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
lgregoir

Showing 1 response by gregm

Of course wood, in my book, is MUCH nicer to the eye than the proverbial metal rods, pipes, shafts etc... MDF is a mixed bag of goods, not a priori bad; the thicker IMO the better.

About the rack/shelves: (Not being a specialist, take my comments w/ a grain of salt...)

I think the positive effects that Bob refers to are, that you may have the whole rack (shelves included) being vulnerable to less frequencies on the vertical plane. The rigidity of the rack would restrict vibration on the horizontal plane -- albeit its height looks like it would make it more vulnerable to resonances there.

OTOH, the wood mass may be "friendly" to low-frequency --higher amplitude level resonance. This is important, I think, and can only be addressed at each shelf-to-component level, by either DAMPING (i.e. find s/thing that turns some of the vibrational energy into s/thing else say, heat) or TUNING each component (using cones, pucks, etc that alter the resonant frequency of the component-rack system).

Strange though it may sound, I get better (subjective) results when resonant frequencies are higher than lower -- probably due to the lower amplitude of higher frequencies even though they play well within the critical audible spectrum (lower mid-range...). Whatever.

As Bob implies (I think) start out with components directly on the beautiful wooden rack, maybe putting sources/pre closer to the bottom (less prone to vertical movement) just for starters. Then change around. Take notes. Then play around with devices between component & shelf. If you can, try out a damping device such as Neuance shelf: sit the component on a Neuance, couple the Neuance to your shelf with s/thing rigid (cones?). Jadem6 has been successful(and so have I, copying his epxeriment) using bubble wrap b/ween Neuance and other shelf.

Input on sound & pics appreciated! Cheers