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MY ultimate stereo system

I finally finished my smuglers box subwoofer enclosure. The funny colors are to help it photograph better. I also put sealed enclosures in the door. I used a piece of tubing to get the airspace. The nice thing about this is no rattles and really tight mid-bass.

Evan with a cab it is not to obnoxious out side, very loud in car with great impact. It rattles the mirror when it is cranked. Being sealed and firing int the cabin no bass escaping into the trunk and no rattles!

If any PNW pelicans want to hear it or are interested in getting one let me know. I do have one made for a coupe for sale. They are different for a coupe and a targa/cab.
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Old 02-09-2004, 12:11 AM
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Nice I have been thinking the same thing, though I will use 8" on the doors
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Old 02-09-2004, 12:38 AM
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Oooo, that's nice. What size sub did you use? And correct me if I'm wrong, but normally there's no hole there, right? How difficult was it to punch through the firewall?

If I wasn't pretty happy with my current sub I would be sorely tempted to jump on the coupe enclosure.

How did you do the door enclosures? It doesn't look like fiberglass. I need to redo my doors. I just dropped them in before, and they really could sound better.

Dan
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Old 02-09-2004, 11:05 AM
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I used a 8" sub. If your car has A/C there is a rectangle hole there for the condeser. If no A/C-no hole. It is actually single ply there, cuts quite easy with an airsaw.

I'am using MB Quart Q's which the grill is 7.5", as long as you don't go to deep should have no problem. Also make sure 8 is a mid bass driver there is not enough airspace for a sub.
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Old 02-09-2004, 12:21 PM
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Sorry I didn't see the rest of your question, the doors started as cardboard tubs and shop-vac hose plugged at one end, then it was all fiberglassed together. After mounting the assembly I covered the area in duct tape (installers best friend) to make sure it is sealed. On the door panel it has foam insulation tape to seal it the panel.
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Old 02-09-2004, 12:29 PM
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You say that there is a hole for the condensor there if a couple has AC. Is that to say that to put the Sub there you have to take something out? Still have the 2nd enclosure?
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Old 02-09-2004, 03:06 PM
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Yes this replaces the A/C up front, not a problem for me as my car came without A/C. On my coupe I had I took my A/C out long before I got a wild hair to build these. Definately not for everyone. But if you don't care about A/C and want your back seat useable(?) or at least a stealth install this is the way to go.
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Old 02-09-2004, 03:17 PM
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Sorry Yes I still have the enclosure for a coupe.
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Old 02-09-2004, 03:18 PM
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nicely done, did you reinforce the tubes with fiberglass or what?
my carrera is currently under the knife.......40sq/ft of dynamat should be here next week, then new carpet, then the door panels will be rebuilt from scratch for my quart 8s, a single 10" is in the smugglers box.
watch for a new thread from me in the next couple weeks of the progress
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Old 02-09-2004, 03:41 PM
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I just fiberglassed the end where I plugged it and where it goes into the enclosure. The tubeing is not very pliable, quite rigid.
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Old 02-09-2004, 05:30 PM
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The only issue you might run into with the "port" in the door like that is a specific bass note, that may or may not be desirable. It's challenging to "tune" a port like this, since the actual airspace is not very measurable. You'll notice about a 3db boost with the port, (if it's the correct size) but the woofer won't be as compliant in the lowest of it's potential range. if the port is too big then there is too much blow by and not enough back pressure... Great idea, and looks like a great job. Another good option for good low, mid bass is a total cover of the door with dynamat or other similar products. The issue with this is 'too much' air space potentially, so it's a trade off. Generally, though your lower bass will be better sealing the door with the dynamat, since the sound waves can disperse a bit better. The hole (enclosure) you have is rather small and can potentially cause too much back pressure in some speakers. Of course, all of this is gobbledy-gook in the big sceme of things... Good job, very well done!!!

P.S. we won't even discuss the weight issue of dynamat etc... Great tunes... light car??? hmmm...
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Old 02-09-2004, 06:20 PM
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The tube is completly sealed it is just to get enough airspace for the mid range driver. Tuning a port is quite easy if you have the woofer specificatuions. Although you get a up-to 3db gain for a ported box most manufactures are shying away from that kind of woofer because it reguires a bigger box. The market trend has been forcing the manufactures to make smaller and smaller enclosures while maintaining sound quality.

My woofers optimum sealed enclosure is like .38 while if I was to port it it likes to see 1.25.

The reason I went with a sealed enclosure in the door was to stay away from the dynamat and to have a nice controlled midbass that could handle a lot of power with-out distorsion. Granted dynamat does more than just make a door not rattle but my car is so loud that the other benifits would not be worth it.
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Old 02-09-2004, 07:27 PM
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Ya I just did an Alpine 12 in my truck and the sealed enclosure is just at 1 cubic foot. Unheard of a few years ago for such a large power handling speaker...(1000 watts RMS)... It's nice to use the "golden ratio" and be able to build a box that will fit with optimal dims.

Very cool, and something I've thought about for awhile. I think I'm going to dynamat though, more for the sound/vib deadening than the sound quality. I'm running 6.5's as I haven't had the nuts to cut bigger holes in the doors. I'd love to hear that JL sub in the box. Looks cool. I'm running JL 6.5 and 5.25 in my Dodge Ram... JBL's in the p-car...
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Old 02-09-2004, 07:43 PM
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How did you calculate the volume required for the speaker? Also, what alignment is this for?
Old 02-09-2004, 08:22 PM
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I don't remember the exact numbers because I made those about a year ago. Where I used to work we had a program that we could punch in the theil-small parameters and it would calculate the optimum enclosure size. You could also go backwards and tell it what size enclosure you had (this is what I did) and it would calculate the performance.

I am not sure what you are meaning by alignment. I did not use any rhyme or reason other than using stock location for mids and keeping the tweeter close.In my last 911 which was a coupe I used 6.5" coaxials with swivel tweeters mounted in kickpanel pods. The further away you can get your spks the better chance you have of getting a NON-processed stereo image. I aimed the mids between the seats and aimed the swivel tweets approx. at the rear view mirror. If you are refering to time alignment I am not using any prossecers at this time.

I am still constructing the amp rack (which will replace the spare) and collecting the final gear. I am going to replace my phoenix gold amp with a JL 5 chanel amp. I am also going to add a base cube and a stiffining cap.
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Old 02-09-2004, 09:30 PM
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i too use the JL 500/5, it a wonderfull piece
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Old 02-10-2004, 05:20 AM
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Quote:
Originally posted by piedogger
The further away you can get your spks the better chance you have of getting a NON-processed stereo image. I aimed the mids between the seats and aimed the swivel tweets approx. at the rear view mirror.
These days, with time/delay correction and variable cross over levels for tweeters (higher end stuff) you can get away with more spacing if nec. One just has to be meticulous in the system setup to get the imagining correct. The nice thing about the 911 is it's reletively easy to get a voice coil alignment and distance that is very suitable without tweeter level changes or sound processors.
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Old 02-10-2004, 06:58 AM
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"what you are meaning by alignment"

- you answered it -- Thiel-Small is the alignment. Thanks.

Do you want to post the exact dimensions and speaker parameters so others can replicate? Or are you gong into business to sell these? If the latter, how much will they be going for and how much did they weigh?
Old 02-10-2004, 10:29 AM
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Quote:
Originally posted by Randy Webb
"what you are meaning by alignment"

- you answered it -- Thiel-Small is the alignment. Thanks.
The Thiele-Small parameters are actually a group of individual measurements that help determine the desired enclosure alignment (target "Q") and filter network values. There are several different enclosure alignments for different desired functions/limitations (Chebychev, Bessel, Butterworth, etc.). If in doubt, a Q of .7 (Butterworth) is usually a good starting point. This can be altered (with a sealed enclosure) by simply changing the size of the box, or changing the amount of fill. If you have the driver parameters and enclosure volume, I can tell you where you're at. Also, I would recommend using passive Zobel networks on the mid-bass and especially the sub to tame the inherently large impedance spikes. You might want to look into a Linkwitz Transform (equalization) circuit to get the most out of the sub as well. As far as time (phase) alignment is concerened, you can passively help the situation by mounting the high frequency driver below (but still close to) the mid bass. You will still have the left/right delay, but it's pretty negligible at such short listening distances. That said, I think we can all agree that the inside of a 911 isn't the environment to be worrying about optimum loudspeaker design!

Last edited by Eric Coffey; 02-10-2004 at 11:01 AM..
Old 02-10-2004, 10:57 AM
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Well said, and Q is how peaky or broad the resonance curve is.

BTW, avoid the plastic thing that fires the speakers downward from the dash.

Eric - want to design a nice audiophile enclosure for the door speakers?
Old 02-10-2004, 11:39 AM
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