" Matches the Unibox sim pretty well though.

I think I do need the tapped horn or another three of these 11Hz IXL designs if I want effortless reference level playback in this place. Since the RMX was clipping, I can only conclude the woofer was getting all 600W of safe power before the bottoming out point. If I could give it more, I'd just go ahead and bridge the QSC.

Edit - the IXL's Unibox sim for those interested:



Predicted diaphragm displacement is 25mm at worst with 600W... I'm letting it exceed Xmax just a bit.
 

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Hi Jeremy,

That's some serious output for the vented IXL Unibox.

I'll attach two Hornresp Input screens, one for an IXL-18.2.2 tapped horn, and one for a dual (push-pull) W8Q-1071D tapped horn. I simulated both with small throat chambers. The response of the Tang Band is amazingly flat, and both models show good impulse response.

Just some more food for thought :).

Regards,
 

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Discussion Starter #54
Yeah, I've been thinking about one based on the IXL. Problem there is box size - it likes a huge one and this horn already needs 3 sheets of plywood. Not sure I want to buy the wood for the IXL, let alone try a design I've only done once or twice with a $300 woofer. I've been working on Hornresp sims with Hifonics car audio woofers lately - most of them model pretty well.

The W8Q-1071F is indeed a pretty good TH woofer. Unless I'm mistaken, your L12 is too short though - the woofer won't fit. I figured mine was the best compromise of performance vs. ease of assembly... we'll have to see when the time comes to get it built.
 

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Hi Jeremy,

It would make a lot of sense to build some of the monster boxes from OSB, especially for testing. The cost of baltic birch plywood is just too high. And for looks one can always laminate some thin plywood (or other material like formica) to the outside of the box. One set of enclosures I build from 1/2" particle board, and laminated the outside with 1/4" Alder plywood; they looked and sounded just fine. It's also an easy way to hide screws used for braces, blend in access covers, etc..

As to the L12 distance: the reason for the small throat chamber is to provide coupling from the woofers to the horn throat. There is no actual L12, and for this reason I'm using the minimum distance that Hornresp allows. This method seems to work. The other method is to reduce S1 to minium with a L12 of approximately one woofer diameter, and the S2 area at the midpoint between the woofers (obviously no chamber). Reducing S1 to minimum, or using a small throat coupling chamber, seems to help with the impulse response in Hornresp. JLH posted an interesting example of a taped horn with throat chamber in the diyAudio Collaborative Tapped horn project around Post #2362 (I cannot post the link).

Regards,
 

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Discussion Starter #56
Ah, right - I see it now. Just needed sleep, which is hard to come by around here lately.

Regarding box material, my physical health issues won't let me work with anything that produces a lot of fine dust (allergies and asthma). Plywood is ok, but still gives me problems. I also have to drive two and a half hours to get anything decent for a fair price. More than that though, I'm not sure about compression ratios with the IXL, which is why I want to get a few tapped horns under my belt before I try it.
 

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Discussion Starter #57
Shamelessly copied and posted from my AVS thread...

Gasp - something's actually happening!



This is the week, folks - I have wood, I have spare time, I have PL Premium, and I have no semblance of sanity. This thing's getting built. That's a new 98" saw guide next to the wood - cheap, but should work I hope.

Wood shopping went ok. Home Depot was a disappointment as usual - Arauco only up to 5/8" and not very cheap at $45 a sheet. So, I ended up at Windsor Plywood where the best and cheapest they had was, once again, import 11 ply C2 shop birch. $40 a sheet.

After getting these sheets down to the basement, I'm wondering again why I thought I needed to use 3/4" stock. This project is going to be heavy as all get-out.

For those who use the stuff routinely - how long do I have after popping the seal on my PL Premium to put the stuff on before the tube is no good anymore? Worried about the length of time it'll take me to get this together. I just bought one big tube of the stuff - I probably should have gone with multiple smaller ones.
 

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Tape over the tip every time your finished and you will be able to coax it out for around a month. When it gets a bit to hard you can use brute force and a twist drill in a power drill and drill a hole through the plug that eventually forms.

Mark
 

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Discussion Starter #59
Okie dokie. If it takes me a month to get this horn together, there's something wrong with me, I figure :D

Here's a graph for comparison purposes later - my REW measurement of the IXL at the listening position:



No EQ, Reckhorn B-2 SSF set at 10Hz. The horn's going to be firing at the same corner the IXL is in now.
 

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Discussion Starter #60
Got all the panels cut today. Started at 1:30pm, done by 5pm. Every part of me aches right now.

Didn't have too much trouble, except when it came time to cut the long panels - the two sides and the driver baffle. That 102" saw guide isn't that great. Led to those panels being as much as 7mm off in places, and dead on in others. Argh. One is glad one bought PL Premium - one is going to need its expansion abilities.

Other than those three panels, the rest are about 1-2mm of being within proper measurements.



This is at the end of cutting sheet #2, and getting ready to start on the hard one. You can see my long saw guide in this pic - it's held on with clamps, which got in the way of the circular saw. Had it not been for the clamps, I feel those three panels would have come out a bit better.



I'm done for the day right here - the only thing missing in the picture is the bracing. Will cut that on test assembly day. I will say the dowels are planned to be part of the bracing... they're only 5/8" thick (best I could do locally), but they will only be doing side to side bracing. Everything else will be either CDX plywood or the leftover C2 shop birch.

I'm still impressed with this wood. Cut through three sheets of the stuff, and still no voids of any consequence.
 
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