Matthias McCready
Active Member
- Joined
- Jul 2, 2021
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I am attempting to expand my knowledge of loudspeaker measurement and verification, and the scientific processes involved.
At work I have been tasked with going through 7 venues loudspeaker systems, both line-array elements & point source enclosures, and to verify that all of the components are working as they should. Some of these systems are older, and have been pushed hard over the past decades. Previous methods of checking have been simpler, and I think we may have missed problems, so I am wanting to up the ante.
I know SMAART will give me measurements for magnitude, phase, and measurement coherence over frequency; with which data I should be able to verify that:
A) Boxes are generally in phase (it may be hard to verify individual drivers without pulling boxes apart).
B) Drivers are working (If 1 of 2 woofers in a box is not working that should result in a drop in magnitude over the respective frequencies, compared to other boxes of the same model).
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Additionally I am looking for a way to quantify if drivers are blown or "tired," and I am not sure if this would necessarily show up in the magnitude traces in SMAART.
For background when there are large PA systems that have been pushed hard for several years it is not uncommon for there to be many drivers in the overall system that while they produce "noise,"they do not perform to spec. As the system is so large, especially with line arrays, it can be harder to pin-point which exact enclosure or driver is having problems from a distance. Overall there is a feeling that "things don't quiet sound right." Not to mention that non-functional drivers can dramatically change the array behavior. Going through boxes individually with a sine wave can audibly reveal problems, but I would like a more scientific DUT process that gives actionably date in the form of a pass/fail to an enclosure, at which point the box can be dropped, taken apart, and drivers measured individually.
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So for those of you who have dealt with "blown" or "tired" drivers what is your method of scientific verification?
I read on ASR that REW has a distortion test. If I utilized REW to perform a sine wave sweep, to calculate THD over frequency per box, would this be a good way determine if there are tired/blown drivers? Or are other ways that you would recommend?
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I know many PA manufactures have ways of testing boxes and drivers via their amplification. Specifically the systems I will be working on are D&B and L'Acoustics (Load Monitoring for D&B and Enclosure Check for L'Acoustics). If I understand these respective systems would give information on individual driver impedance and whether or not they are functioning properly; however I am not certain I am setup to utilize these features as:
1) Install systems have some LONG cabling going in (I think these systems like less than 30ft between the amp and speaker)
2) None of the D&B systems have 1:1 box resolution.
Thanks in advance for the help, I am excited to learn and get my head around all of this!
Matthias
At work I have been tasked with going through 7 venues loudspeaker systems, both line-array elements & point source enclosures, and to verify that all of the components are working as they should. Some of these systems are older, and have been pushed hard over the past decades. Previous methods of checking have been simpler, and I think we may have missed problems, so I am wanting to up the ante.
I know SMAART will give me measurements for magnitude, phase, and measurement coherence over frequency; with which data I should be able to verify that:
A) Boxes are generally in phase (it may be hard to verify individual drivers without pulling boxes apart).
B) Drivers are working (If 1 of 2 woofers in a box is not working that should result in a drop in magnitude over the respective frequencies, compared to other boxes of the same model).
---
Additionally I am looking for a way to quantify if drivers are blown or "tired," and I am not sure if this would necessarily show up in the magnitude traces in SMAART.
For background when there are large PA systems that have been pushed hard for several years it is not uncommon for there to be many drivers in the overall system that while they produce "noise,"they do not perform to spec. As the system is so large, especially with line arrays, it can be harder to pin-point which exact enclosure or driver is having problems from a distance. Overall there is a feeling that "things don't quiet sound right." Not to mention that non-functional drivers can dramatically change the array behavior. Going through boxes individually with a sine wave can audibly reveal problems, but I would like a more scientific DUT process that gives actionably date in the form of a pass/fail to an enclosure, at which point the box can be dropped, taken apart, and drivers measured individually.
---
So for those of you who have dealt with "blown" or "tired" drivers what is your method of scientific verification?
I read on ASR that REW has a distortion test. If I utilized REW to perform a sine wave sweep, to calculate THD over frequency per box, would this be a good way determine if there are tired/blown drivers? Or are other ways that you would recommend?
---
I know many PA manufactures have ways of testing boxes and drivers via their amplification. Specifically the systems I will be working on are D&B and L'Acoustics (Load Monitoring for D&B and Enclosure Check for L'Acoustics). If I understand these respective systems would give information on individual driver impedance and whether or not they are functioning properly; however I am not certain I am setup to utilize these features as:
1) Install systems have some LONG cabling going in (I think these systems like less than 30ft between the amp and speaker)
2) None of the D&B systems have 1:1 box resolution.
Thanks in advance for the help, I am excited to learn and get my head around all of this!
Matthias
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