Port on 820 cab.

[kestudio]

Hi there!
After having decided to build a 820 cab. for my 604E speakers, i think about changing the port to a tube!?
I?m afraid to hear mid-freq. through the port
and think a tube may be better to stop them coming through because of the air-volume in the tube.
Any experiences? I wouldn?t like to put more damping-material inside the cab as absolutely must be and think this a little bit few for mids not to come outside . . .
I?m in the start to build - phase, you know. .

regards, Klaus

[GM]

You'll hear it through a tube vent also. Damping material won't affect LF output until >1.5lbs/ft^3 is used. I recommend using a tube though as it 'pumps up' quicker than a large reflex vent, ultimately loading the driver more uniformly over a wider power range.

GM

[kestudio]

Hi GM!
Thanks! May be i?ll try an array of very thin tubes inside the tube. That shouldn?t effect lows too much but should prevent mids to get outside!?

regards, Klaus

[kestudio]

right!

best, Klaus

[GM]

This makes the vent aperiodic and will rapidly roll off the response with little impact on the upper harmonics. A good way to critically damp the cab though, like stretching cloth over the vent. Won't have much LF output though.

Really, IMO the best thing is to tune with a pipe for best output, then experiment with various density materials to use as grill cloth to voice the driver/vent combo, then use EQ to lift the extreme HF as required to offset the cloth's effect.

GM