Cab tuning

[dlhughes]

This may be better posted in a DIY speaker group, but I haven't gotten any satisfaction from them on it:

Most 10 & 12 inch 'bass' drivers have a F3 of around 50-60 Hz, and from what I've seen of several combo cabs, their speaker chambers' porting is tuned around there, as befits the driver's F3...so how is it that you can get a 42 Hz (low E) tone from it without hammering the 'unloaded' driver?

Is there some psychoacoustic trickery involved, or just how does that work?

[Passinwind]

Bass frequency/waterfall plots: what they mean to rigs

[dlhughes]

Let me ask this another way...
If I have a speaker with a free-air resonance of, say, 65 Hz, do I design my ported cabinet to be tuned at that 65 Hz? Or can I 'trick' the driver by tuning the cabinet lower than that, say, at 40 Hz?
And if I tune the port at 65 Hz, what'll happen when I hit a low E at 42 Hz? Doesn't the driver 'unload' below the cabinet's tuned resonance because the driver and the port are then out of phase?
Or yet another phrasing...how would I use this driver with a F.A.R. of 65 Hz as a bass driver? What do I do with the port tuning?

[billfitzmaurice]

Originally Posted by dlhughes

Let me ask this another way...
If I have a speaker with a free-air resonance of, say, 65 Hz, do I design my ported cabinet to be tuned at that 65 Hz?

You use modeling software to see the driver response and displacement limited power across the proposed bandwidth in the proposed enclosure, altering the tuning until you get it where you want it. The trick lies in knowing where you want it.

how would I use this driver with a F.A.R. of 65 Hz as a bass driver

I personally would not use a driver with a 65 Hz Fs for electric bass. 55 Hz is as high as I would go, depending of course on Qes/Qms and Vas.