Hello
I have a 20 watts 4 ohm 4" Subwoofer that i took out from a pathetic philips subwoofer box that had big amounts of chuffing and used to vibrate and change it's position. Besides its power and impedence I have no parameters to go and build a subwoofer box of my own. Looking out for some general idea for making a box ported or transmission line.
I have a 20 watts 4 ohm 4" Subwoofer that i took out from a pathetic philips subwoofer box that had big amounts of chuffing and used to vibrate and change it's position. Besides its power and impedence I have no parameters to go and build a subwoofer box of my own. Looking out for some general idea for making a box ported or transmission line.
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It is difficult without the T/S parameters. You are playing a guessing game. One way to deal with it when you have no measuring equipment is to make a test box larger than the woofer is in now and increase the port diameter and length. Make one side of the box easy to remove. Listen to it and then piece by piece add solid material like wood blocks or brick to decrease the internal volume and at the same time fool around with the port by adding stuffing like rockwool or even old socks. Shorten the port a little and see if that is better or worse. Keep experimenting until you are happy with it. Then you decide if you keep that box or you build one that has the corrected internal volume and port. It's not the best solution but it's pretty much how it was done half a century ago.
It is hard to call ay 4” a subwoofer. That name is from the marketing department.
Without T/S you will have issues coming up with an optimum design.
dave
Without T/S you will have issues coming up with an optimum design.
dave
Just use the details you have and build a more substantial box using 16-18mm walls. Since it's chuffing, I assume it's vented and the port is probably too small in diameter.
Use the same internal volume or a bit bigger (see post #2) and add more for a larger and longer port after you know the size. Use WinISD (pick any 4" driver) and put in the existing volume, power and port details (diameter and length). Increase the port diameter so the velocity is below 20 m/sec at the desired power. For a 4" woofer a 40mm or larger port should work fine.
Other than that, scrap the driver and start from scratch with a driver with known parameters.
Use the same internal volume or a bit bigger (see post #2) and add more for a larger and longer port after you know the size. Use WinISD (pick any 4" driver) and put in the existing volume, power and port details (diameter and length). Increase the port diameter so the velocity is below 20 m/sec at the desired power. For a 4" woofer a 40mm or larger port should work fine.
Other than that, scrap the driver and start from scratch with a driver with known parameters.
Except that many of these multimedia woofers are tuned to have a bump in the bottom so as to be “impressive”.
If the vent is simple you can use this to calculate a larger vent: http://p10hifi.net/FAL/downloads/ChangingPortSize.pdf
dave
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