Need assistance with Amp/Cab vibrations

[Wasnex]

The motive force applied by the voice coils is enough to move driver cones back and forth a quarter inch or more in each direction, so it's not hard to see why the pressure generated by that cone movement can make the cab panels vibrate back and forth by 1/32 inch, which is plenty to cause a head to move about. Bracing like that in the thread I linked to a few posts back can eliminate panel vibration, or at least make it so slight that even a ten pound amp won't move around. Thicker panels work too, but at the cost of weight. One brace connecting the middles of a pair of 1/2 inch thick panels is the equivalent of using 1 inch thick panels. Three braces spaced equally is the equivalent of using 2 inch thick panels.

My intent of awakening the zombie thread was to say that my Dually seems to be well braced. If you wrap the panels with your knuckles, they produce a well damped and relatively high pitched sound. Adding mass to the design should further reduce vibrations, but the cabinet's light weight is one of it's strong points.

Some builders offer different construction materials including okoume. I don't know what my Dually is made of, but I can lift easily with one hand and carry it up a few stairs. I wonder if anyone has compared Duallys made out of different materials to see if there is any noticeable impact on tone and vibration.

 

[Wasnex]

Which is kind of where I was getting hung up Rick...I've just never owned an oddly (I'm being kind) designed/built cab where this kind of problem existed. On all my cabs, a 6 pound head pretty much stays put.

You must buy only good gear .

The cabs I mentioned modding in post #58 where made with really low grade plywood. I believe the volume of the cabs comes out to about 5.5 cubic ft and they had no internal bracing, so the panels vibrated like crazy. These cabs are truly junk, but they were loaded with Electro Voice EVM18Bs so I thought they were decent. I bought them in the late 70s at a going out of business sale for less than the cost of the raw drivers.

I put all of the panels, except the front, under tension. The bracing greatly reduced panel vibrations and also tightened up the sound of the cabs. Before the mod the sound seemed thick and wooly up close, but the sound did not project. Now the sound is thinner but projects better.

 

[Al Kraft]

You must buy only good gear .

The best! The only cabs that I notice any type of obvious vibration with at heavy bass levels are the newer lightweight ones. My Mesa Power House cabs are rock solid...maybe more solid than some rocks? My CN212, SW112&115, and AK C12T never seem to have even lightweight heads moving around. And in no case have I ever seen a 20-30 pound head move a fraction of an inch on any cabs I've ever owned.

 

[Coolhandjjl]

The cab is not internally braced properly. Look at the plans for fEARful cabs online and you will get an idea of what properly engineered bracing is all about. Then do that to your cab. I’ve run a fEARful full stack at over 1000 watts of Crest CA9 goodness with just a tiny preamp on top and it didn’t move at all