Quote:
Originally Posted by Mobile Enclosures
As an acoustical engineer, I have to say that all of these statements in bold are incorrect. If you would like me to shed some light on the subject of wave propagation and different enclosure designs advantages and disadvantages (real world and calculated), please let me do so. This post needs much help with all do respect, but I do understand where your trying to come from. Im not hating on what you said at all, Just want you to understand more accurately what you said and correct the misconceptions.  |
Quote:
Originally Posted by dontlookback
a sealed can bang more and be closer to a wall then a ported cus u cant block a port with a wall it just wont be loud. the subwoofer and the port works different when close to a wall. a ported box will not be louder than a sealed when u place the sealed box 3 inches from a wall. sealed boxes will get loud. u can have a resonance at 38 hertz but the sealed box will be louder with the perfect wall and it wont even have a resonance at 38 hertz. many sealed boxes will have resonance at 45 hertz or 42 for about 1.2 CF. We not talkin about test tones because they are a different story but when u put a song on a sealed box might bang more. The wall does the work while u have a ported box port do the work. the walls only help a little bit with a ported box but u can put a sealed box on the wall and nothing is blocked. all u hear it bass. reflections and more sound is heard. You can make a sealed box hit the frequencies of a ported u dont have to tune it or nuthin. EQ does the job. if u know how to eq the right way. it takes certain frequencies to raise up and which ones to lower. and all you need is a truck. a sealed box in free air will defenitly be loud. and how can a sealed box be louder? you dont even need a meter you can see where ur bass goes outside the vehicle as bass travels. you dont need 20 hz in a truck from a sealed box to triple or quadriple sound. u can even have ur cutt off at 36 hertz so u wont play nuthing under it. at 39 hertz a sealed box is very loud with a wall. ported is just loud like they say with an open space. sealed gets there noise especially in a car. when u have a port where do u face they port? and a sealed sub cant be treated the
same as a port with bass coming out of it. theres differences man
Sealed boxes can take power right? i dont wana sound so convincing but at low frequencies they can take
power and ported boxes even distort quicker than a sealed box. i know they make nice ported boxes but
talk about ur average ported box in the street . ones u hear. many people dont even build there own so how
can they be so perfect?
main thing: the way bass travels in a sealed box and a ported box is different. the way bass travels has a
effect on noise, dont think a ported box just makes a lot of noise but which box is more noticable in a vehicle?
they always said a perfect bass wave a wave formed by the wall and that is a sealed box very close to a wall. the more perfect a bass wave is the more creation and completion the wave will have. a sealed box will have that advantage way over a ported box. is a wave from a ported box formed the same way as sealed box in the same vehicle?
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Ok, for most of these, the answer mainly relies in the fact that it is based on many variables that are not mentiioned in this post and for most, it becomes relative to the equipment and listening preference and design goal. But for sake of arguement, let's say we are talking about both design types being identical: same enclosure persay, same applied voltage and amplifier and same driver and even vehicle. So, the first statement says a sealed can "bang" (which it seems this term is the expression of percieved loudness to this person), more than a ported and be closer to a wall cuz u can't block a port with a wall, it won't be loud.....to this I say first...the "bang" relies on much more than the location of the design but as a stand alone variable, placing the port near a wall has other effects on the propagation of the sound than loudness. I do agree that blocking a port is obviously a no no, as this would limit the output and likely affect the calculated response a little, but as far as output in sound pressure terms, it will not affect the "loudness" if close to the wall without touching the wall, as the only physical change that will take place would be the compression ratio of the sound waves, which in turn will likely increase sound pressure if anything....to a point of normalized distance that is, where the port can be close to the wall and again not "fully blocked" or closed up.
Now I have read this over agin and comprehended the terms used as some of them are just not put the right way, but do make some sense, so my bold statements might have changed a little, but not much. So, numvbr two...
Says, a port will not be louder than sealed when you place the sealed 3" from the wall. Now, again relativity takes major place in this as again many other factors are to be considereed, such as...is the ported placed the same distance, is the power the same, same song, etc. These need to be considered when making a relative statement such as this. So, this is incorrect in that it was not thought through as to what other factors alow or do not allow it to be true...which again have to be evaluated first. Its possible a sealed can be louder in that sense as it is correct that it will cause pressure gain, but for any design type this is existant as the gain from the environment is based on room mode and transfer function as a concrete response without the added enclosure response. So this mentioned gain will have the same effect on the response of any design. But if the gain has a harmonic resonance identical to the sealed design and the ported design was not designed for a resonance at that frequency or others, then yes, this statement may become true for obviouse reasons.
Number 3, states u can have a resonance at 38hz but a sealed will be louder and not have a resonance at 38hz....this like all others will rely on variables. Now, in general, under the same operating conditions, the mentioned resonance will exist for both design types if they are calculated to have that resonant frequency. What it sound like her is that this person is saying because it is sealed, it will not have a resonance at all. This is not true. The parameters and propagation of the driver and environment are existant to the point in any enclosure design where resonances occur. Its just that in a sealed design, those resonances are containedand compressed more so than a ported design which utilizes it for further extended output. But a sealed enclosure will not always be louder nor quieter as this is a change that exists independantly for any design goal and type.
Number 4..states many sealed enclosures will have a resonance @45hz and 42hz for 1.2 cubic ft... now, I'm not sure why this matters in this paragraph along with the fact that it is not always true, to a point that each drivers mechanical parameters will show different resonances added to the environmental resonances in any sealed enclosure of equal volume. Each driver will have its own unique respoonse regardless of the enclosure size and shape and layout....again....to a point. So, in this statement, it becomes partially true in that drivers of similar parameters will show near identical resonances, but this is not true for an absolute statement to be used with exact numbers.
Number 5 and more will continue on the next post.....
Sealed box Vs Ported box
"A good looking box doesn't mean it will sound good, but a good sounding box does make it look good!" -Jason Evans
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