Sensitvity

[tom1040]

Okay. Why is the JBL 1400 Array's sensitivity rating 'low'. 89. The rest of the current "higher end" JBL's horn speakers are around 92-95.

Is it because of the area that most of the sales are going to-Asian marketplace? Can someone please explain this and also explain why a 400 wpc amp may not be enough for speakers rated for a maximum amp of 300 wpc? This has been bugging me.:banghead:

Thank you.

[4313B]

The LE14H-3 has a nominal sensitivity rating of 91 dB plus or minus 1 dB (2.83V @ 1m). The answer to your question can be seen in the voltage drive to the LE14H-3 in the 1400 Array:

300 wpc should be plenty for a pair of 1400 Arrays in a typical living room unless you like ringing ears and eventual hearing loss.

[tom1040]

Thanks. If you say so. I am an accountant not an engineer, Jim.:)I guess my question gets down the the notion that horn speakers are usually higher in sensitivity, are they not? Perhaps this is not true for all horn speakers.

[Robh3606]

Perhaps this is not true for all horn speakers.

Normally it depends on what the woofer sensitivity is. If you want a good solid low end like you get from the LE-14 or 2235 you sacrifice efficiency to get it. But it also depends on the type of horn used as well. If you do a passive compensation on a CD horn you attenuate the midrange and again that can also set what the maximum sensitivity is for the system. Case in point would be a 4435 for that example. Once you try to push things beyond about 96dB the passive compensation won't work and you loose the top octave.

Rob:)

[JoMoCo]

If your amplifier is an auto former output as stated in your other thread...then low impedance, current / voltage demand / sensitivity are factors your auto-transformer output circuit is designed to interface-modulate-filter back to the amplifier a more benign load. :yes:

If you did not have an auto former output then low impedance / phase at crossover / current / voltage demand / sensitivity issues be come more interactive with the amplifier output in a wider range of possibilities.:hmm:

[Mr. Widget]

I guess my question gets down the the notion that horn speakers are usually higher in sensitivity, are they not?:yes:


Perhaps this is not true for all horn speakers.:yes:

While the answer above in post #2 was exacting and complete, I suppose to answer your question in words instead of graphs, you need to understand the following.

In most horn systems, the drivers when mated to the proper horns are quite sensitive. However, frequently they are not extremely linear. Some classic designs are fairly linear on axis, but due to rapidly falling frequency response off axis, they have a rather poor power response. (The response of a system taken through and entire listening arc.) This can be extremely important in some rooms and will always affect the coloration or lack of coloration of a system.

To remedy these failings of vintage systems, JBL has engineered systems that sacrifice some of their high sensitivity to provide excellent frequency response and power response. Because of these improvements, the 1400 Array sounds significantly better than almost all horn systems and most conventional non horn systems as well.


Widget

[speakerdave]

In order for a speaker to have flat frequency response the acoustic output of all the drivers must be the same. Sensitivity rating of drivers is an acoustic rating. It states the acoustic output for a given electrical input voltage. Consequently the drivers in a system which are more efficient (sensitive) at transforming electrical energy into acoustic energy must be fed smaller amounts of electrical signal. Usually the woofer is the least sensitive driver. In fact when choosing drivers for a speaker, midranges and tweeters less sensitive than the woofer are usually carefully (and easily) avoided.

As Widget said, electrical signal to midranges and tweeters is incidentally reduced by measures taken to correct frequency response anomalies in the drivers and to balance frequency response and power response in the system, because these corrections, when done with passive devices like crossover filters, involve damping higher responding frequency ranges in the driver, not boosting low response frequency ranges. You can see in the graphs posted above that the electrical signals to the midrange and tweeter are much less than the signal to the woofer, and that the individual signals to the drivers are tilted and/or notched to correct for nonlinearities in the drivers' response. After these corrections have been made, whatever excess acoustic output remains in the midrange and/or tweeter can be compensated for with the use of L-pads, either adjustable or fixed.

Therefore, two speaker systems may have the same horn midrange and tweeter, but if they have different woofers of differing sensitivity, the system with the less efficient woofer, after all the compensating measures have been engineered into the system, will have a system sensitivity that is lower than the system with the more efficient woofer.

Generally speaking, when considering woofers of the same size, for use in an enclosure of a given size, to design a woofer with linear response that will reach well into the VLF entails a heavier cone, which will require greater energy to move, and therefore will be less efficient, less sensitive. The LE14-3 is such a woofer, and therefore a system designed around it will end up having a lower sensitivity rating.

[boputnam]

In order for a speaker (system or cabinet) to have flat frequency response the acoustic output of all the drivers must be the same. ... Consequently the drivers in a system which are more efficient (sensitive) at transforming electrical energy into acoustic energy must be fed smaller amounts of electrical signal. +1

This a critical aspect of balancing the acoustic output of biamped, tri-amped or quad-amped systems. In SR, once we tune and time-align a system, we use differential gain technique to maintain proper acoustic balance between the band passes. The "proper" balance will change as the room response changes with more, or less, audience.

[Mr. Widget]

+1

This a critical aspect of balancing the acoustic output of biamped, tri-amped or quad-amped systems. In SR, once we tune and time-align a system, we use differential gain technique to maintain proper acoustic balance between the band passes. The "proper" balance will change as the room response changes with more, or less, audience.Sure but this would suggest the 1400 Array would have a sensitivity of 91dB... and it would if it used a simple network that only padded down (shelved) the HF and UHF drivers to match the woofer... this is the way older JBL systems and everyone else's systems used to be... however since JBL is using a significantly more sophisticated network and constant directivity horns, the frequency response and power response are truly excellent at the expense of overall sensitivity. The system sensitivity is brought down a couple of dB lower than even the woofer alone.


Widget

[tom1040]

Okay. Thanks to all. I understand. However, some additional questions if you don't mind. Why is the 1400 Array 'only' rated to 300 wpc rms recommended amp? Are the Mid & HF transducers 'delicate'. One of the other misconceptions I have, I guess, is that 'horn' speakers are built to handle alot of power and be driven hard.

Sorry to continue to show my lack of knowledge in this area but since these speakers are on my list I must aquire more information about them.

Thanks for your time.

[Mr. Widget]

One of the other misconceptions I have, I guess, is that 'horn' speakers are built to handle alot of power and be driven hard.Yes, that is a misconception.

Sure there are PA systems that take tons of power, but systems designed for domestic use rarely can handle even 300 wpc. The Klipschorn is rated to take 100 wpc, the 4333 (L300) was rated to take 75 watts, the original Everest was rated at 200 watts.... but yes the K2-S9800, K2-S9900, and Everest II are all rated to be able to withstand more than the 1400 Array... because the 1500AL and 1501AL woofers can take more power. The HF components are not the limiting factor. That said, these ratings are fairly generic. All speakers can withstand considerably more power than their rated power on peaks, but the actual amount depends on the type of source material.

Regardless, you seem to be overly concerned with something that really is third tier in relative importance.


Widget

[tom1040]

Please expand on the first two.

[Mr. Widget]

Please expand on the first two.Could you be more specific... I don't understand the question.


Widget

[tom1040]

I am sorry. Your explanation in your last post ended with this:

"Regardless, you seem to be overly concerned with something that really is third tier in relative importance"

I guess I was wondering what the first two items of relative importance of the 'tier':blink:

Thanks.

[Mr. Widget]

I wasn't being literal, I was merely suggesting that you are focusing on something that simply isn't all that important in the normal use of the product... especially since you already own an amplifier that has ample power.... now if for some reason you were locked in to using a 10 watt amp, you might have a real concern, but that isn't the case.

In general, power handling and sensitivity are not a real issue for home music systems... in pro audio it is a very significant consideration, but in the home few people play music at sustained levels much above the high 90's... you may be the exception, but unless you really need to play your music at sustained levels above 110dB, there is simply little reason for concern. Beyond that, many older systems that can play at these levels will suffer from dynamic compression... the 1400 Array like most current high end JBLs is far less susceptible to this very real problem.


Widget

[tom1040]

Thank you.

[Allanvh5150]

Something that no one has touched on is the fact that horn speakers were designed back in the day when amplifier power was quite small. The engineers needed a way to get more sound per watt. However, when the world changed tack and moved to direct radiating systems the horns remained for the simple fact that th HF drivers were quite small and didnt need a lot of power to produce a high acoustic level. The horn is also used to obtain a specific coverage.

Allan.