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Thread: PC for RMAA and other measurements

  1. #1
    Devil's Advocate Adam_MSS's Avatar
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    PC for RMAA and other measurements

    I know there is some good knowledge here around the use of RMAA an other similar measurement tools, so I want to pick your collective brains.

    How would you configure a desktop PC to provide good measurement performance? Soundcards, power supply, OS, etc.

    I've got a used Thinkpad that runs soundeasy pretty well but with as much as it gets used for other tasks, I'm thinking a dedicated desktop might be the way to go for all measurements going forward.
    You don't use science to show that you're right, you use science to become right. - R.Munroe

    The important thing in science is not so much to obtain new facts as to discover new ways of thinking about them. - W.L.Bragg



  2. #2
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    I haven't really paid much attention but to get an idea, what are some of the sites that do RMAA testing using?

    I have my thoughts about going towards an external solution just to avoid the analog section picking up noise, but having not personally used it myself it is only an opinion and not real world.

    OS: If it's supported by RMAA then rock it.
    Power supply: I wouldn't worry, it's usually noisy bus lines screwing things up (hard drive access noise, etc).
    Last edited by durwood; 10-05-2011 at 01:51 PM.

  3. #3
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    Buy a laptop and run it off the battery. Decouple your measurement device from 60 cycle and you improve noise, sometimes dramatically.

    You also want them to share the same grounds. Saw similar issues in the car, with bus-powered USB sound cards performing better than externally powered ones. If the computer is also the "stim", then you might want to think about how isolated your amplifier's input stage is. That's probably another topic that won't guide your computer purchase.

    Alternatively, there are some specialized measurement devices (check out that measurement computing link I provided in that other thread) that do a good job of PSRR and have a smart grounding strategy.

  4. #4
    Devil's Advocate Adam_MSS's Avatar
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    Well that works well with having bought a laptop already. I need to check on my Art USB dual pre. I have always used it with the external power source but I believe it has the ability to run off an on-board 9v battery. I'll check out that link from the other thread when I get a little more time to focus this evening.
    You don't use science to show that you're right, you use science to become right. - R.Munroe

    The important thing in science is not so much to obtain new facts as to discover new ways of thinking about them. - W.L.Bragg



  5. #5
    Devil's Advocate Adam_MSS's Avatar
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    Durwood, here's an example I found of a test setup in use:RMAA Testing of Audio IC Op Amps
    You don't use science to show that you're right, you use science to become right. - R.Munroe

    The important thing in science is not so much to obtain new facts as to discover new ways of thinking about them. - W.L.Bragg



  6. #6
    Tester Extraordinaire ErinH's Avatar
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    Yep. Your USB XLR was 9v ready. I agree with outboard sound card. Never know when you'll want to test somethin you don't feel like lugging somewhere. Of course your speaker testing needs to be controlled.
    Your ears: The best tools you have... and they're free, too!

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    Be careful with RMAA

    NwAvGuy: Cowon i9 Review

    Scroll down to the "test results"

    Like nwavguy said, it either works or it doesn't and there isn't anything to compare the result to so you don't know if they are correct.

    I guess I can say it has worked for me in what I've used it for. My iphone 3gs results tend to follow his ipod 3G results pretty well. I do use version 5.5 however which lets you change a lot of the parameters that the newer version doesn't (at least the newer free version).
    Last edited by t3sn4f2; 10-08-2011 at 07:44 PM.

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