Question on Zaph's 5.5" and 6.5" FR measurement

Jay_WJ · 28th July 2007, 01:41 AM

Looking at Zaph's 5.5" and 6.5" midwoofer infinite baffle FR measurements, I found something strange. In his FR plots, most of 5.5" drivers' bass roll off begins little over 100 Hz. But most of 6.5" drivers' bass roll off starts at as high as 250 - 300 Hz. This seems counter-intuitive to me. 6.5" drivers should have stronger bass that 5.5", don't they?

Zaph mentioned that he didn't use indentical settings to measure these groups of drivers. For example he said that he did not merge near field measuremnt for his 6.5" measurements. Is this the reason for different bass roll off behaviors? Then which of his measurement data (5.5" versus 6.5") show more accurate bass response on an infinite baffle?

augerpro · 28th July 2007, 09:00 PM

He used a 5ms gate with no merged nearfield on teh 6.5", so yes these are not accurate in the lower frequencies. I wouldn't believe them much below 300Hz or so.

The 5.5" group has a better representation of these lower frequencies.

Jay_WJ · 29th July 2007, 04:33 AM

Thanks, Brandon. Yes, now it makes sense if he used 5 ms gating and no merged near field measurement for his 6.5" FR.

28th July 2007, 01:41 AM	#1
Jay_WJ diyAudio Member Join Date: Mar 2006 Location: Indiana	Question on Zaph's 5.5" and 6.5" FR measurement Looking at Zaph's 5.5" and 6.5" midwoofer infinite baffle FR measurements, I found something strange. In his FR plots, most of 5.5" drivers' bass roll off begins little over 100 Hz. But most of 6.5" drivers' bass roll off starts at as high as 250 - 300 Hz. This seems counter-intuitive to me. 6.5" drivers should have stronger bass that 5.5", don't they? Zaph mentioned that he didn't use indentical settings to measure these groups of drivers. For example he said that he did not merge near field measuremnt for his 6.5" measurements. Is this the reason for different bass roll off behaviors? Then which of his measurement data (5.5" versus 6.5") show more accurate bass response on an infinite baffle?

28th July 2007, 09:00 PM	#2
augerpro diyAudio Member Join Date: Aug 2006	He used a 5ms gate with no merged nearfield on teh 6.5", so yes these are not accurate in the lower frequencies. I wouldn't believe them much below 300Hz or so. The 5.5" group has a better representation of these lower frequencies. __________________ ~Brandon DriverVault Soma Sonus Old Driver Tests

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29th July 2007, 04:33 AM	#3
Jay_WJ diyAudio Member Join Date: Mar 2006 Location: Indiana	Thanks, Brandon. Yes, now it makes sense if he used 5 ms gating and no merged near field measurement for his 6.5" FR.

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