Was planning on either building or buying a subwoofer box. What would be your recommendation for a balance of good output and sound quality? I plan on running on 2 four ohm 12" alpine type r's.
If it's 4ft total figure about 3.5 foot net (you must subtract any bracing, port volume, and sub displacement for the net volume). Alpine recommends 34hz (though i'm not sure which exact model you plan to get), but anywhere from 30 to 35 would be good. The higher you tune the more SPL, the lower you tune the flatter the frequency response will be. They specify a port area of 15 square inches per sub. A single 6in diameter port will get you 28 square inches, so that would be a minimum port diameter for a single chamber box with both subs sharing the same airspace and port.
For a 4ft box total, minus the sub displacement (-0.142), and minus Oh let's say a single 6" diameter PVC port 15" long (-0.274ft), you get a net volume of 3.58 and with a bit of internal bracing it would be right around 3.5ft net, giving the box a tuning frequency of 33hz. Just a bit deeper and larger than Alpine suggests, but i guarantee it will be plenty loud and hit the low notes very effectively.
For 30hz, the port would need to be 19" long. 35hz would be about a 12" port. Going lower than 30hz would reduce power handling, so if you want to give them full RMS power than that's the lowest tuning freq you would want. Higher than 35hz would cut off the deeper bass lines in some rap/hip-hop songs.
Anything more questions?
Tuning frequency isn't the only factor to consider. A 1ft box tuned to 30 hz won't play deep notes as loud as a 3ft box tuned to 35hz. The enclosure volume has a big effect, and bigger boxes play deeper. What"s the vehicle? How much space would you be happy to give your subs?
Thanks for the reply, sorry for the late reply. I'm was thinking of having a 4ft box. Going to be in a 00 Grand Prix.
J Ro:Anything more questions?
