Impedance dips and power/sensitivity?

[yepimonfire]

Is it correct to assume that an impedance dip at, say, 100hz down to 4ohms would require double the wattage to achieve the same spl as say, 8ohms at 2khz? In other words, if a speaker spends most of its time at ~4ohms from 100hz to 1khz, would it measure 93dB @2w if the rated sensitivity was 93dB @ 2.83v?


Sent from my iPhone using Tapatalk

 

[shadyJ]

Is it correct to assume that an impedance dip at, say, 100hz down to 4ohms would require double the wattage to achieve the same spl as say, 8ohms at 2khz? In other words, if a speaker spends most of its time at ~4ohms from 100hz to 1khz, would it measure 93dB @2w if the rated sensitivity was 93dB @ 2.83v?


Sent from my iPhone using Tapatalk

That looks like a correct assessment, yes.

 

[yepimonfire]

That looks like a correct assessment, yes.

Since many speakers, especially 2 way designs, generally have a 4-6ohm impedance In the midbass and midrange, and a good deal of real music/movie content is heavily weighted in this range, is it incorrect to assume a speaker actually needs about 1.5x the power than would otherwise be assumed based on the 2.83v sensitivity? For example, let’s say my speakers are 93dB at 2.8v, but are 4-6ohms from 100-1khz, if I wanted to achieve 95dB at 11’, if really need 30w vs 20w to account for that.


Sent from my iPhone using Tapatalk

 

[shadyJ]

Since many speakers, especially 2 way designs, generally have a 4-6ohm impedance In the midbass and midrange, and a good deal of real music/movie content is heavily weighted in this range, is it incorrect to assume a speaker actually needs about 1.5x the power than would otherwise be assumed based on the 2.83v sensitivity? For example, let’s say my speakers are 93dB at 2.8v, but are 4-6ohms from 100-1khz, if I wanted to achieve 95dB at 11’, if really need 30w vs 20w to account for that.


Sent from my iPhone using Tapatalk

Basically, yes, but the impedance of your speakers is not exactly a static value. It will change at different amplitude levels, if you wanted to get that precise.

 

[yepimonfire]

Basically, yes, but the impedance of your speakers is not exactly a static value. It will change at different amplitude levels, if you wanted to get that precise.

Not more than a fraction of an ohm according to a Stereophile experiment, unless you were to drive it with something like compressed music with no more than a 6dB crest factor at very high levels right? For example wouldn’t I have to drive my RP-150m at say, 98dB rms with a crest of 6dB? That would equate to about 75w avg with peaks of 300w?

I’m not sure if this is actually a concern for home theater. Unless of course someone uses very inefficient speakers (ie 85dB) in a big room.

Would movies with an average 75dB rms, and 95dB 5-15 second peaks be enough to really cause power compression? That’s only about 1/4w most of the time with occasional 30-40w peaks.


Sent from my iPhone using Tapatalk