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Soundsplinter RL-p15...port surface area?


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#1 of 13 OFFLINE   ShaunO

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Posted June 11 2006 - 02:23 PM

Hi there, first post on this board. Im building a coffee-table/speaker. I plan on putting a Soundsplinter RL-p15 in there with a Behringer EP1500 on it. Im going to be giving it 4.5 to 5 cubes, tuned to 16hz. Obviously I don't want this to be a HUGE table...which brings me to my question. Im torn on how much port surface area to use. Obviously I don't want port noise, but I'm also slightly limited on space. What is the bare-minimum surface area I should be giving this/these ports? I was contemplating using If I use PVC I don't know whether to use 1 or 2 ports. Im assuming 1 4" PVC pipe is not nearly enough...so I thought about 2. Im also debating on making a slot port...again I don't know how big. Either way, I plan on beginning construction on Tuesday.

I also have one more question. Im building this out of MDF, and I was planning on using a black lacquer to finish it. What kind of primer/sealer do I need to use to obtain a good finish?

Thanks for any help,

Shaun

#2 of 13 OFFLINE   al lout

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Posted June 11 2006 - 06:53 PM

What is the dimension of the box you r looking at? There might be enough clearance for the 6" port. As you have already pointed out, 4" port will probably give u some port noise in the lower freqs. With 2 4" ports, the port might be longer than your box size. Let us know the dimension of the box. Also, the RL-p15 has high xmax i wouldn't consider slot box if I was you. I would plug the t/s numbers in unibox just to get an idea of how things behave. Good luck.

#3 of 13 OFFLINE   Owen Bartley

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Posted June 11 2006 - 11:19 PM

Check out the local Home Depot or whatever and see if they have small diameter sonotube. I ended up using a piece of this to get a 5.5" port on my sub. It's not a ton smaller than a 6", but it will give you a little more room to play with. IIRC they had a bunch of sizes, in between 4 - 8 or so.

#4 of 13 OFFLINE   ShaunO

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Posted June 12 2006 - 02:53 AM

Quote:
Originally Posted by al lout
What is the dimension of the box you r looking at? There might be enough clearance for the 6" port. As you have already pointed out, 4" port will probably give u some port noise in the lower freqs. With 2 4" ports, the port might be longer than your box size. Let us know the dimension of the box. Also, the RL-p15 has high xmax i wouldn't consider slot box if I was you. I would plug the t/s numbers in unibox just to get an idea of how things behave. Good luck.
Well internally I'm looking at 17.5 x 18.5 x 34.5. Im a total newb when it comes to HT, but I know quite a bit about car audio. I know the box is long and slender and isn't going to give me the best response because of this...but its all I've got to work with because, as I said, It's going to be a coffee table, so I want it to at least resemble one.



Quote:
Originally Posted by Owen Bartley
Check out the local Home Depot or whatever and see if they have small diameter sonotube. I ended up using a piece of this to get a 5.5" port on my sub. It's not a ton smaller than a 6", but it will give you a little more room to play with. IIRC they had a bunch of sizes, in between 4 - 8 or so.
I work at Lowe's, we only carry 8" and 12". Well, its 8" nominally, they range from 7.5" to 8.5".

#5 of 13 OFFLINE   Robert_J

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Posted June 12 2006 - 08:21 AM

Quote:
Originally Posted by ShaunO
I know the box is long and slender and isn't going to give me the best response because of this...
The shape of the box will have no effect on the sound at all. As long as you have proper air space, shape is not important.

As for port area, just use what I sent you in my Sound Domain PM.

-Robert

#6 of 13 OFFLINE   ShaunO

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Posted June 12 2006 - 11:59 AM

Quote:
Originally Posted by Robert_J
The shape of the box will have no effect on the sound at all. As long as you have proper air space, shape is not important.

As for port area, just use what I sent you in my Sound Domain PM.

-Robert

I was referring to the Golden Ratio. It works in car audio, I only assumed it would apply in HT as well. Basically, enclosures closer in size to the Golden Ratio will have better response and sound less boomy. It was developed by the National Academy of Mobile Electronics...so again I only assumed it would apply here as well. There is a thread over on SD about it...]

http://forum.sounddo....&f=11&t=069744

#7 of 13 OFFLINE   Robert_J

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Posted June 12 2006 - 01:50 PM

The golden ratio works for full range speakers because most of the soundwaves are shorter than the interior of the box. Makes no difference on subs.

http://www.diyaudio....ad/t-57976.html
http://forums.audioh....hp/t-5997.html (12/14 5:53pm post)

DIY Audio and Audioholics are both widely regarded are some of the most sound quality DIYers on the net.

-Robert

#8 of 13 OFFLINE   ShaunO

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Posted June 12 2006 - 03:09 PM

Quote:
Originally Posted by Robert_J
The golden ratio works for full range speakers because most of the soundwaves are shorter than the interior of the box. Makes no difference on subs.

http://www.diyaudio....ad/t-57976.html
http://forums.audioh....hp/t-5997.html (12/14 5:53pm post)

DIY Audio and Audioholics are both widely regarded are some of the most sound quality DIYers on the net.

-Robert
Ahh...my misunderstanding

#9 of 13 OFFLINE   Mattak

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Posted June 13 2006 - 04:18 PM

Since I didn't read any area recommendations, I'll give mine of 40-60 sq inches of port area for a 15" driver. I've used about 45 for both a brahma and tumult without issue.

#10 of 13 OFFLINE   al lout

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Posted June 13 2006 - 06:54 PM

Quote:
Well internally I'm looking at 17.5 x 18.5 x 34.5
I think this box is a little small to tune it to 16hz. With 1 port of 5" or 6" dia, the length of it will probably need to be more than +35". Best way is to tune it a lil higher (19hz - 20hz?) and hopefully room gain will help you out. Can you post the T/S of the RL-p15?

Al,

#11 of 13 OFFLINE   ChrisBee

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Posted June 13 2006 - 08:49 PM

If you use PVC you will have the option of ready-made elbows (bends) to extend the port. These bends add considerable flexibility in box dimensions where long ports are necessary for a particular tune. Bends can be tight or slow and there are various angles available.

With Sonotube ports you won't have that option unless you are very lucky in finding a close diameter match.

Flared plastic port ends are available from some speaker suppliers. These will help to reduce port noise regardless of port size. Finding the correct base pipe diameter could be a problem with a very large port though.

Searching through the PVC accessories at a drainage or DIY outlet could provide something like a flare in the form of an adaptor of some sort.

There is inspiration to be found in browsing through stocks of PVC drainage pipes and fittings. Posted Image

#12 of 13 OFFLINE   ShaunO

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Posted June 14 2006 - 05:04 PM

Thanks for the advice guys. I went with the double 4" PVC. I've already got 99% of the assembly done...which can be seen here.


http://www.cardomain.com/ride/2381161

#13 of 13 OFFLINE   David-Wright

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Posted June 23 2006 - 12:38 PM

looks great I can't wait to hear how it sounds.
David-Wright


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