KU40

it's not really calculated. Nobody says "Oh, I know I'm going to gain 3.5 db at 32 hz and 2.4 db at 39 hz from cabin gain, so this box is ok like this......" I mean you could measure your box's frequency response curve outside of the vehicle in an environment that won't affect the SPL readings, then put it inside the vehicle and do the same thing and compare the two graphs. But I've never seen anybody actually do that. Normally it's just used as a generalization, and usually with sealed boxes. People get worried when they see that most sealed boxes have an F3 of 40 hz or so, but cabin gain usually increases the 30-40 hz zone so that the sealed box is fairly level from 30-80 hz or whatever. You'll have to divulge more on what you mean by "optimize." That could mean a flat response curve to one person, maximum SPL to another person........ In the end, you'll never be able to construct a box that will even out every peak and valley that your vehicle introduces to the response. You'll have to EQ it if you want to do that.

I assumed the 5" started from where the wood starts going that direction, just like the L1 length included the front baffle thickness. Not board cutout lengths. I guess that's something the OP would have to tell us. Either way, it's only .75 inch. Not going to affect a thing.

PE

you may as well go with the BTL. I fit a 15" sub in my trunk in the sub back, port back configuration, so it can be done. There are no guarantees that it will be louder than your Type Rs.

It'll work

It'll work. Just be easy with the amp.

Look sorta like older Cadences, but can't really tell.

One of your biggest challenges will be fitting the box through the opening to the trunk. Build a test box out of cardboard or something first to check it out. Unless you want to build the whole box in the trunk.

I just used Birch Plywood on my latest box. Excellent stuff. I'll never use MDF again as long as I can find it.

That was going to be my next question as well.

I didn't forget the .75. He mentions his first port length being 17.25" long. Well, if his box is 22.5" deep externally, that leaves only 21" internally. since his port is 4.5" wide, the first port board would have to be 4.5" from the back wall. Add 17.25 + 4.5 + the .75" for the back wall, and you get 22.5". Therefore, his L1 includes the front baffle. Then 17.25 for the first leg + 4.5" for the corner from measuring down the center, plus 5" for the second leg = 26.75". I didn't take end correction into account, I never think about it.

If those are external dimensions I get 5.25 cubes gross. Port displaces about 1 cube, let's say .3 cubes for the drivers. That leaves you with 3.95 cubes net. A port 12.5" tall, 4.5" wide and 26.75" long gives a tune of about 34 hz. You'll want to add about 6" onto the port to make it close to 32 hz. At least that's why winISD alpha is telling me.

I fell asleep at 9:00 last night, so consequently I woke up 8 hours later, at 5:15, this morning. On a sunday. Boy I'm a lamo I guess. I was going to do some early morning Christmas shopping.

Niiiiiiiiice

and you still haven't told us whether you are running 2 or 4 of the speakers If you're running one set, there's no way you can wire them to 2 ohms and use either a 2 channel or 4 channel at its best. It would be silly to wire your speakers from the two sides of your car in parallel onto one channel of an amp. Not only would it mess up your imaging, but it wouldn't give the speakers more power because they'd just be splitting the amp's power anyways. Assuming you are using one driver per door, you can use either of those amps. Either wire them straight to the 2 channel with one side per channel at 4 ohms or get the 4 channel and bridge it and run one set of bridged channels to each side, again at 4 ohms. Personally I'd do a 2 channel for easier installation, but you may want to get a more powerful 2 channel.

It will give you a more peaky response in that small of an enclosure, even if you tune low. If you go ahead with it, definitely add polyfill to the enclosure to help it out.

I've never seen a tutorial on cabin gain. It's different for every car though, so it would be hard to generalize. What do you want to know about it and frequency response?

If you decide to get rear fill anyway, there really isn't a reason to get two 2 channel amps. Just get a 4 channel. Cheaper and easier to install.

I agree with John, separate crossovers on subs is a silly thing to do. One amp for all three subs would be much easier as well.

Not to be a killjoy or anything, but if he's in a tight spot shouldn't he be saving his money for bills that might come up? Also let him know that if he'll want to upgrade in the somewhat near future when he has more money, he should just wait and not waste the money now. That being said, I had a memphis ST amp a few years ago and it was nice. The Alpine PDX line is really good, but out of his price range. Their other lines are just decent.

it's all those stogies. Hopefully not the Strep or whatever my gf has had for the last week.

Drove to work with no bass this morning. When I put my faceplate on my headunit there came a crackle and pop from the sub, then nothing. There also seemed to be a power draw from my electrical system, so it would seem that the sub amp (Crossfire BMF1000D) drew a bunch of current. Hopefully it just blew the fuses on the amp, I didn't have much time to inspect. The pop has happened before, except from my interior speakers. Twice in the last month there has been a real loud pop when I put my faceplate on. But my mid/highs amp survived those times (Planet Audio TT2300), just like my new Kenwood KAC-X40 survived this one, though there was no sound from the interiors this time. So maybe there's some static electricity thing going on or something, I'm not sure. Maybe I'll have to start leaving my faceplate on at night, or find out how/where static electricity is building up. But what I am sure of is that I'm getting tired of car audio. There always seems to be something. If I wasn't addicted to the bass massage I'd give it all up. I've already had two crossfire amps mess up on me before, this could be the third. My first BMF1000D blew, but I bought it used from an SPL competitor so I chalked it up to a hard life. My VR404 blew about 3 months ago, not sure why. My factory speakers that it were on may have blown, but isn't that what the protection circuitry is for? I know I won't be recommending Crossfire anymore. They're underrated, sometimes wildly (I think the BMF1000D was measured to be about 80% underrated at 4 ohms, 50% underrated at 2 ohms, and 25% underrated at 1 ohm), but this is why I've said underrated/overrated means next to nothing. It's the quality of the components that matters.

If you're going to do that, just buy a 3-way component set. You don't need 4 tweeters up front. Heck I turn my 2 tweeters down 4.5 db's on my crossover.

Hey if it was up to me I wouldn't. But like I said- Christmas present.

Plus chicks dig scars