Positioning of Box in SUV

[audioholic 5,000+ posts]

It will vary from system to system, vehicle to vehicle. Ive had best luck with the box mounted 8-12 inches from the hatch, but again it all depends what you are running, what you want out of the system, and what you consider an 'improvement'.

 

[kballa422 10+ year member]

Not to threadjack, i think this will add insight into the thread, but I am about to run 2 15" Magnums, 800watts a piece, so I'm not too worried about making them a little louder if I have to sacrifice SQ. Like posted b4, Nick recommended me facing them back to get the most (SPL) out of them, but do you guys think having the subs close to the hatch (6") will have any negative effects on the SQ vs. running them facing up?

 

[CAMSHAFT 10+ year member]

I would have thought that someone would have said something about the size of the sound waves that are traveling to the listener........interesting.........

 

[audioholic 5,000+ posts]

Not to threadjack, i think this will add insight into the thread, but I am about to run 2 15" Magnums, 800watts a piece, so I'm not too worried about making them a little louder if I have to sacrifice SQ. Like posted b4, Nick recommended me facing them back to get the most (SPL) out of them, but do you guys think having the subs close to the hatch (6") will have any negative effects on the SQ vs. running them facing up?

Yes. Firing the sound waves directly off a wall immediately will lead to some cancellation and reinforcement (non-linear output). Many people still like this setup because it does tend to reinforce, and therefor boost the output of, the 40-80hz region (more output). But when dealing with strict SQ, reflections are bad, they create unnatural anomolies. In a true SQ situation, in theory your best situation is the speakers firing directly at you with no sound wave reflection what-so-ever. Since this is impossible, we live with what we can, and many times utilize this 'disadvantage' as an advantage.

I would have thought that someone would have said something about the size of the sound waves that are traveling to the listener........interesting.........

Why would we? Developement of the waveform is not the issue here.

 

[SuperTrooper 10+ year member]

Before I secured my enclosure to the floor board the vibrating and thumping would walk my box towards the back door ( Nissan X-Terra ) making for some crappy sounding bass. I moved it around at a few different lengths and I found the sweet spot at around 12" from the back door. Much more clear and deep sound and can feel much more air movement up towards the front. But I'm sure all SUV's are somewhat different.

 

[kballa422 10+ year member]

Right, obvisouly I can't have it firing straight at me with no reflections, so out of firing up and firing towards the back, close to the hatch, which would produce more cancellation and reinforcement causing a negative effect in SQ. I'm not too worried about a bass boost (2 15's will get plenty loud for me, and plus I prefer LOW bass, definitely not looking at anything near 80Hz), so although it may be slightly louder firing back, will it decrease my SQ vs. firing up?

 

[questionaire 10+ year member]

Good rule of thumb is at least port's width from the hatch. Say you have a 4" wide port....you put that thing about 6 inches from the hatch and you will love the results. I like to go just a little more than the width of the port.

So generally with a wider port the better the sound?

 

[audioholic 5,000+ posts]

So generally with a wider port the better the sound?

Your system only displaces so much air, given a specific enclosure. What happens when you increase the port size (cross section)? The larger the port, the slower the air needs to move to displace the same amount (or more even). The slower the air speed in the port (called port velocity), the less audible any turbulence will be that's caused by anomolies in the ports (such as sharp corners). Think of a whistle, the harder you blow, the faster the air travels through its passages, and the louder the 'noise' becomes. Blow the air very slowly through it and the noise is lessened greatly. Basically same principle applies to port velocity.

This is exactly how square ports get away with such sharp edges (lots of turbulence), sheer port size decreases port velocity in the system.

 

[audioholic 5,000+ posts]

Right, obvisouly I can't have it firing straight at me with no reflections, so out of firing up and firing towards the back, close to the hatch, which would produce more cancellation and reinforcement causing a negative effect in SQ. I'm not too worried about a bass boost (2 15's will get plenty loud for me, and plus I prefer LOW bass, definitely not looking at anything near 80Hz), so although it may be slightly louder firing back, will it decrease my SQ vs. firing up?

For the flattest response possible (given a specific system), the most direct firing position will (generally) give you the least reflections, which leads to all those anomolies. Think of it as drops in a pond. The drop hits the surface, the 'wave' reflects out in every direction. Once one edge of this wave finds an opposing surface, it reflects back. This reflected wave can then collide with the original wave, causing either cancellation (to some degree) or reinforcement (to some degree).

Therefore, a system that reflects virtually all outputted material off an opposing wall before it reaches your ears (firing rearward and reflecting off tailgate)...... will have the most anomolies. The arguements past this point usually boil down to people arguing they think it sounds better reflecting backwards rather than straight up or at you. But that's not SQ, that's personal preference. Make sure you know the difference. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Hope this helps.

 

[Platestacker45 10+ year member]

mid/high box? theyre in boxes? why? youve got slots in the doors and stuff right?

Yea man, check out my gallery. I have (4) 8" Eminence loudspeakers in the box that obviosly won't fit in my doors without major rework. And the box also houses (4) Super Tweeters for my highs. I will also be adding a 6" Eminence to each door as well very soon, some more tweets in my A-Pillars and maybe even a couple horns. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[audioholic 5,000+ posts]

Yea man, check out my gallery. I have (4) 8" Eminence loudspeakers in the box that obviosly won't fit in my doors without major rework. And the box also houses (4) Super Tweeters for my highs. I will also be adding a 6" Eminence to each door as well very soon, some more tweets in my A-Pillars and maybe even a couple horns. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

Why? I gurantee you the correct horn front stage setup will be more than enough for you to be able to listen to. Ive heard some that brought pain, and they didn't require 57 speakers to do it. Keep it simple man. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[kballa422 10+ year member]

Thanks, definitely helped. I'm leaning towards firing them up, I just think it looks better hehe, and plus like you said there will be less anomolies. Facing them back may get me more SPL, but really I doubt I will be looking for more output with this setup.

 

[HitManSE 10+ year member]

How about subs facing up & the ports facing to the rear.

 

[kballa422 10+ year member]

^ That's what I'm doing. Were you recommending that or asking how that would work out?

 

[Jeremiah25 10+ year member]

I have tested my explorer very extensively. Subs firing up and port firing back is definately louder than subs firing back and port firing back, no "ifs, ands, or buts" about it. Also on the box position, alot of it has to do with the enclosure. I've built ton's of boxes for my explorer for SPL and the best position is different for every box. In general, slot port boxes seem to be better the farther away from the hatch they are, and aeroport boxes seem to be better up close to the hatch. That isn't always the case, but that is the definately the most common result I have found.