small sealed sub

[invaderzim]

I currently have the Dayton 8" reference sub in their sealed enclosure and am thinking of adding a second sub. I really like the sound of the dayton and even with just a 100 watt amp it goes plenty loud for my music listening levels.
I don't have enough room to add a second of the same and I've read that it isn't good to mix sealed and vented subs. Is there a problem mixing different sealed subs? I was looking at either LS10-44, or W8-2282 in a small sealed enclosure.

[Chompy]

Maybe someone smarter than me can tell you if this crudely calculated phase graph means they would sound fine together. (I don't know how many degrees difference it takes to cause a problem, just that 180 is completely out of phase IE total cancellation, and I'm pretty sure drifting phase is the reason for the usual recommendation against mixing sealed and ported playing the same range). I only modelled the slim 10.

bottom line, highlighted: RSS210HO-4 in .75ft3
next up, LS10-44 in .75ft3
top line, LS10-44 in .33ft3

Max phase difference between dayton and LS10 in equal volumes is ~20 degrees. Max between dayton and LS10 in .33ft3 is about 45 degrees.

[waxx]

It's never good to mix two different drivers in the same passband, so no, it's not a good id.

[invaderzim]

thank you for the information, it was very helpful.

[weltersys]

Originally Posted by Chompy

Max phase difference between dayton and LS10 in equal volumes is ~20 degrees. Max between dayton and LS10 in .33ft3 is about 45 degrees.

Chompy,

At 45 degree phase difference, the loss in level compared to two perfectly "in phase" (0 degree phase shift) sources is less than one dB.
In other words, if phase response is within 1/4 wavelength, output is nearly the same as two identical sources which sum to +6 dB.

Small room modal response can easily result in variations of over 12dB between various room positions, making the small difference level due to +/- 45 degree phase differences between two sealed subwoofers looks quite small.

Good information here:
Merlijn van Veen - Displacement is Key

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