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Author Topic: Transient response?  (Read 1751 times)

Art Welter

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Re: Transient response?
« Reply #30 on: April 14, 2021, 03:24:41 pm »

I used to run a pair of single JBL rear horn loaded "scoops" per side in a DJ setup.  JBL E-140's in them, Phase Linear 400 for power with Altec 511 horns.

Thinking back, the JBL + or red phase for DC was for the cone to pull in with a positive voltage applied to the red terminal which is the opposite to many other brands.
Altec changed their polarity conventions to the AES standard in the late 1960s, JBL continued with their "backwards" negative polarity on legacy woofers like the E-140.

A system or transducer is said to be negative if a positive-going voltage applied to its red (non-black) terminal causes a negative pressure at the output of the device. As of 2005, the following JBL woofers were still negative:
E110, E120, E130, E140, E155, LE8T, 2118, 2202, 2220, 2235, 2241, 2105, 2123,  2206, 2226, 2240, 2245.

However, in most cases, JBL loudspeaker systems, even if they make use of negative polarity transducers, were internally wired so that they “behave” as positive systems. That is, a positive signal at the 1/4" phone plug tip or red or positive terminal of the system, caused the low frequency cone to move outward.

Fun.



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Ivan Beaver

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Re: Transient response?
« Reply #31 on: April 15, 2021, 05:03:16 pm »

Altec changed their polarity conventions to the AES standard in the late 1960s, JBL continued with their "backwards" negative polarity on legacy woofers like the E-140.

A system or transducer is said to be negative if a positive-going voltage applied to its red (non-black) terminal causes a negative pressure at the output of the device. As of 2005, the following JBL woofers were still negative:
E110, E120, E130, E140, E155, LE8T, 2118, 2202, 2220, 2235, 2241, 2105, 2123,  2206, 2226, 2240, 2245.

However, in most cases, JBL loudspeaker systems, even if they make use of negative polarity transducers, were internally wired so that they “behave” as positive systems. That is, a positive signal at the 1/4" phone plug tip or red or positive terminal of the system, caused the low frequency cone to move outward.

Fun.
I learned the hard way about JBLs backward polarity.

It is the first gig I did with all of my woofer cabinets.  Half were loaded with JBL and the other half with EV.

WHen I fired them all up, it wasn't as much bass as I needed or expected, so obviously I TURNED IT UP MORE.  What else do you do when you are young and stupid.

I had some replacement EV woofers on hand (just in case).  The guy providing the lights (who also owned a large PA in town) was helping me replace the drivers and he said "Did you know your JBLs are wired up backwards?".

He told me to take a battery to them after I got them reconed.

The lessons we learn the hard way.
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

Mike Caldwell

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Re: Transient response?
« Reply #32 on: April 15, 2021, 08:55:21 pm »

Altec changed their polarity conventions to the AES standard in the late 1960s, JBL continued with their "backwards" negative polarity on legacy woofers like the E-140.

A system or transducer is said to be negative if a positive-going voltage applied to its red (non-black) terminal causes a negative pressure at the output of the device. As of 2005, the following JBL woofers were still negative:
E110, E120, E130, E140, E155, LE8T, 2118, 2202, 2220, 2235, 2241, 2105, 2123,  2206, 2226, 2240, 2245.

However, in most cases, JBL loudspeaker systems, even if they make use of negative polarity transducers, were internally wired so that they “behave” as positive systems. That is, a positive signal at the 1/4" phone plug tip or red or positive terminal of the system, caused the low frequency cone to move outward.

Fun.

The models still in production from your list 2206, 2226, 2241 are still backwards just to to keep it less confusing when working with different eras of the same model.
Some thing applies to their compression drivers.

New JBL models note the standard polarity on the speaker as a reminder.

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Re: Transient response?
« Reply #32 on: April 15, 2021, 08:55:21 pm »


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