HD Crew-Cab woofer box

pablontx · May 7, 2005

Hello:

Just had 2 10s installed behind the rear seat of my 03 Crew-Cab HD. The fit is a little off (can't put pass seat all the way down), but it's livable. Also had a 300W amp added.

The problem is although there is a lot more power, the bass is not too rich. We also added a self-amp 10" woofer in my wife's car and it has a nice thump to it with the right music. However, if I put the same music in my truck you can hear the bass, but it doesn't have a thump to it.

I was hoping with 2 10s and a 300W amp I would blow away her car. The speakers are in the same league so I believe it's an apples-to-apples comparrison.

Is my truck flat b/c the boxes are smaller? It's got the Bose system, could that be it? Would it be better to get one big custom box vs. the two smaller?

Thanks!

carbuster · May 7, 2005

Well it all depends on the RMS range of the subs, the ohmage output of the amp per channel, and the airspace of the boxes the subs are in. To me, it sounds like there isn't enough juice going to the woofers.

pablontx · May 7, 2005

Here are the specs I could dig up:

Car: Kenwood 10" Dual-Voice-Coil w/ Integrated 200W Class D Amp Model KSC-WD250 .... sounds awesome and it's comfortably in the trunk

Truck: Rockford Fosgate Punch 900W Mono MOSFET Amp; Pair of Rockford Fosgate Punch 10" Single-Voice-Coil 4-Ohm Subwoofers with polypropylene cone and 38-oz. single-stacked magnet RMS 150W... good power, but no thump

Truck subs: http://www.rockfordfosgate.com/products/ez...ch%20Subwoofers

Truck amp: http://www.rockfordfosgate.com/products/ez...ch%20Amplifiers

And I think these are the truck boxes snugged behind the rear seats: http://www.crutchfield.com/S-U1CZgNdjSfI/c...6510SE&g=178650

masterp2 · May 7, 2005

The problem is going to be your selection of drivers. The CC is a big space compared to any car, and it takes more driver to pressurize it, room gain low. That driver does not have much capability due low excursion specs, xmax. You will be lucky to see 100 dB at 30 HZ. Add to that, you have stuffed it into .5 cf (net) when it needs more like .7 (.8 gross). I would guess you have no audibility below 40HZ, and some audibility to 60HZ. You need to get some test tones (bass mechanic CD) If you were sold this combo, maybe you can get your money back.

You need a driver with shallow mounting, high RMS power rating like 300+, and x-max over 12-15 mm. Then it still has to be designed for "small sealed box" in it's thiele small specs. You have only .5 cf per driver, a design challenge for the audio engineers, but there are a couple of good drivers out there.

I use a driver in a sealed enclosure I designed for this specific application, which plays 132 dB at 55HZ. I also designed a PR type enclosure that uses only 1 10" driver, and plays 124 dB down to 20 HZ. Both of these are at 300 RMS. Very impressive for a single, and none of these restrict the back seats, as they are designed for that space.

pablontx · May 7, 2005

Thanks for the info! If I got one custom box to fit both subs in would that make a difference or is the x-max and RMS still just too low? Errr... hit the net and can only find boxes that appear to be the same size....does a larger box acutally have two chambers?

Yep, it was a combo deal; however, the shop advertised it with a bigger box, but it would not fit. I'm thinking about seeing if they'll exchange the two little boxes for a larger custom, b/c I'm concerned the box will end up getting cracked if someone jumps in the back seat. Thoughts?

Overall, the new power is pretty sweet, but for $550 (subs, boxes, amp, cables, install, and uncle sam) I'd like to have a thump if I want. Btw, did I get taken to the cleaners? or is that a good deal?

Btw, what is xmax and RMS?

Halen5150 · May 7, 2005

RMS = root means square. Baiscally, it's actual power. Most companies advertise peak power, but actual power is what you want to look for. Xmax is the maximum excursion of the subwoofer(how far it will "jump out"). $550 is not bad for all of that. Here are some good subs for your situation(and good subs overall, imo) Alpine Type-R

masterp2 · May 7, 2005

Those drivers won't impress your neighbors (if that's what you're after) no matter the alignment. For nice balanced bass in a Sound quality app, they would be fine.

A drivers abilty to produce big SPL is in x-max, or linear excursion capability. It defines how much air the driver can "move" to produce soundwaves. A 20 HZ soundwave is 20 feet long, and that takes a lot of swept air to make it audible.

Anyway, those drivers just don't have excursion compared to many hi-x drivers. A driver that has twice the excursion of another will "feel" twice as loud, at max excursion. One problem hacks run into, when squeasing a driver in too small a space, is that it takes more than the rated power capacity to reach maximum excursion, because the air "spring" in the box is too stiff. Hence the driver doesn't have the "freedom" to sing.

SPL is sound pressure level, expressed in dB, what our ears register on the ear "drum".

Not sure what you mean by "thump". A poorly designed box often thumps in what is known as "boombox" or "one-note-bass". It is the result of too much SPL in a narrow freq band, that prevents you from hearing the rest of the band. This is commonly available in audio shops because it sells. Not my idea of good. Much more difficult to obtain is a combo that doesn't do this, but provides copious amounts of bass at all freqs.

masterp2 · May 7, 2005

In your application, there only a handful of 10" drivers with specs you need, and shallow mounting depth. You will need a driver that fits in the box you use, and many of the hi power variety are 6-7". I use one that is 4.25" and still takes peaks of 600W and 300 RMS. They are fully recessed into the cabinet, so that the driver does not pound on the seat back. Important in longevity, and distortion.

Seriously consider a well braced box with 8" subs that is more shallow, so you can restore utility to you truck. You don't have to compromise. The 8W3's are pretty good I hear, you might even be able to use 3 of them.

pablontx · May 7, 2005

Thanks everyone! I have learned a ton in just a week from y'all!

I went back to the shop and talked to one of the installers and he said my issue was I had a sealed box vs. a ported box. He said a ported box would give the sound a more "round and rich" sound...what I was trying to describe as a thump. ;)

I too was thinking about getting higher quality 8's and putting in a better box. What really is the difference between and 8 and a 10 all things else being equal? Granted, I'd probably get high-quality 8s than my 10s are now, but so I can get the concept, is the rule of thumb basically bigger speaker, makes bigger air wave (think that's what you explained is SPL)?

Here's what one of the guys recommended: http://www.proboxrocks.com/chevy/01-03crew.shtml

Mark_in_Tulsa · May 7, 2005

Is the box that you got a downward fireing box?

Also did they say they can make that box ported, or did they say you should of bought a ported box?

pablontx · May 7, 2005

Is the box that you got a downward fireing box?

No, they are behind the rear seat facing forward.

Also did they say they can make that box ported, or did they say you should of bought a ported box?

The installer I talked to was different than the guy who installed the setup. After describing the sound in my wife's car, vs. my truck, he said I wanted to get a ported box. That's why my wife's car sounded different. You've sparked my curiosity though, could I somehow make the box ported?

What about doing one ported box and leaving the other sealed?

I'm going to drive my wife's car more today with some different music to make sure I do like her sound better. When we put in some low bass music last night we couldn't stop laughing b/c the sound was unreal and what I would have drooled over in high-school! ;)

carbuster · May 7, 2005

I still believe the amp isn't sending the enough power to the subs. Each sub requires 150W, but at 4 ohms, and the amp only sends 150W at 4 ohms to one channel, not two.

masterp2 · May 7, 2005

Pablo

If you want to get up to speed quickly, go to radio shack and buy an spl meter. Then go to a big cd store and buy a test tone cd, Bass Mechanic has a few with 20-100 HZ test tones, beginning at track 20.... Measure your wifes response, then you will understand what you are looking for, and why.

A port (correctly implemented) will enhance a specific "tuned" part of the bass spectrum. But you will learn this if you do the simple response curve that I can help you with, after you get back from the store.

Normally, in SQ apps, a port is not preferred in cars. But if irritating, jaw vibrating, mind numbing, neighbor non-compliant thiumping is what you seek, then the ported box, tuned to around 35-50 HZ is the thing.

I hope you don't live near me.

If you want the procedure for a response curve, i have a spreadsheet that will help you graph it. It may be more than you are interested in, I don't know. One thing is for sure, it doesn't lie (like our ears). Oh, and you will have a hard time porting an enclosure behind the seat. The small volumes typically require fairly long ports, and you should accept no less than 3" diameter for 2-10"s.

As for 8's vs 10's, approx 3 8's equal 2 10's, if x-max is about the same. SPL is SPL. The drivers you have may be perfectly suited to ported, but just know that ported boxes have to be 50% +/- bigger than sealed.

Try to do some learning on the audio forums. DIYsubwoofers.org. caraudioforum.com. diyaudio.com. there are others.

pablontx · May 7, 2005

masterp2:

Thanks again for all your help! Next time I am over by Radio Shack I'll pick up an SPL meter and test everything out.

I've been reading almost non-stop and have hit a couple of those sites, but still am just a chump beginner. ;) And we live in different states so no worries!

Q: Will the cone part of the subwoofer move further out than the outside rim of the speaker? I'm asking b/c the outter edge of the speaker presses into my seat and I was wondering if the cone could be hitting out that far.

Q2: I keep reading about putting some type of foam in the box. With my box probably too small for my woofers and amp, what about adding this filling material stuff? Can a box be re-opened or is it glued shut?

Halen5150 · May 7, 2005

I think you mean poli-fill(sp?). You can find it at any wal-mart where they keep all of the sewing materials. I've added it to boxes before. I beleive it slows down the sound waves to make your sub sound as if you had a bigger box, but I'm not 100% on that. I prefer not to use it, but you could always try it and see how it sounds. You have to take the sub out of the box to add the poli-fill. The boxes are glued shut. In your case, you don't have enough room for a ported box behind the seat, unless you went with one 10" sub, and that might still be pushing it. Subs in sealed boxes will get plenty loud though. Did they bridge your subs at the amp, or are you running your subs at 8-ohm stereo? You said your amp is a mono amp...can it do 1-ohm mono? If so, you should get some dual 4-ohm subs and run it at a 1-ohm mono load. Here's another webite to go to... www.termpro.com, check the audio forums there. Hope this helps...