In my quest for the ideal driver break-in rig/process, I decided to not reinvent the wheel and just to take a proven design and make it my own. Sitting drivers on top of my workbench and vibrating them all over the place just wasn't working for me.
So, up front: This is not my design. I copied what I made based on what I saw on Data-bass.com. Thank you, Mr. Ricci for pioneering this design. I'm sure you burned through a lot of 2x4's before coming up with what worked well.
I'll try to be brief. My stand is made from 4"x4"s and 2"x4"s. I used 5/16" lag bolts all around. 6" lags join the 4x4s and 3.5" lags join the 2x4's. No glue. The driver clamp uses 12" x 1/2" all thread, lock washers, flat washers and bolts.
PICS OR YOUR CONTRAPTION DIDN'T HAPPEN! But of course!
Four UM18's wondering "What's going on? Why are we here?" Mwuahahahaha! You'll find out....
Let's fast-forward to some action shots. The design just works. Thank you, Mr. Ricci.
Some pics of the stand. For reference, the long 2x4"s are 68 inches long. The 4x4"s are 25 inches (I think). BTW, all this wood is left over from other projects and I used it as-is. I cut nothing tonight. I keep ALL my scraps from disassembled or failed projects. The fact that the long 2x4s are almost 6 feet long really helps with this stand being almost tip-over-proof. The UM18 is 45 pounds and the stand isn't even close to tipping. I will state that at higher voltages the whole stand gets moving so I had to weight it down b/c it was vibrating too much for my tastes but it was NOT "tippy."
In this picture, you might thing the uprights that hold the driver look weak and unbraced. There are four, 6-inch lag bolts holding each upright to that bottom horizontal piece. It is extremely strong!
THE MONEY SHOT!!!
So, what's a UM18, running free-air at 15Hz and 60 volts sound and look like? Gotcha covered.
Using a Voltage Matrix I downloaded a long time ago, 60 volts @ 4 ohm load = 900 watts. I ran it like this for about 20 minutes; no bad noises from this driver! I then raised it to about 64 volts for a minute, which at 4 ohms is more than 1Kw. Hooray! I lowered the level to 37 volts, which at 4 ohms is 350 watts or about 1/3rd of RMS MAX. I will let it run overnight. I will repeat this test for the remaining 3 drivers and hopefully will have no problems with the remaining 3 drivers.
Initially, I broke-in these four drivers using a 23Hz tone @ 4 volts per driver for about 14 hours. I think THIS break-in can be considered "The Real Deal."
I had fun building this thing. Hope you enjoy this thread.