transmission line sub box

Hey all, I am new here and just bought a dual 12" advanced transmission line slot ported box from caraudiofactory.com. This is the one: HB2x12 SPL1. Has anyone used this box before? I have 2 Kenwoods KFCW3011 subs, and I am hoping to keep them...if they sound good in this box. Please let me know what you think of the box. My brother in law has the single box of the same type with a kicker cvr 12 in it and it slams!

thanks

Sorry, I also was wondering if I should line the inside of the box (not the port) with polyfil?

thanks

no need to line a ported box with polyfill.

There is no such thing as a transmission line ported enclosure (at least that I have ever heard of). That enclosure is simply a ported enclosure. A transmission line is going to simple be a port without any internal volume. They are also typically tapered. Click here to see my transmission line enclosure to see what they look like.

It looks like a Diamond Audio enclosure that they have on their website. It is going to be tuned fairly high (around 40Hz I'm guessing). It may hit pretty hard if that is what you are looking for. You could do better with a custom designed enclosure though.

You would only need to add polyfill if the internal volume of the enclosure is too small for the subs. Adding polyfill will increase the internal volume acoustically which will also lower the tuning frequency slightly.

your enclosure is nothing close to a transmission line.

It is a simple prefab bass reflex enclosure that the website tagged "transmission line" so it would look more appealing.

IMO the enclosure is crap.

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Custom Enclosure Design

aznboi3644 wrote:

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your enclosure is nothing close to a transmission line.

It is a simple prefab bass reflex enclosure that the website tagged "transmission line" so it would look more appealing.

IMO the enclosure is crap.

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Ouch, a little harsh.

I wasn't going to go that far but I'm not going to disagree. With a custom enclosure you would get much better performance. If you are simply looking for loudness and nothing else then that may give you what you are looking for.

aznboi3644 wrote:

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IMO the enclosure is crap.

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I was being nice, but you are right.  I think all prefab encloseures are crappy, esp ported ones.  much better to build one to your subs specs.

Although you all are right about building a custom box to woofer's specs, I don't have all of the resources to do that. I have to disagree that all prefab boxes sound like crap though. My brother in law's sounds good.

I called the place and they said that it was tuned to 30hz.

if you like it get it.  your opinion is the only one that matters when it comes to your stuff.

I never said it would sound bad. I am just saying that a custom enclosure will sound better then a prefab enclosure.

If you want to save a little money by buying that prefab enclosure then go ahead and use it. If you are happy with the way it sounds then that is all that matters.

Alright guys. I got the box today and put the subs and polyfil (9 Oz. each side) in them. Not too much better than the sealed boxes. So, looks like I am going to get some new subs. I am thinking about getting the same as my brother in laws...Kicker CVR07122. I am trying to keep an open mind for some other kind of subs though. I will be adding another 11 Oz. of polyfil to each side with what ever subs I buy for the box. Anyone live close to Little Rock AR? I will sell my previous boxes and subs for $60 bucks a pop together.

you shouldn't polyfill ported enclouses.  The ports will get full of the fill.

IMO it will sound bad compared to a GOOD enclosure. Chamber volumes are way too small...only around 1 cu ft net for a 12 inch subwoofer!!!!!

That is barely enough for one 10" subwoofer

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Custom Enclosure Design

"IMO it will sound bad compared to a GOOD enclosure. Chamber volumes are way too small...only around 1 cu ft net for a 12 inch subwoofer!!!!!"

That is why I am putting polyfil in it; to raise the seen enclosure size. The polyfil is lined on the inside of the box with 3m spray glue. When I get some different subs I am going to put enough fil in them to equal 1 1/4 lb per chamber. That should "increase" the seen size of the chamber to 1.75^3 ft/ chamber.

The KFC-W3011 subwoofers are just not doing as well as I had hoped they would. (I hoped they would sound fine because I did not want to buy more subs.) I am looking into getting 2 kicker 07CVR122 subs. Now, this is with a Pyle 4 channel amp bridged to supposedly 400 watts a piece. I haven't got my new amp yet, BAMF2000/1d. So, I hope that livens them up a bit.

Anyone have some suggestions on subs?

Even with stuffing you can NEVER get more than slightly less than a 10% gain. You will not EVER gain 75% as you seem to think you will. Additionally, that 10% gain happens at roughly .5 pounds per cubic foot stuffing density. Beyond that density, the fibers actually begin to occupy volume, and make the enclosure even smaller.

Your box is too small. Period. You will never get the enclosure volume to what you have to have for those drivers.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

First of all, with the port and displacement from the subwoofer, the volume of the actual box is 1.24^3 ft. Not 1^3 ft. According to Lucas Gilkey, who ran tests on this subject, I can get a 36% gain in seen enclosure size by the woofer by adding 1.25 lbs. of polyfil to the box. This would make my seen box size to the woofer 1.69^3 ft. Pretty close. Now, have you done any tests to refute his?

methos123 wrote:

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First of all, with the port and displacement from the subwoofer, the volume of the actual box is 1.24^3 ft. Not 1^3 ft. According to Lucas Gilkey, who ran tests on this subject, I can get a 36% gain in seen enclosure size by the woofer by adding 1.25 lbs. of polyfil to the box. This would make my seen box size to the woofer 1.69^3 ft. Pretty close. Now, have you done any tests to refute his?

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I have seen a similar study in this link so you may be able to get that much gain. But that does not mean it is going to be an ideal enclosure still. The enclosure is still a prefab enclosure and could still be better. The 1.75 cubic foot you are refering to is the minimum recommended enclosure. Going a little larger would be better off then just barely making the minimum enclosure. It may sound decent but you can do better.

I was highly doubtful when I read that the company said it was tuned to 30Hz so I modeled the enclosure in BassBox. I used a height of 14" which was listed and a width or 2" for each port (which I guessed) I got an overall length of over 60 inches needed to have a 30Hz tuning. The enclosure you listed did not have a 60" long port so it is not going to be tuned to 30Hz. I believe it is closer to between 36-42Hz. That isn't horrible if you are trying to only get output but it does show how much the company knows about their own enclosures. Once you fill the enclosure with polyfill the tuning will go down to the lower 30s.

What I can't understand is why you posted this thread in the first place. You asked what we thought about the enclosure and we all gave our opinions. We also gave our opinions about adding polyfill. After all of this you have not listened to anything we have said and just refuted everything we have said. So I'm wondering what you want from us exactly? You obviously are going to do it your way no matter what we tell you.

I stand corrected. Those are handy charts to have, and I have already added them to my favorites list.

I have always used the numbers I said, but I have been building for (apparently) longer than those articles have been around!

However, those gains are THEORETICAL! Take all of them with a grain of salt, and be certain that you use EXACTLY the same stuffing material (fiber diameter, fiber material, fiber length) as Tom did when he did his study, or your numbers will be different.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

"So I'm wondering what you want from us exactly?"

All I want from you is discussion and input. I value your opinion on this subject being that you all have spent some time with these things, and have an understanding that is deeper than the average Joe. I don't know why you,(WhiteRob) are upset that I don't do whatever you say. This is after all a discussion forum, not a do as your told forum. I don't want to have this thread be a shouting match or anything like that, but I don't want things being take out of proportion to what they really are.

the enclosure is still a poorly designed enclosure...stuffing also lowers the efficiency.

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Custom Enclosure Design

methos123 wrote:

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"So I'm wondering what you want from us exactly?"

All I want from you is discussion and input. I value your opinion on this subject being that you all have spent some time with these things, and have an understanding that is deeper than the average Joe. I don't know why you,(WhiteRob) are upset that I don't do whatever you say. This is after all a discussion forum, not a do as your told forum. I don't want to have this thread be a shouting match or anything like that, but I don't want things being take out of proportion to what they really are.

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I'm not upset or anything I am just truly wondering what you are trying to get from this thread. I don't mind that you are using that enclosure I am just wondering why this thread was created. To me, there hasn't been much of a discussion. You haven't changed your plan since the beginning and nothing has been accomplished.   

Again, I'm not trying to come off being angry or upset. I don't really care if you listen to our advice. I just was wondering what exactly you wanted us to say or what you wanted help with.