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DIY PB13 Ultra ?

post #1 of 28
4/23/12 at 8:46pm
Thread Starter 
I just purchased this woofer from a forum member.

I want to build a ported box comparable in solidity and performance to the 13 Ultra if possible, while not necessarily using the same dimensions.

I have a never used EP4000 on standby.

My dilemma is this. I found out after purchase (unfortunately) that SVS doesn't publish their T/S parameters so I don't know how I'm going to get a proper sized box built without this info. The seller said that SVS told him that for a PB13 Ultra to be effective it needs an internal volume of 5.5ft^3. I don't know if this was given to him as a guideline for the box he was planning on building for the extra PB13 woofer or if that is the actual internal volume of the Ultra box, or both.

All help is appreciated.
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post #2 of 28
4/23/12 at 9:05pm
You may want to do a search, i'm sure someone has parameters for the driver somewhere.
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post #3 of 28
4/23/12 at 9:09pm
Thread Starter 
I did a pretty thorough search already and haven't found anything yet.

I have until tomorrow night to figure out if this is doable or not, as the seller isn't shipping until Wednesday. I hope he will consider refunding my payment if I can't get this to work out.
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post #4 of 28
4/24/12 at 6:47am
You can deconstruct and replicate the SVS enclosure. I'm pretty sure you can find the net enclosure volume and port width/length and tune.
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post #5 of 28
4/24/12 at 7:23am
Don't do a vented sub without measuring the actual driver and designing the box accordingly.

Lilmike has a nice impedance-measuring jig that you can use with various software packages. There's also an easy-to-assemble diagram of one in the manual for FuzzMeasure Pro that can be used with that measurement package.

Or if you have a not-a-Mac you could pick up a WT3 from Parts Express.
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post #6 of 28
4/24/12 at 9:14am
Thread Starter 
Mcsoul, I don't want to replicate the original box. I was hoping to size it according to my room which will be behind a couch so ideally skinnier than the Ultra is, longer is not a problem.
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post #7 of 28
4/24/12 at 9:58am
Thread Starter 
I just spoke with Ed Mullen at SVS and he assured me I couldn't go wrong as long as I stayed close to the original internal volume, or .5 cubic ft less. He suggested I use double 4" ports for an 18hz tune. He also said if I was going with a pro amplifier to use no more than about 700 watts if there are no filters built in for safety such as their dsp amps have. I can't remember if my EP has these or not. I think it does.

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post #8 of 28
4/24/12 at 10:01am
Thread Starter 
The Data-Bass.com website shows 6ft3 internal volume. Does this account for the driver and braces? The seller told me it was 5.5ft3. I just want an accurate starting point.

Thanks.
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post #9 of 28
4/24/12 at 2:13pm
Thread Starter 
Anyone?
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post #10 of 28
4/24/12 at 10:35pm
Quote:


I just spoke with Ed Mullen at SVS and he assured me I couldn't go wrong as long as I stayed close to the original internal volume, or .5 cubic ft less. He suggested I use double 4" ports for an 18hz tune. He also said if I was going with a pro amplifier to use no more than about 700 watts if there are no filters built in for safety such as their dsp amps have. I can't remember if my EP has these or not. I think it does.

the difference in a 5.5 and 6.0 cubic foot enclosure on driver excursion is very small. don't worry about that difference at all.

it would be stupid to run high power into a ported without a high pass filter. with a high pass filter, that drive should be able to do at least twice what ed is suggesting and maybe more.

bottom line:
minor cab variations in size = does not matter
running big power with no high pass on a ported sub = potentially big/expensive mistake
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post #11 of 28
4/25/12 at 9:53am
Thread Starter 
Thanks for the help LTD. I have more questions, but I will ask later.

I still would like to know actual internal volume of the Ultra.

Wes
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post #12 of 28
4/25/12 at 10:37am
Quote:
Originally Posted by WesM228 View Post

I just spoke with Ed Mullen at SVS and he assured me I couldn't go wrong as long as I stayed close to the original internal volume, or .5 cubic ft less. He suggested I use double 4" ports for an 18hz tune. He also said if I was going with a pro amplifier to use no more than about 700 watts if there are no filters built in for safety such as their dsp amps have. I can't remember if my EP has these or not. I think it does.


Those dual 4" ports will have to be 35" long for an 18hz tune in 5.5ft3, in 6ft3 that drops to 31 3/4" long. You might be better off with a slot port, as that will allow you to easily wrap the port around the inside of the cabinet. A 1.75" x 15.5" wide (assuming your box is 17" wide) x 36.5" long slot would acheive the same tune in 5.5ft3, 33" long in 6ft3.
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post #13 of 28
4/25/12 at 11:11am
"I still would like to know actual internal volume of the Ultra."

the external specs are listed on the site.
•Dimensions: 22.5" (H) x 20.5" (W) x 27" (D)
if you subtract out .75" for the enclosure material, that gives ~5.9 cubic feet.
subtract the port volume, there is about ~5.5 cubic feet.
subtract the amp enclosure and the driver and your are right around 5.0 cubic feet.
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post #14 of 28
4/25/12 at 11:29pm
Thread Starter 
Quote:
Originally Posted by Jay1 View Post

Those dual 4" ports will have to be 35" long for an 18hz tune in 5.5ft3, in 6ft3 that drops to 31 3/4" long. You might be better off with a slot port, as that will allow you to easily wrap the port around the inside of the cabinet. A 1.75" x 15.5" wide (assuming your box is 17" wide) x 36.5" long slot would acheive the same tune in 5.5ft3, 33" long in 6ft3.

I like the slot port idea. Is it harder to brace the cabinet with such a port or does the port itself act as a brace?

I've been watching lots of Youtube videos on building subwoofer boxes. Most are for cars of course, but it's still helping me to understand the build process.
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post #15 of 28
4/25/12 at 11:38pm
Thread Starter 
Quote:
Originally Posted by LTD02 View Post

"I still would like to know actual internal volume of the Ultra."

the external specs are listed on the site.
Dimensions: 22.5" (H) x 20.5" (W) x 27" (D)
if you subtract out .75" for the enclosure material, that gives ~5.9 cubic feet.
subtract the port volume, there is about ~5.5 cubic feet.
subtract the amp enclosure and the driver and your are right around 5.0 cubic feet.

How did you figure out the port volume? And how did you know how much space the amp enclosure and driver took up?

I'm guessing there is a calculator available for figuring this type of stuff out.
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post #16 of 28
4/26/12 at 12:03am
^^ πr².l or (πd².l)/4, both times # of ports.
Use the outside dimension of the tubes.
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post #17 of 28
4/26/12 at 12:13am
Quote:
Originally Posted by LTD02 View Post


the difference in a 5.5 and 6.0 cubic foot enclosure on driver excursion is very small. don't worry about that difference at all.

it would be stupid to run high power into a ported without a high pass filter. with a high pass filter, that drive should be able to do at least twice what ed is suggesting and maybe more.

bottom line:
minor cab variations in size = does not matter
running big power with no high pass on a ported sub = potentially big/expensive mistake

Can you please explain why it would be a mistake? I just ordered my first passive sub and plan to pair it with an ep2500 but now you have me worrying!
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post #18 of 28
4/26/12 at 12:17am
Thread Starter 
Nevermind, I found the Enclosure Volume Calc. at HTS.

Still learning here..
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post #19 of 28
4/26/12 at 12:33am
"Can you please explain why it would be a mistake? I just ordered my first passive sub and plan to pair it with an ep2500 but now you have me worrying!"

at and above tuning, the driver is fighting against the air inside the sub enclosure, so excursion is held in check.

below tuning, it is kind of like running the driver in free air and it can easily bottom out and/or be destroyed because the driver is facing very little resistance.
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post #20 of 28
4/26/12 at 4:30pm
Thread Starter 
I want to use 1" mdf but Lowes and HD website only show up to 3/4".

There is a salvage lumber place nearby. I will have to check there tomorrow.
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post #21 of 28
4/26/12 at 4:56pm
Quote:
Originally Posted by pokekevin View Post

I just ordered my first passive sub and plan to pair it with an ep2500 but now you have me worrying!

What ya get??
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post #22 of 28
4/29/12 at 12:03pm
Thread Starter 
I bought a Velodyne SMS-1 sub eq for $295 shipped..
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post #23 of 28
4/29/12 at 3:19pm
Just use one channel of the ep4000 and you will get around 700 watts but first I would figure out the ts parameters by either having another member run them for you or get the program from parts express that will test the sub for you. Once you have the ts parameters input them into winisd to figure out box size (internal volume), number of ports and length and finally the required power. If you can find the ts parameters somewhere else even better because you can skip the first step. After you have all that information you will be able to design the box any way you want as long as the internal volume is correct. I have played around with trying to clone an ultra 13 before and found that going with 3 ports was unnecessary and two worked out much better. Good luck tho and I'll definitely be interested to see what you come up with.
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post #24 of 28
4/29/12 at 3:31pm
Quote:
Originally Posted by WesM228 View Post

I want to use 1" mdf but Lowes and HD website only show up to 3/4".

There is a salvage lumber place nearby. I will have to check there tomorrow.

To get 1" you can get it at any cabinet building shop. Honestly tho there is really no point in going with the 1". 3/4" will work fine and these cabs end up being extremely heavy when completed so why not save yourself some $ and your back.
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post #25 of 28
4/29/12 at 4:24pm
If you ain't running the ep4000 bridged do you think the fan is necessary?
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post #26 of 28
4/29/12 at 4:37pm
Quote:
Originally Posted by pokekevin View Post

If you ain't running the ep4000 bridged do you think the fan is necessary?

You need to use a fan no matter how you run the amp. If you find the fan annoying, which is definitely is, you can swap the fan out for a lower db one which takes about 90 seconds but will void your warranty. Just search "ep4000 fan mod" to figure out which one you need.
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post #27 of 28
5/1/12 at 2:17am
Thread Starter 
I cross my speakers over at 90hz as they are only spec'd down to that. I see the LPF for the SMS-1 is fixed at 80hz. I may be able to lower the crossover point in my processor without any speaker issues but this still concerns me.
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post #28 of 28
5/1/12 at 12:29pm
Quote:
Originally Posted by WesM228 View Post

I cross my speakers over at 90hz as they are only spec'd down to that. I see the LPF for the SMS-1 is fixed at 80hz. I may be able to lower the crossover point in my processor without any speaker issues but this still concerns me.

The difference between 80 and 90hz isn't much. If it really bothers you get a minidsp and get xover as well as lots of EQ capability.
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