Phoenix Gold Phorum

So, I did what any rational, audio lover would do, and spent the whole day building a 2.9 ft3 box that fits under my rear extended cab seat in my '99 Silverado and dropped in one of my oh so pretty CV Stroker 12D2's. Running it with one PG zx600Ti 'till it's break in period is up, then I may throw my tantrum 1200.1 on it for a while.

The thing is obnoxiously loud with only 600watts on it. And, OMG, I can't believe how low it hits for just being a 12. You would swear there was a 18 back there. I seriously can't believe I have 4 of these things, I am not real sure if I can handle it

Later,
Jason

Where da pics at???

I just got in dude. Cut me some slack. It is pitch dark out right now, had to finish wiring stuff up with a flash light.

I will take some pictures, but no making fun of my box. It was coming along okay, looking fairly nice, and then I got to the point where I went to drop the sub in the counter sunk cut out, and I blew it, I had cut the upper hole about .25" too small. It was already 9pm, and I had to make a choice, either recut the new top piece tomorrow, and go another day with out tunes, or, butcher the counter sink hole with the rotozip and get to hear it tonight... You can guess the path I took. The top two pieces were already glued together, and since this is only temporary until I finish my bronco, I said fuck it, I want tunes!

I stil haven't worked out where to mount the amp. It is sitting on the rear passenger floor board right now. I will get it bolted up somewhere soon. Probably to the front of the box.

Later,
Jason

Pics as promised. Rewired my ground today, mounted the amp, and threw in the cube, as it really helps cut down on the obnoxiousness. The box is tuned at 39hz. 4x5x10 port. I will probably tune the bronco a bit higher, or I am going to have to incorporate some serious midbass...







Later,
Jason

Oh yeah, I know the truck is a freaking wreck, but in my defense, it is a work truck, and I cart my dog around with me virtually everywhere. A 120Lb great dane makes a huge mess. Tears up any wrappers she can find and sheds about 10 lbs of hair a month...

That's an awesome box! You've got some serious DIY talent buddy!

Thanks for the compliment! I don't think it is worthy, but it is serviceable. I really wish I had made the time for a sweet install, and that was alway my plan, but I just haven't had the time to take the truck down for it since it is my DD. The Bronco will be a different story though, that one will be sweet!

The problem with a box this big and trying to cram it all under the e-cab seat is there is no room for anything else. I couldn't mount an amp and have it look good anywhere in the truck now. Well, I guess I could extend the center console into an amp rack... It isn't worth the work though for a temporary setup.

Later,
Jason

How's the room behind your rear bench, or under the front seats?

stipud wrote:How's the room behind your rear bench, or under the front seats?

The rear bench sits tight against the back of the cab. The seats have all sorts of adjuster crap under them, and I couldn't squeeze a fart under there, least of all an amp.

I am not to worried about it, the bronco is less than a year away from done... I hope!

Later,
Jason

Whats your port area? Looks a bit small

Port is 4x5x10. I did the math manually. It is correct. I ran it in WinISD after it was built and it came up with the same tuning freq. that I did... Air flow is modeled at mach .12 which is plenty low enough not to have odd port sounds. CV recommends a ridiculous port of 4x12x24 for rectangular. There was no way I could do a 24" long port, so I spent 2 hours crunching numbers.

The larger the port is, the longer it has to be to tune to the same freq. There are some trade offs, as when the port cross sectional area decreases, air speed increases, and beyond a certain point you will have very noticeable port noise. This one I cant hear any oddities. The CV recommended port had a air speed of something like mach .05 when I modeled it. Chances are, that is why they made it so large.

Pics of said Great Dane?

I have a 10 month old Blue Male.

nice pics! makes me miss my stroker!

trckydve wrote:Pics of said Great Dane?

I have a 10 month old Blue Male.

Ask and ye shall receive:








She is about 5 years old now. Blue Merle. And before anyone asks, no, I don't normally sleep on the couch with the dog. That was just before I had back surgery, and the couch was the only place I could sleep and still get up in the morning.

Oh, and my wife is not stoned, I think maybe a little tipsy though

Later,
Jason

She's beautiful. My next one I'd like to get a Blue Merle.

Here's a couple pics of my boy.

Jacampb2 wrote:Port is 4x5x10. I did the math manually. It is correct. I ran it in WinISD after it was built and it came up with the same tuning freq. that I did... Air flow is modeled at mach .12 which is plenty low enough not to have odd port sounds. CV recommends a ridiculous port of 4x12x24 for rectangular. There was no way I could do a 24" long port, so I spent 2 hours crunching numbers.

The larger the port is, the longer it has to be to tune to the same freq. There are some trade offs, as when the port cross sectional area decreases, air speed increases, and beyond a certain point you will have very noticeable port noise. This one I cant hear any oddities. The CV recommended port had a air speed of something like mach .05 when I modeled it. Chances are, that is why they made it so large.

sux u didnt have the room. The bigger the port, the better I always say.. Much more potential in the spl section if need be You can never have a big enough port. lol Nice box, i know trucks are very limiting..

I am not questioning you, but help me understand why a bigger port would mean higher SPL.

My understanding is that a port is basically a passive radiator, although a significantly different approach than that of the mechanical variety. Now your port cross sectional area is is directly proportional to the woofer area. With a woofer area of 113 in^2 and a port area of 20 in^2 my ratio is about 5.65:1, so for every inch of woofer excursion, the passive radiator has 5.65"s of excursion. With a larger port area, you get closer to a 1:1 ratio, the passive radiator does not have to cycle so far, thus reducing noise, but the volume of air remains the same, so the SPL in theory should remain the same.

From what I understand, the reason behind the port length needing to be longer for a larger port cross sectional area is so that there is enough "friction" to keep the air in the box where it belongs. This is also what limits the ability to make a incredibly large port, as there comes a point where you simply cannot make it long enough to provide the needed friction and thus just gives you what amounts to a very leaky sealed box.

Like I say, I am just trying to understand better. I am new to ported box design. I thought I had a fairly good handle on the theory when I started (I always try to understand a concept before I try to implement it ). Hell, before I began this project, I had no idea that a ported enclosure had virtually nothing to do with the woofer itself. It is a tunning that is almost entirely specific to the enclosure. Obviously the subwoofer design has a lot to do with how well it will behave in a ported enclosure, but any 12" sub dropped into this box will be tuned at the same frequency.

Share with me your knowledge. I am always eager, and happy to learn, as are others on here I am sure.

Thanks,
Jason

"There's no replacement for displacement"

Large bore, short stroke... small bore, long stroke... different strokes for different folks?

If your port is too small, it will offer resistance, thus slowing down the displacement of air. This is why, generally speaking, a bigger port is better. Not just to overcome port noise, but to lower the port resistance so that it displaces more air as well. This is why flared openings and Aero ports are also popular, since it lowers the resistance to the air getting sucked through the port, thus making it louder.

The way I see it is, there's a certain point where you keep making the port bigger, but it doesn't displace more air. A massive port isn't necessarily "louder" than a smaller one, as long as both are equally capable of displacing the same volume of air.

Judging from your picture it looks like you have a sufficient size port. I would recommend flaring the port openings just for peace of mind, but beyond that I wouldn't worry too much about it.

^^Internets been down.. YOu beat me to it though... Looks decent for 1 12 though.. I know with my upcoming setup, you will be able to fit your head in the port