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Old     (bzubke1)      Join Date: Feb 2010       09-24-2010, 2:30 PM Reply   
I have made the box for my sub and it has enough volume according to the manufacturer to be able to make it a ported box. I'm just trying to figure out if I will benefit by adding a port or if i should leave it sealed. The box will be under the helm btw.
The amp is an Alpine MRV-T320 so the sub should be getting 220 Watts.
The sub is a 2003 model 12" Kicker Comp VR with a rating of 400 watts rms.
The box is 16x22x11.





Old     (bawshogg)      Join Date: Dec 2005       09-24-2010, 2:54 PM Reply   
Depends on what you are looking for. A ported inclousure will generally give you more output at it's tunning or resonate frequency than a sealed enclosure per say. So here's a quik example. If your box is tunned for 40 hz you will likely see greater output at that frequency than you would per say in a sealed enclosure. Ported and sealed enclosures definetly have differnt tonal characteristics and what you prefer is really up to you. Sometimes a ported enclousure may offer more output at or near it's resonant frequency, but it may do so at a sacrifice of ouput in the surround ranges. You can always try it as sealed enclosure and then add the port later if you are not happy with the results. Are you sure on your dimensions? Most often the size ranges for a sealed enclosure are smaller than for a correctly ported box. I personally like the sound of a sealed enclousure, but in boats users are looking to get maximum output and usually go the ported route. I have had both and am currently running a ported box. Hope that helps ya and not complicates things further.

Last edited by bawshogg; 09-24-2010 at 2:56 PM.
Old     (david_e_m)      Join Date: Jul 2008       09-24-2010, 3:16 PM Reply   
Brandon,
I like a sealed box in a car due to the shallower roll-off and extended response. But in an open boat I really like the extra leverage and output you get with bass-reflex and you need it oftentimes. It can be like taking the governor off. A well-damped bass-reflex box will sound very good while a misalignment can have kind of a single note characteristic. So pay very close attention to the manufacturer recommendations. A ported box will require considerably more displacement than a sealed box. Some of this volume is going to be the displacement of the port and port wall thickness. If space gets too tight you can install most of the port to the exterior of the enclosure. Or you can lengthen the port to offset the smaller box and still tune at the same frequency (to a degree).

David
Earmark Marine
Old     (tuneman)      Join Date: Mar 2002       09-28-2010, 10:35 AM Reply   
Just say NO to porting. To properly tune a ported enclosure, to gain the benefit of it, is a pita. Sealed enclosures are always dependable. Bass reflex enclosures are for big and boomy, but you're beyond building one of those. Sealed enclosures give you the tight, punchy bass that most people prefer.
Old     (bzubke1)      Join Date: Feb 2010       09-28-2010, 11:01 AM Reply   
Yeah i have since decided against porting the box there are too many things that can get messed up. We installed everthing and are very happy with how it sounds sealecd so were just gonna stick with what we have for the time being.
Old     (05mobiuslsv)      Join Date: Apr 2006       09-28-2010, 3:45 PM Reply   
Quote:
Originally Posted by tuneman View Post
Just say NO to porting. To properly tune a ported enclosure, to gain the benefit of it, is a pita. Sealed enclosures are always dependable. Bass reflex enclosures are for big and boomy, but you're beyond building one of those. Sealed enclosures give you the tight, punchy bass that most people prefer.
Sounds like you've never witnessed a properly constructed bass reflex box to me.
Old     (AP)      Join Date: Mar 2010       09-28-2010, 3:49 PM Reply   
MMMMMMM Port of Subs...

sorry for the useless post. =D
Old     (david_e_m)      Join Date: Jul 2008       09-28-2010, 4:42 PM Reply   
That ship has already sailed. But I have just gained a new respect for a well executed bandpass box . 10, 12 and 13-inch bandpass enclosures in modest sized enclosures. 6 dB more output than a sealed system. Yes, four times the power. Low and highpass minus 3 dB down points an octave and a half apart. All the bandwidth that you can use. Relatively linear (smooth) response. Used selectively when the application dictates like in vented storage lockers. When you are forced to put a box within a box like you have with a subwoofer enclosure inside a locker or compartment you would be hard pressed to tell the dfference in sound quality between one type of loading system and the other. So in this situation the bandpass is absolutely the ticket.

David
Earmark Marine
Old     (hatepain)      Join Date: Aug 2006       09-28-2010, 5:05 PM Reply   
Bandpass enclosures sound awesome for sure but they're so damn long so you need a good bit of space. I remember my introduction to them waaaay back in the day, I was blown away by a box with a couple tens in it just crushing. I tried to build one and failed miserbaly
Old     (david_e_m)      Join Date: Jul 2008       09-28-2010, 5:38 PM Reply   
Hate,
Yeah, its a very complex enclosure to design and get right. Definitely not a trial and error thing. But when you look at a Bose home theater subwoofer that uses only two tiny 5-inch woofers to fill a full size living room you have to pause and give this bandpass some consideration. Imagine that a 13-inch bandpass is only 27"x16.5"x16.5". The port can be oriented out the end or side with equal results to best fit the job. 'Crushing' is a great description.

David
Earmark Marine
Old     (hatepain)      Join Date: Aug 2006       09-28-2010, 6:02 PM Reply   
Quote:
Imagine that a 13-inch bandpass is only 27"x16.5"x16.5".
Yeah thats not bad at all. I guess I always think of them in terms of 3 chamber rather than 2.

Love Bose! They're not to expensive and offer a lot in a little package.
Old     (tuneman)      Join Date: Mar 2002       09-29-2010, 7:16 AM Reply   
Nu Bu, I've built hundreds of sub boxes in the past. Many were bandpass, many ported, most sealed. Even built a few transmission lines. I used to be the lead installer for a large mobile electronics company up here in Minnesota (Mach 1). And, I built all of their custom boxes for every store. I was also the sound quality judge at many car stereo competitions. That was an awful lot of years ago.....now I feel old.

Anyway, I know a little about bandpass boxes and have made a few that absolutely rocked. They do put out a lot for a little power, but they are typically boomier/muddier than a sealed box and you can run the risk of easily blowing speakers. It's hard to tell when a speaker distorts in a bandpass/bass reflex box. My point was just to say that seald boxes are just way more forgiving and it's hard to go wrong with them.

As far as Bose goes, they are nice that they are so compact. But their sound leaves a bit to be desired.
Old     (david_e_m)      Join Date: Jul 2008       09-29-2010, 8:39 AM Reply   
I can tell from Tuneman's post that he has REAL experience and isn't just blowing smoke. We competed in Car Audio Nationals, USAC, IASCA and other car audio competitions and earned two national titles. The standards were incredibly stringent and the judges were typically brutal in their critique. Many of those purist elements will permanently manifest in your perspective as they have in mine. I think we are all in agreement its just a matter of degrees and circumstances.
The OP was considering a port retro into an existing sealed box which is kind of like putting the cart before the horse.
A sealed box can display better transients and a softer roll-off with deeper bass extension. Its optimum for sound quality in the enclosed cabin of a vehicle. But there are exceptions in an open boat. You don't have the deep bass rising effect like you do in a car. Because the sealed woofer may not have the output or the same leverage in a boat when you exceed its capacity its not particularly pleasant sounding. There are many types of abberations. The idea is to keep your woofer running within its limits or find a way to extend those limits via one or another loading method.
Ported boxes can sound great but its not something a do-it-yourselfer can trial and error with any degree of success. Some of the most esoteric home speakers are bass-reflex as are the majority of the very best recording studio monitors that our music is mixed on. The Thiele-Small formulas that most bass-reflex modeling is based off was designed for very low power levels in the eariest days of solid state amplifiers. Recently a few manufacturers have updated their programs for higher power usage and longer xmass woofers. This has greatly enhanced the accuracy of bass-reflex enclosures. There is a falacy that a bass-reflex system only gives you more output at a single frequency. While that can be more of the case with a misalignment, a well damped design can provide increased output over a much wider bandwidth and in a linear (smooth) manner. A bass-reflex will have a steeper roll-off and is vulnerable below the tuned bandwidth so if you listen to rap you've got to have a subsonic filter which is a good idea regardless.
Yeah, Bose was just an illustration of what two tiny woofers can do in the context of home theater. I wouldn't recommend a LIfestyle system in your boat. We only use a bandpass enclosure within lockers or compartments where the question of the finer sound quality aspects are a moot point by the nature of the application. Its true that a bandpass enclosure naturally filters the upper frequencies
making it more difficult to distinquish distortion. Good tuning should go a long way in making sure that the woofer's limits are not exceeded. But in the hands of some people there are no safety measures that will ever be enough.

David
Earmark Marine
Old     (hatepain)      Join Date: Aug 2006       09-29-2010, 9:40 AM Reply   
Quote:
As far as Bose goes, they are nice that they are so compact. But their sound leaves a bit to be desired.
Not to me considering their size. I can't stand these in house systems that are so obtrusive and destroy ones decore, its bad form. Not to mention I certainly cannot afford the likes of Marten Design.
Old     (david_e_m)      Join Date: Jul 2008       09-29-2010, 10:07 AM Reply   
"...so obtrusive and destroy ones decore, its bad form." Hey, I ressemble that remark!
Old     (bendow)      Join Date: Sep 2005       09-29-2010, 10:13 AM Reply   
Really unrelated, but I think Elemental Designs blows Bose out of the water for HT in terms of sound quality and for half the price.
Old     (hatepain)      Join Date: Aug 2006       09-29-2010, 11:28 AM Reply   
Quote:
Hey, I ressemble that remark!
LOL, I knew with one of you two I'd strike a nerve with that remark
Old     (guido)      Join Date: Jul 2002       09-29-2010, 12:41 PM Reply   
Hmmm.... Yeah. It always blows me away when people get all ga-ga over Bose. IMO it's junk, but who am I? I still have vaccuum tubes in my home audio equipment.

Bandpass boxes rock when under powered and use crappy drivers. Ported boxes rock when properly tuned, have good drivers and decent headroom. Sealed boxes are easy to build and take up little room, with no tuning necessary.

IMO in a boat the most important things you can have are: good power supply, lot's of amp, and (most importantly) sub location. I had a solobaric Kicker 15 under the dash in my Sanger. Noooo sound came out of that location. Moved it to the driver side under the dash and it was crushing for a single driver set-up. My advice for anybody building their own system is to build a quick, easy box that can be moved to multiple locations and see where it sounds best. Boats like a X-star have a ton of options for where you can place your sub. Some better than others. Some will let out a ton of sound, some will just shake the boat to pieces. Also, putting the boat in the water will totally change how the system sounds. Don't be disappointed by this, just work through it with tuning. It's a long process to get a boat to sound right. Sometimes it's worth going to somebody that has already done the homework for you.
Old     (guido)      Join Date: Jul 2002       09-29-2010, 12:43 PM Reply   
Oh, and just adding a port..... Man, I agree with what's been said. That's a great way to mess up a decent sounding box. I love the phrase "it's not rocket science", but in this case, it kinda is.
Old     (brucemac)      Join Date: Dec 2005       09-30-2010, 1:34 PM Reply   
evan makes a good point that i struggled with a couple years ago. what sounds great in the garage (or in the driveway for that matter) can often disappoint on the water.

david, you folks ever hear that?
Old     (david_e_m)      Join Date: Jul 2008       09-30-2010, 3:10 PM Reply   
Bruce,
Oh sure. Tuning a system or listening to it in a garage with all the reflected radiation off the walls will sound much different out on the water where the same energy evaporates and you get little beyond the direct radiation. Backed up to the house will create the illusion that you've got more power than you really do. The bass can be stronger once the boat is off the trailer and resting down in the water.
Also speakers, particularly woofers, can sound different after an initial break in period. So its not unusual for a customer to get a fine retuning if its not exactly to their liking. But these issues really don't change the fundamental principles of designing a good system.

David
Earmark Marine

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