sub box, port
Printed From: the12volt.com
Forum Name: Fiberglass, Fabrication, and Interiors
Forum Discription: Fiberglass Kick Panels, Subwoofer Enclosures, Plexiglas, Fabrics, Materials, Finishes, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=114503
Printed Date: April 28, 2024 at 6:06 AM
Topic: sub box, port
Posted By: maniak2005
Subject: sub box, port
Date Posted: June 16, 2009 at 7:33 PM
i had a quick question for anybody who knows. when doing a ported box that is bigger and has a large port area (over spec) that will heat the coils up faster, than being smaller and small port area (under spec), provided the length is adjusted accordingly for tunning frequency.
Replies:
Posted By: sparkie
Date Posted: June 16, 2009 at 8:42 PM
The voice coils heat up from the current an amp delivers to them. When you overdrive an amp, it will put out more distortion and cause the voice coils to heat up more than they should. Building a ported box wrong will only hurt either the sound quality/output of the speaker or hurt the speaker itself. If the box is made wrong, it can cause the speaker to overdrive itself and kill it. If you can't build the box correctly based on your desired outcome, then use a different speaker or redesign the box. Do it right the first time.
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sparky
Posted By: maniak2005
Date Posted: June 16, 2009 at 9:03 PM
i can build ported boxes all day that allows the sub to take a beating with alot of power over thermal rateing. i've almost never built a box to manf. specs. and i've heard a few people lately, talk about a larger box and port will allow the coils heat up faster with the same amount of power than a smaller box and port, because it allows the sub to have less of a linear response and less control like a smaller ported box. from what your saying is that a sub can only handle what it handels and it from the amp and only the amp that causes this. that is not true. why do you think small sealed boxes allow the sub to handle more power. thermal compression is what i'm refering to in my question.
Posted By: sparkie
Date Posted: June 17, 2009 at 6:27 PM
The design of a sub box determines what it will sound like. Sealed boxes and ported boxes have their own distinct characteristics. Each sub has it's own characteristics and is sometimes better suited for one style box over another. You need to understand the pros and cons of each box style to decide which one to use, provided your sub is suited for either. Sealed boxes tend to control the woofer's excursion more so than a ported box. A ported box will generally deliver deeper and louder bass until your try and get more out of it below it's tuned frequency. Building a small sealed box prevents the sub from reaching full excursion and allows it to handle more power because the air in enclosure is more like a stiff spring against the woofer. Making a sealed box bigger, will allow it to play deeper bass but it won't handle as much power. Making the box too big will cause the woofer damage due to severe excursion. To make a sub box, you need to determine what you are trying to achieve. Then pick a sub and box design that will do that. Try doing some research on box design and you will learn that there is a lot to it. There is no best box, but some do things better than others. Remember that distortion from an amp or a poorly designed box are what usually kills speakers.
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sparky
Posted By: maniak2005
Date Posted: June 17, 2009 at 7:08 PM
i allready know everything your telling me. like i said i have built boxes for 10+ years. i also know how to keep the cone on control based on t/s. i know how to read and interprit t/s and apply it to an enclosure. my question is if you have a sub in a ported box with 1000 watts rms (clean), same everything and all your changing is the box size and port size. i have heard (but never had a problem with) that if the box is big with big port area that it will allow the voice coil heat up faster than a smaller air volume and smaller port area, with the same tuning frequency. is there any truth to this. i know all the other factor that will pop a coil. if none of the other factor are going to blow the sub. i can design a any box to hit how ever i need it to hit. it may say rookie under my name but far from it.
Posted By: soundnsecurity
Date Posted: June 17, 2009 at 9:11 PM
maniak2005 wrote:
i allready know everything your telling me. like i said i have built boxes for 10+ years. i also know how to keep the cone on control based on t/s. i know how to read and interprit t/s and apply it to an enclosure. my question is if you have a sub in a ported box with 1000 watts rms (clean), same everything and all your changing is the box size and port size. i have heard (but never had a problem with) that if the box is big with big port area that it will allow the voice coil heat up faster than a smaller air volume and smaller port area, with the same tuning frequency. is there any truth to this. i know all the other factor that will pop a coil. if none of the other factor are going to blow the sub. i can design a any box to hit how ever i need it to hit. it may say rookie under my name but far from it.
i would think that a bigger box( same tuning frequency) would be more dangerous if the tuning frequency was high, 45hz and up, because as it goes lower that tuning frequency and it unloads, a bigger box would have even less control over the sub thus leading to mechanical failure. although this is true with all ported boxes, it might be more true if the box is bigger. -------------
Posted By: stevdart
Date Posted: June 17, 2009 at 9:14 PM
I think that you should consider disregarding these few people you've heard lately and their pro/con discussion. The discussion you referenced seems to be, does the box airspace cause voice coils to overheat? In your posts, you've created a confusing scenario by combing box net airspace with port airspace. It is only the net airspace that you really are discussing here. It is the volume of air that will affect damping and Q of the woofer. You should leave port airspace out of the picture altogether, as it is a box tuning mechanism. As you know by being an experienced builder, the net airspace is made larger or smaller to achieve the desired Q, SPL and/or sound quality that you want for that particular woofer / environment / user. Achieve the sound you want and build the box so that the coils don't move past their limitations. As sparkie said, coils are overheated because of the amplifier / user. ------------- Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
Posted By: maniak2005
Date Posted: June 18, 2009 at 1:07 AM
alright thanks you pretty much answered my question. i figured that they were just tunning wrong and that was allowing them to loose control over the cone and that is why they were killing subs and or power reasons. but when i heard what they were saying i figured i would look into it, and and see if they're was any kind of truth to it. i look at it is everybody has different ways of doing things and some are right and most are wrong. most ported boxes are needed more for sq rather than spl 1 note wonder. but hey you can always learn something new. thanks man.
Posted By: hungry_eye
Date Posted: August 16, 2009 at 10:47 AM
In regards to a ported box. There is no evidence to suggest the size would matter at all. A larger box (with different sized port) would just change the sound characteristics of the box. For example, we used to build small sized ported spl boxes that enhanced a natural frequency "hump". That frequency hump dominated that sound range and provided more spl on that one note. we'd play tracks that hit that note and was quite successful in doing so. We never burned out our subs by doing that. The only thing is, when you played normal music, that frequency would buzz out louder than others. it really annoyed me, so I just kept that box for actual competitions. Good luck, i hope it works out for you.
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