posted
how do these boxes work? is it 1 small ported box into a lager ported box? how do they sound,what kind of response do you get? thanks for the help
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Posts: 17 | From: portage,michigan,usa | Registered: Aug 1999
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quote:Ok, here it comes one time! I only explain these in detail once a year (I make $$ on them ) For that DVC 15. Build a box with 2 chambers, one at 3 cuft and the other one EXACTLY half of that, ie 1.5 cuft. Next cut 3 ports all IDENTICAL in length. Put one in the face of each chamber and the third in the wall separating the two chambers. In this instance each port would be either 12.5" long for a little deeper response or 8" long for a little more SPL. Now you have a box with a big chamber with a vent in it, a small chamber with a vent in it, and a third vent in the wall between the two. The woofer also mounts in the large chamber. The way they work is that, at low frequencies, it all functions as one big box with 2 ports, and is tuned to 30Hz (12.5") or 35HZ (8"). At higher frequencies the middle port starts to restrict air movement and the second chamber begins to act more as a resonance chamber but not as part of the box. At this point a second tuning frequency develops 1.9 times (almost an octave) higher than the lower one , ie. either at 57Hz (12.5") or 67Hz (8"). This is similar to a vented bandpass but has more output and smoother sound due to the woofer not being tucked inside the box. The results are that it plays both low and loud, while being relatively nice sounding. The drawback is the box size.
Did one 2 years ago in a sedan with 1 12 on 400 watts and pulled a 138 on music. There's a guy around here with 2 DVC 15s like this in a Daytona off a single 800a2 pulling 149s. They work but can be intense to build. They are the ONLY box I take care to factor exactly both port displacement and woofer displacement. Mess one of these up and they work very poorly....
If you what to see all the posts on the ABC goto the search at the top of most pages and gust type in abc. Sellect search entire message and you will get over 20 post with some tallk about the ABC's.
posted
but i have 3 jlaudio 10W6 subs. so could i do 1.3cuft ported into a 3cuft, useing 2-3"ports12.5"long&then use2-3" ports for each box 10 "long. thanks for the help
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Posts: 17 | From: portage,michigan,usa | Registered: Aug 1999
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posted
No not quite. The subs are to go into a 3Ft^3 box? Also have 3x12.5" ports? If so this is what you need to do... build a box 2Ft^3 with the sub and one 3x12.5" port, then using another 3x12.5" port into a box 1Ft^3 from that 2Ft^3 box, then port the 1Ft^3 box to the out side using the final 3x12.5" port. So what you need is three 3x12.5" ports (or two of what your subs need for a 3Ft^3 box) and a box 3Ft^3 net after you correct for port displacment and woofer dis. too. Here did you see this post it has pics of all of this. My total box size needed to be 2.4Ft^3 in thes photos but the vol of them befor the sub and ports is 2.77Ft^3. http://www.termpro.com/ubb/Forum8/HTML/000240.html
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