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Author Topic: Sub Question  (Read 8186 times)

Mark McFarlane

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Re: Sub Question
« Reply #10 on: August 17, 2014, 01:01:22 PM »

In essence it is saying that 42Hz is 3db softer than whatever the peak of the sub is, and 36Hz is another 7 db (i.e. a lot) softer.
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Mark McFarlane

Bob Burke

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Re: Sub Question
« Reply #11 on: August 17, 2014, 01:48:18 PM »

Thanks Mark.

Scott Holtzman

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Re: Sub Question
« Reply #12 on: August 17, 2014, 04:40:39 PM »

Sorry to resurrect this thread, but I'm confused about the specs JBL provides for this sub, particularly the frequency range(s).

(http://www.sweetwater.com/store/detail/EON518S/)


System Type: Self powered 18", bass-reflex design
Frequency Range (-10 dB): 36 Hz - 130 Hz
Frequency Response (±3 dB): 42 Hz - 100 Hz

Crossover Frequency: 120 Hz (HPF switchable on outputs)
System Power Rating: 500 W continuous, 1000 W peak


  What is the difference between the -10 dB and the  +  3 dB rating? Does this sub produce down to 36 Hz or 42 Hz? I know that I should know, but I've forgotten half of what I did know already! ;D


Thanks.


Bob

The -10 is a sloppier spec.  It means that within the stated frequency range the driver can reproduce that frequency with -10db(spl I think) of 0.  That's a big swing, more than three orders of magnitude.

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Scott AKA "Skyking" Holtzman

Ghost Audio Visual Solutions, LLC
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Mac Kerr

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Re: Sub Question
« Reply #13 on: August 17, 2014, 04:45:12 PM »

The -10 is a sloppier spec.

It is a looser spec, being equivalent to +-5dB instead of the +-3dB we see most often in specs.

Mac
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Bob Burke

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Re: Sub Question
« Reply #14 on: August 17, 2014, 04:54:32 PM »

Thanks for the info guys. I just ordered the sub, so.... fingers crossed.

Ivan Beaver

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Re: Sub Question
« Reply #15 on: August 17, 2014, 06:18:41 PM »

Does this sub produce down to 36 Hz or 42 Hz?

ANY loudspeaker (ever tweeters) will easily "produce down to" 1Hz.  No problem.

NOW HOW LOUD it is at that freq is a TOTALLY different story!

There are all sorts of different "games" that manufacturers "play" with specs.  Some more than others.

In MY opinion (others are willing to differ), the low freq response HAS to be tied to the rated sensitivity-or else it has very little meaning.

For example (I'm just making this spec up) let's say the rated sensitivity is 100dB.

The freq at which the response in 3dB down (97dB) should be the -3dB point.  The point at which the level is 10dB down (90dB) is the -10dB rating.

If these are not tied together-then you can come up with all sorts of specs that don't mean anything.

In the above example let's say that there is a peak in the response at 500Hz (we are talking about a sub here).  The manufacturer could rate that peak as being the "sensitivity", but it would be VERY misleading as to how loud the speaker would be in the intended range it would be used.

Let's say this peak is 6dB higher (106dB) than the "realistic" rating of 100dB (as measured down in the sub range).  This would mean that you would need twice as many subs to get the levels you would "think" you would be getting-based on the rating at 500Hz.

Yes the numbers MATTER-and it is VERY important to not only look at the "simple number" but ALSO the measured response-to get an idea where the numbers came from.

If you don't see a measured response then you have no idea where the numbers came from or how realistic they are.

There is no standard-so you HAVE to look a bit closer when comparing specs to see how well they REALLY stand up to each other.

Of course none of the specs even begin to tell what the speaker actually SOUNDS like.

That is a totally different subject-for which I am not sure there is any metric or spec-other than subjective.

And even THAT is very different.  Some people like a smooth response-others like the "agressive ice pick in the forehead" type sound.  Yes I have had a good number of people tell me over the years they want the system to "hurt" the audience and "drill through" the audience.  So they prefer a system with "an edge" to it.

Oh well-------------------
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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!

Tim Padrick

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Re: Sub Question
« Reply #16 on: August 17, 2014, 10:25:09 PM »

Lets not forget distortion.  At the -10 freq I'll bet it's very high, so don't bother trying to get more out of the sub with an EQ boost.
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Mark McFarlane

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Re: Sub Question
« Reply #17 on: August 17, 2014, 11:43:58 PM »

...
If you don't see a measured response then you have no idea where the numbers came from or how realistic they are.....

And, unfortunately, the measured response 'graph' that is published may be smoothed so much as to be misleading.
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Mark McFarlane

Bob Burke

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Re: Sub Question
« Reply #18 on: August 18, 2014, 07:04:58 AM »

  Man, I learn so much here it's incredible. I'm just a ham and egger, but through all the advice I've received here at PSW, I've managed to put together a nice little, good sounding rig. This JBL sub will give us some boom, and help keep people on the dance floor.

  Thanks again to you all.


Regards,

Bob

Bob Burke

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Re: Sub Question
« Reply #19 on: August 18, 2014, 08:27:18 AM »

Just when you thought this tedious thread was over...... ::)  I  need advice on hooking this sub up.

This is the sub:

http://www.sweetwater.com/store/detail/EON518S/

 I have a Soundcraft EFX8 (http://www.sweetwater.com/store/detail/EFX8/) into a Dbx 1231 (http://www.sweetwater.com/store/detail/1231) into a QSC PLX 1804 (http://www.sweetwater.com/store/detail/PLX1804/).

  Normally, I run the main outs from the mixer into the EQ, then to the power amp, then to my passive Yamaha S115V mains. What is the correct method of hooking the JBL sub into this system? I have to buy the cabling, and want to make sure that I get the right stuff.


Thanks,

Bob

ProSoundWeb Community

Re: Sub Question
« Reply #19 on: August 18, 2014, 08:27:18 AM »


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