Hey, so I was reading through Ray Alden's Speaker Building 201 and trying to play around with some of the new Dayton Designer series woofers. And I'm running into something I don't quite understand here.

I know that Vas is the volume of air with equivalent compliance of the driver's suspension. And the equation in this book for the optimal box volume is:

Vb=15*Vas*(Qts^2.87)

I don't know how common this formula is among everyone here but I've been playing around with it for a few drivers and it seems to make sense. The last one I was looking at was the 6-1/2" (295-428). It has a Vas of .61 cu.ft. and a Qts of .30

What I'm trying to grasp here is that if I get an optimal Vb of .289 cu.ft. and an F3 of 59Hz, what happens if you increase the volume even more?? I know that if you decrease it, the F3 will increase and there will be a peak, but I've not read about what a larger box will do. I guess it wouldn't have enough air spring? What impact would that have? The equations I'm using are pretty simple and obviously don't take any other factors into account as far as acoustics.

To find the F3 I'm taking the square root of (Vas/Vb) and multiplying by Fs (40.9Hz). So according to that equation, any driver will have an F3 the same as the Fs if Vb=Vas. Keep in mind, I'm very new at this and trying to find the best way to get the right cabinet sizes and port sizes. I'm starting to understand more about crossovers, but haven't begun trying to design them yet. I was just thrown off when I saw that it said "oh this driver can play at full rated volume down to 40Hz" but then the recommended boxes show an F3 no less than 59Hz.

Thanks in advance for all your wisdom

I know that Vas is the volume of air with equivalent compliance of the driver's suspension. And the equation in this book for the optimal box volume is:

Vb=15*Vas*(Qts^2.87)

I don't know how common this formula is among everyone here but I've been playing around with it for a few drivers and it seems to make sense. The last one I was looking at was the 6-1/2" (295-428). It has a Vas of .61 cu.ft. and a Qts of .30

What I'm trying to grasp here is that if I get an optimal Vb of .289 cu.ft. and an F3 of 59Hz, what happens if you increase the volume even more?? I know that if you decrease it, the F3 will increase and there will be a peak, but I've not read about what a larger box will do. I guess it wouldn't have enough air spring? What impact would that have? The equations I'm using are pretty simple and obviously don't take any other factors into account as far as acoustics.

To find the F3 I'm taking the square root of (Vas/Vb) and multiplying by Fs (40.9Hz). So according to that equation, any driver will have an F3 the same as the Fs if Vb=Vas. Keep in mind, I'm very new at this and trying to find the best way to get the right cabinet sizes and port sizes. I'm starting to understand more about crossovers, but haven't begun trying to design them yet. I was just thrown off when I saw that it said "oh this driver can play at full rated volume down to 40Hz" but then the recommended boxes show an F3 no less than 59Hz.

Thanks in advance for all your wisdom

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