When reading a response graph...

mazeroth · 27th August 2004, 12:40 AM

From Parts Express, which line do you look at? The top or the bottom? I'm mainly looking at tweeters and their response graphs have 2 graphs. Not sure which one to look at or what their differences are?

Thanks!

5th element · 27th August 2004, 02:11 AM

Im not entirely sure what you are refering too. For instance if I look at the Tang Band 28-847SA tweeter. You have four files to look at. One is the specs the manufacture produce which are pretty self explanatory. And then there is the measurements PE have taken themselves I assume. These both contain impedance -the thre resistance of the voice coil changes with frequency. And frequency response, which is how the output SPL of the tweeter varies with frequency. Both of those are equaly important. Then there are the Clio export txt files, which can be used by ppl with simulating programs to get the PE measured Freq res and impedance of the driver into their program easily.

If you are asking which do you use, the manufactures or PE? I would say none, measure yourself. But failing that Id probably use the PE. Why? they are not a manufacture trying to smooth out a bumpy freq graph, they will tell is as it is more often then not.

5th element · 27th August 2004, 02:13 AM

I just had a rethink, are you refering to the 0 degree and 30 degress off axis response of frequency response on the same graph? If so its up to you which one to choose. We rarely listen at 30 degress its more like 10 when sitting in a properly set up system. Either way its not that important. Although the off axis gives you a good indication of a woofers high frequency performance.

mazeroth · 27th August 2004, 09:10 PM

Thanks 5th, that's what I needed to know. After hearing you say the 30 degrees off axis it clicked in my mind and now I remember reading that before. Thanks

BillFitzmaurice · 27th August 2004, 09:38 PM

That 30 degree off axis response is far more important than on axis. For proper imaging it's recommended that the 30 degree response be no more than 6dB down from on axis, and that applies to all drivers, not just tweeters. This is how most designers decide on the crossover points.

27th August 2004, 12:40 AM	#1
mazeroth diyAudio Member Join Date: Jul 2004 Location: Columbus, OH	When reading a response graph... From Parts Express, which line do you look at? The top or the bottom? I'm mainly looking at tweeters and their response graphs have 2 graphs. Not sure which one to look at or what their differences are? Thanks!

27th August 2004, 02:11 AM	#2
5th element diyAudio Member Join Date: Oct 2002 Location: England	Im not entirely sure what you are refering too. For instance if I look at the Tang Band 28-847SA tweeter. You have four files to look at. One is the specs the manufacture produce which are pretty self explanatory. And then there is the measurements PE have taken themselves I assume. These both contain impedance -the thre resistance of the voice coil changes with frequency. And frequency response, which is how the output SPL of the tweeter varies with frequency. Both of those are equaly important. Then there are the Clio export txt files, which can be used by ppl with simulating programs to get the PE measured Freq res and impedance of the driver into their program easily. If you are asking which do you use, the manufactures or PE? I would say none, measure yourself. But failing that Id probably use the PE. Why? they are not a manufacture trying to smooth out a bumpy freq graph, they will tell is as it is more often then not. __________________ What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz! Droggon Attack!

27th August 2004, 02:13 AM	#3
5th element diyAudio Member Join Date: Oct 2002 Location: England	I just had a rethink, are you refering to the 0 degree and 30 degress off axis response of frequency response on the same graph? If so its up to you which one to choose. We rarely listen at 30 degress its more like 10 when sitting in a properly set up system. Either way its not that important. Although the off axis gives you a good indication of a woofers high frequency performance. __________________ What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz! Droggon Attack!

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27th August 2004, 09:10 PM	#4
mazeroth diyAudio Member Join Date: Jul 2004 Location: Columbus, OH	Thanks 5th, that's what I needed to know. After hearing you say the 30 degrees off axis it clicked in my mind and now I remember reading that before. Thanks

27th August 2004, 09:38 PM	#5
BillFitzmaurice Banned Join Date: May 2004 Location: New Hampshire	That 30 degree off axis response is far more important than on axis. For proper imaging it's recommended that the 30 degree response be no more than 6dB down from on axis, and that applies to all drivers, not just tweeters. This is how most designers decide on the crossover points.

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