Hello all, was wondering if someone can help to tune a box. I downloaded win isd and I cant seem to understand it. I have a 7.1 cubic box with two 2231's and i would appreciate help with the ports, I have no clue where to begin.
Thank you.
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Hello all, was wondering if someone can help to tune a box. I downloaded win isd and I cant seem to understand it. I have a 7.1 cubic box with two 2231's and i would appreciate help with the ports, I have no clue where to begin.
Thank you.
Design for a single driver 2231 and for a box 3.55 cuft per driver.Quote:
Originally Posted by Sandor the hun
ruediger
Hi Sandor,Quote:
Originally Posted by Sandor the hun
so 101 Lit, per 2231A driver, tuned at 29Hz, port diameter 105mm, length L=21.4 cm, F3 =40Hz, F6=33Hz.
regards
ivica
Thank you, is that 2 ports?Quote:
Originally Posted by ivica
Hi Sandor,
RE: "port diameter 105mm"
A 4" (105 mm) vent for one or two 15" driver(s) sounds like a pretty small vent diameter to me, especially for driver size and box tuning frequency of 29 hz, and even more so to avoid vent noise if you intend to push it in terms of input power (2231A 100W and 2231H 200W continuous program capacity as per JBL spec sheets).
The larger feasible vent, the better for sound. In his Loudspeaker Design Cookbook, 5th Ed., 1995, Vance Dickason recommends the following:
"... 4" diameter ports are good for 8" and 10" speakers, and usable but MINIMUM for 12" and 15"; 6" ports are good for 12"and 15" types..." (P. 53)
So, unless the box will always be driven at relatively low power and never pushed, I would forget about 4" port(s) here and go for larger vent diameters such as 6", alternatively you may use multiple 4" or 5" vents instead, there's a formula to calculate this easily. But multiples use more space (re space needed between them). All this depends on space available in and on your box. BTW according to Dickason also, larger ports (e.g. 6") behave better when located closer to the woofer(s).
Doing it this way you won't regret it later, compared to using smaller 4" vent. Regards,
Richard
Hi Sandor,
To clarify for you or to put in different terms what Ruediger wrote in post # 2, there is a "rule" regarding double woofer box: dual identical woofers require twice the net internal volume of a single driver, along with double vent area, but vent length remains unchanged (i.e. same as for one driver).
The vent area may be all-in-one (vent), or divided into two or more separate vents, but the total area of all separate vents has to be the same as for the single vent. Use of multiple vents may require a small length correction (reduction of perhaps 5-10%; see doc. below).
As an addition to my previous post re vent diameter, JBL indicates "A good rule of thumb would be to avoid ports whose circular area is smaller than AT LEAST 1/3 the diameter of the driver ..." (i.e. 5" or more vent for a 15" woofer). From: JBL, The Most Commonly Asked Questions About Building Enclosures, p.4. Regards,
Richard
Thank you for all your help, greatly appreciated.