Speaker Efficiency

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So I'm just wondering what defines an efficient speaker? How can I tell how efficient my speakers are? In the D class forum they talk about the fact that a Tripath amp can drive efficient speakers to relatively high volume levels. However, I don't know what defines speaker efficiency.

Thanks!
 
from above wikipedia citation


180px-4-Wege_Lautsprecher.jpg




An unusual 3-way speaker system. The cabinet is narrow to reduce a diffraction effect called the 'baffle step'.

emphasis mine,


anyone, anyone, .... Bueller?



I read it on the internets, so it must be true
 
I trust that the old boys' club here at the Full Range forum has gone and fixed up the Wikipedia article?

Anyway, sorry for the OT:
In short, efficiency is a quantification of how many dB the speaker puts out with a certain number of watts.

Then, technically unrelated to speaker efficiency, but important in practice, some amplifiers like certain speaker impedances much better than others. Since you mentioned Tripath amps, most of them love 4 Ohm impedances, and only put out half as much power into 8 Ohms.
 
Scottmoose said:
Ah, wikipedia. The font of all wisdom & knowledge. :rolleyes:

And still more accurate than most of the printed encyclopedia's out there ;)


Speakers are all about tradeoffs. You can get really high efficiency, usually at the expense of bass and Xmax (linear cone excursion).

A speaker of same dimensions for example rated 95dB will sound just as loud with 1 watt as a common 85dB speaker will at 10 watts. BUT... the 85dB speaker may be able to go to 50Hz, while the 95dB one to 120Hz in the same cab.

Cheers!
 
Geek said:




Speakers are all about tradeoffs. You can get really high efficiency, usually at the expense of bass and Xmax (linear cone excursion).

A speaker of same dimensions for example rated 95dB will sound just as loud with 1 watt as a common 85dB speaker will at 10 watts. BUT... the 85dB speaker may be able to go to 50Hz, while the 95dB one to 120Hz in the same cab.

Cheers!

good points..

your trading excess xmax for a lack of cone area
because you need move lots of air at low frequencies

your right there are trade offs..how close is the 85 db, high xmax speaker following the music sine wave at it highest frequencies ?
 
Hi Steve,

steve shiels said:
your right there are trade offs..how close is the 85 db, high xmax speaker following the music sine wave at it highest frequencies ?

HF response is a completely different matter and varies widely with speaker. Some are pretty flat right up to 20K, others head for the hills and can be +10dB or more above 12K or so, making for a shrill crunch that lacks the finesse the speaker may have below that.

There's a lot of factors in play and they're interactive, so it can't be pinned down to one thing. But suffice it to say the surround and Xmax have little effect up there, since the active cone area is closer to the voice coil.

Cheers!
 
Geek said:
Hi Steve,



HF response is a completely different matter and varies widely with speaker. Some are pretty flat right up to 20K, others head for the hills and can be +10dB or more above 12K or so, making for a shrill crunch that lacks the finesse the speaker may have below that.

There's a lot of factors in play and they're interactive, so it can't be pinned down to one thing. But suffice it to say the surround and Xmax have little effect up there, since the active cone area is closer to the voice coil.

Cheers!


quite right, i was refering to bass ,..sorry i did not make that clear...
there are not many quality 85 db full rangers.. or are there?
 
steve shiels said:
quite right, i was refering to bass ,..sorry i did not make that clear...
there are not many quality 85 db full rangers.. or are there?

The FR125 by Creative Sound Systems is a nice entry level fullrange. ~85dB and in an 18L ported goes as low as 40Hz, w/room gain.

Though the new Mark Audio CHR-70 may be a contender for entry level.


As for bass frequencies, again each driver handles its Xmax differently. Aurasound NS3-series compress rather smoothly, FR125's will "fart" and a Fostex will just distort.

HTH
 
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