Improving a stone rack


Hi all, I have a large stone rack for my system, in beautiful granite, which works great for stability, but maybe not so good for other aspects of the sound. I wonder if it contributes to some treble ringing and harshness. I want to improve the sound, thinking of felt damping on the wall behind the rack, some form of cloth to cover the reflective surfaces of the shelves, and adhesive rubber type mats on the bottom of the stone shelves. Is this the way to go? Experience based advice is very welcome. My rack weighs a ton. It is not easy to compare to a wood or composite rack. I need advice on how to counter the sound problems of stone or similar polished surface shelf racks. I want to try this, before I consider a new rack or shelf arrangement.

Ag insider logo xs@2xo_holter

I have experimented with isolation materials. Hard surfaces like granite, glass, etc is going to emphasize the treble freq. Soft material IE Vibrapods, sorbothane will soften the highs but often at the expense of clarity. Muddy sound come to mind. A tone wood IE maple is the best I have found. I've also used DIY roller ball  type footers with good result. I recently changed from those to springs and saw no degradation to the sound.

I have used Granite for many Years as Sub Plinths for Audio Equipment on Racks and as a Cabinet Speaker Sub Plinth.

I find I prefer the sonic that has been created when using it, when the Granite is a Sub Sub Plinth or a Sandwich Material in a Build up of Materials to create a Plinth or Sub Sub Plinth.

For Speakers I always uses a Spike Coupling and Pneumatic Footer to create some suspension.

On the equipment Rack, I always use Cork as the Isolation footer for the Granite when in a Sandwich or as a Sub Sub Plinth.

Other Materials used in conjunction with the Granite will have  a selection of Footers tried out to discover which tidies up the sonic to a standard I am happy to experience.

Today, my usage of Granite is seemingly being superseded by the use of Phenolic Resin Densified Wood Board Materials, such as the Board Materials from the Brands Permali or Panzerholz.

I recently bought a rack from Acora audio and the shelves are African black granite. The underside of the shelves have some type of anti-resonate material attached to it. I always wanted to upgrade from my 20+ year old Target rack. I was thinking about the aesthetics of the new rack but the improvement in clarity, resolution and musicality has taken my sound up a few levels. I had my doubts about buying a granite rack but when it’s done right, it sounds great. Try reading some info regarding Acora’s racks, you might get some insight on what to try.

Try using a very dense wood that has a totally different sound signature from the hard granite in conjunction with the granite.  I've tried many different types of materials for a rack.  I have been using a pair of Sistrum racks from Star Sound for many years.  Anything that is placed on it immediately sound more live but without ringing or any other sound issue.  I also use RTS couplers to clamp each component to its shelf.  The combo is about twice as effective to improving the SQ as the Sistrum rack alone.  I was very lucky to have a former owner sell me all his Sistrum racks used at very good prices.  You can even install this racks between the speakers with little or no drop in soundstage info.  My two racks are about 18" behind a line between the two speaker fronts.  They allow so much air to circulate w/o ringing vibrations behind heard it's wonderful.  Used they are MUCH MORE affordable.  Thanks Al Jennings.

Bob

 

“African black granite” is not granite but instead fine grained gabbro. It’s denser than granite, as different minerals make it up. No quartz, and denser, more calcic plagioclase feldspar, and relatively dense, iron rich pyroxene. I am retired now, but I was a volcano guy and used to analyze igneous rocks. Catchy trade name, though. I agree that this material really works for speakers, as all the Acora speakers I have heard are really special. And the owner is a truly nice guy, who I am delighted with for buying Audio Research.