i don't have pics, but i took out my back seats and built my own custom box that blends in with the interior. Suttle and sweet.

 

80hz is definately better than 200hz, but 80hz is nearly useless for a subwoofer application. Remember, anything below the tuning frequency the speaker will essentially be "free-air".

8" subwoofers are not limited in the low end either... unless you're using THUMP speakers, lol.

 

80Hz is nearly useless for a subwoofer application? That sounds alot like a statement based upon someone looking at sound like a bunch of numbers, rather than listening to the differences.

Most music doesn't have a lot of content below 60-80Hz. You want a system that people feel 40 feet away, then yah, that 40hz tuning is pretty important. But these are completely different goal sets.

Bass cruiser tracks, techno, synth stuff, sure. But most music doesn't need 40hz, and a vert isn't the right situation at all to try for that type of system.

It's hard enough in a vert to get loud, clean, well balanced sound.

 

While it is a much more difficult goal to obtain in a vert for sure, especially if you want to keep your cargo area, it doesn't mean you shouldn't try, or that it can't be done, my box has an out of car F3 of 40hz, it is actually tuned a little lower than that (can't remember exactly at the moment) and sounds comparable to the sealed 12" I had in my previous car in both depth and volume, while not taking up my valuable cargo space. It won't set any SPL records but the sub bass region is well represented.

Just out of curiosity, how well does your box seal the trunk from the passenger compartment? I ask because I think you may want to consider opening up the "ports" to a larger size so that you are actually running the subs in an infinite baffle configuration. If you did this you may want subs with a lower Fs though, Just a thought.

 

Well balanced and 80hz tuning don't belong together, unless you're talking about vented midbass speakers. Even then, it's kind of high. I know you probably think I'm some assclown that just wants to shoot you down, I don't. I just want people to understand that 80hz tuning is not something you want to shoot for.

Here's a little background information for you -- I ran an audio shop for a good portion of my teenage years, up until recently I was a SLAP/DB Drag/IASCA competitor. I know what it takes to make good sound, I just want to pass that on to some other folks. I own a convertible too, so it's not like I'm just making **** up. Much better sound can be made.

Another thing, tuning @ 40hz is STILL high for a subwoofer. Unless you are going for unbalanced, peaky, punchy bass. If I tune an enclosure for range and accuracy (yes, you can do that with vented boxes) I go for 28-32hz.

You'd be surprised how much music there is below 80hz... That's the reason why subwoofers are made.

 

First off, I am not trying to be a butthead, just pointing out that your blanket statement is not necessarily correct, although it can be. Peakiness will be dependant on the properties of the particular driver and its interaction with the given enclosure and the cabin of the vehicle. While one may not get the lowest notes with a 40hz tuning, it is not necessatily going to be peaky. In addition, after cabin gain plays its role, you can have reasonable responce down to between 30hz and 35hz. My point is, that done right, a ported box tuned around 40hz can sound pretty darn good.

I choose this tuning (my calculated tuning is 37hz) as a trade off between port length/noise, box size, and extension, to tune lower would have required me to go with a smaller port (due to the required length) which would have made a lot of port noise, or to increase the box size, which just wasn't an option. It's all about the trade offs.

Of course you are right that there is a lot of music info below 80hz, and some below 35hz, and ideally it is better to cover the whole 15hz+ range so you don't miss out on anything. I would love to see you come up with something that can meet this goal while not requiring a rear seat delete or taking up the trunk. Unfortunately, I couldn't figure out how to pull it off (not for a lack of effort mind you), if you have any ideas I would certainly be interested to hear them.

 

I bought a $25 box for a 12" infinity sub from Walmart. If you flip it around the right way, it will fit in the back. My amp is bolted to the frame just below it. It gives me enough room to get a "few" things beside it in the trunk. Not much room though...maybe a hanging bag and a briefcase/duffle bag at most. Surprisingly though, it sounds really good...4 ohm speaker being pushed at only 180watts.

 

I'd be really happy to see a wedge style box that can mount only on the shelf area, not interfere with the trunk space or the top, and be tuned for 4 8" subs to 30Hz.

I'd build one in a heartbeat. You got those plans, post em up - the people want em.

Oh, and I never answered John's question about halving the port area - I see no volume loss with my head unit low-pass crossover set at 120Hz. It's actually punchier, which is to be expected given the tuning drop.

However if you sent the box a full range signal, it'd be a lot quieter because of the 150-200hz content no longer being reineforced.

 

I finally played w/ my box a little, blocking the ports w/ a piece of wood. Since I had to hold the wood in place w/ my hand, my ears were probably not in the best position (w/ the top up too) for a "scientific" assessment. My crossover is set for around 100Hz too, so about the only noticable difference was a slight attenuation of the upper bass w/ the ports half-blocked. I really didn't notice much difference in the low bass, so I couldn't tell if blocking the port added "gain" down low. However I didn't notice any attenuation of low bass until the port was >3/4 blocked.

 

I'm still having trouble finding out if I can get away w/ using a roll bar (6-8 point) or if I need the full cage (6-8 point) to get on the track legit.
Any help from my fellow raggers would be much appreciated.

 

Well there was a debate about it a while back. It seems there are new rules this year, but some of us couldn't agree on which class applies for when at the track. I interpreted it as if the car is close to stock and a vert, you can run as fast as like 11.49 if I remember right without any bar or cage. I went with mine last year with no bar or cage, but it was a rental so they were probably more lenient. But anyway, I found some of the rules at www.dragway.com, look around on there maybe find more info, or find your local track's website and/or call them and ask.