I found an article on TNT Audio from Italy . I clipped this section out and specifically noted that they choose birch plywood anywhere that they are not using solid hardwoods.
Despite less high-tech resources the home constructor can conduct original research, which may be more relevant to him or her, to help guide design and construction decisions, rather than rely on published research more suited to production in the commercial domain.
To summarise, in these experiments, for low frequencies below perhaps 300Hz (I did not explore different frequencies, so a bass-to-mid crossover point anywhere between 200Hz and 400Hz would probably suffice) 25mm materials of any type were better than thinner materials of any type. Birch-plywood (void-free birch all the way through, sometimes known as BB grade) was slightly better then the much cheaper mdf; birch-ply also has no health hazard rumours, but is more difficult to work. You pay your money and you make your choice. I now choose birch-plywood anywhere that I am not using solid hardwood.
For midrange frequencies, 12mm birch ply loaded with foam+bitumen sheets sounded clearest in our little experiment. The human voice range sounded most natural with this cabinet configuration. Voices singing have much of the energy concentrated in the decade from about 500Hz to 5kHz, even though bass voices can reach fundamentals of around 100Hz, tenors 165Hz and even sopranos lower than 300Hz, the lowest fundamentals of each human sound are isolated 20-23dB peaks at the lower end the spectrum analysis (Driscoll p51) with the centre of a bell-curve cluster of harmonics typically a decade above fundamental (i.e. bass voice 1kHz, tenor 1500Hz, soprano 3kHz), many harmonics 12-15dB in amplitude. The 15mm chipboard official cabinet was obviously inferior in the midrange. All thicknesses tried of mdf squashed the life out of the music, but fear not if you have mdf cabinets; I will explain how to rescue them and give them a new lease of life in a future article.
For now, if you are planning a new project, or rehousing some familiar drivers, the message is simple, the home constructor has the time and resources to build far superior loudspeaker cabinets to any that can be bought ready-made at real-world prices.
Despite less high-tech resources the home constructor can conduct original research, which may be more relevant to him or her, to help guide design and construction decisions, rather than rely on published research more suited to production in the commercial domain.
To summarise, in these experiments, for low frequencies below perhaps 300Hz (I did not explore different frequencies, so a bass-to-mid crossover point anywhere between 200Hz and 400Hz would probably suffice) 25mm materials of any type were better than thinner materials of any type. Birch-plywood (void-free birch all the way through, sometimes known as BB grade) was slightly better then the much cheaper mdf; birch-ply also has no health hazard rumours, but is more difficult to work. You pay your money and you make your choice. I now choose birch-plywood anywhere that I am not using solid hardwood.
For midrange frequencies, 12mm birch ply loaded with foam+bitumen sheets sounded clearest in our little experiment. The human voice range sounded most natural with this cabinet configuration. Voices singing have much of the energy concentrated in the decade from about 500Hz to 5kHz, even though bass voices can reach fundamentals of around 100Hz, tenors 165Hz and even sopranos lower than 300Hz, the lowest fundamentals of each human sound are isolated 20-23dB peaks at the lower end the spectrum analysis (Driscoll p51) with the centre of a bell-curve cluster of harmonics typically a decade above fundamental (i.e. bass voice 1kHz, tenor 1500Hz, soprano 3kHz), many harmonics 12-15dB in amplitude. The 15mm chipboard official cabinet was obviously inferior in the midrange. All thicknesses tried of mdf squashed the life out of the music, but fear not if you have mdf cabinets; I will explain how to rescue them and give them a new lease of life in a future article.
For now, if you are planning a new project, or rehousing some familiar drivers, the message is simple, the home constructor has the time and resources to build far superior loudspeaker cabinets to any that can be bought ready-made at real-world prices.