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Frequeccy response? [message #23870]

Sat, 14 July 2007 19:29

Tom R.
Messages: 51
Registered: May 2009

Baron

When measuring frequency response of a line array, should the mike be at the standard one meter distance from the speaker, or further back at the listening position?

Tom R

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Re: Frequeccy response? [message #23872 is a reply to message #23870]

Sun, 15 July 2007 19:33

Wayne Parham
Messages: 18789
Registered: January 2001

Illuminati (33rd Degree)

You could measure at 10 meters with 100 watts of input power. This would give you the same decibel value as 1W/1M, and would reduce the problem of path length differences from different points on the line.

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Re: Frequeccy response? [message #23875 is a reply to message #23872]

Mon, 16 July 2007 19:54

Tom R.
Messages: 51
Registered: May 2009

Baron

Wayne - Why 10 meters and 100 watts? Not sure the test gear can can go up to 100 watts, and 10 meters will be way beyond the nearfield I will be listinging to? Please explain, thanks for responding.

Tom R.

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Re: Frequeccy response? [message #23877 is a reply to message #23870]

Tue, 17 July 2007 12:36

Rick Craig
Messages: 115
Registered: May 2009

Viscount

How many drivers and what kind? What measurement gear do you have?

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Re: Frequeccy response? [message #23878 is a reply to message #23875]

Tue, 17 July 2007 12:40

Wayne Parham
Messages: 18789
Registered: January 2001

Illuminati (33rd Degree)

When measuring at 10 meters, you'll have less path length differences between the measurement microphone and different points on the line. Using 100 watts, the SPL will be the same as 1 watt would be, when measured at 1 meter.

If you want to measure nearfield, you'll have to do something else. You could measure close to each element, but this wouldn't show the effects of summing. Perhaps the best thing to do would be to measure at several places and create polar plots at various distances. Then you would know the response everywhere in 3D space.

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Re: Frequeccy response? [message #23879 is a reply to message #23877]

Tue, 17 July 2007 20:58

Tom R.
Messages: 51
Registered: May 2009

Baron

8, Focal 5.25" 5K013L's mid bass drivers perside and a single Raven 1 ribbion tweeter, offset to the side.
Test gear is an old HP signal generator, paper chart recorder, and Mighty Mike micriphone.

Tom R.

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Re: Frequeccy response? [message #23880 is a reply to message #23879]

Tue, 17 July 2007 21:20

Rick Craig
Messages: 115
Registered: May 2009

Viscount

The Raven isn't going to work in this design. You'll need a tweeter than can handle a much lower crossover point. Sorry to bring the bad news but I hate to see you waste time (and possibly $) trying to make this perform well.

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Re: Frequeccy response? [message #23882 is a reply to message #23879]

Wed, 18 July 2007 06:38

Marlboro
Messages: 403
Registered: May 2009

Illuminati (1st Degree)

Did you already build this bad design, or are you just contemplating it?

I know how this can work. I have a really badly designed line array myself, which sounds spectacular. This is probably because I have bad ears.

I would ask you if you are using a neutral mic. What is a Mighty Mike?

Marlboro

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Re: Frequeccy response? [message #23883 is a reply to message #23882]

Wed, 18 July 2007 06:59

Tom R.
Messages: 51
Registered: May 2009

Baron

The speaker cabinets are built, (sealed) drivers installed. I have some finish work to do, grills, and mount the Ribbon tweeter.
I do no own the test gear, but a friend does. In a few weeks I will have the spare time to take the new speakers to his house for initial measurements, and am looking for proper test procedures for measuring line arrays.
Mighty Mike is a brand name of the calibrated micriphone that will be used for the test - I may not have the name 100 percent correct - working from memory.

Tom R.

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Re: Frequeccy response? [message #23884 is a reply to message #23880]

Wed, 18 July 2007 07:24

Tom R.
Messages: 51
Registered: May 2009

Baron

The Raven is olny a temporary solution as I own them. I hope to purchase an array of ribbons / plainers/ something in the future The midbass drivers are mounted as close together as possible, and the raven is mounted off to the side. I view this as a long term project with many development stages as my knowledge grows and money becomes availabe.

Thanks,
Tom R

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