| How do you guys do your measurements?? [message #35146] |
Sun, 17 February 2002 10:57  |
Robert Hamel
Messages: 93
Registered: May 2009
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Viscount |
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Hello, I am in the middle of getting my project together and was wondering what types of measurements and how you do them?? I have an SPL meter and a crude 10 octate RTA set-up. So I can do them nearfield but how do you guys do the system measurements say 6-8 feet out so its all blended while minimizing the rooms contributions?? I have one cabinet built and I am attempting the crossovers now. The obvious thing would be to measure outside but that is just not practical. I am in NY and its too damn cold and the speakers are way to heavy to get up and down stairs. Any ideas would be appreciated. Thanks Rob
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| Measuring loudspeaker performance [message #35152 is a reply to message #35146] |
Sun, 17 February 2002 18:45  |
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Wayne Parham
Messages: 18831
Registered: January 2001
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Illuminati (33rd Degree) |
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You might check out the shareware measurement system "Speaker Workshop" at Audua.com. It is a gated MLS system, so you can gate out early reflections when doing indoor measurements. This is called pseudo-anechoic, because while the room still causes reflections, the measurement system gets its samples prior to the first arrival. Therefore, no reflections are present in the gathered dataset. The thing is, it can only work down to the frequency range where boundaries are more than a wavelength distant. This prevents you from accurately measuring the bass. You'll have to go outside for that. On the other hand, you may want to measure the sound distribution in your room. This will not require gating. You can do that with your RTA or with gating turned off in Speaker Workshop. You'll need to make several measurements in the room, forming a grid of listening positions. Put the microphone in the first grid position and take a measurement, then move on the the next spot and so on until all grid points have been done. Then you will be able to see response at each of these points, and you will then know the energy distribution is in your room at all frequencies.
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| Re: measure where the rubber meets the road [message #35161 is a reply to message #35153] |
Mon, 18 February 2002 19:15 |
Robert Hamel
Messages: 93
Registered: May 2009
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Viscount |
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Hello Sam That's about what I have been doing. Just looking for a better way. You are absolutely correct about that window being big. I had the driver in with no fiber glass and the back panel just laid in and the first cut sounded real good. Didn't measure as good as it sounded but I was sure happy. I am trying to determine if I have a room issue or a sensitivity issue. My cabinet is tunned for 50 Hz and crosses over with a L/R at 250 hz so at 250HZ I am down 6 db and the peak is right smack in the middle of the too!!! I already tried the woofer full range and the peak is still there so I am leaning towards the room. I have not moved it yet as that is the next step. This sure does keep you thinking. Thanks for the encoragement.
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