[AvFan]

I have a love-hate relationship with Medium Density Fiberboard (MDF).  It is very easy to work with, flat, consistent, relatively cheap, veneers well and has a long history in speaker enclosure construction.  But the dust makes makes me sick if I don't wear a respirator and I've had some skin irritation when I don't get the dust off me promptly.  I used MDF when I made my MTMs that Rick designed but as I look at making a full range speaker (the Ottavo is a top candidate) I'd like to find an alternative to MDF.

I know Bamboo plywood has been used by several manufacturers but all the information on how it performs as a speaker enclosure seems anecdotal.  Has anyone made one of Selah's speakers using bamboo ply?  In general, how does bamboo perform as a speaker enclosure in comparison to MDF?  Thanks!

[planet10]

In general, how does bamboo perform as a speaker enclosure in comparison to MDF?  Thanks!

Bamboo Ply (stranded (better) or vertical grain) is quite a bit better than MDF in our experience.

dave

[FullRangeMan]

if I don't wear a respirator and I've had some skin irritation when I don't get the dust off me promptly

I may be the formaldehyde, one of MDF components, it is carcinogenic.
Take care.

[WGH]

Bamboo plywood will make excellent speaker cabinets, it has a higher strength-to-weight ration and is 10 times stiffer than MDF. Click on the link to see a chart comparing the properties of bamboo ply and MDF:
http://www.makeitfrom.com/compare-materials/?A=Bamboo-Plywood&B=Medium-Density-Fiberboard-MDF

Wayne

[AvFan]

Thanks for the replies and thanks for posting the chart!  It certainly looks like bamboo is about the same density but much stiffer than MDF.  I know the first Ottavos' owner used 3/4" phenolic resin for his build and I bet it is much stiffer than MDF too.  I doubt I'd use phenolic (even if I could find and then afford it) but bamboo ply is available locally and might match the performance of phenolic.  A few speaker companies offer bamboo cabinets, and at a premium, but I don't find any comparisons between how commercially available speakers are enhanced by using bamboo versus MDF.  I wouldn't want to mess up Rick's Ottavos by using a cabinet material that its not designed for.

On MDF, yep, I'm pretty sure the formaldehyde is the culprit.  It doesn't help that when you cut it the dust is really fine and goes everywhere even with a vacuum.  I do my best to avoid the stuff.

[Rick Craig]

Sorry for my late reply - just returned from a weekend at an AVS Forum event. We have used bamboo ply and I would suggest adding a heavy damping material to the interior. Like plywood it's fairly stiff but has less internal damping so it tends to ring a little.

[AvFan]

Thanks for the insights Rick; a ringing cabinet can't be good.  Do you recall the type of bamboo ply you used?  I used 3/4" Sonic Barrier from Parts Express to line my MTM cabinets, so would it prevent the bamboo from ringing?  So if there was no concern regarding working with MDF which would you prefer, MDF or bamboo for the Ottavo's cabinet?

[jparkhur]

Another option would be to get good Russian Baltic Birch.  Cost is less than half of Bamboo.  I have used both and only have chosen to use bamboo when working with a statement piece. 

[Rick Craig]

Another option would be to get good Russian Baltic Birch.  Cost is less than half of Bamboo.  I have used both and only have chosen to use bamboo when working with a statement piece.

Good suggestion.

[Rick Craig]

Thanks for the insights Rick; a ringing cabinet can't be good.  Do you recall the type of bamboo ply you used?  I used 3/4" Sonic Barrier from Parts Express to line my MTM cabinets, so would it prevent the bamboo from ringing?  So if there was no concern regarding working with MDF which would you prefer, MDF or bamboo for the Ottavo's cabinet?

I don't remember the specific brand but it's very expensive. Baltic birch is probably a better alternative if you plan to add a veneer. Some MDF brands don't have formaldehyde if that's what's bothering you. Sometimes the  particles used in the MDF can be from woods that cause allergic reactions.

As long as you properly damp it the bamboo or birch should be fine compared to the MDF. The Cascade VB-2HD sheets are good for damping. Add the Sonic Barrier over that to minimize the internal reflections.

[jparkhur]

Baltic stains very well too.  I like edges, so don't mind them.  You could also cut 45's to not have edges or put in 1/4 rounds.

[planet10]

Like plywood it's fairly stiff but has less internal damping so it tends to ring a little.

All cabinets ring. In general quality ply (including bamboo) ring at higher frequencies and at higher Q than MDF . This means that it is much less likely to get excited than MDF cabinets that have lower frequency, lower Q resonance that gives a characteristic ooze of time-smeared sound that tends to limit their DDR (downward dynamic range)

Adding mass without system lowers the frequency of potential resonances and broadens the Q. The "cure" might ne worse than the initial problem.

dave

[planet10]

Another option would be to get good Russian Baltic Birch.  Cost is less than half of Bamboo.

I suspect that price differential will usually be larger than that and that differential will vary depending on where you are. We pay about $50 per sheet of 5x5 BB and about $300 for a 4x6 of stranded bamboo. Bamboo does not need veneer, but requires more care with joinery to get the best cosmetics and requires very sharp, quality tooling to work.

An example: http://www.diyaudio.com/forums/planet-10-hifi/214897-minionken-fonken-gallery-pictures-only.html#post3067755



dave

[AvFan]

My local lumber company quoted $340 for a 4x8 3/4" sheet of Teragren bamboo ply and they had to ship it in.  Each face of the sheet is 3/16" horizontal bamboo and the balance of the panel thickness was made of pieces on edge.  Nice stuff but $300 over a sheet of MDF is a pretty big premium. A hazmat suit would be cheaper.     They also confirmed bamboo requires very sharp blades that will need to be sharpened frequently.

So maybe the title of this thread should have been "Bamboo Ply vs. MDF vs. Baltic/Russian Birch Ply".  Baltic birch ply is readily available (I'll have to look for the specific kind Rick noted) and is a joy to work with but I just didn't think it was acceptable for speaker cabinets.  Learn something every day!      Cost is as noted, about $50 for 5x5x3/4, and it would probably take three sheets for the Ottavos so it puts the lumber at less than 1/4 the cost of bamboo.  And these will get veneered regardless of the cabinet material.  So do the cabinets get braced any different between MDF and Baltic Birch?

Lastly, very nice looking speakers guys! 

[Rick Craig]

My local lumber company quoted $340 for a 4x8 3/4" sheet of Teragren bamboo ply and they had to ship it in.  Each face of the sheet is 3/16" horizontal bamboo and the balance of the panel thickness was made of pieces on edge.  Nice stuff but $300 over a sheet of MDF is a pretty big premium. A hazmat suit would be cheaper.     They also confirmed bamboo requires very sharp blades that will need to be sharpened frequently.

So maybe the title of this thread should have been "Bamboo Ply vs. MDF vs. Baltic/Russian Birch Ply".  Baltic birch ply is readily available (I'll have to look for the specific kind Rick noted) and is a joy to work with but I just didn't think it was acceptable for speaker cabinets.  Learn something every day!      Cost is as noted, about $50 for 5x5x3/4, and it would probably take three sheets for the Ottavos so it puts the lumber at less than 1/4 the cost of bamboo.  And these will get veneered regardless of the cabinet material.  So do the cabinets get braced any different between MDF and Baltic Birch?

Lastly, very nice looking speakers guys!

No difference in the bracing.

[planet10]

Each face of the sheet is 3/16" horizontal bamboo

Horizontal outer plies is the least desirable for the job. Vertical grain is better, the stranded better yet. The stranded also has a tougher exterior for reduced long-term marking. We last used PlyBoo.

So maybe the title of this thread should have been "Bamboo Ply vs. MDF vs. Baltic/Russian Birch Ply"... Cost is as noted, about $50 for 5x5x3/4

We have used a lot of baltic birch. The quality we were getting was hit or miss, and we have switched to some better stuff from Miurphy Ply (in Oregon). 18mm maple faced 4x8s are about 50% pricier than BB. They squeeze 15 plies in where BB is 13.

Note that any BB you get will be 18mm (15mm/12mm) and only called 3/4" (19.1mm) for marketing purposes

dave

[AvFan]

I misunderstood; the Cascade VB-2HD is a thin damping sheet applied to the interior of the cabinet and not a brand of baltic birch.     So its purpose is to deaden the cabinet while the Sonic Barrier is to address back waves from the drivers?  I only put the Sonic Barrier on all the interior surfaces of my MTMs except the baffle but does the Cascade VB-2HD also go on the baffle?

[Rick Craig]

I misunderstood; the Cascade VB-2HD is a thin damping sheet applied to the interior of the cabinet and not a brand of baltic birch.     So its purpose is to deaden the cabinet while the Sonic Barrier is to address back waves from the drivers?  I only put the Sonic Barrier on all the interior surfaces of my MTMs except the baffle but does the Cascade VB-2HD also go on the baffle?

If you use the Cascade damping sheets then you'll only need the Sonic Barrier open cell foam version without the barrier layer. Line all interior sides as normal. The inside of the baffle on the Ottavo would be treated only in the area above the upper woofer.

[ellisr63]

They look great, but the price....Wow, Def puts bamboo out of my budget.

I suspect that price differential will usually be larger than that and that differential will vary depending on where you are. We pay about $50 per sheet of 5x5 BB and about $300 for a 4x6 of stranded bamboo. Bamboo does not need veneer, but requires more care with joinery to get the best cosmetics and requires very sharp, quality tooling to work.

An example: http://www.diyaudio.com/forums/planet-10-hifi/214897-minionken-fonken-gallery-pictures-only.html#post3067755



dave

[wushuliu]

I misunderstood; the Cascade VB-2HD is a thin damping sheet applied to the interior of the cabinet and not a brand of baltic birch.     So its purpose is to deaden the cabinet while the Sonic Barrier is to address back waves from the drivers?  I only put the Sonic Barrier on all the interior surfaces of my MTMs except the baffle but does the Cascade VB-2HD also go on the baffle?

I like using a rolling pin and some Play-Doh at 1/4in thickness. Then Ultratouch or wool on top with adhesive. If I used Sonic Barrier and these pricier damping sheets I wouldn't be able to afford the drivers.