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Bedlam in Goliath: RE Audio XXX18 subwoofer build - Page 5

post #121 of 327
Thread Starter 
Well alright. Here's what I've got so far. Keep the following in mind: I did set the level to be about +3db hot relative to the monitors. I have not yet measured the room response or the response of the sub. I don't have a working lap-top now so I can't run REW. That will be remedied soon. Also since I have not had a way to accurately measure things there is no EQ'ing being done yet either. What I have right now is the raw response of the sub in the room, my senses, test tones and a Galaxy CM-140.

Overall it sounds good! Its clean, extended and effortless. Compared to my 2 Velodyne CT-150's it replaced, I think it sounds better. It does sound different though. Honestly it sounds like someone added one of those harmonic bass synthesizer's that adds an extra octave of low bass to the system. It just sounds so much deeper and more like a real bass event even with music. This is all at low to moderate volume. I've got it crossed at 80hz, but I may move to 60hz eventually.

From the small amount of listening I've done so far I would guess that I've got a null maybe 2 somewhere in the upper bass 50-70HZ and a natural house curve starting around 35hz on down due to room gain and the extended response of the sub.


I did get on it for momentarily with some Bass Mekanik stuff and the Twitchy Sines track from ROE and it was very impressive. The low stuff was literally shacking the entire house to the point where I was asked to stop. I've got a lot of rattles and stuff to eliminate. I'll have the house to myself for a bit this afternoon, so I'm going to take the CM-140 and get some readings.
post #122 of 327
Thread Starter 
Ok let me just say that there is no need of a highpass with this system at all and that the low frequency output below 20hz is like nothing I've ever heard. The excursion that the XXX is capable of is insane. I'm inclined to believe what the RE Audio tech's told me about the mechanical limits being somewhere north of 60mm. It's downright retarded. Also the amount of air that the powerport is flowing down around 14-8hz is huge. The entire area between the bottom of the cab and the baseplate is acting like a giant slot port. Freakin huge slabs of air coming out.

I don't need a highpass at all because I've definitely got some roll off in my signal chain. Everything seems fairly good down to 9-10hz and then it starts rolling off and seems to be roughly 12 to 14db down at 5hz comparatively. Remember this is just guesstimation, but it's based on the excursion of the driver at the same levels, which should be way unloaded at 5hz and getting out of hand. 8hz seems to be where the roll off really kicks in. I'll try to measure this when I get a new laptop.

I did take some output measurements, but they are not max-output spl's per se. The Crown never batted an eye and the XXX just kept displacing more air. Honestly I kind of chickened out because the forces involved here are really crazy for one driver and I didn't want to damage anything. I never heard the driver beg for mercy or start to sound bad. The room and house started sounding bad first. At one point a big picture fell off of the wall and a glass in the next room vibrated off of the counter and broke.I didn't know until I walked into the kitchen. Also at 15hz and 16hz the DIY chase thats in the pictures that you guys were making fun of, started jumping off of the floor. The left corner was jumping up and down. I basically took it up to a point where I didn't feel comfortable going any louder due to the driver excursion, fear of clipping the amp or things were falling off of the walls... literally. I may push it a bit harder at some point but honestly I can't really even conceive of a movie hitting those kind of sustained levels and music will be amp limited( doubt I'll be listening at those sustained levels either). I had to cut things short because my girl got back from shopping with my sister and said something to the effect of "quit it!".


After taking into account the CM-140 correction factors. I was able to attain an easy 115db+ at every frequency from 20hz down to 10hz. I just left the volume at -12db and proceeded up. There was some variation with levels up to 119.1db recorded at 17hz. There is definitely more gas in the tank in the 10-20hz octave and my floor joists apparently resonate at 13hz.

At 5 hz The CM-140 showed 105.1db when I quit increasing the volume. The correction value at 5hz is 24db. Giving a reading of 129.1db. Can this be right? I mean it was seriously flexing the room at that point and I will say that it felt kind of like the earthquake tremor we had awhile back here. At 6hz the Galaxy showed 103.1db and the correction factor is 18.8db.a total of 121.9db apparently???? 7hz was 104db + the correction of 16.09db for a total of 120.09db. These are the levels when I didn't feel comfortable increasing the volume any more. I guess I have the magic 30+db of gain below 8hz that Bosso talks about? Hell I don't know.

I do know that Nathan's description of it sounding like a back hoe is assailing the building is pretty accurate. Also that 10hz is not as hard to hear as people make it out. I can easily sense the really low stuff at moderate volumes.

I'm going to have to take some video's at some point.
post #123 of 327
Darned.... too bad I had to get back to Canada... I left Indy for Detroit and then spent some time with some friends... I wish I would have seen that monster. I guess there is next year!
post #124 of 327
Quote:
Originally Posted by Ricci View Post


I do know that Nathan's description of it sounding like a back hoe is assailing the building is pretty accurate. Also that 10hz is not as hard to hear as people make it out. I can easily sense the really low stuff at moderate volumes.

I'm going to have to take some video's at some point.

ULF is easy to hear...feel.The air pressure varies slightly and you can sense the ULF.

In your case the giant sub can reproduce all the sub bass all the way to near DC,that is a major plus. EBS done right is downright impressive. At the cost of sometimes...HUGE size.

I have one EBS half the size of your goliath and it is BIG,now your sub has the size and performance for King Kong's HT.

Talking about pictures falling off the walls...use MIGHTY PUTTY by that screaming irritating bearded comedian. Order NOW ! And get two more tubes FREE!!!!

Seriously,with massive output down deep comes a new challenge replacing all things held by nails with lag bolts.
post #125 of 327
Thread Starter 
Mike,
There's always next year! I'm planning on going to the get together.


So far I've watched Finding Nemo, the Incredibles, 10,000B.C., Cars, and Flawless. Also listened to a bit of music. Nothing to report except subterranean room shaking bass! I'm hearing stuff that I never heard before in these movies. There's actual tonality and dynamic range down low now. I was missing a lot with my old set-up, the really low bass was simply rolled off and unproduced before.

Just got my other CE4000 back for the SDX 15's too. Time to play with them this weekend and start eliminating some buzzes,rattles and creaks.
post #126 of 327
Thread Starter 
Finally got my other XXX back from RE after roughly 9 weeks. This one is going to be used in a sealed application.















Also I have a laptop on the way. Then it will be time to learn the ropes with REW.
post #127 of 327
Goin for a .7 q enclosure, 25 cubes? Thankfully even a 1.0 q box looks great with this driver, 7 cubes, go ahead and power it with 4,000watts, it still won't bottom out!
post #128 of 327
Thread Starter 
Yes you can forget the .707Q with these bad boys, unless you are going to IB them. You've gotta love STILL having the -3db down point in the lower 20's with sealed box Q's over 1.
post #129 of 327
That driver is gorgeous, and the sub you've built is even better looking! Nice job on the build... I can only dream of coming close to something that awesome.

EDIT: DAMN! Are those drivers really $2k? :O
post #130 of 327
Thread Starter 
Yep. Kind of. MSRP is $2,249ea. I paid less than $800ea for my two. I'm actually keeping my eye open for a 3rd and possibly 4th.
post #131 of 327
That's much better, but still... Ouch. Those suckers had better be worth it
post #132 of 327
These XXX's have so much Xmax there is less peak to peak in XXX flicks.
post #133 of 327
Hahah, with your reply and the thread about the overkill subwoofer, I didn't realize AVS had so many comedians.
Thanks for the chuckle at work.
post #134 of 327
Thread Starter 
Ok guys. Here's a crappy excursion video that I recorded last night while testing the driver I just got back for functionality. It ain't the best quality, since I recorded it on an old sony video camera, and didn't feel like editing anything. It's kind of long and drawn out but you'll get the point. Things start off slow but there's a few millimeters of excursion starting around 1:55 in or 3:15 to go and at the very end past 5:10 or 25sec to go.

Enjoy.




post #135 of 327
I liked the part where the measuring tape disappeared.
That is AWESOME.

*Drools*

I want one now...
post #136 of 327
What are the external dimensions of the sub?
post #137 of 327
Thread Starter 
It's an oversized 18".

Overall Diameter - 19"
Bolt Hole Circle - 18.25"
Mounting Hole Diameter - 17.375"
Mounting Depth - 14.75"
Motor Width - 10.5"
Motor Depth - 5"
Basket Depth - 9.75"
Displacement - 0.30 cu. ft.

Sorry. Did you mean the finished sub with the power port?
post #138 of 327
Quote:
Originally Posted by Ricci View Post

It's an oversized 18".

Overall Diameter - 19"
Bolt Hole Circle - 18.25"
Mounting Hole Diameter - 17.375"
Mounting Depth - 14.75"
Motor Width - 10.5"
Motor Depth - 5"
Basket Depth - 9.75"
Displacement - 0.30 cu. ft.

Sorry. Did you mean the finished sub with the power port?

Yes, the size of the enclosure.
post #139 of 327
Hey Ricci, I don't know how I missed this thread.

Great job on the power port sub. I'm the guy that built two of those last year using the TC2Ks. I really like how you used the lathe to make your flow ports. I wish I would have had access to that method. I had to form mine with wood putty. It worked fine, but took a while. Both of mine are behind a screen wall so they really have no finish other than cheap black spray paint. Your's look excellent.

Mine sound spectacular with the twin 15s, so I can only imagine what that 18 sounds like. I bet it gets low.

Very nice job, congrats.
post #140 of 327
Thread Starter 
Swampfox,
The cab is 41.5" W x 22.5" D x 69.5" H overall w casters and the baseplate with 3.25" spacing for the power port. 25cu ft after accounting for bracing port system driver, built in Flemish beer maid and the like.


Video,
You are just now seeing this thread? Dang, where you been hidin man. If the powerport was on mythbusters I'd say it was confirmed. Um yeah it gets low with authoritahhh. I've got full on powerhandling till about 9hz. Now I just have to figure out what to do with the other XXX. Did you see the excursion on these things (6.5L displacement)?
post #141 of 327
amazing build!
post #142 of 327
Quote:
Originally Posted by Ricci View Post

Swampfox,
The cab is 41.5" W x 22.5" D x 69.5" H overall w casters and the baseplate with 3.25" spacing for the power port. 25cu ft after accounting for bracing port system driver, built in Flemish beer maid and the like.

Ricci,
Cool speaker.
How would this driver perform in a sealed enclosure?
SM
post #143 of 327
Thread Starter 
Quote:
Originally Posted by Swampfox View Post

Ricci,
Cool speaker.
How would this driver perform in a sealed enclosure?
SM

Well, hopefully I'll be able to tell you soon. It isn't a small box woofer by any means, so you wouldn't want to try it in a 4ft box. Should be great with a 7ft or bigger box that's been stuffed though. It gets a really low F3 down deep into the 20hz range, or even below. It will need a very powerful amp to get the most out of it's displacement capabilities.
post #144 of 327
Good lord that sub is nice. If you want to crank it around 5:30 today I'll see if I can hear it while I'm driving across the bridge
post #145 of 327
Thread Starter 
Thanks Dradius. I try to crank it when i can.

I finally got REW running and I have some measurements of the XXX sub. Here is the raw FR at the main listening position.



Here is the response across the room at the other main listening position.



This is the close mic'd response of the driver. I set the crossover at 150hz for this one.

post #146 of 327
Thread Starter 
Here are 2 power response graphs I took last night using REW at the main 2 listening positions. I was trying to look at power compression, or port limiting effects. I started at a 95db nominal sweep level and increased the drive level by 5db on my Outlaw processor for each sweep. I ended with a 115db sweep level. The sweeps were from 7-200hz with a 1M file size and lasted 22 seconds each. The 80hz 24db octave SW crossover is engaged. There were no signs of driver distress, or amplifier clipping at the nominal 115db sweep levels, but it was loud. I believe that there may be enough headroom for a 120db sweep. I would've tried to take a sweep at that level, but I ran out of headroom in the input signal chain with the settings I had. I would've had to recalibrate to a higher level and start the process over and I already did that twice trying to get the headroom for a 115db sweep. I may do this again at a later date. The driver's minumum motion notch was clearly seen during the sweeps.

Try to keep in mind that I'm no Finnish subwoofer tester and my equipment is very basic compared to a real test rig. The first 2 sweeps also had what REW termed as a very low input level.

























post #147 of 327
VERY nice! Minimal compression on the 115db sweep above tuning, probably amp induced. A little bit from the port, but excellent for 115db!


Anyway you could have placed the cursor over the tuning point? Looks to be maybe 11.5hz?
post #148 of 327
Thread Starter 
Thanks Steve. The tune is right at 11.5hz. There does appear to be some compression at the 115db sweep, but not too bad. The sweeps were taken back to back to back. I really think it will handle a higher level 120db sweep. The 22sec duration is brutal for the CE4000 though and I'm not sure if it's got that much head room left for a sweep of that high a level for that length. The only point that the driver looks like it is really working hard is between 14-22hz. When I do try the 120db sweep I may go ahead and run some at a much shorter duration also and see what effect this has on the amount of compression compared to the longer one.
post #149 of 327
Quote:
Originally Posted by Ricci View Post

Thanks Steve. The tune is right at 11.5hz. There does appear to be some compression at the 115db sweep, but not too bad. The sweeps were taken back to back to back. I really think it will handle a higher level 120db sweep. The 22sec duration is brutal for the CE4000 though and I'm not sure if it's got that much head room left for a sweep of that high a level for that length. The only point that the driver looks like it is really working hard is between 14-22hz. When I do try the 120db sweep I may go ahead and run some at a much shorter duration also and see what effect this has on the amount of compression compared to the longer one.

Ricci,

Very nice sub.

Please don't take Steve's comments seriously as reading a graph has never been his strong suit.

The final sweep is compressed across the board. This system may be able to 'handle' a sweep with 5dB more input, but there's little point in it. If you do attempt it, I suggest a much shorter duration sweep.

Change your vertical axis to 5dB increments and the compression will be much easier to track. IMO, 12dB per division makes it much harder to see the obvious.

Bosso
LL
post #150 of 327
Thread Starter 
Bosso,
Thx for the input. I know that there is some compression going on in that 115db sweep. I think after looking closer at Illka's tests that next test I will do things a bit different. He does his in reverse with the lower freq's last. It doesn't appear that REW can do this. Also I'm going to omit the frequencies higher than 100hz as they are really not needed. Once I get to the 115db level I'm going to go carefully from there. Probably increase things 1db at a time and see what happens. I think I'm going to try a set of measurements with a much shorter sweep duration too. I'm betting that there will be less compression. I will try to get a better looking graph scale too.

At first I was kind of dissapointed to see some signs of compression on the 115db level sweep, even though this is VERY loud low bass when experiencing it. I kept looking at my graphs thinking that's it? It just seems to be so much louder than that. . I guess it's just because I'm not used to hearing the low bass be really represented at an equal level. I've read where people talk about how their 1 15", or 2 12's slammed their meter at 126db. Maybe so, but I doubt they would do that with this kind of test.
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