Woofer sucking in and out

They do work, but- the good ones are not cheap, timed cooling and all that: (http://drhifihousecalls.com.au/New%20Equipment/Furutech/Furutech%20Record%20Flattener%20DFV-1/Furutech%20Record%20Flattener.htm) It can also be done, in the oven, between two thick pieces of glass(with extreme care). (http://www.radiodismuke.com/forum/index.php?showtopic=670) Happy experimenting!

BTW: I think someone mentioned this, but- a record weight(just in the middle), will cause the circumference of some thinner vinyl records to lift off the mat. If there is an acoustic feedback issue, this will exasperate it. The one mentioned by Ct(with the black felt washer under the label), addresses that nicely, as long as it can clamp to your spindle. Mine is tapered, and I have a thicker than stock mat. I can't use a center clamp, as a result.

Someone might want to ask Luna if his speakers are ported.

Oh, Luna: Are your speakers ported?

If so, do yourself a favour and buy the KAB. Your speakers, your amplifier and your ears will all thank you for it.

When i had my old setup, the woofer pumping was mostly due to acoustic feedback via the floor. The speakers shook my suspended wook floor which shook the table and generated very low frequency output at the cartridge. Playing these inaubdilbe low frequencies suckup lots of power from the amps and displace the woofer cones outside of the linear operation zone. Distortion is generated at the amp level and at the speaker level. Bass is indistinct and spatial clues became weird probably from from increased THD + phase distortion. In addition, the wild woofers may generate a reactive load for the amps.

I got a minus K isolation and put this problem to rest.

The contribution from record warp is solved with a record weight along with a ring. However, acousic feedback is the key issue which magnifies warp problems.

Without properly addressing acoustic feedback, the record warp generate low freq signal from the cart - > speakers ->floor -> table -> cart -> speakers -> etc. The dance of the woofers is a result of positive feedback loop.

Subsonic filters will break this loop too. Betw the woofer dancing and phase shift with the filter, I take the filter anyday; but not all filters are the same though.

I got rid of woofer excursion by paying attention to the effective mass of the arm/cartridge system. Once that was set up right, I had the added benefit of flawless tracking, in fact a lot of LPs that I thought had some wear turned out to have none at all.