DIY surrounds - help please!

[nm2285]

I'm crafting some simple surrounds and planning on using this driver: http://www.madisound.com/cgi-bin/index.cgi?cart_id=3234906.22725&pid=100
one per box and with no crossover.

I want the box to be small...quite small. According to WinISD, using a 0.075 ft^3 box, I get a -3db point of about 87hz. I'd consider this acceptable for surrounds in my application. However, I'm wondering if I can get a bit more out of it (another 15-20hz) by venting the box. This is where i get stuck. I don't know enough about tuning frequency and port selection (which I can read up on).
However, my biggest question has to do with the fact that this is a full range speaker. Would venting the box to get a bit more low end out of the driver hurt its performance on other parts of the spectrum?

-Nick

 

[sploo]

You could try using BassBox Pro to model a suitable enclosure - it should work out suitable port and box sizes based on the driver parameters.

A ported solution will obviously increase bass rolloff, but I'm not aware of any other side effects. My understanding is that at higher frequencies the air in the port doesn't move (significantly) and hence your box behaves like a sealed enclosure.

 

[Dryseals]

Normally you take Fs and divide by Qes to see what the speaker is suited for. In this caes Fs=80 Qes = .73 which come to 109. Value from 50 down tend to be sealed only, values from 50 - 100 for either sealed or ported. Values above 100, ported only.

Madisound recommends 2 to 3 liters sealed and stuffed, I'm not sure why, but I would imagine it has to do with the harmonic distortion below 80 hz.