RL-p18 Sonosub Build

**bob1029** · **07-03-07, 11:34 PM**

So it begins...

Ive ordered the following so far:

For the Subwoofer itself:
24" dia. 12' section of sonotube
Behringer EP2500
Soundsplinter RL-p18 D2
Some Binding Posts

For EQ:
Behringer DSP1124
Behringer ECM8000
Behringer XENYX 802

All that remains is 2-5 trips to HD for remaning supplies, and maybe some monster cable from work.

I cant believe that this is all possible for under 1 grand... it just blows my mind that I can do so much on the DIY path with so little.

Anywho, Im planning a 525L enclosure (about 6'-6" tall), tuning around 14Hz.

Now I've never worked with sonotubing before... Would it be possible to form a port from the unused portion of the tube by cutting it and bending it back together at a 6" diameter?

**Mongrel714** · **07-04-07, 12:09 AM**

Hello Bob, I'm not sure reformimg the Sonotube would yield the best results, especially when HD has many diameters of PVC that would perform much better.

**Sonnie** · **07-04-07, 12:19 AM**

Sounds like this will be a good project to follow... looking forward to some pics...

**bob1029** · **07-04-07, 01:31 AM**

Oh... I didnt know HD had 6" dia pvc... but then again I never pay attention to plumbing when I go shopping. Ill be sure to get out the digital camera for some documentation of the build.

**Geoff St. Germain** · **07-04-07, 08:15 AM**

Get 6" sonotube if you can. My local HD has diameters up to 8". It is a lot lighter and about 1/10th the cost.

**bob1029** · **07-05-07, 11:10 PM**

Well... I got started today... needless to say it was absolute chaos doing the caps without a router. For some stupid reason I figured id just use a sawzall and sand out the rough edges. Turns out that 1 mm can make or break the tube, so i was sanding for about 1.5 hours straight today.

Here is the tube at the actual height of 6' 7" I will be using...

Wood glue is drying on the caps and I will finish them tomorrow and mount the port. Monday/Tuesday I should get in every component I will need to finish the build.

**SteveCallas** · **07-07-07, 12:10 AM**

At "only" 525 liters, I'd bring the tuning up a little from 14hz, and I'd use 8" diameter sonotube for the port.

**bob1029** · **07-07-07, 12:26 AM**

Ive already revised my port to 8.5", and the actual volume is closer to 550 liters. I modeled the port at exactly 48" long, and dont see a problem with the tune (11.2Hz) in unibox or winisd. Am I missing something here?

**SteveCallas** · **07-07-07, 12:36 AM**

Quote:

bob wrote:

Am I missing something here?

Yes. First off, a 48" long port will likely result in an audible resonance. Second, an 11hz tune in that size enclosure will leave you with a rolled off low end response in room. You aren't building a sealed sub, so a drooping low end isn't what you want - <20hz should be flat or increasing in room, not rolling off.

With 550 effective liters, I'd use an 8" diameter port that is 27" long or 8.5" that is 31" long, giving you a ~14.5hz tune either way.

**bob1029** · **07-07-07, 12:48 AM**

Ok... Ill cut it to 31". Now I thought 11Hz was about as low as I would ever want to go... not sure what you mean by "rolled off low end response". As for resonance, I dont plan on taking the woofer up to 118Hz. I planned on using the bfd to roll it off gently after 60hz and then cut it off harder with the reciever/computer at 80-100hz.

**SteveCallas** · **07-07-07, 01:18 AM**

Quote:

not sure what you mean by "rolled off low end response".

In my LLT Explained thread, look at the three different FRs I posted near the end of the 1st post. One is tuned too low and the response rolls off too much - your proposed 11hz tune in 550 liters would look more similar to that than what I would considre the ideal response to be. Room gain typically yields 4-8db/octave, so you don't want the shaped FR to rolloff any more than that until below tuning.

Quote:

I planned on using the bfd to roll it off gently after 60hz and then cut it off harder with the reciever/computer at 80-100hz.

In an attempt to achieve what?

**bob1029** · **07-07-07, 01:34 AM**

Ok I cranked it through winisd again and got a completely different graph than before.

Anywho, it would seem you are 100% correct. I shall cut the port for 14.5hz tune, as it seems to not murder the lower freqs as much as 11hz.

Thanks for saving me the headache of pounding the cap off and cutting the port.

**SteveCallas** · **07-07-07, 02:17 PM**

No problem

**lvisneau** · **07-08-07, 08:58 AM**

Quote:

bob1029 wrote:

Well... I got started today... needless to say it was absolute chaos doing the caps without a router. For some stupid reason I figured id just use a sawzall and sand out the rough edges. Turns out that 1 mm can make or break the tube, so i was sanding for about 1.5 hours straight today.

Here is the tube at the actual height of 6' 7" I will be using...

Wood glue is drying on the caps and I will finish them tomorrow and mount the port. Monday/Tuesday I should get in every component I will need to finish the build.

Wow! bob, that thing is huge! I'd love to hear it when your finished. Are you close to the west side?
There seems to be alot of us around houston doing some sort of sub building/planning. I'm looking into ib for my room, but I don't know if it is workable. I have a 25-31 pci and could only imagine what your sono will sound like.

**bob1029** · **07-09-07, 12:13 AM**

Ok quick confirmation here... I was wondering if simply putting damping material on the top endcap opposite the driver would be sufficient since the walls of the enclosure are curved.

**FlashJim** · **07-10-07, 04:50 PM**

Add me to the demo list.

Leon and I can ride together.

**lvisneau** · **07-10-07, 08:48 PM**

Quote:

FlashJim wrote:

Add me to the demo list.

Leon and I can ride together.

My truck seats 5, lets do a tour

**Sonnie** · **07-10-07, 08:54 PM**

I'm in too!

Look, when all you guys in Houston get all your stuff done... we seriously need to have a few mini-meets.

**bob1029** · **07-10-07, 11:17 PM**

lol... yes I will have to arrange for a demonstration one of these days.

Some quick pics before I sleep:

Finished my fanmod (used a voltage divider and a 12volt pc fan)

The sub finally came in. About 2x larger than I imagined it would be

Finishing the port and top cap

**Mongrel714** · **07-11-07, 05:47 AM**

Looking good bob! soon we'll be looking at the weather map of the U.S. and part of Texas will have slid off into the Gulf do to an un explainable earthquake!

**bob1029** · **07-11-07, 09:09 AM**

That would be nice, actually. Its been really hot around here.

**bob1029** · **07-13-07, 12:16 PM**

Well... its complete

**Scott S** · **07-13-07, 02:07 PM**

Wow! Can't wait to finish my dual RLp18's!

Awesome work, let us know how it sounds.

**bob1029** · **07-13-07, 02:11 PM**

Oh it doesnt sound. It moves things. Thats the best way to describe it. I have yet to push it all the way because im seriously frightenend that it will make something fall off the wall. I ran a 15hz tone through it and it scared the out of me.

**Blaser** · **07-13-07, 02:26 PM**

How big is your listening room?

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