Built A Ported Box This Weekend

[texcon]

So I built a ported box for my round Solobaric this weekend. I ran into a problem with making it 3 cu ft as recommended. The box has a volume of ~2.5 cu ft before sub displacement. I simply don't have the ability to fit in a 3 cu ft box into my trunk given my amp rack and trunk opening.

The port is a 4" round diameter and is 10" long, which will give me a tuning of ~ 30 Hz. The sub in a ported box sounds roughly the same as the 1 cu ft sealed box I was using before in terms of SQL, but with a slight decline in SQ. I did not add any polyfill to the box, at least not yet, and that could help alleviate the problem with the box volume.

Other than that, I am not sure where to really begin. I doubt the box is too big. It is built well and all seams are sealed and there are braces included to give support. So my first guess is too small an enclosure. Any ideas?

[texcon]

So what do you do when you need help about a specific sub? Go to the maker of course! I got with a technical dude at Kicker at the suggestion of Polecat and he gave me slightly different specs on a ported enclosure. Basically, he suggested I make the box smaller (1.75 cu ft rather than 3 cu ft) and make the port length 8" rather than 10". This would give me a 38 Hz tuning frequency. So I May try this and see what results I get.

[fugyaself]

What size sub are you using? I am guessing a 12 due to their recommendation on enclosure size.


For a 12 I would personally run around 2 cubes tuned to 35hz for it. I dont have any modeling software handy at work but I do remember thats what I was considering for a friend.

Keep in mind the higher you tune the more of a peak in the frequency response you will get. This is like adding a huge bass boost but it also cuts out your lower frequencies and indangers your sub when playing below tuning if you push it too far. Get winisd pro and model up the sealed enclosure vs the ported enclosure they suggest and a few that you come up with on your own. Make sure that the enclosure you build will have a decent enough frequency response that will fit to your liking. But remember that the cabin of your vehicle may either tone down or increase the peak slightly. It will also increase your low end.

[texcon]

It's a 12" round Solobaric - the first gen one. I got in touch with a Kicker techie and he gave me some specs for a box. I will try that first and see what happens. This sub may simply not do so hot in a ported box, so I can always revert back to sealed. But my Tantrum 1200.1 has a subsonic filter on it, so I am safe with respect to that. We'll see how it goes in a few days. I am going to just take the box I built and either chop it down to decrease the volume or stick some blocks inside for the time being.

[geolemon]

The smaller the enclosure, the less efficient it is... it'll be quieter.
The smaller the enclosure, the less low-bass capability it'll have.

It's possible that the enclosure isn't tuned properly, or maybe there's some construction flaw or measurement that's not correct that isn't apparant.

Hoffman's Iron Law states the following items are mutually exclusive:
1) Small Enclosure Size
2) Low Frequency Extension
3) High Efficiency
...meaning, you can't have all three.
You can optimize a box to have lots of one, or a little of two... but not all three.
So keep that in mind as you tweak... if you make the enclosure small, you are taking away from the potential 'high efficiency' and/or 'low frequency extension' that you might reach otherwise.

I'm not quite sure what the complaint was, other than "it sounded like the sealed box", so it's difficult to pinpoint... typically sealed boxes sound very good, bear in mind.

[texcon]

My complaint is that the SQL did not increase at all in the current ported box versus the SQL of my orignial sealed box - in fact I think SQL decreased. Keep in mind I was merely having some fun to see what would happen when I dropped this sub into a ported box. I never fully intended on keeping this sub in a ported box, unless it blew my mind. I think I would be sacraficing too much SQ in a ported box.

I got the Tantrum 1200.1 to overcome the efficiency issue, so I may revert back to sealed if the second version of my sealed box is not any better. Seeing that I listen to mostly rock and metal, having a tuning frequency of 38 Hz does not bother me. I was really trying to create a box that allowed my Tantrum to work less hard.

In either case, I'll let you guys know what happens with the other box as soon as I get it done.

[geolemon]

All your ideas are correct indeed...
And if you mean SPL (not SQL ), that's definitely correct thinking as well... I'm surprised too that you didn't see an increase.

Since ported boxes are typically larger than sealed... was your ported box larger? I share in your surprise, particularly if you are talking about a 38hz tune... that thing should have a mother of a knock-your-socks-off SPL peak at least around 35-40hz... in fact, big enough to make the rest of the frequencies seem significantly weaker.

...perhaps you are simply listening to music that doesn't HAVE any 35-40hz, or even 45 or 50hz tones in it? Perhaps whatever frequencies exist in the music you are listening to, are comparable in amplitude, sealed vs. ported?
Seems odd, just thinking off the top of my head...
But maybe you could try playing with a test CD, playing test tones, seeing how a sweep sounds, etc.?

[texcon]

Yeah, I meant SPL - I do that often. I referred to a crossover as a capacitor in another thread.

Here is the deal - I think my ported box may be too big and I also might have a problem with my port. My port is 10" in length and that means the end of the port is too close to the surface of my box's back wall. I am using a round port that is 4" in diameter and I believe my port needs to be at least 4" or more from the back wall of my sub box. My current port only has 1-2" space between it and the back wall. Is that true or just a car audio myth?

After getting in touch with a tech at Kicker (at the recommendation of Polecat), he gave me specs for a smaller ported box with a slightly shorter port. The new box would be tuned to 38 Hz (4" diameter port, 8" long). The box volume he suggested was 1.75 cu ft, port volume included. Right now my box is ~2.3 cu ft, including port volume and before sub displacement. So we are talking over a 1/2 cu ft difference in what the Kicker tech gave me and what someone else suggested. Call me crazy, but I think the Kicker tech might have a better idea about what box to build for a Kicker sub.

I will agree that you are likely right that I don't listen to music that gets below 40 Hz too often - I listen mainly to rock and metal, so unless the band has a 5 string bass, there aren't that many low notes played. So is it possible that I sacraficed some SQ and SPL at higher frequencies going from sealed to ported?

I am no vet, but I know what I hear and the ported box I have now isn't giving me enough in either SQ or SPL to keep it over the sealed box my sub was in before. So I will try a second ported box and go from there. At least I am getting some experience from this.