Big Woofer

[Oklahoma Wolf]

It's here:

http://img.photobucket.com/albums/v297/Oklawolf/Speakers/DSCF1973.jpg

http://img.photobucket.com/albums/v297/Oklawolf/Speakers/DSCF1974.jpg

Looks smaller in the pics than it really is. It completely dwarfs the old Akai and the two 15's right next to it.

Next step - build the box. I figure when that's done I can worry about the amp. The way our weather's been, winter could be starting again at the end of July and I need the box done first :(

[Zero82z]

The way our weather's been, winter could be starting again at the end of July
Did we just go back in time? ;)

[Oklahoma Wolf]

It feels that way.

[madmat]

How big of an enclosure are you building?

[Oklahoma Wolf]

About 405 liters after bracing tuned to 11.5Hz. It's going to be a big box. 48x24x24."

[madmat]

You do know that with a box that size you'll need 184 square inches of port area and a port 274" long, right?

[Oklahoma Wolf]

Not really. I'm basing it off this design, slightly modded: http://www.avsforum.com/avs-vb/showthread.php?t=875108

I don't like the bracing strategy - I'm using 2x2's.

The port's going to be 6" in diameter and 38" long. It models ok in Bassbox and WinISD, but the vent speed could be lower down at the tuning frequency. I'm justifying it by figuring not much content is going to get down to 11.5Hz.

[madmat]

I'd at least use a 6" aeroport. That's way, way too much box for that port. You're supposed to have 16 square inches of port area per 1 cu ft of box, you have 14.3 cubic feet of box before displacement.

[Oklahoma Wolf]

I'm aware of how it's "supposed" to be done, thanks - not really new to this :p

I wanted to use an 8" port - the software killed that one pretty quick. Port resonance is too low and it won't fit the box. Two 4" ports would do, but vent velocity is even higher than one 6" port. As it is, I get around 18m/s at the tuning frequency... I can live with that. It rolls off pretty quick above that, and port resonance is around 160Hz. 7" might be a decent compromise, but then I have to worry about finding something in that size or building a little square tunnel in there.

According to Bassbox, I actually have the box volume at 450L (16 cubic feet), after the bracing and driver. Port is actually 36" long. It's going to be tough finding PVC pipe in that diameter - I looked for it in Swift Current yesterday, and nobody had any. Need to hit a major city for that I guess.

Edit - 415 liters. Was looking in the wrong place - it's 450 before all the goodies.

[madmat]

Aeroport, aeroport, aeroport....

[Oklahoma Wolf]

Yeah, I know - not sure I can find one in 6."

[madmat]

http://www.psp-inc.com/products_6.html

You can get the 17" PSP 6" port from Parts Express but PSP might be able to hook you up with parts to make one the length you need.

[Oklahoma Wolf]

Cool.

I have some graph goodness to show off after discovering Unibox. This is what a 6" port with no flares around 36" long looks like in a 415L box on the IXL.

http://img.photobucket.com/albums/v297/Oklawolf/Speakers/VBPortAirSpeedMach5IXL18.jpg

The point where the air speed crosses the red line is 14.1Hz. At the tuning frequency, it climbs to 45m/s. That's way too high... if I do a lot of listening at subsonic frequencies. I'll be honest, it grates on me to even think about letting port speed get that out of hand, but I have to think about my budget and my intended listening environment. A 600L box with an 8" port looks a whole lot better when graphed, but I can't afford that much wood.

Methinks I'll stick to the smaller box, set the subsonic filter around 14Hz or so, and that'll be that. I can't really let this thing go thundering away at 11.5Hz with regularity in this house anyway, especially at 100+ dB.

I haven't plotted it with flared ports yet - might go do that now. I'd like to tame it a little bit.

Edit - flares do almost nothing. The air speed simply climbs too fast below 14.1Hz.

[Oklahoma Wolf]

Had to show this one off too:

http://img.photobucket.com/albums/v297/Oklawolf/Speakers/VBResponseMach5IXL18.jpg

113.2dB at 20Hz. That's going to hold me for a while.

[madmat]

According to BBP 6 the VV is the same on flared and unflared 6" ports. :(

[Oklahoma Wolf]

Yeah - I confirmed that in Bassbox and Unibox. Like I said, the vent speed just gets too out of hand below 14Hz. 600L and 8" port looks way better.

I really like the Unibox graphs - easier to see what's going on than BBP.

[Oklahoma Wolf]

Did some more playing around and noticed a problem in Unibox - you can't run this design at 1kW. If you do, you exceed the IXL's excursion limits around 17Hz.

So, I dropped the power level to 600W, which is what the QSC RMX-1850HD is rated for on each channel at 4 ohms in stereo mode. Bingo - vent velocity suddenly drops below the red line down to 12Hz, cone excursion stays within driver limits, and you still get something like 110dB at 11.5Hz.

Now that's more like it. And with me only running one channel of that amp, I can easily add a second one of these monsters if I want. Or, maybe I can save some cash and get a smaller amp.

[madmat]

I'd get a second sub. +3db baybee!

[Oklahoma Wolf]

Heh - I watched Beowulf last night and wasn't careful enough with the gain. My two 15's knocked a picture off the wall. I can't imagine those old things outdoing this 18, so I might be happy with just the one.

Just for fun, I modeled the same enclosure on an Exodus Maelstrom-X 18. It's not nearly as linear as the Mach 5 in there, and the port needs to get way too long for the same tuning frequency, but that woofer wouldn't exceed XMax at 1kW+.

Then again, that woofer costs $400 USD.

[madmat]

That's not bad, I've got about $350 tied up in my TSS and I built it. Retail on it is $639.

[Oklahoma Wolf]

Yeah - and Exodus is releasing a 21" version of that monster. I would just about kill to get my hands on one of those suckers when they come out.

http://www.diycable.com/main/default.php

You might be interested in this topic: http://www.soundsolutionsaudio.com/forum/index.php?/topic/30739-new-mach-5-build-zero-power-compression/

Looks like he's getting something drool worthy together.

[madmat]

Hmmm, that's a big coil. From what I gather, T3 will be releasing a sub with a 5.5" coil and 14" spiders. But you didn't hear that from me.

[Oklahoma Wolf]

By golly, I just realized something. My subwoofer amp will be in the lab running off the load testing circuit when it's not in use. That's so I can close the door on the fan noise. My lab has a computer. My lab computer could use a better subwoofer. My home theater sub amp will have a free audio channel.

What's that spell? Perhaps a second IXL :D

[Oklahoma Wolf]

Did some more design tweaking today. Played around with even lower tuning frequencies and different ports, and came to the conclusion it's not getting any better than the original plan.

At 10Hz tuning, there's not enough output. Four 3" ports will replace one 6" with good results, but then I have to buy twelve feet of pipe. A 6x6" tunnel made of wood turns the box almost into a waveguide design... I don't want to build a rat's maze in there, or lose that much volume.

I have got to find me some 6" sonotube. One hopes that'll be cheaper than 6" pipe, if I ever find it in that diameter.

Next step, order the wire off eBay. I'm only pushing 600W over 60 feet, so 12 AWG should do it. I tend to like to err on the too big side of it, and all my other speakers already run 14, but 10 AWG is too expensive. I haven't ruled it out yet though should some eBay seller make things cheaper for me.

Hopefully, the box will begin construction at the end of next week. I'll be in Regina on the 4th - if I can't find 6" Sonotube there, I won't find it anywhere. Rona and Home Depot are within a couple blocks of each other - both are good places to look. Wood will be bought this week (I hope).

Edit - the difference between 10 gauge and 12 gauge came down to $10 Canadian. I bought the bigger stuff. As it turns out, that maxes out the binding posts on the QSC too.

[madmat]

When are you going to quit planning and start building? I'm waiting to see what you think of it.

[Oklahoma Wolf]

When I can:

a) buy the wood - that'll be next week
b) find something to use as a port - that'll be next week
c) it'll go together within a couple days after that point, and then I can:

d) wait for my 100' roll of 10 gauge wire to show up
e) wait for the 50' interconnect cable to run back to the receiver
f) buy the amp
g) buy the subsonic filter for the amp

On G, I'm torn between the Behringer MIC2200 Ultragain Pro and the Reckhorn B-1. One one hand, the Reckhorn is MUCH cheaper. On the other hand, my Pioneer with the Reckhorn may not have enough preamp output to drive a QSC pro amp. I'm going to need to do a test run without the processor to see if I need the gain the Behringer will give me.

Edit - screw the Behringer - the Reckhorn can boost the output. That solves that problem.

[madmat]

Two 4" ports will give you close (28.274" for the 6" and 25.132" for dual 4's) to the same area as the single 6" port if that helps locate tubing. It'd even make for slightly shorter ports too.

You'll have to wait 'til next week to get wood? :(

[Oklahoma Wolf]

Yeah :(

On the upside, my brother in law can get the wood cheaper than it would otherwise cost me.

On second thought, I'll go with the Reckhorn B-2 instead of the B-1. It has finer control on the subsonic filter, and is not that much more money.

[madmat]

Didja get the wood yet? Huh? Didja? ;)

[Oklahoma Wolf]

Nope - thought it was best to make sure I can get the port first in Regina next week. Trying to be patient, but it's not easy.

Found myself tempted by a used JBL pro amp good for 900W bridged, but I think I have my heart set on that QSC now. The QSC is double the power for only $150 more. Better to overkill now and have something left over than get just enough now and regret it later if I end up with that 21" Maelstrom.

The 10 gauge speaker wire will show on Monday I hope.

Found myself thinking about tapped horn designs for the next project... there's a challenge for you.

Did some work in the car today too. Ran wire and powered up all four Chrysler/Infinity amps on all four speakers. At the same time, I installed a new relay so the X792 can keep the antenna down when playing USB. The result is the sound quality is a thousand times better, but the system can't play as loud. Thinking about going to external amplification - the Kenwood doesn't have as much power as the old JVC did, it seems. Maybe I'm just used to non linear earsplitting midrange.

After all this, the subwoofer was too loud for the level control to moderate well, but I solved that problem and killed the boominess issue on that Visonik by crossing it over at 50Hz, the lowest it would go. Fronts are crossed at 100Hz so they'll stop shaking the door paneling (I hate that - glad this deck has such a flexible crossover), rears are at 60Hz.

That evened out the sound a lot, but the Visonik sounds like suck now compared to the rest of the system. So, I'm building a new box and buying an IXL 12" for the car when the home theater sub is done. It will be run off the same Visonik amp - only 400W at most, but I really want a better sounding sub in there now. I can always upgrade the amp later (I'm being tempted by a 1 ohm stable Autotek). While I'm at it, I'll move the sub to the rear corner of the car - the current box is blocking the spare tire mount, and rear seat passengers get no bass where it is now.

[Oklahoma Wolf]

Now I know why this stuff cost so much to ship...

http://img.photobucket.com/albums/v297/Oklawolf/Speakers/DSCF2001.jpg

The smaller wire is some of the leftover 14 gauge currently being used to run to the 7 channel main speakers. You could use that spool of 10 gauge for bicep curls.

Plans have changed. No more plasma - caught myself looking at the prices on the 60" models, knowing I wasn't going to be satisfied with 50." But, I won't be satisfied forking out that much for a plasma either (can't afford it anyway). What to do? One word - projector. Will build the screen myself from blackout cloth, grab the first affordable projector I can find, and laugh my way past the plasma aisle at Visions. Screen size will be 108" diagonal - biggest I can get away with on a 7' 6" ceiling and still put stuff on the floor beneath it (like a 2' tall subwoofer).

[Oklahoma Wolf]

Short update - got the port today in Regina. 6" sonotube, 8 feet long. Grand total was all of seven bucks. No pics at the moment - I'm recovering after a trip to the auto salvage yard where I spent more time cutting and pounding on myself than I did operating on donor cars.

Dad asked me what the big cardboard tube was for. I said, "I'm building a cardboard pipe organ." That's about right with a port almost 40" long. A foot, a languid, and a wind supply and suddenly I have me an 8' Diapason low C with this thing.

[madmat]

So, when you getting the MDF? You have no idea of how hard it was to not make it a double entrada.

[Oklahoma Wolf]

No MDF - plywood. I was hoping to get it this week, but it's hard to say for sure when I'll have the time and money.

[madmat]

Void free plywood?

[Oklahoma Wolf]

That be the plan. I have to go to Medicine Hat to get the stuff I want - that's a 2.5 hour trip each way. Hoping to do that by Wednesday so I can finally start building on the weekend.

[madmat]

Looking forward to seeing it built and hearing your opinion.

[Oklahoma Wolf]

Well, don't forget I don't have the amp or Reckhorn yet. That's going to be end of September at the earliest now. Too much of my bank account is MIA lately.

Although I might run it off the old Noresco for a bit just to see what it does on 60 watts :D

[Oklahoma Wolf]

After much delay, buying of the wood has... been delayed again. There's a Windsor Plywood opening in Medicine Hat next week, and void free baltic birch is going to be on sale. $55 for a 4x8' sheet. I aim to get in on that price. Should look pretty good in the final build :)

The budget is rapidly coming together for the amp now. Might have it in less than two weeks now. And I have the DTS-ES version of The Haunting coming now too. Gonna scare some trick or treaters but good this Halloween :D

[MrWicked1968]

Canada has stores devoted entirely to plywood?

[Oklahoma Wolf]

Heh - yep :D

[MrWicked1968]

canada is so cool.

[madmat]

Hell, they had a lumberyard in Atlanta called Plymart. They sold all kinds of lumber along with windows and doors built on at their shop. Sadly the recession killed it off.

[Zero82z]

canada is so cool.
You got that right :D.

[MrWicked1968]

plywood stores, Kraft dinner, loonies and toonies...

and yes, I know "Kraft dinner" is macaroni and cheese, but still...

[Zero82z]

plywood stores, Kraft dinner, loonies and toonies...

and yes, I know "Kraft dinner" is macaroni and cheese, but still...
Don't forget Poutine ;).

[MrWicked1968]

that sounds like something you need an antibiotic for.

although gravy fries with cheese curds does sound tasty.

[Oklahoma Wolf]

You got that right :D.

You betcha. Tell me about it. Oh ya... oh ya... oh ya...

although gravy fries with cheese curds does sound tasty.

Addictive as hell. My own recipe calls for two kinds of cheese and my own top secret gravy... man I'm hungry.

[Zero82z]

My own recipe calls for two kinds of cheese and my own top secret gravy...
PM please :D.

[Oklahoma Wolf]

Nothing to it really... put down a layer of fries, cover them with thin sliced mozzarella, another layer of fries on top, and a thin cover of cheddar on top of that. Then, just pour the gravy on. If the top layer of cheese is thin enough, it runs all over the place with the gravy and makes a delicious mess :D

Gravy recipe? I'll just keep that one to myself... it's about the only one I have that I'd be confident enough to put up against Gordon Ramsey in one of his F Word challenges :p

[Zero82z]

Cheddar, eh? I'll have to give that a try.

[Oklahoma Wolf]

The trick is to slice the cheese thin enough so that the gravy instantly turns it to liquid and it all runs together with the bottom layer of mozzarella. It's been a while since I made it with two cheeses, but it's making my mouth water just thinking about it.

[Oklahoma Wolf]

I know people say I have a wooden personality but this is ridiculous.

http://img.photobucket.com/albums/v297/Oklawolf/Speakers/Project%202009/DSCF2141.jpg

That's the 5.9" ID sonotube down on the floor there.

http://img.photobucket.com/albums/v297/Oklawolf/Speakers/Project%202009/DSCF2142.jpg

Windsor Plywood tried to pull a fast one on me. They advertised baltic birch in 8x4' sheets. So I went and got two sheets. Surprise! They were really 5x5.' A typo, but I was pissed - can't build my design with only two sheets that size, and a third would have been well over budget. A sealed design would have worked on two of those, but not this monster.

So I made them put them back and got two 4x8's of 11 ply C2 grade shop birch instead. It's pretty much void free anyway (there might be a couple little ones there), and for the price the BB was I could have gotten three sheets of this stuff. Looks pretty darn nice enough to me. One sheet's a bit warped, but I guess that's the tradeoff for cheaper wood. This box will be well braced anyway, and the shop birch is already a big step up from what I used on those 7 satellites (and the rest of the local 3/4" junk I have in the storage room from the old car sub).

This stuff was also on sale - $35 a sheet. Maybe I should have gotten that third one at this price, but it was hard enough getting this stuff home in a short wheelbase '02 Caravan... it started at the liftgate and came up over the front seats almost to the sun visors. I needed a shoehorn to get in there to drive. I'm down to hobbit height now.

But on the positive side of things, all that wood horn loaded the front Chrysler/Infinity 6x9's in the van. I had no shortage of bass in there on the way back :D

[370forlife]

Drink much coke?

Looks like its going to turn out great.

[Oklahoma Wolf]

Drink much coke?

Why, whatever gives you that idea? :D

I can't stand coffee... that's my substitute.

The first thing I did when I got to Medicine Hat was run to Rona to check their wood prices. I ran away from Rona shortly afterward. Poorly stocked for wood, they were, and what they had was not cheap. I could have had a sheet of oak there for $85 full of voids, and spruce wasn't a lot cheaper.

Went to Totem after that... better prices there, but nothing like Windsor had. Shop birch there would have run me $65 a sheet. They had no baltic I could see. Looked like Windsor was having trouble keeping the baltic in stock... no surprise with nobody else in town stocking the stuff.

[Zero82z]

The first thing I did when I got to Medicine Hat was run to Rona to check their wood prices. I ran away from Rona shortly afterward.
Rona is a pretty crap hardware store in general. Lousy prices, bad sales, employees who don't know what they're doing, etc.

[Oklahoma Wolf]

The one in Regina was good. I guess they're the exception though. Much bigger store than the one in the Hat too.

FWIW, it looks like Totem is owned by Rona... that would explain their prices.

[madmat]

So, no poutine talk today? Nice looking ply, 11 layers FTW! Okay, so where's the box already? ;)

[Oklahoma Wolf]

Use your imagination :p

I'm hoping to get the panels cut tomorrow - final assembly should be on the weekend. Still waiting on my brother in law to give me the bracing materials. Will see about buying the Reckhorn this week too perhaps.

[Oklahoma Wolf]

My back is killing me now, but the panels are cut. I might have to kiss that circular saw (with the cord unplugged, of course) - it's already more than paid for itself.

Sheet #1 about to go under the knife:

http://img.photobucket.com/albums/v297/Oklawolf/Speakers/Project%202009/DSCN4937.jpg

#1 went easy. Only three cuts on that one. Good thing I had the good side up, because it took a couple tries with the saw to keep from chipping the birch layer underneath at the end of the cut.

Here are the three panels from that sheet. Two 48x24" and one 48x25.5:"

http://img.photobucket.com/albums/v297/Oklawolf/Speakers/Project%202009/DSCN4938.jpg

Sheet #2 was much harder. Not only did I need to cut another 48x25.5" panel, I had to do two 25.5x25.5" panels as well. Then, I had to cut the wood for the new car sub out of what was left. That took forever, but I got it done. I may have to recut some of the car sub panels (the front panel is only 11.5" wide for a sub that needs an 11" cutout), but I could just go to a 10" IXL in the car and leave the panels as is. Undecided yet.

Here's all six panels for both projects in the door to my load testing lab:

http://img.photobucket.com/albums/v297/Oklawolf/Speakers/Project%202009/DSCN4940.jpg

If there are any voids in that plywood, I sure can't find them :D

Edit - aaaaand the front and back panels for the car sub are off. Too big, and yet not big enough to assemble it a different way. Well, I guess in correcting them with the leftover shop birch I can make that box just a bit bigger to ensure it will take a 12" IXL. Fortunately, the dimensions of the paneling on the big one are all within 1mm of what they need to be. That box is going to look great. Even if I'll need a forklift to move it.

[madmat]

If you'll tape your cut lines top and bottom you'll end up with a lot less chipping. Just a handy tip I saw on some woodworking show.

Glad to see you got it all cut, when does the assembly begin?

[Oklahoma Wolf]

Tuesday - the bracing was a no show yesterday. My brother in law forgot to bring it home with him :(

I was going to re-cut the two messed up panels for the car sub today and get that one together, but the forecast is 35 degrees Celsius. Nobody's making me play outside in the sun at that temperature.

[madmat]

That's pretty warm. I was going to do some work on the car today so, naturally, I wake up and it's raining.

[Oklahoma Wolf]

In my fit of non enclosure building boredom, I came across these videos:

http://video.google.com/videoplay?docid=283422981607670040&hl=en#docid=724828371696599369

http://video.google.com/videoplay?docid=283422981607670040&hl=en#docid=3767650962766358661

This is going to be fun :D

[Oklahoma Wolf]

It is done. I now have a casket next to the TV set. Started at 2pm and ran the last screw into the woofer basket around 7:30pm. I would have gotten it done sooner had the drill battery not croaked... three times.

http://img.photobucket.com/albums/v297/Oklawolf/Speakers/Project%202009/DSCN4941.jpg

Port mounted. I messed up on the cut for that... you can probably tell. It's probably not tuned to 11Hz anymore but slightly higher. Three panels screwy and gluey. Half the bracing installed with the long braces test fitted to see if they'd work. Fun fact - screwing together 2x2 hardwood bracing with 3" long screws is a massive pain. I actually couldn't open my hands back up after a couple of these. I'm going to look like Popeye in a week, what with that and the sawdust in my eye. Didn't help that the drill battery was charging (again) at the time. The bracing holds the port in place.

http://img.photobucket.com/albums/v297/Oklawolf/Speakers/Project%202009/DSCN4942.jpg

From the other side showing my ghettotastic job on the port hole. Santa needs to send me a router for Christmas. I am not doing this again without one. Period. No, wait... exclamation point, exclamation point, exclamation point.

http://img.photobucket.com/albums/v297/Oklawolf/Speakers/Project%202009/DSCN4943.jpg

Getting closer. All bracing in place, four of six panels gluey and screwy. You can see the shims I made from leftover CDX on the two vertical ones in the foreground.

http://img.photobucket.com/albums/v297/Oklawolf/Speakers/Project%202009/DSCN4944.jpg

Binding posts in. 12 gauge wire installed with 1/4" Gardner-Bender screw clamps. Stupid me, I made the positive wire almost too short. Almost.

http://img.photobucket.com/albums/v297/Oklawolf/Speakers/Project%202009/DSCN4945.jpg

All done at last. Sun's going down so I better get the driver cutout done but quick.

http://img.photobucket.com/albums/v297/Oklawolf/Speakers/Project%202009/DSCN4948.jpg

What do you do when you have only a jigsaw and no router? Well, I did this. Before I drew on the box, I drew on some cardboard as a test and then cut out the resulting circle. To be sure it wasn't off, I dropped my cardboard circle on the IXL. Perfect. The driver fits like a glove.

http://img.photobucket.com/albums/v297/Oklawolf/Speakers/Project%202009/DSCN4949.jpg

See? Test fit was perfect. You can't wiggle the driver back and forth, it's that cozy.

http://img.photobucket.com/albums/v297/Oklawolf/Speakers/Project%202009/DSCN4950.jpg

Good God, what have I done? If you look real close, you can see the Noresco is turned on. Yes, I was testing the finished product with a 60W amp (well, more like 120W since this is a 4 ohm load). It works, but naturally the Noresco can't move the IXL too much. I had to watch that it didn't clip, but it did better than I expected it to.

And now for some good/bad news. I thought I had some resonance on the main channels due to the junk plywood I used. Well, I found out it's not resonance. That's the good news. The bad news is, at least two of the 14 drivers have loose tinsel leads to the tweeter. They're loose where they go through the woofer cone. Not an uncommon problem on these old Chrysler/Infinitys. Grrrrr. I hate fixing that. Time to go get some glue.

So, how does all this sound? The IXL is magnificent, as expected, even on that little amp. I am now kicking myself though... I never tried my 7 channel mains in stereo mode with some simple CDs. I was missing out big time. At first, I thought the center channel was still on, the imaging was that good. Sound quality was incredible, especially with that monster handling the low end.

I'm going to fix those loose tinsel leads and run these speakers for a long time to come, I think. They don't sound nearly as cheap as they look. I'm still going to stuff the boxes, but that's probably it for a good long while.

Happy, I is. Now to go buy me an amp that can really wake up the IXL :D

[madmat]

Looks good man. Vids?

[Oklahoma Wolf]

Of what? The 6mm of cone movement the Noresco is capable of? Give me a chance to get the new amp first ;)

Had some fun this morning. The world's largest pipe organ has a 64' stop that bottoms out at 8Hz. I have a demo track of that stop slowly stepping down through the notes. This monster played them all, right down to low C. I heard the wall paneling in the lab rattling 30 feet away from the thing, and that was at only 120W or so.

[madmat]

If you're getting "house flex" off 120W then it's going to be pretty loud on a bunch of power.

See if it'll make a pic dance on the wall at 120W and grab a quick vid of it if it does. Just to show what it'll do off low power.

[Oklahoma Wolf]

Heh - will do, just remember all I have to work with is the Fuji S700 and Nikon 3700 for videos ;)

[Oklahoma Wolf]

http://img.photobucket.com/albums/v297/Oklawolf/Speakers/Project%202009/DSCF2445.jpg

After going on a "vacation" that ended up with me having to borrow a whole lot of money to even get home and left me sick as a dog, I am back with the new amp, as you can see above. It's a monster - 45.5 lbs. The chain is there to bolster the angle brackets holding the shelf up.

Currently, it is configured with only channel one driving the sub. That's 600W at 4 ohms. I don't want to really push it unless I either find one IXL running at 600 lacking in some way, or have the subsonic filter first. And I can't afford the Reckhorn now, so it'll be like this for a while.

Setting the gain proved interesting. I knew the Pioneer would have trouble outputting enough signal to drive a pro amp, so I left the EQ in the chain and maxed out its gain. Even so, I had to dial in the gain on the amp all the way to get decent output.

Using an RCA to 1/4" adapter to run the line to the amp proved problematic - this resulted in the ground and negative signal wire to be combined. This is really the way unbalanced inputs should be connected. But, this gave me a ground loop issue. What I ended up doing is lifting the signal ground by using the screw terminal inputs and only connecting the positive and negative signal wires - ground was left alone. Bam - no more hum.

What's it like now that I have the gains set just about where they need to be? Well, I played some test tones. At 10Hz I couldn't hear much, the woofer wasn't moving much, there was no port noise audible, but the door to the test lab was rattling back and forth like crazy. At 15Hz, I started hearing it and more stuff was rattling.

At 18Hz, around where max excursion is supposed to be reached, the woofer was visibly moving but nowhere near full stroke. Lots of wall paneling and more than one door was rattling. 25Hz - the monster really started waking up... lots of rattling from stuff that hadn't been before. The air in the room was notably pressurized. Woofer still wasn't moving more than an inch peak to peak. People started coming downstairs to find out what in the name of Jeebus I was up to.

And that's where I shut it down for the day and went to go watch House. Tomorrow, I'll run MCACC on the Pioneer and calibrate the gains again :D

I'll need the Reckhorn to get the most out of the amp yet, but so far I'm not thinking I'll need more than the one channel of the QSC for this subwoofer. It's darn well loud enough already. The amp fan does make a fair bit of racket, but with the amp in the lab the racket goes away completely by closing the door. I need to do something about that door rattling yet.

[madmat]

Sounds fun. You might consider getting a car audio line driver and crossover with SSF. Or a crossover with line driver and SSF. There are line drivers that push 9V RMS so it'd be no problem to match the amp to your stereo.

[Oklahoma Wolf]

The Reckhorn has all (well, most of) that functionality built into it :)

I watched Transporter 3 yesterday while I was sick and let 'er rip. Ran the Pioneer at -15 dB, which is hotter than usual. The IXL loafed right along until the part in the garage before the big fight... then it let loose with two big blasts of low frequency energy that shook everything in the house. I figure I saw maybe an inch peak to peak movement of the cone... about half of what it can do.

So, I'd have to say I'm pleased with this thing.

[Oklahoma Wolf]

Just in case anyone's interested to see what the guts of a QSC RMX-1850HD looks like:

http://img.photobucket.com/albums/v297/Oklawolf/Speakers/Project%202009/DSCN4961.jpg

Class H design using an SMPS for the power supply. The eight large caps are 50V 18,000 uF Nover parts.

[MrWicked1968]

the sound of the "seismic charges" used by Jango Fett in Star Wars: Attack of the Clones would be a great one to crank up. If I crank up my Bose Cinemate system, it'll damn near make your ears bleed.

[Oklahoma Wolf]

Hmm... I haven't seen that in a while :D

My ground loop elimination strategy didn't work out. Sure it killed the hum, but then it started popping every now and then. Not often, just often enough to drive me nuts.

So, I reconnected the amp with ground and negative combined once more and cut the ground pin off the amp's power cord. That did the trick, no hum or popping now, but now the amp isn't grounded. I'll have to grab a ground loop isolator. I'm not wild about running a class H amp with no ground long term.

[madmat]

Hook a small capacitor between the ground and the shield. The shield will still work as a shield that way.

[Oklahoma Wolf]

That should do the trick.

Almost bottomed out the IXL this evening... the movie I was watching had entirely too much content below the tuning frequency. I need to get that Reckhorn here before I push it that hard again. Maybe I'll turn on the amp's clip limiters.

Need to fiddle with sub placement yet, it seems. It's not as loud as it should be in room, but it shakes the whole house if you go upstairs.

[Sphere]

Placement is the biggest pain and most important aspect in getting the desired end result. I recommend doing the *sub crawl* to find ideal placement.

If you have it placed on carpet over concrete, then you'll get less *feeling* under your feet/floor in LFE situations. If you have it placed on a suspended floor, you'll have much more of an active feeling.

I have an eD A5-350 on carpet over concrete. I can easily move dishes off the table upstairs, and watch the bottom of my pant legs move, but nothing on my feet due to the damn concrete.

The only way around that is to build a riser over the entire floor, which is not an option for me.

You can also pick up a Radioshack SPL meter and run REW http://www.hometheatershack.com/roomeq/

[Oklahoma Wolf]

Heh - carpet on concrete here too. I moved it a bit this morning, and it's now standing in the corner below the right front speaker with the port facing upwards. This used to be the best place to put the 15's... still not getting much in room action below 23Hz. Above that, it's just sick.

This placement thing could be tricky with a sub this size. Have to watch its proximity to the TV set too. Next step, fire the woofer directly into that corner. That should help a fair bit. I've also enabled the clip limiters on the QSC to reduce the chance of the IXL bottoming out while the Reckhorn is MIA.

[Sphere]

Here's some info for you on the sub crawl For those who don't know about the "subwoofer crawl," it's a technique for finding the best location for a subwoofer in your room. First, place the sub at your listening position and play some familiar music. Then, crawl around the perimeter of the room to find the spot at which the bass sounds the most smooth and even. That's the place to put the sub, which will then produce the most even bass at your listening position.

In your case, the sub needs to go where you normally sit, not in the center of the couch. It does matter—a couple of feet can make a big difference. Moving stuff away from the room's perimeter is best, but if that's impractical, stick your head close to the wall as often as you can while crawling around objects. Keep in mind that you're looking for a place in which the bass sounds most even and where you can actually place the subwoofer.

As an alternative, master acoustician Floyd Toole of Harman International has determined that the best place for a sub in a rectangular room is at the half or quarter point along any wall. For example, if the room is 20 feet long, placing the sub 10 or 5 feet from either end along that wall will yield good results. This rule is not foolproof, and the subwoofer crawl will certainly find the best spot in any room, but if you don't want to crawl, it's a good approximation.

This is about the most fool proof way to go. You may look a little silly, but you can really find the sweetspot.

[Oklahoma Wolf]

As an alternative, master acoustician Floyd Toole of Harman International has determined that the best place for a sub in a rectangular room is at the half or quarter point along any wall.

Heh - that's where I had it yesterday. Quarter point, that is. The problem is, my listening position... the ideal point in this room is way at the back of the room far away from the TV, and at the other end of the basement in the PSU load testing lab. Currently, that's where all the really low bass is ending up.

Ah well - just have to keep playing with it. The sub crawl is impractical for the room and the size of the sub, but I might end up having to do that anyway.

[Sphere]

It's a pain to move the sub, mines is 112 lbs, but once you get it where it needs to be, life is good.

On the other hand, if you have limited space to put it, then you'll have to make due. I was fortunate to have mine happy 1 foot from a corner in the back of the room. The back wall is the only spot I could fit it.

Subs are great, but they can be a nightmare finding the sweet spot when they are big and heavy in relation to moving.

[Oklahoma Wolf]

Yeah. And in my case, all the subsonic stuff below 20Hz is doing is rattling the rest of the house... the concrete doesn't move. I may end up with the subsonic filter at 20Hz just so it doesn't annoy the people living upstairs. No point letting it reproduce stuff I can't hear if the concrete won't let it shake the floor instead of the ceiling.

Of course, I do have one empty channel on the QSC. I'm not out of options in this room ;)

[Sphere]

If your bother the folks upstairs (just the nature of the sub) you can always build a small riser to decouple it from the floor, that will help some as well.

[madmat]

Get a Fosgate I-Beam and attach it to your listening chair and run it off the other channel.

[Oklahoma Wolf]

I have a few thoughts and observations after saving my DTS-ES copy of The Haunting for last night:


the IXL did a pretty decent job of shaking the couch when needed despite the concrete floor
best sounding audio on anything I've played with the new system so far
had the Pioneer at -15dB for a while... seemed to do ok. The fan ran a lot. After the fireplace popping scene, I dropped it down to -17dB for trying to deafen me.
7.1 channel was worth it for this movie alone
I need to fasten down the 12 gauge wires inside the IXL's box a bit differently - a couple scenes had them buzzing on something

This movie needs to be in the collection of anyone who wants to give their subwoofer a serious workout (make sure it's the DTS version). From what I saw, the IXL could have probably handled reference level - it had more to give, though it got crazy loud already. I'll have to try and video it on some of these scenes sometime.

I'm contemplating upgrading the Pioneer receiver to a Marantz or Denon. I don't like how hot this thing gets, and it's constantly running the fan now that five of my seven mains are set to "large." Even with a 140mm fan on top helping out. I'm not sure it would have handled me playing this movie at reference level without shutting down. And that's not a terribly quiet fan either.

I'll think on it some more. I can't afford to upgrade already, so I might be stuck with the Pioneer for a good while. I'm still not sure I don't want another IXL first... though I know I'm not pushing this one too hard, I like the idea of having some headroom. And certainly the Pioneer seems to get loud enough for me without shutting down... maybe I'll get used to the fan yet. I do plan on adding a second 140mm fan on top running at 5V - that should help too.

[Sphere]

All avr's run HOT. I have an HK 247 & 254. Normal listening(TV) I can keep my hand on the top for maybe 5 seconds. This goes for Onkyo, and Denon as well.

[Oklahoma Wolf]

Not all of them - the old Kenwood was stone cold all the time. Then again, that was an old Pro Logic...

I found a cheapie 5.7V Nokia SMPS cellphone adapter at Value Village today for $3. Output is rated up to 800mA. I have it driving two 140mm fans on top of the receiver now - one a Globe Fan high speed, and one a Young Lin Tech medium speed. The adapter powers them both just fine.

Will have to see what two fans can do to keep that 80mm AVR fan quiet now.

[Sphere]

Anything modern with any amount of output is going to generate a lot of heat.

[Oklahoma Wolf]

Mine generates a lot of heat just idling on mute :p

[Oklahoma Wolf]

Did some more fiddling around today despite my messed up ankle. Found the solution for my underwhelmed impressions of the IXL, and I'm kicking myself for not trying it sooner. I should have known better.

I just fired it into the corner, and turned the corner into a folded horn thusly:

http://img.photobucket.com/albums/v297/Oklawolf/Speakers/Project%202009/DSCF2079.jpg

The woofer is firing to the right, with the horn "mouth" facing left. Then I tried The Haunting again in DTS. Same volume level as Halloween night.

Before: impressive performance, but not overwhelming.

After: absolutely scary. At a guess, I must have picked up a good 10dB of extra output here. Everything in the room rattles, or tries to. There were scenes when it could get up and punch me in the chest, and now on the same scenes it kicks me in the chest.

Subsonic performance has not changed a bit. There's nothing there below 17Hz. Due to where the port is, I'm not surprised at all. But, I now notice more output between 18Hz and 22Hz than I did when the IXL was pointed straight into the room.

[madmat]

You might be able to spin it so that the port faces the floor and lift it 3" off the floor. Loading the port on the floor should net you a bit more gain.

[Oklahoma Wolf]

True - as long as I can find a way to do that without it coming up too high and hitting the right front speaker.

I had some fun the other day - ran the Pioneer up to -5dB and played some test tones from 10-20Hz to see if the sub could handle it without over-excursion. It could. 20Hz had the lab door across the basement flapping like a jackhammer. That whole wall was rattling like crazy. Then I smelled warm voice coils and realized I was torturing my main left and right speakers too - had to stop then.

[Oklahoma Wolf]

So the vent is now firing down with the subwoofer firing into the corner as before. I have the thing 1.5" off the floor using the leftover 5.25" cutouts from the main speaker builds as stands. Just got done running my 10-20Hz test tones.

The result is that I am now noticing significant subsonic content at the seating position. I could feel it all the way down to 10Hz. Made a D cell battery dance on a shelf nearby... this was at -10dB volume level. Still can't feel anything through the concrete, but them's the breaks. It shook the couch well enough, so I'm pleased.

I think I found my optimal sub placement at last :D