Monkey see, monkey do... two RL-P18s for me too!

**Bradley** · **10-22-07, 11:02 AM**

Here it is... the fruits of my labor. Almost everything I need to build these two 17 ft^3 (net volume) subs:

May not look like much, but was it a lot of work! I can't help thinking about how much easier a sonotube would have been.

But I'm finally ready to start gluing things together.

On a side note, my flush trim bit isn't looking so hot! To think it was sparkly fresh and new just a week and a half ago.

Sure do have a LOT of scraps left over. Already thinking about what I can make out of these leftovers. Hmmm...

**Bradley** · **10-23-07, 05:31 PM**

The gluing has begun!

**thxgoon** · **10-23-07, 07:09 PM**

So ah, how many router bits did you go through? Lol!

**Bradley** · **10-24-07, 12:45 PM**

Well, this past weekend the bearing fell right off my flush trim bit!

Luckily I realized there is a small screw that holds it on and was able to put it back together.

My 1/4" cutting bit is getting pretty dull, that's for sure.

**tgoode** · **10-24-07, 12:52 PM**

Man I need to buy some extra router bits. Isn't mdf dust great.

Question for you are you using wood glue or liquid nails for glue up.

**Bradley** · **10-25-07, 02:41 AM**

So far I've only used wood glue... Titebond III "Ultimate". I'll probably use some kind of construction adhesive or liquid nails for the port tube as there will be some small gaps to fill. For whatever reason I couldn't seem to cut a circle to the exact outer diamter of the port tube.

Progress is slow but tonight I managed to do 10 more circle cuts and glue the port tube support rings to their respective panels. After the glue dries on these, I can make the flare with the big ol' 1.5" radius rounding bit.

**Bradley** · **10-25-07, 06:43 PM**

I was just out in the garage test fitting panels in preparation for gluing them together. It's pretty exciting to see it all starting to come together and starting to look like a real subwoofer enclosure, so I gotta post a few "teaser" pics!

**SteveCallas** · **10-25-07, 07:54 PM**

Looks great

**Bradley** · **10-26-07, 10:46 AM**

**tgoode** · **10-26-07, 12:18 PM**

Nice job on the flares.

Todd

**thxgoon** · **10-26-07, 04:48 PM**

Looking really nice! It's neat to compare those shots with your sketchup models.

**Blaser** · **10-28-07, 03:34 AM**

WOW....Great Job

**Bradley** · **10-31-07, 05:05 PM**

Thanks, blaser. Finished gluing the first box together. Going to sand and corner round and mount the driver tonight!

**Blaser** · **10-31-07, 05:14 PM**

I am waiting to see some REW graphs man!!!

**Mongrel714** · **10-31-07, 10:10 PM**

Wow Bradley, that is a very beautiful job, you dont see attention to woodworking that good very often, I hope it sounds as good as it looks.

**Owen Bartley** · **11-05-07, 02:21 PM**

Bradley, wow. Really really great work on that sub! I hate when I come in late to good build threads because I love watching them step by step. Yours is coming along very nicely! First of all, a dual RL-p18 is a great project in any case, but when someone puts in the attention to detail that you are, it makes it really fun to watch. I love the rounded internal edges (I did the same in my Tempest, but not nearly as nicely as you have) and the port flares. I'll be watching closely from now on for sure!

P.S. Is that an S4? - Nevermind, I just read the last page and it is. Very nice... but keep the MDF dust off it!

**Bradley** · **11-05-07, 03:26 PM**

Thanks, Owen! I must confess that I haven't update this build thread in a while. The first subwoofer is actually done now. The only thing left is paint which I plan to do later when the second cabinet is completed.

Here are some recent pics:

Subwoofer's view of the room:

Another view of the toys:

**Bradley** · **11-05-07, 03:55 PM**

Quote:

blaser wrote:

I am waiting to see some REW graphs man!!!

That is definitely on my "to do" list! I did take some preliminary measurements with the Radio Shack digital SPL meter with C weighting. Here are some of the uncorrected readings I got at 2 meters from the sub in-room:

99 dB @ 12.5 Hz (near clipping)
100 dB @ 13.0 Hz (near clipping)
108 dB @ 20.0 Hz (no sign of clipping on amp)

The amp is a QSC RMX 2450, rated at 750 watts into into 4 ohms stereo at 1 kHz. I'm just running the sub off one channel in stereo mode for now. A bit nervous about slamming the cone at frequencies below tune, so I am very hesitant to run it bridged.

Playing around with the signal generator, I observed cone excursion to reach a minimum right around 13 Hz, so that would appear to be the effective tune of the system. I was shooting for 14.5 Hz but I don't mind it being lower.

**Bent** · **11-05-07, 03:59 PM**

Tuning frequency would show almost zero cone excursion - not peak cone excursion

**Bradley** · **11-05-07, 04:03 PM**

Right. That's why I said it reached a minimum.

**SteveCallas** · **11-05-07, 04:44 PM**

Do be careful with high output sine waves below tuning, that is just asking for trouble. When it comes to real material, you have nothing to fear, go ahead and bridge the amp.

How are you liking it so far? I'll wait to see your in room FR, but I've noticed a trend that orientations with the driver front firing often don't have as smooth a natural FR at the seat as those with it downfiring.

**Bradley** · **11-05-07, 06:06 PM**

Quote:

SteveCallas wrote:

Do be careful with high output sine waves below tuning, that is just asking for trouble. When it comes to real material, you have nothing to fear, go ahead and bridge the amp.

I am being VERY careful with the test tones. That's why I didn't go lower than 12.5 Hz with the high SPL measurement. By the time you get down to 12 Hz the cone really starts moving. Oddly enough, the 20 Hz test spooked me more than the 12.5 Hz test did with the high SPL and cone movement.

Quote:

SteveCallas wrote:

How are you liking it so far? I'll wait to see your in room FR, but I've noticed a trend that orientations with the driver front firing often don't have as smooth a natural FR at the seat as those with it downfiring.

Interesting. This sub could be converted to down firing pretty easily, with the only real issue being the location of the speaker terminals.

To answer your question... I'm liking it a lot!

I went out and bought a copy of War of the Worlds yesterday and I have to say the LFE output was just totally insane. Good lord... I feared the cone of the RL-P18 might jump right out of the basket.

I had to leap up from my seat and lower the gain on the amp about 3 times as the clipping light was going NUTS! That movie easily has more LFE output than anything I've ever seen/heard. And yes, the RL-P18 delivered the goods with great big gooey gobs of infrasonic goodness.

Getting the second sub completed will be nice so there's a little more headroom and low end extension.

Getting this sub done and putting it to the test has really enabled me to appreciate the low tune/high displacement combo. After hearing this beast reproduce test tones all the way down to 12.5 Hz and belch out all of the LFE material on WoTW, I can say unequivocably that building a sub capable of going well below 20 Hz was a worthwhile venture! Seriously... the pair of Def Tech PF15TL+ subs I had before simply DID NOT EXIST below 20 Hz. So I am now hearing and feeling things never heard & felt before. The difference in output is truly staggering.

Thanks again to everyone here on the Shack that helped to inspire me and guide me along the way during my build.

**SteveCallas** · **11-05-07, 07:04 PM**

Bridging the amp should eliminate the clipping

**Rodny Alvarez** · **11-05-07, 08:33 PM**

Nice work Bradley!!!

What finish are you going with?

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