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I am puzzled by some JBL. Tech sheets list measured at 15 feet

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Posted on February 18, 2024 at 08:26:17
Edp
Audiophile

Posts: 4636
Joined: September 23, 1999
 Was doing some digging on vintage JBL model crossover and was puzzled that JBL listed efficiency at 80 db. I knew the drivers fairly well and thought it to be miss print, but then saw this rating was at 15 feet, not the de facto 1 meter.

Checked a couple of other JBL marks (not individual drivers) of the time and sheets also used that distance. I can see this distance to have more importance to pro audio/ sound reinforcement circles.

Was or is this 15 feet measuring distance a general standard for that segment of audio or was JBL making their own ?

 

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RE: I am puzzled by some JBL. Tech sheets list measured at 15 feet, posted on February 18, 2024 at 08:36:19
Bill Fitzmaurice
Industry Professional

Posts: 5399
Location: New England
Joined: October 20, 2002
 The key word is vintage. Before the 1970s, and in some cases even more recently, many manufacturers went by their own rules. EV, for instance, measured sensitivity at 4 feet. As for JBL, there was a period during which their driver inputs were labeled black for +, red for -, the opposite of the accepted convention.

 

Are there present standards for that segment, not home audio?, posted on February 18, 2024 at 08:47:47
Edp
Audiophile

Posts: 4636
Joined: September 23, 1999
 In the pro audio / sound reinforcement are there standards for performance measurement that are not a normal home audio standard?

I could see, as an example, that polar response of a given setup would be more significant than home

 

RE: Are there present standards for that segment, not home audio?, posted on February 18, 2024 at 09:39:48
Bill Fitzmaurice
Industry Professional

Posts: 5399
Location: New England
Joined: October 20, 2002
 Not really. You see a lot more information, like polar response, because many pros want it, while most average consumers don't know what it means anyway. Interestingly the higher the price the more data you'll get in pro-sound, and the less you'll get in consumer sound. One must assume that high end manufacturers don't want potential customers to know that the Emperor isn't wearing any clothes.
The only instance where I've seen a major data improvement by a pro-sound manufacturer is Danley Sound Labs, who measure sensitivity with 100 watts at 10 meters, which is the equivalent of 1 watt at one meter. That gives a far better idea of how they work in real world conditions.

 

Interesting, thanks, posted on February 18, 2024 at 11:35:34
Edp
Audiophile

Posts: 4636
Joined: September 23, 1999
 Nice insight

Like the 10 meter and its direct relationship to the 1w/1m standard.

Fairly certain most of my home audio creations would sound / measure more like a mid squaker at 40 feet than a complete speaker

 

RE: Are there present standards for that segment, not home audio?, posted on February 18, 2024 at 18:41:01
claudej1@aol.com
Audiophile

Posts: 839
Location: Detroit
Joined: August 17, 2007
 I agree with the Danley measurement methods. They end up Under Rating the speaker performance, opposite of the rest is seems, since those others are overrated with peak sensitivities, etc.

 

RE: I am puzzled by some JBL. Tech sheets list measured at 15 feet, posted on February 23, 2024 at 09:58:07
Scholl
Distributor or Rep

Posts: 1364
Joined: March 8, 2001
 Belore purchasing a woofer I run the numbers through the reference frequency calculator found in the link. Some manufacturers use this some use measured peaks. Knowing this value can be helpful in identifying any rising responses seen on published graphs that'll need addressed with the crossover.

 

RE: reference frequency calculator, posted on February 23, 2024 at 11:13:40
Bill Fitzmaurice
Industry Professional

Posts: 5399
Location: New England
Joined: October 20, 2002
 I don't see the need for that. You get far more information using speaker modeling software.

 

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