Custom RE XXX Subwoofer Build

[Ricci]

I won the FunkyWaves sub giveaway. That's the option that I picked. Dual sealed SDX's in 8ft. The finish is Makore.

[Owen Bartley]

Oh yeah, that's right!! Grrrr... I think that was my option!

Lol, just kidding, it really looks amazing, I'm glad it turned out so well, and I hope you'll have it on display somewhere it can be appreciated! Congrats on both new units!

[SAY IT LOUD]

Awsome job that sub looks great and no doubt packs a punch. Now all you need is a big screen cheers Troy

[Ricci]

Some pictures of the power port...cavernous.Kindly diregard the cables everywher and the clutter. I have to clean that up later.






This is a look up into the power port. You can see the inner flowguide. This is one giant port.



More pictures to follow soon.

[Ricci]

Here's a few shots of the sub in it's final resting place. Excuse the clutter. Cleaning hasn't been my highest priority lately!

[Mike P.]

I'm dying to hear what your impressions are of both subs!

[Ricci]

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.

[SAY IT LOUD]

WOW what a MONSTER is that your bedroom or are your using a bed as a lounge? I am buildind a 200 ltr twin 12" modelled from the svs PB plus 2 i will post pic when finished. That is the largest sub i have ever seen for home theatre. Now all you need is a 500 inch screen to match your sub. Cheers Troy Down Under

[Ricci]

It's the living room and we use it for lounging. I don't do the interior decorating around here, unless you count the electronics and speakers everywhere.

[Ricci]

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. 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 in my signal chain 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 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 possibly 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 Bossobass talks about? . 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.

[Mike P.]

But are you happy with it? Just kidding! Having that amount of low end output makes it all worth while. Kinda brings new meaning to the term "effortless bass", doesn't it?

[Ricci]

Mike P. wrote:

But are you happy with it? Just kidding! Having that amount of low end output makes it all worth while. Kinda brings new meaning to the term "effortless bass", doesn't it?

I'm really happy with it. I've watched 10000B.C., Neurosis: A Sun that Never Sets and The Incredibles so far. It really delivers the goods when called to do so. I'm simply hearing bass that my old Velo's couldn't produce, since they gave up pretty much at 25hz. I can't wait to get REW and get it EQ'd to be even better.

I'm going to try WOTW, Finding Nemo, or Cloverfield next.

[funky_waves]

So far of all the movies I have tried for testing the Leviathan scene in Atlantis, is the best for sub 20hz bass, the opening scene is very good too, as well as several other scenes throughout. I highly recomend it for testing. WOTW was fairly good too, there are many. FOTP was very good as well.

[Ricci]

I'll look into Atlantis and the other tracks that you mentioned Nathan. You should check out the Fireworks demo thats available on the Danley website. It's got crazy dynamic range on it.

Did you ever hear any port noise out of this thing when you tested it? I've yet to hear anything at all. I just don't see being able to hear anything during normal material.

[Ricci]

Here are 2 frequency response measurements taken at the 2 primary listening positions. These are raw and there is no smoothing, or EQ applied and the 80hz x-over in place. They were taken with REW, a Turtle beach SRM soundcard, ECM8000 mic and Xenyx 1202 mixer. Overall I'm really happy with the response I have and I'm not going to use EQ.






This is a close mic'd response of the driver that shows the 11.5hz tuning notch in the response. The crossover is set at 150hz here, which is as high as it will go.

[Ricci]

More measurements

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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 will 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.

[Ricci]

Here is a new set of measurements using a shorter sweep. I think it's about 5secs. Much shorter than the grueling 21.8sec sweep used in the last set. The highest level sweep is IT. That's everything that this system can give when doing this sine sweep. The shorter sweep allowed a bit higher levels, but as you can see there is a lot of compression going on at 9-11hz and 30-50hz(???). This is at the ragged edge of things. The system is amp limited technically, but I don't think that any more power would get much more out of the driver. The amp actually tripped the breaker on the surge protected power strip that it's plugged into once and self protected twice when trying to determine the max sweep level. The amp is none the worse for wear and driver took all of that drama in stride.

[SQCherokee]

looks nice.

[Ricci]

I did some distortion tests yesterday. They were taken from the main listening position, which is across the room about 4 meters away. The test frequencies are 64, 50, 40, 32, 25, 20, 16, 12.5 and 10hz. I didn't sit there and try to calibrate each measure to some predetermined level. The level of these tests for each frequency is reflecting the affects of the room on the FR and also the subs FR to a lesser extent. I just set the sweeps to a certain level and ripped through them.



64hz, 102.5db








50hz, 106.5db









40hz, 105db








32hz, 107.5db

[Ricci]

25hz, 110.5db









20hz, 110.5db









16hz, 108db









12.5hz, 110db









10hz, 108db

[Ricci]

Here's a set at a much higher level. I didn't want to push things much harder as this is with one driver facing the wrath of a 4ohm bridged CE4000 dumped into it with pure sine waves. These tests aren't exactly quick either, as it takes a few seconds for the distortion levels to get calculated and level off and then another few seconds to freeze the measurement and stop the sine wave. Gotta be careful with this kind of test.


64hz, 109.5db, 3.821% THD










50hz, 113db, 4.264% THD









40hz, 110.5db, 3.533% THD








32hz, 114db, 5.183% THD

[Ricci]

25hz, 116.5db, 4.816% THD








20hz, 118db, 16.65% THD









16hz, 116db, 19.7% THD









12.5hz, 118.5db, 5.7% THD









10hz, 113.5db, 13.93% THD

[Ricci]

I'm continually impressed with this sub. I know I've said it before but the <25hz output from this is monumental. I would consider this a great performance distortion wise. There is a lot more output available at 40, 50, and 64hz (maybe 10 and 12.5hz too)than what I tested at here. The distortion levels at 16hz and 20hz are highest because this is where the driver has the highest excursion, since it doesn't fully unload below tuning until about 8 or 9hz. I knew this would happen and it is a trade of that you make when you choose to get a super low tune. I still consider the fact that the THD never reaches 20% at the worst case scenario area of 16 and 20hz with levels this high to be exceptional IMOP, especially considering that the driver excursion was about 3" p2p or maybe more at those 2 frequencies. Also I think that the 10hz distortion reading may be a bit high. I may not have allowed the reading to fully average out, which would result in a higher reading. Had to quit as it was getting late and the GF was getting VERY irritated. I never heard any port noise with these tests. Overall it sounded very clean. I thought I detected a bit of strain or change to the tone at 16 and 20hz but it's hard to say because it was shaking everything in the house. Definitely wouldn't have heard anything with normal material.

Now to figure out what to do with the other 3 drivers I have...

[Toolatecrew]

No wonder she was irritated. 113 db at 10hz?? He insides probaly felt like they were in a paint mixer. That thing is just sick.

[Ricci]

Hey! She was supposed to be gone most of the afternoon. It's not my fault she came home early while I was in the middle of testing!