Now for the other experiment of the night, chasing resonances.
First, flip this heavy cab upright to make it easy to work on.
Lets take a baseline measurement to start things off. My mini tripod didn’t put the mic at the right level, so I had to customize a bit.
You’ve seen it before, but here’s the close-mic baseline anyways:
Now, for the additives. Two $5 Wally World pillows, the lowest-density they had at that price. Plus two additional braces to keep the pillows in place.
Remove the hatch. It sure seems like I’ve done this part before.
Screw on the braces:
If this works out, I’ll PL them in place.
Add a pillow:
Its sitting there loosely, plenty of space for air movement around it.
Seal it back up and take another sweep:
Well, would you look at that. It seems the resonance had been reduced to effectively nothing. Thats great news.
Since one pillow was good, maybe two will be better. Lets open it back up and find out.
They’re very snug in there, no space for air movement.
Seal it and send it again:
The resonance is completely gone now! It looks like the bottom end output has dropped off sharply though. Apparently Helmholtz resonators need air movement to work. The more you know!
The bracing will be attached with PL3x, and the single pillow will be stapled or screwed to it. This turned out to be a very simple solution to a very nasty resonance.
Good call on that one John!
This applies to all Devastators, not just the quad. I will be adding a pillow to any I build.
I will add some to the mini’s, since they also display a resonance at slightly higher frequency, due to the shorter cabinet.