Why Rumble One Side of Album

@big_greg , I have a very effective digital  rumble filter 80 dB/oct @ 18 Hz. I would estimate that 2/3 of the rumble is above 18 Hz and clearly audible on many discs. Pushing a rumble filter up higher destroys your bass especially if it is analog. Having a rumble filter is no excuse for the people cutting lacquers on poor lathes. 

Is it always on the same side?

No..not always and sometimes both, but many records are dead silent.

@mijostyn the RF1 is supposed to cut at 20hz. I haven't listened to anything bass heavy yet. First impressions are very positive. Bass seems present and tight, nothing noticeable affecting upper frequencies. 

My new speakers (been waiting for five months) are 3db down at 31hz and my subwoofers take care of the lower octave w/o high pass filter.  So, I'll start with turning off the subs.

@big_greg , You have to know what the slope is. What They mean by crossover point is that the filter is 3 dB down at 20 Hz. It starts rolling off a little higher depending on the slope. Analog filters can not get as steep as digital without causing problems. You probably start rolling off around 26 Hz. This is not something you would hear. It is something you would feel or rather would not feel.

@vonhelmholtz , that is extremely misleading. Speaker measurements are made at one meter. This means at a normal listening distance in a normal room your speakers are down 3 dB at something like 80 Hz! Never and I do mean never do you want to run subwoofers with just a high pass filter. You miss a huge opportunity to clean up your midrange and upper bass. Cross up higher and use a two way crossover. Subwoofer manufacturers do not want to scare you out of buying their product by telling you you have to spend another 3 or 4 thousand dollars in cross overs and wires to get their sub operating right.