woofer excursion at start of lp

Another option.
If the excursion occurs as the volume is increased, and
if it is some sort of airborn feedback resulting from speaker/table interaction,
another easy solution could be moving your speaker either into the room or to the right. Of course you'd need to adjust both your speaker positions to "dial" them in.....

Another possibility. Isolation.
Given all your geometries are correct....
I noticed you are using an Ikea shelf, which is hollow. And your right speaker is relatively close to your turntable. I think you may be getting some kind of feedback.
My Mississippi River Rig has a Rega turntable on the same Ikea Expedit shelf and I was having the same issue. I was able to eliminate the problem by placing Vibrapods under the turntable feet. Sometimes rigid points are good isolators, sometimes sorborthane or some such softer system. In my case the softer footer did the trick on the Ikea. Might work for you too. Good luck.
Dave

Tbromgard,I've had tonearms that worked better with no anti-skating applied at all. Take off the anti-skating completly and rebalance arm ,then see if that works.

Buy a KAB rumble filter for 179.00 and the problems will stop. It is stuffed with all the audiophile approved parts as well. I have used one for years with my VPI Scout and various moving coil cartridges. I changed cartridges, had the turntable professionally set up, bolted a shelf to the wall studs, moved the speakers around, tried both granite and maple platforms, experimented with 5 different kinds of cones and footers, and in the end....nothing could cure the woofers oscillating.

The KAB rumble filter inserted into the tape loop fixed all the problems and did not change the sound one bit, and I have a fairly resolving system. At least, I can't hear any differences.

My TT is Origin Live Resolution and Illutrious tonearm, Dynavecter 20x2 L.

You don't mention your turntable....you very likely would eliminate the problem with damping....and would bring better sound to your system as well. Your explanation of the problem indicates an "iffy" match of cartridge to tonearm.

There is always more woofer excursion due to record warping which is more present at the beginning than at the end of the record. You probably also have an amplification system which is able to amplify linearly very low frequencies, maybe even DC, which will make the phenomenon more pronounced and visible on the woofer cones. See if you have any kind of high-pass, or capacitor coupling option somewhere on your audio components. If you have one, you can use it in order to attenuate the problem.

Thanks for the responses so far-

As for grounding-everything is tight. I do not have a ground on preamp (Manley Stingray integrated) nor the TT speed control (Origin Live). I use a platter matter (Origin Live) but no clamp, although i have one. It does not appear to help.

I adjusted the anti skate which might have had a small effect, it seems to have lessened, but is still happening. Again, its only on the first half inch or so of the start of the LP, then fades into no excessive excursion. Why would anti skate have an effect?

Thanks again.

I am also thinking the resonations are being caused by a grounding issue. Try tightening the ground wire on the preamp. Does your turntables speed control also have a ground lug?

Try starting the platter with the volume up a little less than at a normal level, and slowly swing the tonearm across the platter. If a hum decreases or increases it could be that you need to relocate the ground wire. Best of luck.

Tonearm and cartridge are resonating! You can try fooling with the anti-skating other wise get a subsonic filter so you do not damage speakers!

Is the record laying completely flat on the platter? Do you use a clamp of some kind or a mat?