GAS Single subwoofer option for a Convertible?

[phenryiv1]

Of course, the first place that I looked was the GAS website. There i found some beautiful 8" and 10" options for the regular e30, and a the dual 8" bandpass design for the 'vert owners.

I just picked up my convertible a couple of weeks ago and it lacks a headunit, so something has to be done. I don't do anything halfway, so after reading the "$500 install" thread and the 'vert sub install thread and a few threads on the merits of a 6.5" versus 5.25" front stage I am moving into the planning phase. Part of the plan hinges on amp selection, space requirements, and weight- all of which are impacted primarily by enclosure design and construction.

After reading the 'vert install thread and other threads about Luke boxes, I still have a couple questions. I want to say right up front that the questions are NOT challenges- that is, I really don't know the answers, hence I ask the questions.

1. Is there a particular reason to not run a single 10" or single 8" woofer in the convertible? I ask that not to ask "can I just run a regular 8 or 10?", but is there a reason that the enclosure was designed to use (2) 8" woofers and not a single 10" or single 8" driver?

2. If there was a guinea pig willing to try out a different design (single 8" or 10") would that change anything? Or is this done because the bandpass design (and the seat cavity) is optimized by running 2 subs?

I want to be clear: I am a HUGE fan of 8" subs. One of my favorite setups in 20+ years of being a shadetree audio guy was a set of (4) 8" Infinity Kappa woofers (each seeing 0.3 cubic feet, sealed) running off of a RF Punch 200ix in the hatch of a Cherokee. So I have no opposition to 8" subs, but lately I have found that a single 10" in the right enclosure is tough to beat, and that a single 8" in the right setup is not far behind.

Thank you in advance.

[StereoInstaller1]

Hey Patrick!

OK, so here is my rationale behind using a pair of 8's: cone area. Pure and simple, more cone area, along with power handling of course. It seems the best compromise overall. It is a true bandpass design, so the woofers just move air, you don't really "hear" them.

The opening is only 10" tall, we don't have room for a box that will force a complete seal against the bulkhead, which is the trick that forces the bass into the cabin.

A major part of the design was incorporating the area behind the seat into a resonant cavity, as we tried a 12" in a bandpass design first, but it was impractical to install, even worse than the current setup. That placed the woofer in a horizontal position and simply vented out of the box through the bulkhead cavity. It sounded pretty good, but the new design sounds far better and has far more clarity. Using that space as a resonant chamber gets us higher efficiency and a wider bandwidth while reducing weight and space loss. I really do wish there were an effective method of using bigger woofers, but there just isn't.

The design we use is the best overall performance/weight/size/cost compromise we could manage, expecting that even a novice installer had a solid chance of doing a good job on.

This was a couple of years ago that we came up with this design, and since then there has been a resurgence in high-performance 8" woofers. There are now several big burly things intended to use 800RMS each, and LOTS of choices in solid performing "daily driver" woofers such as the TypeR or the DD 1508, among others. We have re-engineered the box to use these new woofers, but due to such poor demand, we cannot justify building a completely new design for the E30 Vert.

Thanks for the question! I really do wish I could offer better answers, but that car is one of the toughest vehicles on the planet to get good bass in, and our dual 8" setup works very well, it really does.

Luke

[phenryiv1]

Those answers make perfect sense. While I have (personally) constructed dozens of basic enclosures, there is no real justification to build my own when such a good option exists off of the shelf. My desire to look into a 10" version was pretty short-sighted- I happen to have a 10" Polk dB 10" DVC BNIB that I bought for no good reason and was looking for a home for it.

As far as looking at a single 8" it came down to trunk space. While the e30 has fairly good trunk space for a 4-seat convertible, preserving what is there is never a bad thing. Not that the e30 will be a utilitarian vehicle, but if it can't get groceries on the way home from work then I have to really think about which car I drive on any given day. Of course, if a single 8" woofer does not create appreciable sound then it is just a waste to do the install at all, so if it takes (2) 8" subs to be worthwhile, then it is what it is.

I did see that in an early fact-finding/interest thread that you mentioned some low-cost "bulk" woofers that you were going to test. As far as using something along the lines of a driver from somewhere like PartExpress, are there any that stand out as being a good value and a proper fit for your enclosure?

[StereoInstaller1]

Those answers make perfect sense. While I have (personally) constructed dozens of basic enclosures, there is no real justification to build my own when such a good option exists off of the shelf. My desire to look into a 10" version was pretty short-sighted- I happen to have a 10" Polk dB 10" DVC BNIB that I bought for no good reason and was looking for a home for it.

As far as looking at a single 8" it came down to trunk space. While the e30 has fairly good trunk space for a 4-seat convertible, preserving what is there is never a bad thing. Not that the e30 will be a utilitarian vehicle, but if it can't get groceries on the way home from work then I have to really think about which car I drive on any given day. Of course, if a single 8" woofer does not create appreciable sound then it is just a waste to do the install at all, so if it takes (2) 8" subs to be worthwhile, then it is what it is.

I did see that in an early fact-finding/interest thread that you mentioned some low-cost "bulk" woofers that you were going to test. As far as using something along the lines of a driver from somewhere like PartExpress, are there any that stand out as being a good value and a proper fit for your enclosure?

Actually, if I were to pick a woofer for the new design, I would probably use the Alpine TypeR, it is just incredible.




BTW, we did do a quick freshen-up of the box, this gives a slightly larger vented side and a bit better bracing and a little lower turbulence. We did a short run of these and we have ONE left. It is not yet upholstered, so it could be black or gray. If you think its time to order, shoot me a PM or a text 360-BMW-4840.

Then, go buy pretty much any other BMW so you can get a 10" box for it...LOL.

Luke