Sealed if you are after pristine sound. Ported bass is muddy.
kung mapapansin nyo sa mga episodes ng PIMP my Ride bihira silang mag setup ng ported, puro sealed type lahat, pansin ko din hindi ganun ka clear ang sound ng ported parang distorted sa sobrang play ng cone ng subs napansin ko pa mas advisable lang ang ported sa mga ordinary woofer or acoustic woofer tulad ng ginagamit sa mga Mobile disco at sa mga live-band sound system.
conclusion:
sealed type the best :car:
Tama kayo mga Bro, Sealed is the best set up for Car audio . Pag subra pala laro ng cone sa Subwoofer medyo nagkaroon ng distortion at di gaanong solid lalabas yung Low Frequency attenaution. Sealed inclosure= buong buo bass whereas Ported = malakas medyo sabog tunog. (AFAIK) for ported inclosure you can also get good sound quality by tuning the port hole + location of the port hole itself
Ported if I'm using a low powered amp and low wattage subwoofer. I can aim the port tube to a solid partition or wall in my vehicle for more bass reproduction. Not good for high powered systems because you need to tweak the amp settings very well so that the bass will not be too muddy or distorted.
Sealed if I'm using a moderate to high powered amp and moderate to high wattage subwoofer. My current setup is this and I don't need to aim anything to the walls or partitions of my car. Produces better sounding bass even if you don't know how to tweak the amp settings very well ( as long as you don't put everything on the max positionhence you get an overload!!!)
true, ported boxes won't give bass that is as tight as from a sealed box. however, they should still not sound muddy. if they do, there's something wrong with your box measurements or port tuning. let's not generalize about ported being better than sealed. it's all about proper tuning and your own sound preference.
The first criteria in designing speaker box enclosure is to know the parameters of your speakers:
1. Resonance Frequency * free air
2. Speaker Coil DC Resistance
3. Amount of Volume Space it will Resonate
Out of these parameters with the aid of various formulas, you can determine the exact volume requirement of different Speaker Brands & Manufacturers. The best design is to limit the Hump between +or- 3db for good sound clarity (if requested, I can give you the formulas)
Going back to the issue: Ported ot Closed(Sealed)
I preferred ported for many reasons. In one ported enclosure, you can design 2 low resonance frequencies at one octave apart. Your enclosure is flexible to receive different effective resonance frequencies.
Using port tubes, you can adjust your resonance frequency as long as it is within +or-3db.
Conclusion: If the speaker is enclosed with correct volume, either ported or closed, effective resonance frequency can be achieved, thus good bass clarity is expected.
well tama yun iba na pag you have mid to high power ok ang sealed. muddy bass for ported? you can easily control the woofer movement by adding acoustic materials, say fiberglass or foam, inside your enclosure. may mid bass woofer and adjustments naman so if trip ninyo yun super low bass without the need for big, power zapping amps try ninyo ported with mid bass combination. in the end its how you tweak your system and how you use the most important part of system, your ears.
Tama ka diyan, bro. Generally in my experience, super low bass is not advisable for moving vehicles (that is, matatabunan lang ng external noise with frequencies ranging from 60Hz and above). But, if for indoor use like home, 35Hz is most likely acceptable especially for soft music.
In addition, closed box enclosure is designed for only one frequency resonance. If it is designed at 45Hz, don't expect it to produce 35Hz effectively. On the otherhand, Ported box can be designed with multiple frequency resonances, like 35Hz and 70Hz (an octave apart) at the same time. Meaning, the ported enclosure can provide wider effective frequency response.
Most manufacturers, are investing more on ported box for the purpose of requirement flexibility. Generally, closed box is more cheaper and can be easily designed. Without knowing the required parameters, trial and error method can be applied by adjusting the box volume to achieve the target bass response.
Oscilloscope or frequency generator are instruments used to determine the parameters of the speakers(woofer). If you know the parameters, so with the box volume. Yung box dimensions or sukat ng box, designer ang magde-decide at hindi ang frequency generator. To finally assess your design, you can use the frequency generator to determine the actual resonance frequency response of the box.
so that means yung capacity lang ng sub spkr ang na-me measure ng freq. gen... or yung capacity nito to produce very low frequency, pero yung box depende parin sa gagawa, and that means nasa designer parin ng box ang magpapaganda at magpapalakas ng boom hindi sa tulad mong maker mismo ng sub spkr?
labo ata dre!?
diba dapat kung maker ka ng sub spkrs dapat alam mo rin ang definite size ng box para sa product mo?
paki sagot naman ng maayos para maliwanagan naming mga boom-boom enthusiasts? mahirap kasi yung puro theory o haka-haka lang![]()
yung tungkol sa enclosure (box) may recommended naman ang maker nung sub, usually kasama sa manual, na design at dimensions. mas maganda sundin na lang recommendations ng manufacturer.
Yung recommended dimensions are based directly on the parameters of the speakers. Some manufacturers are giving their speaker's parameters for any designer to start with. If not, you can still determine the parameters by using some testing instruments. It's good kung may manufacturer na nagbibigay ng mismong dimensions, this is to get away from further calculations and testing.
Bro, mas maganda kasi kung actual ang testing. In any case try to figure out nalang.
To design your Bass Speaker Enclosure, the main target is to determine the box volume and at what optimum resonance frequency it can deliver. The resonance frequency (Hz) is the effective bass that the box can produce. Without the speaker parameters and some calculations it will be hard to achieve the correct box volume.
One of my Simple Projects: (Mid range and tweeter speakers are excluded)
Speaker Type: PRO-W88AD
Maximum and Nominal Power: 150/100 Watts
Impedance: 8 Ohms
Manufacturer: DAI-ICHI
First, you have to determine the parameters:
1) Fs = free-air resonance frequency
2) Qts = total magnification factor
3) Vas= equivalent air volume compliance
Free-Air Resonance Frequency:
Set up diagram(see attachment)
First, calibrate by inserting the 10 ohm resistor in place of the driver.
Adjust the voltage output of the audio frequency sine-wave generator until the ac voltmeter reads 0.01 volts.
Replace the 10 ohm resistor with the driver to be tested.
Keep the output voltage constant. 0.01 volts represents 10 ohms, 0.015 volts represents 15 ohms, etc.
Vary the frequency control of the audio frequency generator to find maximum resistance (Rmax). At that point, frequency is resonant frequency (Fs).
With this test I got:
Fs = 53 Hz (*Rmax = 25.7 ohms)
Total Magnification Factor:
Re = 7.4 ohms (measured speaker dc resistance)
Ro = Zmax / Re = 25.7/7.4 = 3.47 ohms
Rx = (ro)^1/2 X Re = (3.47)^1/2 X 7.4 = 13.8 ohms
Impedance to frequency curve(see attachments)
Adjust the sine-wave or frequency generator until the resistance is equal to Rx. This will occur twice as shown in the graph above. F1 is the lower frequency when the resistance equals Rx. F2 is the higher frequency when the resistance equals Rx.
Rx = 13.8 ohms
F1* Rx = 29Hz
F2* Rx = 92Hz
Qms = the mechanical control coming from the suspension system's damping abilities.
Qms = Fs X (ro)^1/2 / (F2-F1) = 53 X (3.47)^1/2 / (92-29) = 1.56778
Qes = the electrical gauge of the control on a driver coming from the counter - EMF generated in the voice coil.
Qes = Qms / (ro-1) = 1.56778 / (3.47-1) = 0.63473
Qts = the total Q of the driver.
Qts = (Qms X Qes) / (Qms + Qes) = (1.56778 X 0.63473) / (1.56778 + 0.63473)
Qts = 0.452
To determine the Vas, it needs test box with volume=0.5154 Ft^3 for 8" speaker or use 1 ft^3 for 12" speaker. Using the above test procedure, determine the FCT or resonance frequency of the speaker while on the test box. In my case, I got 93 Hz.
Vas = 1.15[(FCT/Fs)^2 – 1] X Vbs = 1.15[(93/53)^2 – 1] X 0.5154
Vas = 1.223 ft^3
The speaker Parameters Are:
Fs = 53 Hz.
Qt = 0.452
Vas = 1.223 ft^3
Base on these parameters you can compute the following:
Box Volume:
Vb = 15(Qt)^2.87 X Vas = 15(0.452)^2.87 X 1.23
Vb = 1.889 Ft^3 (This is the volume required to design the enclosure)
Add approximately 10% of the computed volume to compensate the mass volume of the speaker, fiberglass, and any material enclosed.
Box Resonance Frequency:
Fb = (Vas/Vb)^0.32 X Fs = (1.23/1.889)^0.32 X 53
Fb = 46.2 Hz (This is the optimum effective frequency of the box)
So the next move is to determine the size of the port tube and the speaker already fixed. In my case, I used 3” Diameter PVC tube. You can reduce the diameter but be sure it will not create a whistling sound. The length of the tube can be determined from the port table (I wish e-copy is available) or trying different length with the aid of frequency generator. The target resonance frequency is 46.2 hertz at maximum impedance. Try adjusting the length of the port tube until you achieve 46.2 hertz at maximum impedance.
Hope this will help in understanding speaker enclosure. Though, more on theory parin ang dating. Sensiya na bro.
Kung gusto mo talagang mag-design, I suggest the book of David Whims - Speaker Design, which is available in any book store.
Last edited by busy road; October 11th, 2006 at 02:28 AM.
and you thought it's just buy a woofer and put it in a box thing. maraming consideration pagdating sa car audio dahil sa space and power limitation. this can be corrected by using electronics such as parametric equalizers, electronic crossover, etc.
Last edited by afrasay; October 11th, 2006 at 12:12 PM.