What does Nominal Impedance mean?

@ozzy Wrote:

Wonder why companies just don’t make speakers that are 8+ ohm and with high sensitivity? But it seems to be just the opposite, that is; many of the big-name speaker manufacturers produce speakers that are 4-ohm and low sensitivity.

Wonder why that is?

ozzy

Maybe Hofmann's iron law is one of the reason. Article

Mike

@fritzspeaks Wrote:

I vaguely remember that the speaker industry standard rating of impedance as what it is at 1000Hz.

JBL’s impedance graph is from 20Hz to 2KHz conforming to international standard IEC. International Electrotechnical Commission - Wikipedia

Mike

@ozzy,

I think nominal impedance means the industry standard. Impedance should not fluctuate more then 8 or 9% from the standard. I.E. An 8Ohm speaker should be no less then 6Ohms, a 4Ohm speaker should be no less then 3Ohms, if they follow the standard.

Mike

@clearthinker Wrote:

This poor manufacturer behaviour is mirrored by not quoting a dB range when specifying low frequency extension, and by over-stating sensitivity, which occurs very often.

(Proper) measurements matter.

I agree 110%! See the manual below of my speakers, it's the most comprehensive speaker manual of specifications I known of. They even explain how they arrive at their numbers. See last page specifications:

Mike

https://www.lansingheritage.org/html/jbl/specs/pro-speakers/1984-4430-35.htm

@ozzyWrote:

Let me ask another question:

So, does a 4-ohm speaker play louder than an 8-ohm speaker with the same amplifier and volume setting?

As I understand, only in 8 Ohm load does 2.83 volts produce 1 watt. In a 4 Ohm load 2.83 volts produces 2 watts. 😎

Mike

@ozzy Wrote:

So, does that mean they will play louder or does the amp need to work harder? ozzy

Both! Also the lower the impedance the amp operates in, the higher the distortion produced by the amp.

Mike