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Author Topic: Acceptable deviation between boxes?  (Read 1178 times)

boburtz

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Acceptable deviation between boxes?
« on: July 24, 2018, 03:41:04 pm »

I measured transfer functions of 16 KF730 boxes individually, each with the exact same measurement conditions. I am curious as to what is an acceptable variance box to box for stuff like this. Is there a standard?  They average out to something close to the published EAW spec, but individually there are some variations that seem to be pretty large.  Does this look normal? If not, do you have any idea what could be causing this or a suggested solution?
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Nathan Riddle

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Re: Acceptable deviation between boxes?
« Reply #1 on: July 24, 2018, 03:49:33 pm »

I measured transfer functions of 16 KF730 boxes individually, each with the exact same measurement conditions. I am curious as to what is an acceptable variance box to box for stuff like this. Is there a standard?  They average out to something close to the published EAW spec, but individually there are some variations that seem to be pretty large.  Does this look normal? If not, do you have any idea what could be causing this or a suggested solution?

I believe Ivan has spoke about individual components' tolerances are sometimes swings of 3dB. Could explain the 6dB discrepancy between two farthest deviated components?
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Nathan Riddle

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Re: Acceptable deviation between boxes?
« Reply #2 on: July 24, 2018, 03:51:49 pm »

Oh and you've obviously been around via your post count, so I'm assuming the name is Bob Urtz and admins are fine? Threw me for a loop for a sec   ;D
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David Sturzenbecher

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Re: Acceptable deviation between boxes?
« Reply #3 on: July 24, 2018, 04:21:24 pm »

I measured transfer functions of 16 KF730 boxes individually, each with the exact same measurement conditions. I am curious as to what is an acceptable variance box to box for stuff like this. Is there a standard?  They average out to something close to the published EAW spec, but individually there are some variations that seem to be pretty large.  Does this look normal? If not, do you have any idea what could be causing this or a suggested solution?

I would be interested to see the complex impedance curves of these boxes as well, so see if there is corresponding differences there too.


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John Roberts {JR}

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Re: Acceptable deviation between boxes?
« Reply #4 on: July 24, 2018, 05:01:28 pm »

I measured transfer functions of 16 KF730 boxes individually, each with the exact same measurement conditions. I am curious as to what is an acceptable variance box to box for stuff like this. Is there a standard?  They average out to something close to the published EAW spec, but individually there are some variations that seem to be pretty large.  Does this look normal? If not, do you have any idea what could be causing this or a suggested solution?
It comes down to cost... When boxes are intended to be arrayed there is an ASSumption that they will match reasonably well to play together nicely.

I went through this last century with Peavey dealers being unable to convince them why the more expensive drivers required for boxes meant for being arrayed were justified over the otherwise similar boxes playing by themselves, where tolerance matching was not as important.

JR

PS: Of course I have no specific information about those exact boxes, just in general.

PPS: I am not the speaker guy here. I just know a little about a lot.
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Don T. Williams

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Re: Acceptable deviation between boxes?
« Reply #5 on: July 24, 2018, 06:36:09 pm »

This is not specific to this model, but if these were purchased in different lots at different times there could be different brands and models of drivers.  How many versions of the KF850 were made?  Kudos to EAW for trying to keep improving the product.  Drivers do age, and not every box may go out on every show, so they may not have all seem the same use (or abuse).
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Tim McCulloch

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Re: Acceptable deviation between boxes?
« Reply #6 on: July 24, 2018, 11:33:39 pm »

Oh and you've obviously been around via your post count, so I'm assuming the name is Bob Urtz and admins are fine? Threw me for a loop for a sec   ;D

Bob has been around for at least 2 iterations of the PSW forums....
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Scott Holtzman

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Re: Acceptable deviation between boxes?
« Reply #7 on: July 25, 2018, 01:45:58 am »

Man Nate you are going to shit yourself of Abdhul EQ shows up.

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John Roberts {JR}

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Re: Acceptable deviation between boxes?
« Reply #8 on: July 25, 2018, 09:28:43 am »

Man Nate you are going to shit yourself of Abdhul EQ shows up.

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Careful if we repeat his name 3x the dessert wanderer may chime in.... 8) 

but that is not a bad thing to receive his wisdom from the sands of time.

JR
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On the internet people tell you everything "they" know, not the answer to "your" question.....  http://circularscience.com/

Tim McCulloch

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Re: Acceptable deviation between boxes?
« Reply #9 on: July 25, 2018, 04:50:18 pm »

Careful if we repeat his name 3x the dessert wanderer may chime in.... 8) 

but that is not a bad thing to receive his wisdom from the sands of time.

JR

It's about time for him to surface from the sandstorms, was Dec 2015 when he last checked in.
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"Practicing an art, no matter how well or badly, is a way to make your soul grow, for heaven's sake. Sing in the shower. Dance to the radio. Tell stories. Write a poem to a friend, even a lousy poem. Do it as well as you possible can. You will get an enormous reward. You will have created something."  - Kurt Vonnegut
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