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Author Topic: Transient response?  (Read 2957 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.

Steve-White

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Re: Transient response?
« Reply #33 on: May 09, 2021, 01:35:10 PM »

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.

"Young and stupid" has an eerily familiar ring to it...  :)

The worst time I had with drivers was the initial year of running horns for mid-highs.  Altec 511 & 811's with I believe were 802D compression drivers on them.  Whatever crossover I was using I don't remember, but it was Altec passive.  After going though several diaphragms, I purchased my first electronic crossover, Ashly SC80.  Problem solved and the system sounded better to boot.

Then moving into 2" compression drivers and 90 x 40 fiberglass radial horns, meant I had lots more top end available, then the bottom end needed some upgrades to keep up.  Once LF components were upgraded to match the top end, came learning how to dial in the setup.  Sent a few 12" & 18" drivers to the promised land when learning how to setup limiters, system gain structure, and drive levels.

I enjoy reading through posts about how much amplifier for a given loudspeaker system or component and how some members comment on how much power they use.

For me, enough amp to burn down the stacks, then back it off around 2db and you're there.  The ones that mention they use astronomical amount of power, don't mention trips to the recone shop.  Which tells me they haven't hit the top end of the performance envelope - turn it up.  The only way to really know the limit is to push past it.  Talking passive speakers.

No idea if this applies to the pre-packaged powered stuff - but likely varies from brand to brand.
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Re: Transient response?
« Reply #33 on: May 09, 2021, 01:35:10 PM »


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