[earplay]

I've got an old pair of 2-way speakers in a simple sealed box or monkey coffin, as I've heard them called. 

Would it be worthwhile to replace the MDF monkey coffins with Baltic Birch monkey coffins? Is there enough acoustic difference between these materials to warrant the time and expense? Would you do it?

[Tyson]

Use a layer of each.  Since both materials have different resonant frequencies, you end up with a more acoustically inert enclosure.

[JoshK]

In my opinion, not worth rebuilding.  But if starting a new project, the BB is worth the extra money IMO if for nothing else that it a lot less dust everywhere and the dust isn't as harmful.   Its also lighter, but not a great deal.   Its rigid and faster to dissipate energy aparently but at the same time resonates in the audio range.  Which is worse?  Potentially more audible but fast time decay or less audible but longer decay?

I also think that BB is nicer to work with but can chip out a bit (small chips infrequently), so some bondo might be needed before veneering or painting.

[planet10]

What speakers are they? Pictures? (including insides)

Here is a long discussion that goes into some detail on a speaker building strategy that optimizes for good multiply.

Read this post 1st, it puts a lot of the discussion in perspective.

dave

[Wind Chaser]

In my opinion, not worth rebuilding.  But if starting a new project, the BB is worth the extra money IMO if for nothing else that it a lot less dust everywhere and the dust isn't as harmful.

Speaking from experience, I could not hear a difference in the sound between the two materials on the same speaker.  MDF is easier to work with IMO.  If you want to build an enclosure with real acoustic merit, use aluminum or stainless steel. 

[planet10]

MDF is easier to work with IMO

It doesburn nicely if you get the "bonfire" hot enuff.

dave

[earplay]

The speakers in question are Monitor Audio 852's. They have a 6' woofer and silk dome tweets.

I just replaced the crossover cap with Russian mil teflons and upgraded the wires. Wow! Their sound is just tremendous. I've been using single driver horns and had been thinking of giving the MA's to my nephew. No way, now!

The highs are smooth and the bass is articulate giving me a new appreciation for old designs aided by new components.

I probably won't mess about much more with these speakers, but I wondered if birch boxes would yield a worthwhile improvement.

One thing I came across was the notion of installing the tweets on a compliant mounting ala the Roksan Darius.

[face]

After recently working with BB, I doubt I'll go back to MDF.  The only problem for me is availability.

[Pez]

If you're going to rebuild the cabinet you may as well go all the way. Redesign it from a square box to a tear drop shape using layered MDF. You can pretty much do any shape you want with this method.

[doorman]

For those who do use MDF, beware the nasty dust!
Don

[Wind Chaser]

For those who do use MDF, beware the nasty dust!

Wear a mask and eye protection, especially when working with the router.

[sts9fan]

Where do you guys buy your BB?

[Wind Chaser]

Plenty of it in Canada at any place that sells lumber.

[planet10]

Not anyplace... we can't get it at the local 7-11 (oops mean the Home Depot just down the hill) or at Rona. We get it from one of the specialists, like Windsor Plywood. A whole thread on the subject over on diyA.

dave

[Wind Chaser]

Well you must be living on an island.

[face]

Well you must be living on an island.

What are you trying to say?   

So far I've only found one place on Long Island.  I wish they would cut the boards in half for me, it's a pain to lug full size boards 20+ miles home. 

[planet10]

Well you must be living on an island.

Yep. Independent Republic of Vancouver Island. When we seceed we want everything Manitoba West

dave