concrete (cinder) block tower with wood chopping block for turntable stand

Why not top it with a 2'x2' paving slab?

Check my Virtual System for my basement set up. Sounds better than every stand I tried. 

Holy bananas do you have some cool stuff!!

If you tap on the cinder or concrete blocks with a hammer, and this is also true with granite, you will hear it ring.  Not really good materials for a turntable base.  I know because I also tried it once myself years ago.  Better materials to use will "thunk" when you tap on them.  Sand filled or small ball bearing filled wood boxes are a good way to add mass to a base.

Lastly, spring isolation of the base, provided the turntable is unsprung is very effective.

I agree with the efficacy of high mass for turntable stands. My DIY stand uses a section of sixteen inch diameter white oak log as a central pedestal. Three large lag screws in the bottom of the section of log serve as feet and allow leveling of the stand. A piece of maple butcher block serves as the table. Log and butcher block were sanded very smooth, stained with Minwax special walnut stain and given many coats of varnish. I had to get a friend who is a competitive weight lifter to help me get the stand from my workshop to the listening room. The stand works quite well with my unsuspended Clearaudio Performance DC turntable and looks quite nice.