Axiom Home Page Forums General Discussion Advice from Axiom Owners Break in procedure

Hi Lampshade,

I play both those instruments (guitar and violin). Yes, as the wood dries out over the years, the resonating "box" (surfaces) of acoustic guitars and violins become more resonant and rich-sounding. More scientific studies (including one published years ago in Scientific American magazine) show, however, that the changes in tonality of instruments are not as great as some claim.

The same is not true of loudspeaker enclosures. You do NOT want the speaker enclosure to resonate like a musical instrument, because then the enclosure contributes its own set of vibrations to the sound, which make it less accurate and colored.

That's why the vast majority of well-engineered loudspeakers are made of MDF (medium-density fiberboard) because MDF is one of the most non-resonant materials available. Additional internal bracing also helps dampen potential resonances and, in Axiom's case, we use the tapered enclosure to further cancel out potential internal box resonances.

After all, a loudspeaker is NOT a musical instrument. It is a transducer, converting analog electrical signals into acoustic replicas of instrumental and vocal sounds. As such, it should be as neutral as possible, contributing no "sounds" of its own (from enclosure vibration) to the reproduced music.

Regards,
Alan

Thanks Alan. I thought the main reason MDF was used is because of costs. Very interesting!

Cost/Benefit ratio is a very big reason why MDF is the most popular. When a MDF enclosure is well engineered and braced it becomes an effective material to control cabinet resonance. Remember that commercial loudspeakers are for profit and MDF is the best option to be used to keep costs down for the enclosure portion of the loudspeaker. Not only in the cost of the MDF itself but also because of its ease of use in manufacturing process compared to more expensive enclosure materials.

Of course cost is a factor. I could have said "MDF is the most practical and cost-effective material". It's more acoustically opaque than using real wood, for example (I'm not referring to real-wood veneer but actual boards of cherry, pine, birch, etc.) Plywood is better than the latter because it's layered but it's still not as dead as MDF.

Alan

Also, MDF is very heavy and its dust is toxic to breath. The weight makes it difficult to work with, much more difficult than other sheet goods. It dulls and gums up tooling quickly. Plants who machine it, need very elaborate dust collection systems. It may be less expensive, but the costs are a bonus, and not the primary driver for using it. There is a great deal of ignorance with regards to MDF from folks who concentrate on costs more than functionality.

All true. Axiom has a very elaborate and costly dust-collection system installed in its factory. The sucking sounds of the system are so noisy that I often do my listening tests during periods when the saws aren't running and the dust-collection system is off.

We have a single-operator controlled crane thing with huge vaccuum-operated suction cups that picks up each sheet of MDF and positions it on the saws, which are computer controlled and programmed to make very precise cuts for each of the speaker enclosures in the line.

Alan

I can attest to Michael's assertion of MDF after using it for both wainscoting and crown molding....awfull dusty stuff and hard on your cutters.

EDIT: Looks like I missed a page of posts. This was in response to the question of musical instruments changing with age. Excuse me if the little I could offer was already covered.

All speculation based on the tiny bit I know but
An instrument that relies on the vibration of the material, such as a violin or guitar can suffer changes to it's shape and rigidity over time but that would mostly be due changes in humidity levels and such having a direct effect on changing the material, more so than the time itself. Many a guitar or piano has been ruined by a shift in climate. Never move a piano to a new home, they say.

Most wind instruments however, rely solely on the pattern or funnel of the air moving through it to effect the sound. The type of material makes little difference as long as it holds its shape.

Speakers?
Boards turned flabby by humidity certainly might effect the resonating factor and change the sound. Also, I understand older speakers with paper cones or gaskets are much more prone to having the paper dry up and fail. All that being said, I'm still not convinced about the 30 hour speaker break in period though.

Well this thread really went off the rails due to what I would term as a "hijack" but as it turns out it ended up being an interesting and informative read on speaker box materials and construction. Back to the original topic,I'm looking forward to my m3's arriving and I doubt I will put much emphasis on breaking them in.

We're good at hijacks around here. In fact, we've turned it into an artform, although I generally prefer impressionist paintings.