Cabinet bracing

[johnaec]

The thing I'd be concerned about with metal is resonance. In car driveshafts, they have what's called "driveline critical speed", and it's based on the stiffness of the driveshaft material vs. length. vs. speed. I can imagine something similar happening here...

John

[edgewound]

The thing I'd be concerned about with metal is resonance. In car driveshafts, they have what's called "driveline critical speed", and it's based on the stiffness of the driveshaft material vs. length. vs. speed. I can imagine something similar happening here...

John

I can't imagine that being a problem at all. There would no rotational inertia whatsoever to be concerned about. Besides that, the resonant frequency of angle iron is much higher than the resonant frequency of the low frequency drivers exciting the enclosure walls....not to mention they'd be damped further by the wood enclosure.

The higher the pitch of the thud when knocking on the enclosure wall is a good thing. It means the box is tighter,stiffer, and more resonance free than a lower pitch. Knock on a concrete wall...that's the ideal.

[Dougie]

I've been doing a search for a pair of pro nearfield monitors to use with my computer and was looking at Genelec's when I came across these enclosures made of cast aluminum....go figure. It goes against everything I've learned about damping and cabinet resonances

This is copied directly from the Genelec website:

Optimized die-cast aluminium structure
Genelec have developed a very stiff and sturdy, yet thin and light die-cast aluminium enclosure. The cabinet wall curvature has been designed for best rigidity-to-weight ratio and optimal damping to minimize wall resonances. This also maximizes the internal volume improving LF-efficiency. The extremely durable semi-matt finish and acoustically optimized metal grilles, allow for intensive handling without damaging the monitor.

[frank23]

Besides that, the resonant frequency of angle iron is much higher than the resonant frequency of the low frequency drivers exciting the enclosure walls

exactly, so the low freq subs will excite the iron braces and they will be resonating at their preferred frequency, which might be a few 100Hz and you will be wondering where this strange ringing comes from.

if you are using solid metal like in a wooden beam then it will be okay, but if you are using T or I or L profiles there will be thin parts that will resonate

have you tried tapping an L profile that was glued to a wood board, how does that sound?

or any other combination that you might want to test-hammer?

frank