First post straight out of left field

[Ged II]

Hello, this is my first post here, and it's gonna be off the wall, but please bear with me. First of all, I know that this subject could EASILY fall into a couple of different forums on the board, but I came to this one, because I thought it gave me my best chance at a good answer because of the drivers and enclosure under consideration.

Ok, here goes. I have a '96 Mazda B2300 (reg cab) that has a Pioneer DEH-P5200HD for the head unit. According to Pioneer's claims, when you select the subwoofer output option in the menu, you should have 70wx1ch into 2 ohms available from the speaker level (lr/rr) outputs. Based on my reading, I think the actual output is between 30w and 40w. I'm leaning towards 30w to be on the safe side. The head unit has a HPF/LPF, sub gain settings, and bass boost.

I'm wondering if an enclosure can be made for placing behind the bench seat that uses 5.25" or 6.5" woofers and maybe two passive radiators per woofer. The combo that I'm looking at the most comes from Peerless (SDS-830657/SDS-830880). That 6.5" woofer is rated at 60w. It's also rated at 8 ohms, so to show it to the head unit as a 2 ohm load, I would have to wire four of them in parallel. I would probably also use a bass blocker to filter out the really low frequencies that this setup would have trouble with.

I'm not looking to make a traditional subwoofer with "thump" out of this, but rather something economical and fun to build that would take some of the low frequency load off the door speakers (6x8's). I'm thinking it could be clean, smooth, and involving at decent in-cabin volume.

I know it's an odd solution, but it intrigues me. What do you think? Is it feasible? Could it sound good? What do you think it would be capable of in terms of fr, spl, and sq?

Believe me, I know this an answer to a question that almost noone is asking, but if it can be done well, I'd love to have some help designing it. If not, there are definately some more expensive options that involve more expensive drivers and outboard amplification that I'm thinking of that would absolutely rock, but I'll drop down to the car audio forum for that if this isn't workable.

[badman]

I'd suggest a bigger woofer in a sealed box, and rely upon cabin gain, other than that it sounds do-able.

[Pano]

Welcome to the forum.

This might be better in the autosound section, but I understand why you put it here.
Have you tried any of the speaker box modeling software like winISD or Unibox? Or any of the online calcs?

How big a box can you use? (cubic feet) How low do you want to go? Once you know that, you can start looking at simulations and some folks here can help you.

[Ged II]

Thanks, badman. I think power output is gonna limit me on woofer size. If I have to go bigger, I'll probably go with outboard amplification.

Hi, Pano. I've never made any attempt at anything like this, so I don't have any of the software. Not yet, anyway. I'll measure the space today. I'd probably be really happy to get down to 40hz.

[Ged II]

I posted a quick reply to you guys; I'll wait for it a little bit to avoid a double-post.

Here are the links to driver and passive radiator.

http://www.tymphany.com/files/SDS-P8...20Rev1_0_0.pdf

http://www.tymphany.com/files/SDS-P8...0Rev%201_0.pdf

[infinia]

to make a long story short you would get best results ie performance and cost by going to a single, driver. bigger is better. most standard 6.5 inchers will only get to 50 Hz including this peerless fs ~45+15% per the spec. Re passive radiators add quite a bit to your cost! and unless chosen and tuned properly will give worse results than a ported design. Passive radiators are a last resort once the boxes are small and the ports get extra long.
I would suggest looking for a 10" at 4 ohms. Consider downloading free software like WinISD beta and using only Fs, Qt, & Vas size yer own boxes. post yer results back here for opinions. BTW 2 ohms is way too low for a head amp/ chip amp esp in bridged mode.

EDIT> if not using a external amp, read the head unit manual very carefully about your plans.

[DavidL]

I would use an 8 inch driver with lots of xmax but anything over 10 mm would be fine. Use software to design a sealed box with a QTC of .8 to 1 and an FC of around 60Hz. The cabin gain of the truck should give you plenty of low end boost below 60Hz as long as you keep the windows rolled up. Designing a sub for a vehicle is a lot different than designing for a home system. You do not need or want a sub that flat to 20Hz like you would in a home enviroment.The cabin gain will boost the low end a lot.

[Ged II]

Thanks for the replies, guys. I'm keeping an open mind as to the drivers and type of enclosure, so the suggestions are appreciated. Today, when I get a chance, I'll measure the space behind the seat.

Also, I'm going to see if I can find a way to measure the actual output of the head unit when the rear channels are set to sub out. I've seen where a few people have theorized about what the actual output is, but noone seems to know for sure. I don't know what Pioneer has done with the internal design, but I'm not convinced that it's actually bridged. There's a great thread about this on one of the Crutchfield forums that I'll find and link here later today.

[Ged II]

Pioneer's tech support says that the continuous power output for the combined rear channels is 40w.

[mondogenerator]

I tend to agree with the main opinion here. depending on the volume youve got (i guess maybe 1-3ft³) you could possibly squeeze a 10", maybe 2 10"ers, or maybe a 12" in sealed volume, although from what i know of car audio, the nearest you can get is somewhere between infinite baffle or aperiodic-ish loading, so results vary one helluva lot, without a dedicated 'sub box' Even 2 x 8" with the right ts parameters would be decent.

how big a diameter woofer you can use is gonna depend on the ts parameters. winISD beta is great. plenty of drivers in the database and abilty to add others that arent. hell you could get a pair of somthing like visatons al200 or tiw200xs subwoofers. fs is low enough and ported you could prob squeeze 2 into 3 ft³, ill have to have a fiddle in winISD