> those damn solenoids eat a LOT of current
Bad design?
1) I wonder if they take power to stay "open". Simple but wrong. A shuttle valve only needs a short blip to open or close, needs no power to hold its state. Like normal relays versus latching relays.
2) For a fraction of what they charged you they cudda put a mini-turbine in the water path to spin a 59-cent Mabushi motor as a generator and recharge batteries.
They are not optimizing the motor to the load and the cost of power. Such concerns are a *prime* obsession with the speaker engineer.
The ideal speaker is like many other engineering devices: 90+% efficiency. Motors and transformers and gearboxes do this routinely. Combustion engines are awkward because they don't beat 40% efficiency.
The "ideal" speaker for highish efficiency down to 50Hz must have a 120 inch (10 foot, 3m) air-smacker. If any smaller, it can't couple to air well over a useful wife freq band.
Near-Ideal speakers are impractical. (Theater speakers of the 1930s came close; so do some of the very large arrays now used in cow-palaces.)
The 3-inch cone is efficient down to 2,000Hz. Below that efficiency % drops as square of frequency. At 200Hz it is necessarily 1% efficient at best. For "flat" response (and a mass-related reason) the parameters are adjusted to be 1% efficient 200Hz-2KHz. (Above that, efficiency falls but directivity rises; on-axis response may be flat another few octaves up.)
Take a four-12 array as a 24" cone. 8 times bigger than the 3-inch. All frequency benchmarks drop 8X. It loses efficiency below 250Hz (not 2KHz). For other reasons it will never come close to 100%, even 50%, efficient. For guitar we would likely aim for 80Hz, 3X lower freq than the bass/efficiency corner, 10X lower efficiency, around 10% from 80Hz to 250Hz. This size flat array also leads to high directivity in the >250Hz range, so stunning "throw", impressive sound in-front which cuts-through reverberant spaces. Above 1KHz-2KHz the directivity pattern gets very narrow while also growing side-lobes different at every frequency, though a four-12 will never keep all four cones-phase-matched above 500Hz which mixes-up the otherwise beamy directivity.
Unless heavily slugged for deep bass, or assembled by faucet designers, the larger air-slapper will generally put out more sound per electric Watt.
You seem to be leaning on an argument that the amp power and speaker rating must be alike. The ideal speaker is perfectly linear at any power. Yes, MUCH guitar tone is from driving non-ideal non-linear speakers somewhat past what the original (non-guitar) designer ever expected. But some speakers got past the Magnavox designs. The older Altec theater woofers, E-V's EVM series, and the wonderous JBL D-120/130. Some players dislike them as "too clean". Others appreciate clean reproduction of whatever mangled tone you feed them. Running 0.6 Watts into four Brand E speakers rated 25W/each with heavy breakup is a lot like a 50W into an EVM good for 600+W clean peaks.
