Question About Speaker Sensitivity

omahaaudio

Senior Member
Messages
1,878
If I have one speaker, in a 1 x 12 cabinet, with a listed sensitivity of 101.0 dB and add another speaker in another 1 x 12 cabinet (same make & model of cabinet) and the 2nd speaker has a sensitivity of 97 dB will the speaker with the higher sensitivity tend to over-power the other speaker?

In other words, for a balance between the two sounds, is it usually better to have speakers with sensitivities that are close to each other?

Thanks.
 

lemonman

Silver Supporting Member
Messages
1,091
4 db difference is getting to be a lot; 2-3 db is a better limit. But those numbers don't mean as much if they're from different manufacturers. For instance, Eminence is about 3 db overoptimistic on the numbers; their 101 db would be about the same as Celestion's 98 db, for instance. Comparing sensitivity numbers is really only useful among each product line. Or name the speakers you have and perhaps someone with experience with them can compare them.
 

Tone_Terrific

Silver Supporting Member
Messages
34,012
The balance of peaks and valleys is what matters and all you have to do is plug them both in together to try. It's a YMMV, again.
 

omahaaudio

Senior Member
Messages
1,878
Or name the speakers you have and perhaps someone with experience with them can compare them.
I have an Eminence EJ1250 (101dB) in one cab and I'm thinking of an Eminence GA-64 (100.5dB) or an Eminence Legend GB128 (101.3dB) in the other. But I also thought I'd check around for other makes, maybe a WGS Liberator 80 (98dB).
 

donnyjaguar

Member
Messages
4,194
I think if volume is your goal then pick up a 4x12 cabinet loaded with Celestions and be done with it.
 

J M Fahey

Member
Messages
2,940
+1 on downgrading Eminence published sensitivity specs by 3 dB.

Are they cheating?
No, the disclaimer is written right in the datasheet, just that it does not mean much for the average user.
As an example check a very popular speaker , the Legend 1258:
http://www.eminence.com/pdf/Legend_1258.pdf

where they state incredibly high 100.1 dB what actually a JBL or EV class speaker puts out.

So?

By the 100.1dB statement they write 3 asterisks *** leading you to the back of the sheet, where they explain how they got those numbers.
I doubt a Musician reads that.

Sensitivity*** 100.1 dB
* See footnotes on page 2 for information regarding nominal impedance, power rating and sensitivity.
*** The average output across the usable frequency range when applying 1W/1m into the
nominal impedance. i.e: 2.83V/8Ω, 4V/16Ω.
Here the problem starts.

They do not use 1W actual power but apply 2.83V audio , which "is the same" ... if the speaker is actually 8 ohms.

It's very common in Musical Instruments to actually have somewhat lower impedance, so with 2.83V they get more than 1 W ... this translates in apparent higher sensitivity.

Often you get an extra 1dB because of that ... not bad.



Eminence response curves are measured
under the following conditions: All speakers are tested at 1W/1m using a variety of test
set-ups for the appropriate impedance | LMS using 0.25" supplied microphone (software
calibrated) mounted 1m from wall/baffle | 2 ft. x 2 ft. baffle is built into the wall with
the speaker mounted flush against a steel ring for minimum diffraction
Here's the second sensitivity boost.

In general, sensitivity measurements are assumed with the speaker cabinet (which is "small" ) in the middle of free space, imagine it hanging from a baoon or something.

The point is that speakers are allowed to send sound all around ... which is realistic everybody knows that standing behind a closed cabinet you still hear it which means at least some of the sound is lost "behind".

There is a measurement system called "half space" where you mount the speaker in a large wall so all sound has nowhere else to go but towards the front ... this of course increases measured sensitivity , and is real for you too ... if you mount your cabinet flush against a wall ... even more if in a corner because it further reduces "free space" ... but in the real World that rarely happens (except, maybe, in a rehearsal studio) , your cabinets are usually away from walls.

Reread the Eminence measurement description and you'll see that they refer to "halfspace" conditions, which in theory raise sensitivity by 3 dB .
Even if only 2 dB extra, it still looks good in the brochure.

Peavey got pissed off that other brands quoted much higher sensitivities for speakers which were equivalent to theirs, so wrote a (somewhat bitter and with good reason) paper explaining it:
http://peavey.com/support/technotes/concepts/THE_LOUDSPEAKER_SPEC_SHEET_GAME_2005.pdf

this is so good that I think everybody should download, print and staple it to the wall, go figure, or it should be a sticky here.

By the way, they mention a "Brand E" speaker, casually 100 something dB published sensitivity, which in fact is not so.

The Peavey Paper conclusion is:
Conclusion
When comparing loudspeaker specifications, all the numbers need to be stated under the same conditions, if they are not for the same conditions, this can throw the numbers off by more than 10 dB for sensitivity, by 1/3 to ½ an octave for frequency response, or by 3 to 6 dB or more for power handling.
 

TimmyP

Member
Messages
2,488
It also matters how they spec'd it. In the PA world, honest folks spec it in the flattest part of the response. Disreputable makers spec it at that big peak that needs to be EQ'd out (similarly, they spec a sub at frequencies much higher than it will ever see). Most manufacturers split the difference (= semi-disreputable).
 

Bedeaich

Member
Messages
60
I love to mix speakers. Sure the volumes shouldn't be miles apart, but its more about if, when, and how the sound breaks up that counts. To have an EV12L chiming out at high levels next to a dark throaty Fane AXA12..add to that screaming G12 and you get a texture of timbre that's hard to beat. Add to that open and closed back cabs as a variable factor ! Why my wife refuses to understand this need I can not understand.
 

J M Fahey

Member
Messages
2,940
Well, YOU refuse to understand that the $1200 designer cocktail dress she bought 1 month ago can't be used on next Saturday party because "everybody has already seen her wearing it" so when you fork $1200 to buy a new one, she'll accept you buy a new speaker. ;)
 






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