Why have 4 ohm speakers pretty much become the standard and not 8 ohm, 16 ohm or more ....

Cost cutting, pure and simple. It's more expensive to hit sensitivity targets with 8ohm speakers than it is by 'cheating' with 4ohm because of the extra motor force needed, and more compliant suspensions means tighter tolerances required. Both those mean more cost. So instead of spending the bucks, some manufacturers will just parallel drivers to halve the impedance and give a more attractive sensitivity spec.

8 ohm speakers are IMO a must for many of the low-feedback tube amps out there. Into 4 ohms you can see +/-2db swings in the frequency response. What really can be a problem is when some manufacturers call the speaker 4 ohm, but in actuality you see dips to 2 ohm and below. That will give any tube amp fits.

Thank you, makes perfect sense.

McIntosh Mc2301 hybrid tube quad balanced design is very "fit" in this regard. My speakers fall below 4ohms. Most 4ohm speakers do.

Vapor1 said:

Cost cutting, pure and simple. It's more expensive to hit sensitivity targets with 8ohm speakers than it is by 'cheating' with 4ohm because of the extra motor force needed, and more compliant suspensions means tighter tolerances required. Both those mean more cost. So instead of spending the bucks, some manufacturers will just parallel drivers to halve the impedance and give a more attractive sensitivity spec.

8 ohm speakers are IMO a must for many of the low-feedback tube amps out there. Into 4 ohms you can see +/-2db swings in the frequency response. What really can be a problem is when some manufacturers call the speaker 4 ohm, but in actuality you see dips to 2 ohm and below. That will give any tube amp fits.

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Ryan a question. IN your speaker line up the only 4ohm speakers to have are the Aurora and the Derecho. Why 4 ohms for those two designs when all others are 8ohms ?

CPP said:

Ryan a question. IN your speaker line up the only 4ohm speakers to have are the Aurora and the Derecho. Why 4 ohms for those two designs when all others are 8ohms ?

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In those cases, necessity. The Aurora is also available as a 8 ohm with a much higher quality woofer. There isn't enough demand for that design to have a custom driver commissioned, so we're limited to off the shelf offerings. And there just aren't that many quality 8" woofers to choose from. The "higher quality" woofer from AudioTech is a custom job since they will build us custom drivers even for a 2 piece order, but very expensive.

And the Derecho, we were trying to squeeze as much out of it as possible - high sensitivity, good bass extension, and a manageable cabinet size. So to get all those things we had to cheat a bit and parallel up 2 8" woofers for a 4 ohm load.

Devil is in the details though. The Aurora drops to a min of 3.8 ohm, the Derecho drops to a min of 4 ohm exactly and is in the 8-12 ohm range from 500hz up.

Thanks Ryan.

Ryan, as I understand it, one of the benefits of a bridged design amplifier (stereo amp into mono block) is that by bridging the stereo amp you can pick up a significant amount of power. I've read that some stereo amps that are rated at 150 watts into 8 ohms when bridged can quadruple the power rating up to 600 watts into the same 8 ohm load.

But as in all things audio there are always trade offs. It is my understanding that a when a stereo amp is bridged and is fed a 4 ohm load it "sees" a 2 ohm load. Thus lower ohm rated speakers can put tremendous stress on a bridged design. So assuming the above is correct wouldn't a bridged design amp make a poor choice for a 4 ohm speaker?