Back in the day, the only T-S parameter commonly available was resonance. Sometimes they also provided efficiency.
GM's advice is solid and a good starting point. When I was in high school, I bought some Eminence surplus drivers. This included a 15", very high efficiency, very high Q "full range" woofers. I was dismayed to measure the resonance as around 70 Hz (I really had no idea what I was buying) and so based on what I read in a Howard Sams book I build a large (6 cubic foot) enclosure and tuned it to 55 Hz. I did an impedance sweep and it was exactly what the Sams book predicted; two small impedance humps with the larger "hump" below the resonance.
Long story short, by tweaking the ports I was able to get solid bass all the way down to 40 Hz. Since the speakers were large and efficient it wasn't hard to reproduce super high (too high!) SPLs. Large horns were used for the midranges and tweeters and although it wasn't hi-fi like we think of today, it was super loud and super clear, with tight but slamming bass that punched you in the chest and played LOUD.
My point is that you can optimize the enclosure for these speakers with some very basic equipment and procedures. You don't even need a signal generator any more; you can get frequency sweeps on your phone from Youtube.
GM's advice is solid and a good starting point. When I was in high school, I bought some Eminence surplus drivers. This included a 15", very high efficiency, very high Q "full range" woofers. I was dismayed to measure the resonance as around 70 Hz (I really had no idea what I was buying) and so based on what I read in a Howard Sams book I build a large (6 cubic foot) enclosure and tuned it to 55 Hz. I did an impedance sweep and it was exactly what the Sams book predicted; two small impedance humps with the larger "hump" below the resonance.
Long story short, by tweaking the ports I was able to get solid bass all the way down to 40 Hz. Since the speakers were large and efficient it wasn't hard to reproduce super high (too high!) SPLs. Large horns were used for the midranges and tweeters and although it wasn't hi-fi like we think of today, it was super loud and super clear, with tight but slamming bass that punched you in the chest and played LOUD.
My point is that you can optimize the enclosure for these speakers with some very basic equipment and procedures. You don't even need a signal generator any more; you can get frequency sweeps on your phone from Youtube.
Thanks!
That’s one of my concerns with using these. I love the concept of high efficiency, but lots of these old drivers have that loud effect to them. 12” midrange tends to beam also in my opinion. A 5 cube cabinet is an investment so I’m not sure whether or not to pursue this effort. Thanks for the suggestions guys!
That’s one of my concerns with using these. I love the concept of high efficiency, but lots of these old drivers have that loud effect to them. 12” midrange tends to beam also in my opinion. A 5 cube cabinet is an investment so I’m not sure whether or not to pursue this effort. Thanks for the suggestions guys!
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