Ben Building

Ok, some unknown 15s I was looking at got me thinking about dusting off the old Bass Mekanik CD to measure some Thiele/Small parameters the old-fashioned way; by hand. You see, subwoofers are like snowflakes; every one is different. Even subs from the same manufacterer differ in small ways that can affect overall performance. The numbers that tell us what a subwoofer is doing (or is capable of doing) are called parameters. because of the work of the two engineers who pioneered the terms, Neville Thiele and Richard Small. Parameter is just a fancy way of saying "characteristic." This Topic is devoted to measuring those parameters for yourself. That way, you will know that the next box you build will be a PERFECT match for the subwoofers you're running. Is anyone interested?

Oh, I forgot: The advantages to using a smaller port in the same-size box is that you get to use a shorter port. This saves on total enclosure space, but there is a huge trade-off in both port noise and efficiency.

Where ever you got 211 from is on point because that's about what you are going to need. Well within acceptable margin for 2 18s in a vehicle. :hairtrick:

How much power do you plan on cramming through that port?

Hmmmm...

NEW PRICES: $275 + Shipping.

Bump because everybody needs single-DIN touchscreens!!

You can look at the AudioPipe Eye Candy subs. They come in blue (txxapx15bl), red (txxapx15rd), black (txxapx15b), and white (txxapx15w). They handle 1000 RMS and are pretty efficient. Cheap, too.

Lanzar SDBT75NU Single-DIN Motorized Detatchable Face Indash Head Unit: 7" Widescreen TFT/LCD Touchscreen Monitor Bluetooth AM/FM Tuner Remote 24 Presets Front/Rear AV Inputs A/V Output RCA Video/Coaxial Output Front/Rear RCA Outputs Subwoofer Output Last Position Memory Anti-Shock Mechanism USB Interface The deck is 1-month old, 9/10 Cosmetics, 10/10 Function. Box, manual, and all accessories are included. Price $275 plus shipping Alpine CHM-S620 6 Disc CD Changer Comes with an FM Modulator, Controller, Changer Cable, and (1) 6-Disc Magazine. 7/10 Cosmetics and 10/10 Function Price: $40 plus shipping.

What is the resistance of the front speakers at the deck?

This is very good, assuming you could get them shipped for a reasonable rate.

Save some bread and get either 2 Crunch GP3000.1D Pros or 2 AudioPipe AP30001Ds for about $800. If you don't care about blowing money, I would definitely look at the Sundown amp, though.

It sounds like your're running into cancellation from your ports. If you build that box in the trunk right, it can sound almost as good as in the back seat. Plus, you'll be able to get laid back there to boot.

x2

That is a strong little amp for the money, dude. It makes 950 watts RMS at 2 ohms, which should be perfect for your 2 CVRs.

I built a sealed box almost just like that in a Cutlass Supreme for 2 Crunch ProCast 18s back when. They had an Orion 2150SX pushing them and sounded AWESOME. The subs were ideal for ported boxes, but I put them in a small sealed enclosure for a shallower roll-off. Your box will probably pound like that if you're in the ballpark port volume-wise.

I also agree with Boon about the phasing concerns. On the other hand, Bose has a patent on an enclosure almost like that, and it mangages to sound awesome.

The volume of air inside your port (and, thus, its mass) will change as the subs play. To me, this would suggest a change in tuning frequencies around a mean point. Further, the difference in port volume with the subs inside the port will be different at different power levels. A sub displaces more air at 900 watts than it does at 150 watts, right? I think you would have a funny sounding box. I would definitely like to see you build and test one, though.

If I were you, I would look at the AudioPipe AP15001D. It can be had for about $200 shipped and makes lots of clean power (1500 watts RMS). As far as the box, you are heading in the right direction. 32 hertz is a pretty good tuning freq for rap; just make the strongest enclosure you can and you will make your sub system more efficient.

What brand HIDs are those? They look pretty bright from the pics, but you didn't mention whether or not you are pleased with them? How is the turn-on with the ones you have, by the way?

2 Fi BTL 15s on 2 AP30001Ds :hairtrick:

If 3 pre-outs is mandatory, then you will need to step up to the DEHP7000BT. Here's a link: http://www.savinglots.com/lotprod.asp?item=DEHP7000BT

You have more space inside your enclosure with them inverted; but, other than that, virtually no difference. You may hear a little noise from the pole vent with them inverted though.

The DEHP6000UB is a very nice deck for the money. Here's a link to one for $175. http://www.savinglots.com/lotprod.asp?item=DEHP6000UB

1 18 has more surface area than 2 12s, so all things equqal, with a given excursion, the 18 will make more pressure. But all things are not equal. 18s have more moving mass than 12s, so it is likely to want to play (resonate) lower than the 2 12s. The 12s may sound better, though. Also, you might end up saving space with the 12s, if that's important to you.