Cabinet construction - compare wood types

Quite a lot of wood types out there for cabinet construction. What are your favourites? I'm excluding MDF and concentrating on real wood, plywood and other wood products?

Bamboo looks really nice
Birch play is popular
Spruce ply is cheaper - how does it compare to birch?
Wood - does it need to be kiln dried, or glued in strips?
Any other recommendations to look for?

andy
 
Stranded bamboo ply makes a REALLY nice box.

Stranded is made of 3 layers, a block inner core sheathed in some sort of amalgum of bamboo strands. Really stiff.


ASTM D 3043 Method D Flexural Strength (MOE/MOR)
3/4 inch thick, 1-ply, Edge Grain: 179 MOE/11,371 MOR average
3/4 inch thick, 3-ply, Cross Core: 148 MOE/9,109 MOR average
3/4 inch thick, 3-ply, Cross Core Strand: 268 MOE/14,762 MOR average

dave
 
Hi dave

I may start on the spruce as a learning exercise. I went with dowelling in the end as a joining technique. I got the Joint Genie with a long bar of 7 holes of 8mm. Haven't tried it yet, but it looks really easy to use and good for joining right angles over a long side like 4ft. So I expect to be drilling and gluing away with my new toy.

There again, I may just make a couple of utility cabinets out of whatever wood I have stashed behind the kitchen door as a learning exercise and go straight for the BB. You're right - the number of layers makes a big difference to the looks. OK enough to show.

Armed with my dowelling kit I'm eying up some plain timber I have in 144mm wide by 21mm thick. I've heard bad things about wood distorting and splitting, so was thinking of gluing and screwing it onto a backing panel for the front so I'd get two layers and the outer one would be real wood.

What kind of glue or techniques do you recommend for gluing two panels together, one on top of the other for front and/or back?

andy
 
May be some merit in using a soft setting adhesive if bonding panels.

The BBC Research/technical Dept' has archived a wealth of material that can be accessed by the DIYer. There is at least one paper on speaker cabinet construction that discusses the damping of large surfaces etc. Can't place it exactly now from memory so you may need to scroll thru' a few years to find it. 60's or 70's most likely.
Good luck.
Jonathan
 

MJL21193

Disabled Account
2007-03-10 1:20 am
My first question is about spruce ply. Doesn't quite look as nice as birch but my local hardware supermarket (B&Q in the UK) has 8ft by 4ft sheets in 18mm for £26, and they cut it too which makes for quick assembly. Local wood stores charge double that for quality baltic birch.

Nothing wrong with using the cheaper stuff. It's all in the execution.
The old saying is: "You can't make a silk purse out of a sows ear" and, although this is true (you need actual silk to make a silk purse), its usual implicatioin is that quality in = quality out. Not always the case. First, one needs to be able to build the purse, regardless of whether it is from silk or a low budget material such as a sows ear. Follow?
:)
 
My two favourites probably aren't relevant for you guys in the northern hemisphere, but for those of you in Australia, I like to use solid Tasmanian Oak and solid Pacific Maple.

Tasmanian Oak is dense, stiff and heavy. It also looks quite nice with nothing more than clear varnish.
There are however two problems with Tasmanian Oak: If you don't choose carefully, you quite often get lines of resin through the timber which is brittle and doesn't look very nice. The other problem is cost. Build small speakers with Tassie Oak!

Pacific Maple isn't quite as dense as Tasmanian Oak, but it's very stiff and has a nice red untertone to it.
My first muli-way speaker project (all other speakers have been 2-way) - My Photo Gallery
But it's pricey too.

AJ
 
having built the same speaker design in both mdf and bb, i can concur that bb is definitely the more 'lively' sounding, which also makes it more colored. the birch i used was 9 ply of cheapish quality and the coloration is rather pleasant and not bright at all. it has more midrange warmth and rounder bass than the same speakers built out of mdf; due to the lowered resonance frequency from lighter density of the bb, i suspect.
 
Last edited:
having built the same speaker design in both mdf and bb, i can concur that bb is definitely the more 'lively' sounding, which also makes it more colored. the birch i used was 9 ply of cheapish quality and the coloration is rather pleasant and not bright at all. it has more midrange warmth and rounder bass than the same speakers built out of mdf; due to the lowered resonance frequency from lighter density of the bb, i suspect.

Let me address the last comment 1st. With 2 materials of the same stiffness, the lighter one will have a higher frequency resonance. If is well established that BB is stiffer than MDF, which also means higher resonance.

BB sounds livelier than MDF under external stimulation because it has a higher frequency resonance that dissapates with less time smear.

If we can push resonance up it is less likely to ever get excited. The energy in a signal decreases with the square of the frequency. Further, once one passes a certain minimum there is less content in the music as frequency increases. It also makes sense that as the wavelength gets smaller with respect to the dimensions of the material, it becomes easier for the material to damp the energy.

If the last 2 hold, we have an approximately 4th order decrease in the likelihood of a resonance being excited as its frequency increases. A pretty solid reason for pursuing cabinets that push panel resoaonces up in frequency.

One could further decrease the likelihood of a resonance being excited if one actually placed resonances between notes of the well-tempered scale.

dave
 
Nothing wrong with using the cheaper stuff. It's all in the execution.
The old saying is: "You can't make a silk purse out of a sows ear". First, one needs to be able to build the purse, regardless of whether it is from silk or a low budget material such as a sows ear. Follow

Thank you John. This is perfectly clear.

I build a purse shaped speaker cabinet out of sow's ears. I phoned my local sows ear store, and happily they have good stocks, and a special offer on Baltic sows ears which I think I'll go for.

The only thing that worries me is that in the latest issue of "Organic Bio-Speaker Builder" there's a really good featured system with purse shaped speakers made out of silk. I might regret not going down that route, especially if I exhibit my speakers at shows and they are laughed at by the silk fraternity.

What to do?

andy
 
Last edited:
Wood - does it need to be kiln dried,...
It may just be me...this part of the question alerts me to the possibility of a lack of understanding. :confused:

All the other materials in the list have been processed into sheet goods (layered) with alternating strand orientation.

The implied quality of "kiln dried" is a moisture content low enough (~6%) to minimize movement through moisture loss in a conditioned (hvac) space.

Using solid wood construction brings a set of challenges that are better met by using "kiln dried" lumber.
 
Spruce plywood has voids within the layers that are left as is. They will only fill the voids on the outside two plys. The voids are typically knots that fall out when cut into the thin sheets used to laminate.

I have seen "Baltic Birch" used as a lumber type but what you really want is marine grade plywood; ie Joubert Okoume (British Standard BS1088 and BS6566). There are other grades of Marine Plywood but Lloyd's of London won't insure your boat with the others. Good enough for speakers, though.

Baltic Birch is made to a Russian standard (GOST 3916.1-96); it is not marine grade. There are four grades; B, BB, CP, and C. The grades refer to how the voids are handled on the visible faces and internal plies. The only grades suitable for speaker cabinets are B (no voids allowed) and BB (knots are cut out and replaced with [American] football shaped patches of defect free birch). Both grade B and BB allow pin knots. If you must compromise on price, choose CP which is BB rejects and may have unfilled cracks. C is unsuitable, but you will know it by the un-sanded face wood.

"Baltic Birch" was once a term, prior to about the last 10 years, referring to Marine Grade plywood made in Scandinavian countries. They still make marine grade birch plywood in Norway and Sweden, but it's become hard to find since most lumber yards now import the cheaper Russian product. Paul Klipsch used to use the genuine scandinavian marine grade in his speakers (Hersey, Cornwall, La Scala, Belle Klipsch and Klipschorn).
 
Last edited:
Some people seem afraid to use solid timbers. If you're building large enclosures with thin timber, butt joined with PVA then yes you may have issues but if you are using kild dried hardwood with decent joining methods you can get very solid and stable results. Not to mention appearance.

I'm currently building a pair of hybrid open baffles using solid Queensland Spotted Gum which is a VERY hard timber 1270mm high x 460mm wide x 42mm thick. The timber was from a staircase that had been in the sun for years so is pretty stable by now.

These are solid Victorian Ash (VERY similar to Tasmanian Oak) 33mm thick and all mitred using expanding polyurethane adhesive.
IMGP1658.jpg


This is one of my BOFU open baffles in solid slabs of Camphour Laurel 60mm thick which had been drying in my grandfathers shed for 15 years. Phase plug is of the same timber.
IMGP2021s.gif