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Author Topic: Speaker measurements  (Read 8247 times)

Kent Thompson

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Re: Speaker measurements
« Reply #10 on: July 30, 2012, 01:36:10 pm »

"Oh Great Guru Tucci" has too many syllables. ;)

Paul, what I find interesting is the uniformity of results regardless of measurement coherence.  Also, since the OPs are measuring boxes with passive crossovers I wonder *why* a manufacturer would ship such products; i.e. I think the OPs need to contact the OEM and ask "is this what I should be seeing?"

I'm yet to be convinced we're looking at valid measurements.

I will contact the OEM and ask. I know I can do that right  :P
Since measurements are new to me I would not doubt that I could be doing something wrong. Hence my posting here to ask.
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Paul Tucci

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Re: Speaker measurements
« Reply #11 on: July 30, 2012, 04:20:31 pm »

I will contact the OEM and ask. I know I can do that right  :P
Since measurements are new to me I would not doubt that I could be doing something wrong. Hence my posting here to ask.

My money is on a valid measurement indicating that the acoustic crossover region has issues.
If we could just flip polarity of the top and to see if the current dip raises in amplitude without causing damage elsewhere.
I'm not a doctor, but apparently I play one on the internet. My diagnosos from the pictures presented...I'm seeing a relatively narrow bandwidth of overlap that is equal amplitude and therefore prone to either constructive addition or interference. I'll hazard a guess to say the the combined crossover slopes (the physical passive crossover and the natural rolloffs of the component drivers) are steep. And one is out of polarity in relation to the other IN THAT NARROW BANDWIDTH THAT SHOWS A DIP IN AMPLITUDE RESPONSE.

What is the speaker in question anyways?

PT
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Ales Dravinec

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Re: Speaker measurements
« Reply #12 on: July 30, 2012, 04:34:49 pm »

What is the speaker in question anyways?

PT

http://www.zzounds.com/item--PEVPR12N

... if I've read the original thread correctly .

w/r
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Kent Thompson

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« Last Edit: July 30, 2012, 05:06:04 pm by Kent Thompson »
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Ales Dravinec

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Re: Speaker measurements
« Reply #14 on: July 30, 2012, 05:04:59 pm »

This is a different speaker the model is SP4

Ahhh, my bad. Sorry, Kent.

This is now a whole new ball game for me .... :)

There's no certain way for me to know about LF drivers being paralleled or whether one of them is rolled off lower. The manual doesn't say.

If LF drivers are in fact wired in parallel, you may indeed experience funny behavior, highly dependent on measuring position in vertical plane. Especially in the crossover area where you have now 3 points of origin (sound sources) .... Moving the mic FAR away would lessen the dip if that topology in fact stands.

The 'trick' with covering individual components of the box can be revealing and rewarding enough.

w/r
« Last Edit: July 30, 2012, 06:10:17 pm by Ales Dravinec »
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Tim McCulloch

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Re: Speaker measurements
« Reply #15 on: July 30, 2012, 05:28:22 pm »

Ahhh, my bad. Sorry, Kent.

This is now a whole new ball game now for me .... :)

There's no certain way for me to know about LF drivers being paralleled or is one of them rolled off lower. The manual doesn't say.

If LF drivers are in fact wired in parallel, you may indeed experience funny behavior, highly dependent on measuring position in vertical plane. Especially in the crossover area where you have now 3 points of origin .... Moving the mic FAR away would lessen the dip if that topology in fact stands.

The 'trick' with covering individual components of the box can be revealing and rewarding enough.

w/r

This was exactly what I was speculating about in an earlier post.
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Kent Thompson

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Re: Speaker measurements
« Reply #16 on: July 31, 2012, 01:30:22 pm »

Ahhh, my bad. Sorry, Kent.

This is now a whole new ball game for me .... :)

There's no certain way for me to know about LF drivers being paralleled or whether one of them is rolled off lower. The manual doesn't say.

If LF drivers are in fact wired in parallel, you may indeed experience funny behavior, highly dependent on measuring position in vertical plane. Especially in the crossover area where you have now 3 points of origin (sound sources) .... Moving the mic FAR away would lessen the dip if that topology in fact stands.

The 'trick' with covering individual components of the box can be revealing and rewarding enough.

w/r

Just the sort of info I needed. So I need to make sure to be farther away on these type of cabinets when measuring the whole cabinet.  The only way to tell what is happening is to not only measure the horn and woofers separate but also the woofers individually to see what is happening with them? What distance would  be needed to get a decent measurement on cabinets like these?  Any other hints on the process I should use to measure these?
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Arthur Skudra

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Re: Speaker measurements
« Reply #17 on: July 31, 2012, 03:47:22 pm »

Just the sort of info I needed. So I need to make sure to be farther away on these type of cabinets when measuring the whole cabinet.  The only way to tell what is happening is to not only measure the horn and woofers separate but also the woofers individually to see what is happening with them? What distance would  be needed to get a decent measurement on cabinets like these?  Any other hints on the process I should use to measure these?
As a rule of thumb, I tell my students to place the mic at least 3 to 4 times the diagonal dimension of the front face of the box, and try to center it between the individual components.
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Kent Thompson

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Re: Speaker measurements
« Reply #18 on: August 03, 2012, 01:18:04 pm »

I did get a message back from the manufacturer who echoed what was said about where I measured from. He also gave me a lot of good information on how the cabinet performed and what to expect. It was a very good email I was impressed. I did not expect them to be this forthcoming with information. He was also concerned about what looked like a polarity reversal on the horn. Something I will have to check next time I have access to the speakers.
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Re: Speaker measurements
« Reply #18 on: August 03, 2012, 01:18:04 pm »


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