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Twelve 10" NHT Subwoofer Build. - Page 6

post #151 of 274
Thread Starter 
I promise, they will be done tomorrow.

I almost had a disaster today actually. I do a lot of construction work on my home (like nonstop) and for others, so I'm not too bad with tools and measuring. WELL, this project was picking up pace a few weeks ago and I went down and did the initial measuring for the ceiling height.

78" was my "quick" measurement. I never went back to get the dead accurate measure though! I just got caught up in the design and then went full bore on it. My ceiling looks like a drop ceiling, but I "invented" a way to do it without losing height by putting the tracks directly on the studs. So it can't be pushed up.


Well, turns out, I measured to the ceiling tile......but the box needed to go under one of the tracks, which is about 3/16" lower than the tile. Yeh, it was a very very tight squeeze that took a lot of pushing. But I'm pleased to say that the 3rd one is now in place (that's the hardest one). The other side won't be an issue because the floor slopes a bit and I have more clearance.

I thought I was going to have to power sand 3/16" off the side of a box. But it's okay.


Disaster avoided! But I really did have to wedge it in. Hey, no need to secure it to the wall anymore! One of the dumbest mistakes I've made with building anything!
post #152 of 274
About a year ago, a close friend asked me to supply the PA system for his sister's wedding. Of course I said "Yes" and then proceeded to decide that I wasn't really 100% happy with my current PA system, so I would build a new one for the wedding.

I got the satellite cabinets about 70% finished and started to test fit the drivers. Oh S**t! The compression driver on the horn wants to stick out the back of the cabinet about 1/4". Somehow during the wood layout process, I had forgotten to add in one more layer of 3/4" plywood. I ended up having to carve out a recess on the inside of the cabinet for the compression driver, with a Dremel tool (yuck) and mill about 1/8" off of the front of the horn. In the end, it all worked out, but I can't believe that I screwed this up after having built 100-150 speaker cabinets by hand.
LL
post #153 of 274
Thread Starter 
Well Jack, it's nice to know I'm not the only one to make an easy error then!


Okay, so it's 1:40 a.m. and the good news is that all the boxes are done and even in place. They look really really nice. The bad news is that I'm a little tired and don't want to do any wiring tonight because I don't want to mess anything up.

So tomorrow they get fired up!
post #154 of 274
Erich, you may want to shim the other side's bottom enclosure against the floor so that both sides are equally tight against the ceiling. You'll notice the difference at that eyeline, but not anything against the floor.
post #155 of 274
Thread Starter 
Gentlemen, feast your eyes upon the Wall - O - Subs!

Ugh, I had time to wire them up, but now I have to go to the parents anniversary party! I hope to listen to them when I get back. AHHHHHHHHH!!!!

I did turn them on to check if everything worked, but only played a CD for a couple minutes. It was some "Big Hair" rock (Firehouse). Let me just say, I won't be hitting their peak any time soon without the house coming down!!! And I can say that I'm very far away from what they can do, but I don't want to push them hard just yet. The kick drum just pounds like crazy. It's amazing actually, and they have lots of room to go! Very very solid punch to the chest. That's was just a few minutes, and not turned up too high. Right now, I'm smiling. I can't wait to get back this evening to listen some more. No one in my family knows about this yet. And they won't until they are invited over for a movie!


Here's what they will be staring at:





Here's what you see from the seating position!








Jim, I did need to shim up the other side, and I might still need to do a bit more. I will also be adding a top border as well. I will probably make it the depth of the boxes I guess. And of course I will do the same with the center channel area once I make a shelf for the amp. And I will be filling in the corners with insulation wrapped in black.
post #156 of 274
Erich,
way to go man! That looks KICK A$$
post #157 of 274
Thread Starter 
Thanks a lot Dan. I'm running late but I had to go down with my SPL meter just to see something.


I know this doesn't really mean much, but I'll do more later.


I put in a CD with some decent low end bass. Denon LFE is set to -2, EP2500 set all the way up. Denon volume at -15 and my Radio shack meter was giving me 124 db from the seating position. But as mentioned, the subs aren't being worked.


More later, I gotta run!
post #158 of 274
Looks better than I thought it would... great in fact! This is probably the best screen border ever.

Now you just need to add a strip of black along the top of your ceiling, between the two towers.

Was your 124db corrected to the frequency or uncorrected?
post #159 of 274
That looks great. Wish I had a setup like that. Are you going to have any problems with light spray with the enclosures that close to the screen? Might have to put some non reflective material on there.
post #160 of 274
Look at his earlier photos...dead matte material with no reflections! Erich, looks terrific!
post #161 of 274
Thread Starter 
Thanks guys. Yeh, I'm not getting any extra light reflections on the material. It's some fairly drab black fleece fabric covering those boxes.

As for the 124db, it surely wasn't anything scientific at all. I will be ordering an EQ this week to get them all set up properly.

I have a laptop, but I'm not sure about what kind of sound card it has or how to run the tests to put some graphs up. So I'll have to learn. I also have a desktop computer that I can drag down there if I need to.
post #162 of 274
I'd be very surprised if you had a laptop that will work. I'd plan on dragging the desktop down there so you can do it right. Do it now and save yourself a lot of headaches later.

I officially have sub envy. Looks great!
post #163 of 274
Erich,
what do you think of it so far? You get a chance to watch any movies yet?
post #164 of 274
beautiful setup. that has got to be pumping some serious air. golod to some finished projects. good luck. keep the pictures coming.

robert
post #165 of 274
Thread Starter 
Well, I'm a bit worried about turning them up too much right now. However, I did watch Pans Labrynth a couple days ago and was immediately impressed. The explosions and especially the gun shots were incredibly solid. A few parts made my girlfriend jump just because of the sheer impact of the bass. One part in particular (if you've seen it) was when the girl ran away from that odd creature with eye's on his hands. After she slams the door and the creature bangs on the floor. Wow, it felt like the entire theater room was being beat on with a sledge hammer! It was really something. Enough to rewind and listen a few times. And the girlfriend didn't mind rewatching it one bit.....so you KNOW it was good!!!


Here's how much I'm worried though (unfounded worry I'm sure). After I watched that movie, I thought I would play it safe at first until I know how they do. I set the high pass filter on the EP2500 to 30hz. Then sent only 32 hz and down to two 15" sonotubes. That did give me some serious shaking, but then again, those are located behind the couch so they should.




Anyway, before I go nuts with these, I want to hook up the Feedback Destroyer and go through all the testing and tweaking. I should have it in a few days from Amazon.


But initial testing with that movie even without the 15's was very very nice. Certainly worth the effort, and certainly worth the price.

Once I figure out what sound card my laptop or desktop has, I will figure out how to do get some graphs up for a bit of help. Should be no later than this weekend.

I'm also going to try and get a video up to show how much the subs are moving. Then you guys might be able to tell me if they are in the 'okay range'. That was one reason why I asked if the amp can actually hurt them or not. I simply don't know.
post #166 of 274
the BFD has no filter in it so there's no reason to not test now, I'd recommend downloading the TRW demo disc to check ULF excursion.

Disc Image:
http://www.rotarywoofer.com/demodvd/basstestdvd.dvd

Use ImgBurn to burn it:
http://www.imgburn.com/
post #167 of 274
Erich,

I wouldn't worry very much about damaging the woofers. They have a felt pad ring on the top plate. This lets the spider bottom out against the felt without allowing the voice coil former to hit the back plate. They will sound bad when the spider hits the felt, but no damage will occur. You will really have to overdrive them untill it sounds awful to damage them.
post #168 of 274
Nice
Felt dognuts save you from screwing the pooch, LOL
post #169 of 274
Thread Starter 
That's great news. I'll turn off the filter then, and do some light experimenting tonight.

I will drag the desktop down there and start figuring out how to do some tests.
post #170 of 274
So what do you think now
Here are the filters on the EP2500:
post #171 of 274
Hmmm. Little bit of boost below 10hz. .

Dan,
How did you take that measurement? I just fried my sound card trying to get a fr of my CE4000's. I made a stupid mistake.
post #172 of 274
Looks like we will both be shopping for a new sound card, as I do believe my card is fried due to the EP2500 going into oscillation. I think I'm done with M-Audio. E-MU looks tempting.
post #173 of 274
Next round I intend to use my MIC2200 in line because the XLR pin 1 is Chassis Ground, hopefully the common chassis ground plane will prevent this situation from happening again.
post #174 of 274
Thread Starter 
Well, I got the feedback destroyer today, which was quicker than expected. So I might as well hook that thing up prior to testing. If I need extra cables, then I'll wait for the weekend to hook it up and just go ahead and turn this thing up a bit now to see what it can do.

I hope I made the right choice, I thought the Feedback Destroyer was pretty much a necessity? But I also thought it had a high pass filter. So maybe I made a mistake. Any ideas here????


I have a Sony desktop that I don't really use anymore. I think it's about 5 yrs old or so. It does have an optical output, so it must have a decent sound card, but I'm bnot sure how to even check! I do remember when I got this computer, it had a lot of music editting/making software included. Hopefully the sound card is fairly nice.
post #175 of 274
Optical out is the way to go


Forget the BFD for a second and flip the flippin' switch, LOL
I just want a reaction from you after you turn off that 30Hz filter and crank the mother up
post #176 of 274
Do you have the 1/8" stereo to RCA adapter, and a RCA interconnect for your meter?
post #177 of 274
Thread Starter 
Yeh, I'm fairly confident I have those things.

I'll be taking the computer stuff down there tonight and gathering up all my cables to see if I can figure this stuff out.

And I will also be turning off the 30hz filter as recommended for now.


I had them moving pretty good this evening, but only with some music, so nothing really low. Firehouse of course. A 30 second run was showing me 125db at the listening position which is 13' away. Denon sub level was -2, volume was -8. Not that that matters much at all, but it is what it is!
post #178 of 274
Cool,
it'd be nice to get some impressions of it before you suck the life out of it with the BFD

Calibration loop:
PC optical out to AVR to Left Pre Out(default in REW) to RCA to 1/8" adapter to PC input
Don't forget to turn off the gimmicks in the AVR, and set it up for Large/full-range speakers
post #179 of 274
What happened?
Did you get chained to your desk ?
post #180 of 274
Thread Starter 
Well, something like that. It's a busy part of the year for me. But all is well now.

I tried doing the testing last weekend but I must have something set up wrong. I'm off today so I am going back down to give it another shot.


If I'm just testing the subs, is there any reason to set 'Large full range speakers'?
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