Baltic ply for speaker cabinets?

[Qwin]

Chipboard was the material used in the sixties/seventies. This was eventually replaced with mdf for a couple of reasons, including machine ability. Apart from ply, mdf seems to be expected, these days (even used as a selling point.. or not!). I have a pair of three-way 'speakers made of chipboard and closed box loading (from the '60's). Don't like mdf/reflex loaded, too much boom boom for me.

Back then, that's all they had.
Then and now, particle board is 1/4 of the price of decent Plywood (without voids) and solid wood was/is even more expensive.
MDF became a cheaper alternative, machines well and takes veneer/stain. I hate the stuff, expands like crazy if it gets wet, doesn't take screws well, bends over time, even under small loading, is very heavy and its acoustic properties are dubious. But its obvious why it's used so much in lower/mid priced speakers.
I too like sealed box bass and my NS1000m had thick chipboard cabinets, as did my Celestion 66 monitors (ABR).
I made new cabinets for the Yams MDF/BBirch sandwich, worked extremely well, here is the build:
https://www.jkwynn.co.uk/Project_Images/Yam_Rev/YamRev_Cabinet.pdf

 

[Helen Bach]

loverly construction, but there must be better stuff to use for the stuffing. Fibreglass gets everywhere, even in the voice coil areas!

 

[Chris]

For stuffing absorbent, I used a recommendation off the Wam. It was to use motorbike exhaust stuffing material as used by hairy bikers to tune their exhaust note. Apparently upmarket Ducati etc. exhaust silencer boxes can be opened, restuffed and then closed back up again.
The one I bought was by a company called Athena (Italian, I think) and I managed to source it here in the Canaries, go figure, no hifi shops to be found but dead easy to find this stuff. I think it is fibre glass woven with cotton rather like a stiffish blanket, say 90 x 60. It didn´t manage to irritate my gentle epidermis and I was advised to just make a loose swiss roll of it so I did and no suspicious noises so far. If it can tame "a hog", I´m sure it can tame some genteel yammies.

 

[awkwardbydesign]

think it is fibre glass woven with cotton rather like a stiffish blanket,

I would be very surprised if it included cotton, due to the heat. FWIW, there has never been anything like that in the silencer stuffing I have bought.

 

[Chris]

You are probably right but mine feels like a thickish woven blanket and nothing like rockwooly crumbly stuff. Are /were you the wammy who suggested it ?

 

[Qwin]

loverly construction, but there must be better stuff to use for the stuffing. Fibreglass gets everywhere, even in the voice coil areas!

For stuffing and side wall damping, I used the same materials and qty's as the original design.
It sounds good, so no need to reinvent the wheel, or risk altering how they sound.
The mid and tweeter on the Yams are sealed backs, there are thousands of sets still going strong, using the Fibreglass.
Incidentally, I have used other types of stuffing on other projects, it was a conscious decision to stick with the original on the Yams. The Felt lining took some finding, but worth the effort.

 

[Helen Bach]

OK, but I live in long-haired sheep country, I'm trying to source some for a project (but I wouldn't use a whole one). Someone in Wireless World a long time ago (was it Arthur Radford?) advocated long fibre wool for stuffing transmission lines.

 

[Qwin]

Yes, loose wool is supposed to be the best stuffing, not just for transmission lines.
The amount of stuffing is very important, I tried using more/less Fibreglass than was used originally and it sounded over or under damped, they had it spot on.
You will have to experiment a bit, to find out how much wool is needed.

 

[Qwin]

For stuffing absorbent, I used a recommendation off the Wam. It was to use motorbike exhaust stuffing material as used by hairy bikers to tune their exhaust note. Apparently upmarket Ducati etc. exhaust silencer boxes can be opened, restuffed and then closed back up again.
The one I bought was by a company called Athena (Italian, I think) and I managed to source it here in the Canaries, go figure, no hifi shops to be found but dead easy to find this stuff. I think it is fibre glass woven with cotton rather like a stiffish blanket, say 90 x 60. It didn´t manage to irritate my gentle epidermis and I was advised to just make a loose swiss roll of it so I did and no suspicious noises so far. If it can tame "a hog", I´m sure it can tame some genteel yammies.

I had enough work in my project, I didn't fancy trying/comparing different types and quantities of stuffing/lining, hence keeping it all as original.
It took me five years to get both the passive and active XO filters spot on, many many builds and component changes.
My Yammies are anything but genteel, I changed to 12" Scanspeak woofers, excursion +/-12.5mm linear +/-28mm max. They go nearly an octave deeper than the originals, in a similar volume sealed box. They are refined modern drivers, but with 700w of class D up them, they can rumble with the best. I use 35w EL34 Tube Amp for Mid/Twt. I would put them up against any stock NS1000 or NS2000 for that matter. I take them to HiFi meetings and they go down very well. Flatter response, smoother top end and bass to keep most folks happy. A long term, but very satisfying project.