WinISD Plots of My Bass Cab Projects

So! Here are some of the plots I've been making decisions with. The yellow plots are the Eden Nemesis 212 with the MCM 55-2982 drivers, and the white plots are the Peavey TNT130 that I'm converting into a cab with the Dayton Audio PA380-8 (Parts Express's house brand). 

First, expected SPL:

SPL from my amp

The white trace is lower since, as an 8 ohm cab, it's only going to get ~125W from my amp, while the 4 ohm 212 gets the full 250W. That peak around 80 Hz makes the 212 sound really fat, and somewhat boomy, though I'm hoping that adding bracing will reduce that somewhat.

Maximum Power

Power ratings of speakers in bass cabs are largely useless; most speakers are excursion-limited rather than thermally limited. You can increase the safe power handling by raising the port tuning, though that comes with tonal consequences. I did that somewhat already with the TNT cab, but 50Hz is a pretty common cab tuning in commercial cabs. I'm guessing this is partially why. As you can see on the SPL graph, it doesn't hurt the low end (only down 3dB by 50Hz).

Cone Excursion. Yellow = 7mm Xmax, White = 5mm Xmax

Also on the "safety" front (or just designing speakers that don't explode from regular use), here's a plot of the cones excursions at various frequencies. The MCM drivers have a specified Xmax of 7mm, which is huge (probably meant to be a subwoofer) and the Dayton has an Xmax of 5mm (not showing up on the graph for some reason.)

Clearly neither speaker is going to take much (any) 30-40Hz content, so a high-pass filter is a good idea. Fortunately the Trace Elliot head I have does have the ability to remove these two bands. I might still add one to deal with any extraneous subsonic noise that gets through.

Port Velocities. Good enough, Eden.

 And the last plot is of the port velocities per frequency. There are various rules of thumb to avoid port chuffing, but the one I was following was 19 meters per second. Eden does fine with the single 6" port, and my gigantic shelf clearly is going to be fine.

So yeah, I like music enough to get into math, physics, and now woodwork. Good times.