Hi All,
Working on my first DIY MTMs and wanted to begin by first confirming the measurement technique that should be employed.
I’ve read through the “Measurement Preparation with ARTA” document, but still have a couple of questions (included below). I think I’ll be okay measuring the tweeter. My question(s) mostly pertain to measuring the two 4ohm mid-woofer that will share the enclosure volume and will be connected in series for an effective 8ohm nominal load:
1) When taking fair field measurements, should the amplifier be only connected to one of the two mids?
a. If so: Would SPL not be artificially high considering the amp will be feeling a single 4ohm load?
b. If not: If the mic in on-level will one of the two mids, would the sound from the second woofer not impact the measured response?
i. Or is one supposed to take the measurement with the mic placed mid-way between the two mids? If so, and assuming that is where the tweeter is placed and assuming that is the design axis, do you indicate 0x,0y,0z for specifying the diver location in the program?
I think the document was quite clear that the impedance measurement shall be performed exactly as how one plans on making the final connection (e.g., in my case, with the mids connected in series). It was also clear that, when taking near-field measurements, both mids should be connected and an attempt should be made to muffle the sound of one of the two mids.
My understanding from reading the document above was that only one of the mids in the MTM needs to be measured (assuming symmetrical vertical/horizontal locations). If that is the case, then how does one correctly enter the x,y,x coordinates? I’m specifically concerned with the y coordinates here.
For example, if you really only measured the top woofer, the 10 degree positive vertical measurement would be different for the top woofer than the measured 10 degree positive vertical response for the bottom woofer. In my mind, measured 10 degree positive vertical response of the top woofer would match the 10 degree negative vertical response of the bottom woofer. Do you tackle this by reversing the file names? For example change “_ver_deg+10” to “_ver_deg-10”?
I’m sure I’m over complicating things. Just trying to understand how the software treats measured inputs.
Working on my first DIY MTMs and wanted to begin by first confirming the measurement technique that should be employed.
I’ve read through the “Measurement Preparation with ARTA” document, but still have a couple of questions (included below). I think I’ll be okay measuring the tweeter. My question(s) mostly pertain to measuring the two 4ohm mid-woofer that will share the enclosure volume and will be connected in series for an effective 8ohm nominal load:
1) When taking fair field measurements, should the amplifier be only connected to one of the two mids?
a. If so: Would SPL not be artificially high considering the amp will be feeling a single 4ohm load?
b. If not: If the mic in on-level will one of the two mids, would the sound from the second woofer not impact the measured response?
i. Or is one supposed to take the measurement with the mic placed mid-way between the two mids? If so, and assuming that is where the tweeter is placed and assuming that is the design axis, do you indicate 0x,0y,0z for specifying the diver location in the program?
I think the document was quite clear that the impedance measurement shall be performed exactly as how one plans on making the final connection (e.g., in my case, with the mids connected in series). It was also clear that, when taking near-field measurements, both mids should be connected and an attempt should be made to muffle the sound of one of the two mids.
My understanding from reading the document above was that only one of the mids in the MTM needs to be measured (assuming symmetrical vertical/horizontal locations). If that is the case, then how does one correctly enter the x,y,x coordinates? I’m specifically concerned with the y coordinates here.
For example, if you really only measured the top woofer, the 10 degree positive vertical measurement would be different for the top woofer than the measured 10 degree positive vertical response for the bottom woofer. In my mind, measured 10 degree positive vertical response of the top woofer would match the 10 degree negative vertical response of the bottom woofer. Do you tackle this by reversing the file names? For example change “_ver_deg+10” to “_ver_deg-10”?
I’m sure I’m over complicating things. Just trying to understand how the software treats measured inputs.
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