Opinions on Glass Shelves

I am thinking about buying a new audio rack. When I tap on the shelf below the shelf on which my turntable sits while the needle is on an LP at rest, I can hear the a slight echo in my speakers.

I’ve looked into various audio racks including some from Billy Bags. The salesperson at Billy Bags told me that their ¾” cracked glass was sound-deadening and would provide excellent sound isolation. To me this is counterintuitive.

Has anyone had any experience with cracked glass from Billy Bags?

Has anyone had any experience with glass shelves in general?
No idea about cracked glass but generally you not going to get the best from glass
toss the glass, and head to your local granite counter top guy. Will cost you about 125 per shelf for real granite.
Much more dead than any kind of glass and much more rigid than glass.
This doesn't sound like your average glass shelf. There is not much info on the Billy Bag's site but they do refer to 1" thick glass shelves. I'm guessing that the cracked glass provides a very large number of random surfaces to break up/slow down any vibrations. Sounds like a good question to ask the factory. Don't just take the salesman's explanation. I would move carefully. By going to a more deadened stand you may lose some of what you have now. I can tap on my stand with the stylus down and hear it in my speakers. I know people make a big deal of this, but I'm not convinced that it means anything. If I smack my preamp with a hammer I'm sure I'll hear that through my speakers as well. But what does that really mean?
Some will tell you any glass shelf should be avoided.

Some very highly regarded shelving systems including those from Naim and Wilson Benesch use glass shelves.

Unfortunately you will get people on both sides who are convinced those on the other side are clueless. Sorry to be of no help but the effectiveness of things like shelves, footers, etc. are highly dependent on the equipment they will used with.

Buy used and experiment. Have fun.

If the shelf is "cracked glass", chances are the shelf is a laminated unit of 3 seperate pieces of glass fused together with a clear rubber-like innerliner. The unit is heated in an autoclave to melt the innerliner and fuse the peices together. The "cracked" part would be a piece of shattered tempered glass in the center position. You could justify that the rubber innerliner could have dampening properties but that alone does not assure a good performance.
I have glass shelves in my system and unless I tap pretty hard there is no effect.
Take a look at slate. I believe it to be the ultimate constrained layer material. Sound travels though it slowly, and is actually changed along the way. The downside is its weight, but the payoff is excellent.

Glass reflects sound, and sound travels through granite faster than through water, so I wouldn't choose either of them. They do look nice, and may not actually be detremental.

Then, there is concrete and wood. Depending on the composition, one of them may be decent. Of course, there are the foam composite shelves that are engineered for the task, too.

I have a Sound Organization rack with glass shelves. I replaced the top shelf with a custom made Neuance shelf for my TT. The other shelves have 12"x12" sheets of asphalt damping material applied to their bottoms. Not a high end rack by any means, but it works reasonably well.
Cracked glass is a three piece laminate; there is no ringing effect which is the case with regular glass- rap your knuckle on ¾” plate then do the same with cracked glass- it is not just cosmetic- It is acoustically dead.

Billy Bags Designs
Thanks for posting, Jmstogo! Can you give us a brief description of what the laminates look like and/or the process to make these shelves? I'm not looking for secrets, just trying to get a mental image of these shelves.
Jean from Billy Bags sent me samples of the cracked glass. When you rap on it, it does not ring or sound like cracked glass just as I was told. It sounds very close to a hard synthetic material like Corian or acrylic. In fact after rapping on it, I had to study the cracked glass carefully to make sure it really was glass.

I’m not sure what that will mean in a system, but the glass itself is very gook looking.