Why MDF so Bad???

Hi everyone,
I've been reading left and right about how bad MDF seems to be for equipement racks. Everyone seems to agree that MDF shelves will color the music badly. The only thing I wonder is why do many speaker companies use MDF in their speakers?

Also, does MDF sound bad in every thickness? Did someone try to use 1 inch thick MDF shelves?

I'm very curious about MDF so I'm getting a woodsmith to build a 5 shelf equipement rack made of 1 inch thick MDF (only 1 inch thick MDF will be used for the whole unit). The shelves will be fixed to the frame. The whole rack will be assembled using high strength glue only. No nails nor screws will be used. The rack will be veneered with 1/28" thick mahogany wood (no paper backing)... Also, the back of the rack will be reinforced by MDF braces... The overall rack will be as rigid as possible.

One more thing, the rack will sit on the same kind of spike Verity Audio uses on their Parsifal encores (I guess I want the rack construction to be as close to a speaker cabinet as possible)...

I'm getting this rack made as an experiment, not as my definitive rack.

Any opinions as to what I should expect from this rack (sonic qualities)?

I was also thinking to use some sound absorbing material under each shelves and on the inside of the sidewalls to try lowering sound reflection (am I off the track here?)...

One last question, any thoughts as to how I could improve this rack (please don't recommend to throw the rack out the window and get a brand name rack)?

If anyone is interested, I will be able to post some pics when the rack is ready...

Your input is greatly appreciated.

Thanks ahead
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.


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

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?