I have had great results with Granite as a singular material.
I have improved on these results by adding additional materials and isolation implements.
Chipboard, is not a usual go to material, but it has merit for what it can do.
It has many densities available and is a great at eating external energies, as it is produced in various compressed states , it can be swapped out for other types and can be almost attenuated to suit a individual taste.
To produce the base,
I couple the Chipboard to the floor on spikes.
I put my Granite flat onto the Chipboard, I start out with no isolation separation devices.
I then put the Speakers onto the Granite and have a listen, I will use a variety of devices to isolate the Speakers from the Granite, from Cork, to Foam and Rubber, and then Spikes direct or spikes into a receptor base.
When this is as good as it can be on the ear, live with it for a period of time, and then see if there is a further benefit to be got, by using isolation devices of the same used materials between the Granite and Chipboard.
The above was the old way using available materials collected over many years.
Today, I would say, get a Slab of Granite or Chipboard on Spikes or both together if they are available as referred to in the above to be used as the base.
Here is the next requirement that has been developed from trialling different isolation devices on a range of speaker types.
Use dedicated Isolation Suspension Devices.
My experience started with the Solid Tech 'Feet of Silence' being re-purposed to a position under a lightish weight speaker, as well as Audio Technica AT-616 Pneumatic Footers.
They were set up under a individuals speakers who was close to purchasing Townsend Isolation for their speakers.
What was already a high quality presentation from a three way cabinet speaker with a dedicated base, was much improved with the addition of the suspension/isolation devices, and on the isolation devices removal,
it was very evident of the much improved SQ that was just being heard.
The individual bought the Townsend Products as the result.
At a later date a similar set up was placed under a Stand Mount Coaxial Horn Speaker, the owner of these is anal about detail retrieval, and had spent much time with his bases, where a sand box and African Black Wood was in use.
The Suspension/Isolation footers were sat directly onto a timber flooring, and to say the outcome was night and day, would be the best.
The Speakers owner has now built their own Suspension Bases using a platform that is suspended on O Rings, so there is a DIY option if a little thought goes into it.
Another option but not trialled by me but that is getting great feed back, is a method being carried out by a local group of HiFi enthusiasts, after hearing my 'Feet of Silence' under equipment there was a search put on to source a device that was much more affordable and comparitive in performance.
The group now believe this has been discovered, in the form of IsoAcoustics Pucks.
On hearing about the results that were being had under speakers with my devices, they Pucks were used under Quad ESL Speakers, the reports I have received are on par with my above reports on the improvements being detected.
IsoAcoustics have a range of devices, and there is a good used market as well, to allow for a cheaper entry into any trialling if so wished.
The used market might also allow for the purchase to be comparative to the outlay required to produce a DIY version of a Suspension Device.
I hope this helps with your enquiry.
