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

@jtcf I worked for years in the masonry industry carrying bricks and mortar (for my dad the brick layer) and mortar fills gaps but isn't a great bonding agent.  working from the top down it would be easy to take he blocks apart tapping with a rubber hammer.

@fjn04 the morter will take care if imperfections in the blocks.  they aren't perfect to they won't stack up as rigid as you imagine.  Rubber in between is a lot more expense and a lot more trouble and won't work as well.  

Your idea will work if you control the joints.  You may be able to do it without mortar and you may not.  Now I'm not saying to lay them like a block wall.  Use a small bit of mortar under the low spot if you have a block that rocks.  Don't use a lot or it will squeeze out onto your carpet. 

Try it without mortar first.  blocks vary from different manufacturing plants.  You might get some that are very consistent, but probably not.  You can also look at knocking any high spots off the bottom.  (they are made upside down in a form, the tops is ususally very smooth and the bottom, not so much).

  You cay "concrete" blocks but most blocks today are "haydite" which is about 2/3 the weight.  Either will work but concrete will probably be the best.  Just want you to be aware of the weight issue. 

Jerry

@fjn04 I admire your adventurous endeavor in to creating a supporting Structure.

I do not intend on steering you away from this Support you are producing.

My thoughts on the materials used are that you have 3 x Stacked Concrete Blocks for the Lower Tiers with Voids (Unknown Dimensions but assuming 8.5" in Height). Plus 1 x Tier of 8.5" in Height Solid Concrete Blocks. 

What I suggest is, if I am understanding the materials used correctly:

1, Put in place a Base, that is mounted on a Damper Footer, (I avoid Spikes as a coupling to the Homes Structure).

2, My most successful Base to date has been a 1/2" Steel Plate, but at present do suspect better is to had (more later on this).

3, The Hollow Concrete Blocks can be Built up from the Steel Base.

4, Use Ceramic Tilers Cruciform Spacers to create the Spacing between the Base and individual Blocks.

5, There are very good quality Silicone Adhesives that are compatible with Stone.  A super bond can be achieved if a Primer Coating is used, prior to applying the Silicone Adhesive. ( For this Structure I see the super bond as overkill). 

6, Running a 1/2" wide line at the centre of the Blocks Side Wall's and Bedding the Cruciform Spacer into the Adhesive, will allow for a Nice Bedding and should avoid a ooze out, as the Spacer will prevent further compression of the joint. (If ooze out is occurring, it is best to learn the Adhesive Manufacturers Clean Up advisories, and have the Cleaning Kit on Standby. Usually a Soapy Water in a Spray Bottle, a Scraper and Wipes to Clean the Scraper is sufficient.

7, I would raise the Hollow Blocks to 4 x Tiers if the aesthetic is acceptable. (The extra height does work for the better when dealing with a Vinyl Source). 

8, Use Kiln Dried Sand to infill the voids in the Concrete Blocks, fill to a height, that is a 1/4" lower in level than the Top of the Top Tier.

9, Cap of the Void in the Concrete Block with a Material of choice. (Trialing Different Material is also part of the learning experiences to be had). 

10, The Cap Material will have a 1/4" Clearance all around the Void. The Thickness of the Cap Material can be of choice and is best if a Minimum of 1/2". Any Thickness up to 3" will be good to try out.

11, Think of the Cap Material as your first Sub Sub Plinth, and is to be built of.

12, The Footers to be seated on the Cap/ Sub Sub Plinth can be any type, this is where the learning starts, as this is where the first real impact on a sonic is going to be discovered. Is is also where the deselection process commences and the setting the structure to suit ones own preferences takes place.

14, The Sub Plinth will be best if immediately starting with a Phenolic Resin Densified Wood Board (The same Material I belief will supersede the use of my earlier mentioned steel sheets)

15, Footers used to separate the Source to the Sub Plinth, are again worth while trialling out of the variety of options.

My experiences to date are showing a 2 x Tier of Densified Wood, adds a very valuable impact on the sonic.

My suggestion is to live with each change to a Sub Sub Plinth / Cap or footer arrangement for at least 20 Hours of listening to really get the feel for the impact it has. It is not long before the desire to swap a material comes quickly when it muddies the Sonic and details and dynamics are noticeable for being masked.              

If you do use the cinder blocks, my suggestion would be to sandwich a layer of a thin (1/4"- 1/2"), rubbery material between the layers. This should eliminate any transfer of vibration between blocks.

That being said, unless you live alone, a stack of concrete blocks will be extremely hideous and won't last long if your partner has an opinion on it.

Either way, good luck with it.

It'll cost you next to nothing to try it, quit asking opinions and do it!

I'd initially adhere nothing, that way you can see how butt ugly it is and easily dismantle it.

Then take the blocks outside and plant herbs in the holes for you and the Mrs.

Win/win!

One can certainly bond them together with a structural adhesive like SikaFlex.
(That would also likely provide some container layer dampening.)

A grinding wheel to knock down high points and then another layer if adhesive to hold the top on can make them flat in a similar way to how a shoe orthotic provides a platform for the foot.
One could probably use a layer of sorbethane type of stuff.

At some point if the floor is vibrating, then keeping that from telegraphing up through the structure can be helpful.