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sub woofer box design

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please help :oops:

i need to design a box for a subwoofer for a home thearter system.
i have an 8 inch 100w rms speaker
i need to know the box diemensions, port size and length

this is connected to an old radio amp with two speaker output. but is enough power to drive the speaker but i need to build a low pass filter

thankyou :D :D :D :D
Try bass box 5.1, it is from Harris Tech. You give them the specs they need and they tell you how to build your perfect box.
Actually, I got it on software. But I'll try to locate them on the web.
Re: Do you need speaker box help?

todd_verne said:
8) If anyone needs help with i speaker box design, email me the details and i'll throw you a couple idea's. I'm available during the day, it get's pretty boring at work, so give me something to do. I need to know what subs, what the max dimensions are of your trunk and what kind of box you're looking for.
Match a 'Sonotube' [heavy duty cardboard tubing used to cast concrete into pillars] of 4 foot length filled with 3/4 pound puffed pillow stuffing [Dacron] PER cubic foot [do your own math] - this will FAR out perform a ported box
It is NOT a good idea to start posting cracks, keygens or links to them.

Remember that the Forum Owner - ElektroMaster - is legally responsible for what we post. If you must send something then do it via email.

Quite recently a forum owner was 'visited' by the authorities and forced to hand over the IP addresses of certain users. This was because cracks and keygens for major electronics software packages were being passed around on the board. Once the IP is known then it is very easy to trace you. The software producer is claiming substantial damages from the illegal users.

There are better ways of passing such information than using a publicly accessible forum such as this.

Be careful.

Dear Luk, please remove those ill-legal links from your post or i'll have to do it.
Box design

I have 4- 10" round Kicker subs.....they are going into box is under driver seat and is spec'd ok.......The other is under seat and well I dont know if we could get more out of it..

THe box is 10" x 11" X 78 = about 5.0 cubic ft of air space.........

Would I be better off with one smaller box in this location and put the other 10 some place else? THe 10" s fire up into seat.......dont know if this is best way.... I have 1200.1 Kicker Mono AMP powering the 10's
2 800.4W Kicker amps to power the 6.5's........
About 7 yrs ago my son asked me for help in designing speaker enclosures for his truck stereo system. After doing a little research and design we built the enclosures. My only measure of performance was the smile on his face, comments from his friends and polite requests for consideration from the neighbors. Those measures suggested success.

A couple of things that I recall from the work - that each speaker has some unique characteristics, beyond size, frequency range and power handling, that are useful or possibly required, for proper enclosure design. One of the electronics magazines published some enlightening (for me anyway) information on the behavior of a speaker in terms of impedance. If what they published was correct the impedance varies significantly with frequency and the enclosure - the variation is not linear and actually has some abrupt peaks or valleys. In the article they described how they addressed these - either in enclosure design or in the amplifer design - to yeild a predictable and the preferred response. How much difference (to the listener) all this extra work makes is unknown to me. I suspect that these kinds of things are what enables the manufacturers to produce small, lightweight enclosures with incredible sound quality.

I am sorry I can't pass along an author or publisher but the "how to design" stuff was nicely published in a couple of books and it was my opinion that you did not have to be an engineer to actually design your own system - if you followed the procedures in the book(s).

I just re-read my post and though it was worth pointing out that the impedance determines how much power is delivered. If the impedance varies significantly with frequency and the amplifier has a generally flat response to frequency (they don't but let's pretend for a moment) then the power delivered across the speakers won't be flat and could be extremely high or low in one or more spots degrading the quality of the sound.
hsvgtsr1 said:
What details do you need? :D

Vented or closed designs only need the Thiele-Small parameters. These are the resonant frequency, equivalent volume, and 'Q' of the speaker. The rated impedance will affect the low pass filter design. All of these values are available from the manufacturer of any modern driver. You can also measure them yourself with fairly primitive equipment, but it would be rather involved for a one-off project. Any of the above mentioned box design programs will then spit out appropriate vent sizes, depending on your choice of box size. The response of the system is absolutely determined by a fairly simple mathematical formula involving these parameters. However, it is still somewhat 'black magic' due to the variability of the parameters, electronics, and environment, and also due to the subjective nature of the perceived quality.

Steve, the impedance response is very peaky and frequency dependant, but fortunately, the coupling efficiency at resonance offsets the main peak, and a fairly smooth 'response' of a bass driver usually results in a gradual dropoff at higher frequencies. The trick is to extend the maximum smooth response on the bottom end. This can be done as you mentioned by either punching up the amplifier response, equilization, or by using active second (or greater) order filters. This is what has sparked the revolution in tiny subwoofer design. By offsetting the naturally poor low end response of a small box, with both the low-end punch from the reflex vent, and the electronic boost of an active filter, you can squeeze a lot of sound out of a tiny volume.

Mosfet, you are right that a tuned column will far outperform a vented box in loudness. This is great for cars and boats where you want to thump the crap out of music and blow a few windshields out. But hsv mentioned a home theater system, where you probably are better off concentrating on even response, and rattling the windows is actually a negative consequence. Tuned columns sound crappy in a closed room where the natural resonances of the room interact with the 'tuned' frequency. I am not trying to be a purist here, either. I could care less whether the music is faithfully reproduced, I just want the maximum thump for the buck, too, with the least amount of rattle.

One way of getting that sub-audio shake is to use vibrating transducers attached to the floor (or, perferrably each seat). A little spendy, but cheaper and smaller than corner horns.
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