Sub positioning.

I have not got any feedback the last 2 times I've asked this in other threads so I'll ask here. In the Plexiglass box thread I was wondering if all you guys had them pointing downward or towards the outer hull due to sound quality advantage, or simply to get a better view through the plexi. I faintly remember somewhere on here reading that you lost a lot of sub effectiveness pointing them towards the cabin, so i can see the advantages. Also I was going to ask the Sound Illusions guys or anyone with big subs (W7's and so on) if they ever had any problem with malfunctions in the gauges, or even loosening the dash with that much sound under there. My final question is about grounding. I know it's best to ground as close to the Amp's as possible, but is 1/0 wire grounded to the block good enough over the 15 or so feet to the distribution block? I'm adding 2 1000/1's and a 300/2 for reference here. Thanks for the feedback.

im sure someone will answer different but run the port out toward the drivers seat and face the speaker into the side of the boat that way you can load the woofer

I'm using sealed boxes.

Most subs like some thing to load off of. That would be why you see a lot of them pointed towards a wall or the side of the boat.

Damn Matt, 2 1000/1's thats going to be pretty nasty. I'm planning to run 1 1000/1 to 2 13 W7's in JL wedge boxes on either side of motor. I'm not sure if it will be quite enough power but we will see.

Sorry I don't have an answer for you as far as sub placement go's.

I was just curious about your alternator and batterry setup your going with.

you will be starving the w7's with just one 1000

Ok can someone explain that term? Loading the sub.

Johnny: As far as it goes I have read endless debate about under powering being more dangerous than overpowering subs. I'm no expert but I have derived that using an underpowered amp with excessive gain is the big problem. I think you should be fine, but I'm not the one spending your nickle. Those subs are big bucks to repair, trust me. Batteries are 4 US-2200's on position number 2 of the integrated battery switch. I'm never going to run the boat in that position since I know that would kill the Alt. charging them, but I'm going to see how the stocker does powering the system while running before I outright change it.

I'm still wondering on these questions friends, speak up!

(Message edited by xaggie on February 27, 2007)

Matt,
Hate to steal your thread, but I did some riding up on the northside of conroe Sunday, It was butter.

Hope to see you out there soon bro.

subs produce a low frequency sound wich is a longer wave if you put something in front of them A>K>A loading. the wave hits and then loads on itself producing more output. A great example would be put a sub in a parking lot aimed at you standing back 30 ft. You will hear the bass sound but not at a high level. Take that same box and aim it at the ground on stilts six inches up. The sound will increase from the pressure loading off the pavement. Pretty generic explanation, but hopefully you get the point.

Nice buddy, I'm looking forward to it was well! It's getting warm and I want to get all this taken care of before we hit full on Summer. I was up there about a month and a half ago, and it's so sweet when no idiots are out there tubing/power turning. Looks like a totally different place. What did the water feel like?

Thanks Chris, I think I get the concept, but is there anywhere I can read about it in more detail?

The sound wave propagating out of the sub, at 20 hz, is (approximately) 13552 feet long. At 20 khz it is 13.552 feet long. That is how far the sound would (theoretically) travel in the time it took the signal to make one complete sine. That distance and multiples of it determine what happens when the wave at a given frequency hits an object and bounces back into itself. The wave essentially folds over on itself, and both cancels out and amplifies certain frequencies. So, the "loading" people refer to is the standing wave distortion (that's ALL it is!) makes the sound resonate at certain multiples of the distance between the speaker and the object in front of it. Technically, it is just distortion. Some people like it, some don't. I don't. I like accurate reproduction of sound. To me, it is as annoying as a car with a great system and a rattling license plateIt is not as critical with sub freqs as it is with higher frequency audio. ex. at 20khz, if you placed an object at 1/2 of it's wavelength (1/2 of 13.552 or 6.75 ft)directly in front of the speaker it would bounce a wave right back into the speaker that is 180 deg out of phase with the source, causing significant and noticeable phase cancellation. If you want to hear what that sound like, just wire one speaker in a pair out of phase (swap red and black on one speaker)

Psyclone, I believe your math is way off.
Here's a chart I found online.. ( and these charts assumed fixed speed of sound because that is variable depending on temperature. I think one chart went with 1130 ft/sec and the other did 1127 ft/sec.)

http://www.installer.com/tech/freqandwave.html

this chart even states
"Notice the low frequencies wavelengths are much longer than the high frequencies, with 20Hz being 56 feet long where as 20kHz is only 6 hundredths of a foot! (that's a little more than half an inch)...:

and the one below has a few music refs, but only shows 1/4 wavelengths..

http://www.yourfriendpaul.com/Music/WavelengthTable.html

Actually kind of interesting. I used to have a chart that had wavelengths for every musical note and the frequencies.. I need to find that again..

Yeah, my math IS off, that info is correct. I'm jet lagged out of my mind right now but the theory is the same.

Thanks for the links, good stuff.

(Message edited by cyclonecj on February 28, 2007)

This is good stuff. I didn't realize a lot of this. I would like to read more if you guys have some good references or links for technical discussions. I dont want to hear the typical "Kicker vs. Blah vs. Blah" debate on most car audio forums.

Matt, I live out on Lake Houston. My w6 in the driver's footwell rattles my dash quite a bit, but I've dynomatted most of it to keep the rattling to a minimum. I've played aroudn with that setup...I currently have the sub and port firing up (the rattling sthe smae regardles of how I face the sub) I've also tried the sub and port facing out, the sub facing hte exterior wall and port out and a selaed box. The sub firign up creates a kind of bandpass effect. two w3's are under the back seat. I haev a buddy with 2 10's in an 06 x-star that lives across the lake from me that supposedly soudns very good (he just got it back from the shop)

Thanks for the help guys!
Adam: Man that rough to hear. I can just see having my 13W7 under the dash and the vibration knocking a couple of gauges out, and heaven forbid my Perfect Pass.

Any other thoughts on the dash, and grounding questions guys?

My question relates to sub placement also. Would it be better to put two 12s under the clam hatch or put one in the clam hatch and one under the dash?

would the sound cancel each other out if both were facing opposite sides of the boat?

Im using the new TI tc3000 subs?

One on each side usually does better. Since most boats with one under the clam drop off real bad with the clam closed. Unless you feel like cutting up your boat.

Still alive! I'm going to kick this one till it's beat!

Whats to kick. As Far as I can read all q's answered. Unless I missed something.

Grounding, and only one person with advice about having dash problems?

(Message edited by xaggie on March 01, 2007)

matt i would build a box under your dash. i know with the x star that you would have to cut a section out. look at the round two system build. they put two 12s in that area and i also have that same set up. its the best place to put a box. in the hatch you would need to let the bass vent out into the boat. with the hatch closed the bass has nowhere to go. my boat has 7 12s and the boat doesnt rattle when its in the water. when its on the trailer now thats a different story

Both my dash and my glovebox areas rattle with a single 12 in each area. Both subs are facing toward the transom.

I would always try reversing the polarity or adjusting the phase of the sub output while listening to all of the system speakers. When you are happy with that, I would also try reversing the polarity of one of the subs, regardless which direction they are facing. You will get some phase addition/cancellation with both setups but one may sound "better" to you.

It can't hurt to experiment.
DON'T reverse the phase of one voice coil on a dual VC sub, that is a bad thing, you might burn up the speaker.

How do you reverse the polarity or adjust the phase of the sub output?

Matt, I am in N Houston. Here's the answer to your grounding question. Run your 1/0 gauge from the batteries to your AMPS. Keep all power + and - sourcing from the same starting points (batteries). Make sure the head unit/eq are also sourced on the same set of batteries. My rule on AMP power wiring is no more than 1800 watts RMS for each 1/0 run to the amps. In other words, I would run two sets of power wire, one for each 1000/1. You can run up to 25 feet with no issues following that basic info.

Before someone asks the question about wiring a 5000 watt bass amp. I suggest reading the installation/owners manual for the amp or contacting their technical support staff. When running amps of this power (5000 watts), I would not run more than 3 feet from the batteries unless I did not care about maximizing the amps capabilities.

If you face the sub down, should the port be facing down as well? I would think the port facing out would sound better. am I wrong?

Many head units allow you to reverse the sub output or adjust the phase. If you are using two subs driven off the same sub output, you can reverse one of them by swapping the speaker wires. That changes the phase of that sub by 180 deg. Head units that offer phase adjustment will allow you to change it by small increments (10 deg or so) around 180 deg.

my HU doesn't have that changing ability, but I don't think that my subs are out of phase necessarily, I just think the one in the driver's footwell is quieter because it's facing forward instead of backward or into the side of the boat. Nothing for it to reverberate off of like the one under the observer seat.

I guess I really don't know to be honest with you. I'd like the driver's side sub to hit as hard as the observer's side sub, it just doesn't. btw - they are identical subs, identical boxes, and identical amps powering them. Amps are set up the same too.

A ported box enhances a certain single frequency. That enhanced frequency will come out of the port. You'll need to experiment with placement since everyone's tastes are different and the areas where the sub is located is different for every boat. Generally, if you want boomy bass, get a ported or bandpass box. If you want tight thumping bass, go sealed.

David, experiment with rotating the boxes and/or adjusting the gain to even them out.