Why MDF so Bad???

Try listening to the shelf and the equipment with a stethoscope. Many shelves, especially MDF, pick up and amplify the 230Hz to 350Hz range, and depending on thickness, also "boom" around 60-100Hz.

The former is from the particles themselves talking- inside the material, and that is what cones avoid touching many of.

The latter is the entire middle of the shelf going up and down, and you either straddle that motion with cones or brace the shelf or lay that hunk of maple right on the MDF, so they damp each other for that trampoline motion.

There are other solutions of course, but those are the two modes of vibration in a shelf, assuming the frame is rigid. A perfect shelf would dissapte all sounds coming into it, and that is achieved, or approached, by looking at the various acoustic impedances of all the materials involved.

Acoustic impedance must decrease as you go deeper into the material- that is how one makes sound "go away"- via no reflections. Check out this link- the Java Applet in the middle of the page.

http://www.ndt-ed.org/EducationResources/CommunityCollege/Ultrasonics/Physics/reflectiontransmission.htm

It shows how the % reflection changes with impedance mismatches- for ultrasonics, but completely applicable to audible sounds.

Best,
Roy
Green Mountain Audio

MDF is the most boring, lifless material i have used. I have made many racks, cabinets, shelves out of many different materials. I love working with wood. I make all my furniture. I would like nothing more than to make a beautiful custom wood rack that performs as well as it looks. I have used MDF shelves with several different footers and spikes. I have filled the wood columns with lead shot and sand. I have used granite, marble, glass, corian, sand boxes, bladders, and maple. For best DIY results for me was maple. I do not mean to offend anyone with my opinions. If you have not tried comparing a Neauance board on a rack or a Sistrum rack to a well made wood rack then you are missing much in performance that will never be realized until a comparison is made. I believe both Neauance and Sistrum have a 30 day trial. IMO, these products are as important as your gear.
I have found that both Sistrum and Neauance work best spiked to the froor as opposed to sitting on a shelf.
You can never know what can be gained or lost without a comparison. My post is to help and not critize based on my never ending search for racks that perform and not degrade.
I hope all find what works best for them as i have. I find no value in opinions based without comparison or experiance.
Bob Bundus, please do not take offence from my post. I have nothing but high regards for you and your contributions.

Brulee, have you tried using any of these materials for speaker cabinets? I agree that mdf sounds boring, and yet have used it for speaker boxes (double laminated).

Royj, good idea to use a stethoscope. That is much cheaper than an accelerometer, preamp and headphones.

I'm considering maple shelves for a wooden cabinet. I assume the grain should run horizontally. Has anyone tried a verical grain such as a butcher block?

Hi Bruce et al thanks for your valuable input.
I fully agree with the "posting our experiences" philosophy.
Zargon: from what I've read (I have not tried it myself) the long grain should run horizontally for best results with maple vs. the vertical grain butcherblock. The Mapleshade people also agree with that approach FWIW.

Both Roy's & Bruce's comments above are very interesting & in fact are applicable & valuable info. regarding my latest rack issues. I've recently observed that when changing my equipment from the old veneered MDF all wood cabinet to the new cherry veneered (+ ? wood, I don't know what kind of wood is inside there) shelved Target rack (which has steel tube framing) that the initial results weren't quite as desired. I much perferred the sound of the older higher-mass cabinet. Many of the previous tweaks that I'd 'perfected' no longer do the job on the new rack, & in fact I've determined that the Vibrapods topped by Black Diamond shelves topped by brass or titanium cones are now actually making matters worse.
So to experiment, I am going to get a Neuance shelf & a Mapleshade shelf + probably some of their other cones & IsoBlock footers etc. Last night I placed mini tennis balls under the preamp, which helped to restore the now-thin midbass, but hasn't yet fixed up the low bass back to what is was previously; I'm going to try some superballs tonight instead. Also the highs aren't as scintillating as they were previously, so I still have a lot of work left to do. Fortunately at least the CDP still works prety well on a Zoethecus Z-slab, with Vibrapods underneath it & Nordost titanium Plusar Points above.
If all else fails then I'll either go back to my old cabinet (a last choice for space limitation reasons only) or I may look for someone to build me something similar to my old cabinet, but with more shelf space. Bruce I don't know where you're located but it sounds like you might be the perfect man for the job, if you're willing?