I've known about baffle boards all my life. When my grandfather bought his first AWA tower model in the 1930s, a relative built him a freestanding baffle board for an extension speaker. It was a massive piece of Australian hardwood, stained and polished, around four foot tall by three foot wide, standing on the floor angled back on a baseplate. I remember it sounding very authoritative when he listened to the news or the cricket, but maybe it just reflected the stern presence of my grandfather. He used that well into the 1960s.

In 1950 my parents bought the Philips Radioplayer that I now have, and somebody made a baffle board to go with it. It had to be light enough for my mother to move from room to room on a long flex, while she did the housework and listened to classical music. I still have that baffle board but never looked closely at it. Now I realise that the main baffle is a 2 foot by 2 foot square of low-density composition board - I believe it is what used to be sold as Canite, made by CSR from the fibrous waste from sugar mills.

Over the decades this Caneite has deteriorated and is now flaking and cracking, so I'm rebuilding the baffle board. It must be absorbing a high proportion of the energy developed in the speaker coil.

My plan is to replace the caneite with a very solid 120mm plywood. I thought of using MDF, but I want a more live response in the board.

Modern audio design seems to be focussed on projecting the deadest possible sound from the front of the cone, and it mostly assumes closed MDF cabinets and multiple speakers. My aim with this baffle board is to have the whole board resonate warmly and fill the room without any narrow directional focus. I'm hoping the plywood will be a good balance between a resistance mass for the driver, and resonance easy on the ear. Maybe something like my grandfather's baffle board from 1937.

Maven

Update: - I did the rebuild yesterday and the plywood baffle is a big improvement over the old caneite. I guess that baffle board had been underperforming for about 60 years.

Maverick high-end speaker designer Alon Wolf believes only heavy gauge machined aluminium baffle is inert enough for his Magico speakers.

Nearby movie theatre to where I lived in Qld in '60s had curved ceiling of Caneite (very good acoustics to complement their Western Electric Mirrophonic sound system, which, incidently, used open plywood baffles of uneven left/right sizes - to cancel resonant peaks?)

Caneite never completely loses a faint whiff of molasses - perhaps your Queensland cinema smelled slightly sugary?

Yes, I guess designers always have to strike a balance between looking for resonance that is favourable to the desired tone range, OR going for maximum inertia so that the cone itself dominates generation of the accoustic waves.

I've remembered also that many Victorian State Schools in the 1950s had speakers on baffleboard mounted above the blackboard in every classroom, to relay educational broadcasts from the ABC, or announcements from the headmasters office, where stood a large humming receiver and amplifier with PA mike and an impressive array of toggle switches. I wonder if any of those school PA units exist in collections anywhere?

Maven

I guess designers always have to strike a balance between looking for resonance that is favourable to the desired tone range, OR going for maximum inertia so that the cone itself dominates generation of the accoustic waves.

I recall reading about some audiophiles constructing concrete speaker boxes in the 1960s.

I wonder if any of those school PA units exist in collections anywhere?

AWA made a radio/PA/gramophone unit for schools and there was one at the school where I did 5th and 6th class. I was reminded of that when I attended the AWA Centenary celebration back in July.

I have two mono valve amplifiers, one an AWA and the other a Philips. Photos in my following post.

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A valve a day keeps the transistor away...

"some audiophiles constructing concrete speaker boxes in the 1960s."

The most extreme example I read about was a guy, (Australian I think), who built a huge reinforced concrete horn extending into the garden, with the mouth of the horn forming one entire wall of his listening room. You would virtually be sitting inside the horn. This would have been early sixties - before stereo took over.

Maven

Maven,

I have heard the same story .... an engineer out of Monash University with a passion and ability to design and build speakers and amplifiers .... late 60's early 70's .....if the same guy, then I have a set of speakers designed by him.

Cheers,
Ian

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Cheers, Ian

These are my amplifiers. The only speakers I have are the AWA Bakelite ones from the 40s and 50s.

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A valve a day keeps the transistor away...

^ I recognise both of those amplifiers from my youth. The top one was used by my swimming club at the pool when I was in my teens and the bottom one was in the local church.

The one I remember from State School was a floor-standing model and included the tuner and bank of toggle switches so classrooms could be patched in or out individually. I wonder if thsi was a special contract job for Victorian schools of the period (1950s)

Maven

I have an STC piped music system from the Royal Ryde Rehabilitation Hospital which is in a rack cabinet. It was being thrown into a skip bin during a spring clean whilst I worked there in the early 1990s. It was half way into the skip when I yelled STOP!

For a few years I used it as a general radio in my garage though it sits idle at the moment because I don't have the time to restore it.

There are three six valve STC radios in it to provide a selection of radio programming, along with a switching panel, monitor speaker, phone jack and a big terminal block inside to distribute the three outputs to the bedhead panels in the wards.

Each of the three chassis is a mix of octal and baseless valves, hinting at a similar era - the early 1950s.

On the subject of baffle boards, there were loudspeakers fed from this system too, in the common areas - patient dining room, sitting room, etc. These loudspeakers were mounted on a wedge-shaped baffle board mounted in the corner of each room they served - not unlike the speakers used in schools (including mine) at the time.

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A valve a day keeps the transistor away...

In some old houses you can make an infinite baffle between rooms or floor-to-cellar/crawlspace. I always wanted to try planar spkrs in walls like Magnapan or electrostatics to get real bass from them - am still going to try this. I replaced trapdoor in closet with a baffle for inf baffle Altec's - front loading with corner horn. By adding door panel with planar driver I can experiment for "faster bass".

"STC piped music"

That's a cool Deco 19" Rack (rounded corners) Could be used for home sound system as racks are expensive and hard to find and not as good as the old ones like that.

The origin of the 19" rack goes back to 1800's railway signalling relay systems. Then adopted for broadcast & movie sound equipment in 1920's.