Plywood 1930s till Now -- rethinking the love of Baltic Birch (vintage or new)
I had to process-in an interesting 3pc set of late 1950s era DiY Tone/HiFi cabinets....It was actually really interesting and fairly beautifully done job – –(using some speakers I don't see too often; very old garish 50s hifi grade Utah 15 inch coaxial's – – these would be the predecessor to the much more common and dreadfully cloth-surround disguised ceramic magnet"Celesta" (also sold by R/S inhouse for a spell) will be selling these) a topic for another time))
– I'll be letting these go so if anybody's looking for a matched pair let me know! (I have 3 perhaps)
I was expecting simple boxes – but these are bass reflex and a nice implementation with side ports at that!
On top of that they're using the type of plywood I'm always recommending.... that is to those DIY'ers / audiophiles interested in Primo vintage sound.
My suggestions on cabinet construction materials are always met with a little bit of frustration – – "So where do I get that 1950s interior plywood?"
Well.... If you don't live in Ward Cleaver's, soon to be gentrified neighborhood (stripped kitchen cabinets, walls, floors of a 1950s Frank Llyod Wright house perhaps?), I suppose one source might be a pair of estate cabinets like these!
1950s's plywood no-good you say? That's certainly true in the eyes of most any cabinet maker... They'll laugh you away as you approach them with that old yellowed knot-filled stuff..too much work to make it look pretty. The exposed and very stylish look of Birch's perfect lams mean little veneer work.
Those who build with wood love Baltic Birch ply. What kind of woodworker wouldn't? It's smooth, void free, cuts so & beautifully and it's pretty cheap (or at least it used to be, err, thanks Putin!)
It seems to me, that this beautiful Baltic Birch plywood came very prevalent to the market, sometime in the late 1980s or 1990s. It soon became a fan-favorite and replaced MDF in speaker building in a lot of cases. My father and I really welcomed it too at first .... because we have been dealing with lifespan woes and ho-hum sound of particleboard. Electrovoice and JBL pioneered its use going all the way back to the 1950s. Before Birch from overseas, so called "Marine graded" ply cost a fortune.
Like MDF before it, Baltic Birch ply was spoken of as a miracle material. And at least in the case of beauty, durability and deadness it kinda is.
When it came to audio... we never thought birch ply the best sounding – – especially when put head to head with other, nastier looking domestic pine/spruce/fir type plys with lots of sap and knots. The reason we knew this was from experience. None of the manufacturers pre-1960s used high-quality plywood ...not really .. if it showed, they used veneer over it..... And If you look at the first use of plywood (plywood goes back to the 1890s, but it's early commercial uses AFIK are in these baffles) Cinema 1930s Western Electric and Lansing Sound Co (pre Altec) -- Through the late 1950s Altec VOC models ... As well as various other stuff along the way – – you'll note that it's primarily made out of interior grade 3/4" and above Douglas Fir type ply. This is not usually pretty stuff. There are definitely some hit or miss applications of what someone else mentioned on here – – "void free" (of course that might have just been luck of the draw).
Some of the very high-quality tone cabinet manufactures like Lyon and Healy .... Hammond, etc -- did do better...((As well as a Western Electric (early 50s 753, by mid 50s it was Weldwood or GP Douglas Fir)) it's earliest products – – Used a solid middle, with veneer top/bottom called Lumber-Core... Interestingly enough the very first generation of a AR1 and AR3 (only the super early ones) speakers also use lumber core probably for it's void free density and those guys were looking for the absolute straighest, best looking, rigid thing they could get, so that they could avoid hardwoods. The Lumber-Core very shortly moved to veneered ply and then to crappy MDF/Particle board by the 60s, for most mfr's....
The reason the Douglas Fir plywoods from the 1950s (and before) sound a bit better – – it's a hardness, and a trapped air thing. First off these are interior grade plywood's ... which mean they will quickly disintegrate if exposed moisture. 1950s in before, the most common chemistry was a hide type. Hide glues are still used by Luthiers... they are extremely hard, inflexible, and have a reputation for sound quality.
All very poor traits for building materials.
Since plywood products are very dependent on glue – – the type used is a big deal Along with the high gloss, sometimes a very hard and smelly product was used to be on the plywood – – heavily dependent on phenolic resin. You see this type of plywood in Altec Lansing stuff from the 1950s too. And it's also a very very hard and not very flexible. And example of this material would be seen in early utility cabinets like the rather famously good 618 Utility (8" for the 755 and 12" for the others)... and the 614 and 612 Utility cab's which are infamously implicated with good sound in the Lansing Iconic.
Altec was really never interested in cabinet design....They liked simple approaches that worked and got the job done. These cabinets one could call, just plain boxes – – and the reason they sounded good were oddly the materials used. You can knock up one of these out of birch ply, but the results won't quite be the same.
Typically cabinets made from Birch using these designs sound more mellow. Not bad performance .... but a little bit less crisp and exciting versus the hard-woody, inflexible originals. And when I mean in flexible, I definitely don't mean thick or with bracing. Altec didn't do much bracing, and the wood was thinner (mostly less than the often recommended 3/4") in their stuff either – – way too costly.
Modern builders do a much "better" job, rarely cheap-out.... Modern efforts always have lots more bracing making for a "rubbery" and very dead cabinet (cleaner-tougher materials nowadays). Mfr's assume this is a good thing, but often the results either add nothing or even dull the sound, adding the wrong type of coloration to the mix.
By most accounts, by the time Altec (Hollywood 1940s, Anaheim 50s-60s era) was done slamming together these cabs and spray painting them with that really hard hammertone paint (that had all kinds of lacquer and glass) ... It only added to the pleasant clean resonant tone.
Below photos of the cabinets I'm disassembling (cabinets which will yield the old pine ply; I will surely save it for open baffle projects and remanufactured accessories, for the American Instruments horns and other parts coming...)
I was inspired to throw up this post, as I don't often see the cool ink stamps on the edge of the plywood (Including the "interior" so that builders knew not to get it wet). In this case we are looking at a fairly plain product (made from old growth pine) that was offered probably at the hardware store or building supply circa 1950s. I love to find this stuff, and always save what I can. It delivers, Surprisingly accurate sound, not too dead not to resonant either... thanks to it's three-quarter inch thickness..., and you can see it's loaded with voids. It won't make pretty cuts and the surface ply veneer is just barely good enough to make it look pretty (if you are not a perfectionist).
The other photo is an example– this is a circa 1940 Lansing Sound (Jim Lansing, pre-Altec) mini Shearer horn/baffle – – also made out of the similar low grade Douglas Fir interior building stuff A little bit thicker perhaps, but you can see the voids in between the laminations and event a few knots.
In conclusion, density and quality of building material doesn't necessarily equate to the best sounding cabinet. Any number of audiophiles are lining up around the block to buy original model 618 or 614 utility cabinet which were by all accounts made with really crappy, 1950s "flooring" grade plywood, that was a bit too thin for a speaker designer's taste. Altec's cheapness and carelessness lead to sound quality in this case.... go figure.... these old, sought after models just happen to be very hard with a very correct sounding tone, tons of clarity and detail.
By the 1970s, glues were developed for plywood (very rapidly) to allow them to be nearly waterproof. This type of plywood (if it doesn't rot) will last forever in the sun and rain outdoors. The types of glue – were inherently softer/or at least more "plasticy" as well. This makes the plywood sound different when it's used on speaker cabinets. Chemicals vary...besides phenolic and urethanes – – they tend to use a lot of latex. Latex of course the soft binder which gives the plywood a slight rubbery feel when you pick into it on the edges or in the fill areas.... This type of pine flooring grade plywood that is made for outdoor use is still a choice you can go with – I even recommend this over the much prettier Baltic birch ply if you are after the Classic American sound.
When we were building our little American Instruments Isophon horn-projector back in the early 2000s – – we went with a Italian Poplar or Spruce .... very thin, and it was quite nice, and only about 1/16" thick.
This is not the end all of Birch. Don't chuck your nice project in the bonfire. But next 'round, use your judgment before choosing the pretty wood....Look at the cheap stuff at the store too, sometimes it's better to use. Wrap on it a couple times and judge of the tone ..... *before* you go with it. Avoid overly dead or soft materials.
And most of all, be green, be sensible, and be clever – – save the 1950s wood from that "yarder or dumpster" parked outside of the mid-century diggs under remodel....(kitchen cabinets make great OB's if they're wide enough)
Early @ HiFiTown 2022
I had to process-in an interesting 3pc set of late 1950s era DiY Tone/HiFi cabinets....It was actually really interesting and fairly beautifully done job – –(using some speakers I don't see too often; very old garish 50s hifi grade Utah 15 inch coaxial's – – these would be the predecessor to the much more common and dreadfully cloth-surround disguised ceramic magnet"Celesta" (also sold by R/S inhouse for a spell) will be selling these) a topic for another time))
– I'll be letting these go so if anybody's looking for a matched pair let me know! (I have 3 perhaps)
I was expecting simple boxes – but these are bass reflex and a nice implementation with side ports at that!
On top of that they're using the type of plywood I'm always recommending.... that is to those DIY'ers / audiophiles interested in Primo vintage sound.
My suggestions on cabinet construction materials are always met with a little bit of frustration – – "So where do I get that 1950s interior plywood?"
Well.... If you don't live in Ward Cleaver's, soon to be gentrified neighborhood (stripped kitchen cabinets, walls, floors of a 1950s Frank Llyod Wright house perhaps?), I suppose one source might be a pair of estate cabinets like these!
1950s's plywood no-good you say? That's certainly true in the eyes of most any cabinet maker... They'll laugh you away as you approach them with that old yellowed knot-filled stuff..too much work to make it look pretty. The exposed and very stylish look of Birch's perfect lams mean little veneer work.
Those who build with wood love Baltic Birch ply. What kind of woodworker wouldn't? It's smooth, void free, cuts so & beautifully and it's pretty cheap (or at least it used to be, err, thanks Putin!)
It seems to me, that this beautiful Baltic Birch plywood came very prevalent to the market, sometime in the late 1980s or 1990s. It soon became a fan-favorite and replaced MDF in speaker building in a lot of cases. My father and I really welcomed it too at first .... because we have been dealing with lifespan woes and ho-hum sound of particleboard. Electrovoice and JBL pioneered its use going all the way back to the 1950s. Before Birch from overseas, so called "Marine graded" ply cost a fortune.
Like MDF before it, Baltic Birch ply was spoken of as a miracle material. And at least in the case of beauty, durability and deadness it kinda is.
When it came to audio... we never thought birch ply the best sounding – – especially when put head to head with other, nastier looking domestic pine/spruce/fir type plys with lots of sap and knots. The reason we knew this was from experience. None of the manufacturers pre-1960s used high-quality plywood ...not really .. if it showed, they used veneer over it..... And If you look at the first use of plywood (plywood goes back to the 1890s, but it's early commercial uses AFIK are in these baffles) Cinema 1930s Western Electric and Lansing Sound Co (pre Altec) -- Through the late 1950s Altec VOC models ... As well as various other stuff along the way – – you'll note that it's primarily made out of interior grade 3/4" and above Douglas Fir type ply. This is not usually pretty stuff. There are definitely some hit or miss applications of what someone else mentioned on here – – "void free" (of course that might have just been luck of the draw).
Some of the very high-quality tone cabinet manufactures like Lyon and Healy .... Hammond, etc -- did do better...((As well as a Western Electric (early 50s 753, by mid 50s it was Weldwood or GP Douglas Fir)) it's earliest products – – Used a solid middle, with veneer top/bottom called Lumber-Core... Interestingly enough the very first generation of a AR1 and AR3 (only the super early ones) speakers also use lumber core probably for it's void free density and those guys were looking for the absolute straighest, best looking, rigid thing they could get, so that they could avoid hardwoods. The Lumber-Core very shortly moved to veneered ply and then to crappy MDF/Particle board by the 60s, for most mfr's....
The reason the Douglas Fir plywoods from the 1950s (and before) sound a bit better – – it's a hardness, and a trapped air thing. First off these are interior grade plywood's ... which mean they will quickly disintegrate if exposed moisture. 1950s in before, the most common chemistry was a hide type. Hide glues are still used by Luthiers... they are extremely hard, inflexible, and have a reputation for sound quality.
All very poor traits for building materials.
Since plywood products are very dependent on glue – – the type used is a big deal Along with the high gloss, sometimes a very hard and smelly product was used to be on the plywood – – heavily dependent on phenolic resin. You see this type of plywood in Altec Lansing stuff from the 1950s too. And it's also a very very hard and not very flexible. And example of this material would be seen in early utility cabinets like the rather famously good 618 Utility (8" for the 755 and 12" for the others)... and the 614 and 612 Utility cab's which are infamously implicated with good sound in the Lansing Iconic.
Altec was really never interested in cabinet design....They liked simple approaches that worked and got the job done. These cabinets one could call, just plain boxes – – and the reason they sounded good were oddly the materials used. You can knock up one of these out of birch ply, but the results won't quite be the same.
Typically cabinets made from Birch using these designs sound more mellow. Not bad performance .... but a little bit less crisp and exciting versus the hard-woody, inflexible originals. And when I mean in flexible, I definitely don't mean thick or with bracing. Altec didn't do much bracing, and the wood was thinner (mostly less than the often recommended 3/4") in their stuff either – – way too costly.
Modern builders do a much "better" job, rarely cheap-out.... Modern efforts always have lots more bracing making for a "rubbery" and very dead cabinet (cleaner-tougher materials nowadays). Mfr's assume this is a good thing, but often the results either add nothing or even dull the sound, adding the wrong type of coloration to the mix.
By most accounts, by the time Altec (Hollywood 1940s, Anaheim 50s-60s era) was done slamming together these cabs and spray painting them with that really hard hammertone paint (that had all kinds of lacquer and glass) ... It only added to the pleasant clean resonant tone.
Below photos of the cabinets I'm disassembling (cabinets which will yield the old pine ply; I will surely save it for open baffle projects and remanufactured accessories, for the American Instruments horns and other parts coming...)
I was inspired to throw up this post, as I don't often see the cool ink stamps on the edge of the plywood (Including the "interior" so that builders knew not to get it wet). In this case we are looking at a fairly plain product (made from old growth pine) that was offered probably at the hardware store or building supply circa 1950s. I love to find this stuff, and always save what I can. It delivers, Surprisingly accurate sound, not too dead not to resonant either... thanks to it's three-quarter inch thickness..., and you can see it's loaded with voids. It won't make pretty cuts and the surface ply veneer is just barely good enough to make it look pretty (if you are not a perfectionist).
The other photo is an example– this is a circa 1940 Lansing Sound (Jim Lansing, pre-Altec) mini Shearer horn/baffle – – also made out of the similar low grade Douglas Fir interior building stuff A little bit thicker perhaps, but you can see the voids in between the laminations and event a few knots.
In conclusion, density and quality of building material doesn't necessarily equate to the best sounding cabinet. Any number of audiophiles are lining up around the block to buy original model 618 or 614 utility cabinet which were by all accounts made with really crappy, 1950s "flooring" grade plywood, that was a bit too thin for a speaker designer's taste. Altec's cheapness and carelessness lead to sound quality in this case.... go figure.... these old, sought after models just happen to be very hard with a very correct sounding tone, tons of clarity and detail.
By the 1970s, glues were developed for plywood (very rapidly) to allow them to be nearly waterproof. This type of plywood (if it doesn't rot) will last forever in the sun and rain outdoors. The types of glue – were inherently softer/or at least more "plasticy" as well. This makes the plywood sound different when it's used on speaker cabinets. Chemicals vary...besides phenolic and urethanes – – they tend to use a lot of latex. Latex of course the soft binder which gives the plywood a slight rubbery feel when you pick into it on the edges or in the fill areas.... This type of pine flooring grade plywood that is made for outdoor use is still a choice you can go with – I even recommend this over the much prettier Baltic birch ply if you are after the Classic American sound.
When we were building our little American Instruments Isophon horn-projector back in the early 2000s – – we went with a Italian Poplar or Spruce .... very thin, and it was quite nice, and only about 1/16" thick.
This is not the end all of Birch. Don't chuck your nice project in the bonfire. But next 'round, use your judgment before choosing the pretty wood....Look at the cheap stuff at the store too, sometimes it's better to use. Wrap on it a couple times and judge of the tone ..... *before* you go with it. Avoid overly dead or soft materials.
And most of all, be green, be sensible, and be clever – – save the 1950s wood from that "yarder or dumpster" parked outside of the mid-century diggs under remodel....(kitchen cabinets make great OB's if they're wide enough)
Early @ HiFiTown 2022
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