What's with 4 ohm speakers?

"Quantity becomes quality when it avoids clipping."

Excellent point, Drew. That's why I go with 4-ohm cabs for prosound, where systems get pushed hard, and solid state (voltage paradigm) amps dominate. And even in the bass cab world where some players still use transformer-coupled tube amps, those amps are optimized for 4-ohm loads.

"Quantity becomes quality when it avoids clipping"

I like that and would have to wholeheartedly agree!

Those of us with a little technical knowledge accept and expect it because at lower frequencies dynamic loudspeaker driver output is proportional to voltage.

The statement is ambiguous. We know that doubling power is 3db, and that there is or should be a direct correlation with driver output. Since this is so then driver output is also proportional to power.

Quantity becomes quality when it avoids clipping

This is a bit of a strawman. If the amp is clipping get a speaker with more efficiency or a more powerful amp. Sound quality is not served by quantity if that quantity is also containing annoying distortion products, which are common with a lot of amps without clipping coming into the equation!

"The statement is ambiguous. We know that doubling power is 3db, and that there is or should be a direct correlation with driver output. Since this is so then driver output is also proportional to power."

Wouldn't you have to take other factors into consideration like how the room interacts with the speaker, or possibly, the distance from the speaker to where the measurement is taken? Or is there some type of industry standard and everyone measures these type of things the same way?

Atmasphere writes
> I wrote:
> Those of us with a little technical knowledge accept and expect it because at lower frequencies dynamic loudspeaker driver output is proportional to voltage.

>The statement is ambiguous. We know that doubling power is 3db, and that there is or should be a direct correlation with driver output. Since this is so then driver output is also proportional to power.

Nope. You're confusing voltage and power where power is voltage squared divided by impedance.

Reactive impedance varies with frequency. Inductive impedance magnitude is 2 pi f L with f ferquency in Hz and L inductance in Henries. Capacitive impedance magnitude is 1 / 2 pi f C with capacitance in Farads.

Driver + enclosure combinations are reactive loads with their mechanical parameters reflected in the electrical characteristics at the driver terminals. The driver's in-enclosure compliance Cms shows up as an inductive reactance Lces. The moving mass Mms works as a capacitive inductance Cmes.

Driver voice coils are inductive which also causes impedance to increase with frequency.

You can have a 40 Ohm maximum impedance at driver + enclosure resonance with impedance around a driver's 6 Ohm voice coil resistance as you move through its pass-band before its voice coil inductance becomes significant and increases to 20 Ohms before leaving the audible spectrum.

Over the same range the same voltage can yield the same output. 2.83V might be 90dB SPL although that varies somewhere between 1/5W and 1 1/3W electrical.

As noted complete speakers complicate things more. You get increased output as the speaker transitions from full to half space radiation (baffle step) and can have rising response as driver directivity increases with frequency. When cross-over designers compensate for that with a series load power impedance increases at those frequencies and power dissipated decreases.

Amplifiers which don't accommodate these physical realities with terminal voltage that's a fixed multiple of input voltage regardless of load impedance aren't universally useful in high-fidelity applications for speakers having impedances that are otherwise compatible causing neither instability nor power dissipation issues.