Stovebolt6 Posted October 17, 2002 Share Posted October 17, 2002 I am considering a DIY project utilizing a K-33-E woofer. I would like to end up with a frequency response similar to the Cornwall at the low end. How much of a role does the shape of the cabinet play in reproducing bass? The mid horn I want to use is longer than the 15.5" deep Cornwall cabinet. If I build a cabinet with the same internal volume and same vent size and shape as the Cornwall will I get similar performance or does everything change with the shape of the new cabinet? When PWK calculated the internal volume for the Cornwall was the displacement of the horns, drivers, and crossover considered in the calculation or is that one of those things that "doesn't make a dimes worth of difference"? Quote Link to comment Share on other sites More sharing options...
lynnm Posted October 18, 2002 Share Posted October 18, 2002 V = L x W x D Somebody already said that somewhere..... probably I suspect that enclosure shape will have minimal effect on the sound so long as the interior volume and porting are within the driver maker's specifications. Quote Link to comment Share on other sites More sharing options...
John Warren Posted October 18, 2002 Share Posted October 18, 2002 ---------------- When PWK calculated the internal volume for the Cornwall was the displacement of the horns, drivers, and crossover considered in the calculation or is that one of those things that "doesn't make a dimes worth of difference"? I do not know how he arrived at the CW internal volume. The volume displaced by the drivers should be considered when arriving at the final volume of the enclosure. It is usually provided in the data sheet for the driver being used. Quote Link to comment Share on other sites More sharing options...
j-malotky Posted October 18, 2002 Share Posted October 18, 2002 IF you speaker is sealed, all you need is the same air space to duplicate the sound. In this case shape does not matter. But - Since the Cornw is ported. The shape and post location DOES matter. I was told once that porting is kind of like an organ pipe, or blowing over an open soda bottle. The port location and size dictates the "tune" or frequency the port plays at. I think you will need to re-calculate your port size and location if you change the cabinet shape. Maybe HDBR or somebody else here has a way to calculate this??? JM Quote Link to comment Share on other sites More sharing options...
ChuckElliot Posted October 18, 2002 Share Posted October 18, 2002 The Volume and the Port are the mechanical equivalent to Capacitance and Inductance in an electronic circuit. Put them in parallel and they resonate at a certain frequency. If you change the Volume, you must change the Port to tune the box to the same frequency. The shape of the box does not change the tuned frequency, although a way out of proportion box can have other ramifications. Check out some of the speaker design software that's shareware. The Radio Shack book by Weems is a good introduction, if they still publish it. A very detailed book is the Loudspeaker Cookbook by Dickason. Quote Link to comment Share on other sites More sharing options...
erikjohn Posted October 18, 2002 Share Posted October 18, 2002 J-M, I believe the size of speaker also plays a role in that size of port and box size equation. I don't think I would reccomend the K-33 for a sub though just because it works in the Corn's. I think there would be some better choices like a Monster 18" EVoice that would really hit. Alot of the subs speakers that you can buy from miscelaneous vendors will give box size and port size to tune to the speaker. This kind of takes the quess work out it. EJ Quote Link to comment Share on other sites More sharing options...
STL Posted October 24, 2002 Share Posted October 24, 2002 Just to clear up some inaccuracies previously posted: The internal volume of the enclosure, the diameter of the port, and the length of the port are really the only factors that determine the tuned frequency of an enlcosure. Even the speaker itself doesn't even affect that -- to the extent that you have to make sure the speakers Qts value is one that is compatible with venting. Also the larger the driver to more air it will move so that will dictate a larger port diameter (which always leads to increasing the length to keep the vent frequency the same). The shape of the box can affect the overall sound because of standing waves (just don't make a perfect cube with no internal supports). Also port placement has small effect; it's usually best the port be on the same face as the speaker or the side behind the speaker (but preferibly not on the side). Quote Link to comment Share on other sites More sharing options...
STL Posted October 24, 2002 Share Posted October 24, 2002 This topic made me realized that my sig didn't contain my subwoofer info nor the amp that's driving it -- so it added below now (hopefully)! FYI, I have designed and built A LOT of different woofer/subwoofer enclosures over the last 10+ years (from simpled sealed designs to elaborate sixth-order vented enclosures) so in this particular case I know what I'm talking about. Quote Link to comment Share on other sites More sharing options...
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