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Thread: Sierra 2 - Understanding REW Results

  1. #1
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    Apr 2019
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    Default Sierra 2 - Understanding REW Results

    Hi all,
    Getting my sierra 2's dialed in (they already sound phenomenal, but pursuit of perfection and all) and wondered if the community had thoughts on my graphs.

    My first question, there is natural rolloff from about 7k onward which I haven't seen in other REW charts or my factory calibration results pages. Is this a placement issue? I'm sitting about 14 feet away, they are about 14' apart, and they are toed in about 10 degrees.

    My second question, slight dip at 2.5k, should I ignore this? Crossover interaction I'm assuming?

    Last question, I still need to sweep for the optimal crossover, but do my graphs point towards one that may work the best?

    I've currently settled on LR bypass with audyssey, dynamic eq on (+15db offset), and my subwoofer is a single rythmik L12 placed under the front L channel. S2's are using included felt feet + a dab of museum putty, sitting on floating shelves that are mounted with isolating rubber dampeners.

    Any thoughts or input are greatly appreciated!

    S2 LR Direct.jpgs2 LR Bypass.jpgs2 LR bypass waterfall.jpg

  2. #2
    Join Date
    Dec 2013
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    360

    Default Re: Sierra 2 - Understanding REW Results

    It may have something to do with your room. The easy way to check is to take measurements closer to the speaker, say 5ft away or maybe even 3ft with the mic halfway between the woofer and the tweeter. That reduces the effect of the room. What type of mic are you using?

  3. #3
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    Apr 2019
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    Default Re: Sierra 2 - Understanding REW Results

    Yea can definitely do that, I don't think it's an issue with the speaker as they came with a measurement chart, but that could at least highlight if it's early reflections or room reflections or placement? It's a umik-1

  4. #4
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    Default Re: Sierra 2 - Understanding REW Results

    I held the mic about three feet away centered between the tweeter and woofer, here are smoothed and an unsmoothed graphs. I'm assuming that doesn't look right? Sidewall cancellation as they are both up next to a wall on the shelf?

    It does seem to have improved the treble drop off, but not sure how to correct it for my listening position.

    Forgive my ignorance with reading these, this room and these speaker locations have been my only real baseline.
    Attached Images Attached Images

  5. #5
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    Default Re: Sierra 2 - Understanding REW Results

    Can you post a pic of your room and the speaker locations?

    REW frequency response measurements are good for subwoofer placement and EQ, and for bass response peaks, nulls, and subsequent ringing in the bass range. Above that, they don't necessarily tell you much about sound quality.

  6. #6
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    Default Re: Sierra 2 - Understanding REW Results

    Quote Originally Posted by Agd View Post
    Hi all,
    Getting my sierra 2's dialed in (they already sound phenomenal, but pursuit of perfection and all) and wondered if the community had thoughts on my graphs.

    My first question, there is natural rolloff from about 7k onward which I haven't seen in other REW charts or my factory calibration results pages. Is this a placement issue? I'm sitting about 14 feet away, they are about 14' apart, and they are toed in about 10 degrees.

    My second question, slight dip at 2.5k, should I ignore this? Crossover interaction I'm assuming?

    Last question, I still need to sweep for the optimal crossover, but do my graphs point towards one that may work the best?

    I've currently settled on LR bypass with audyssey, dynamic eq on (+15db offset), and my subwoofer is a single rythmik L12 placed under the front L channel. S2's are using included felt feet + a dab of museum putty, sitting on floating shelves that are mounted with isolating rubber dampeners.

    Any thoughts or input are greatly appreciated!

    S2 LR Direct.jpgs2 LR Bypass.jpgs2 LR bypass waterfall.jpg
    These measurements look good. There are many reasons why you could be seeing a mild high frequency rolloff.

    Are these measurements made with Audyssey EQ turned on? If yes, what target curve for Audyssey are you using?

    Accurately measuring such extreme high frequencies is tricky. These wavelengths are very short -- a 20kHz wavelength is only slightly larger than a 1/2 inch. 7kHz is just under 2 inches. This means the microphone must be perfectly lined up on-axis with the tweeter (both vertically and horizontally), which at a 14 foot mic distance would be quite difficult to achieve.

    Is your microphone properly calibrated above 8kHz?

    What objects are located between the speakers and mic?

    Did you use a tripod to hold the microphone?

    Did you measure with the speaker grilles on or off?

    Without the right equipment and knowledge, measuring the frequency response of a speaker is tricky. REW is a reasonable hobbyist's tool for measuring room acoustics. What you are seeing in these measurements is the response of the speaker combined with your room acoustics at the location you placed your microphone, and in this regard, your measurements look excellent.

    You can go crazy with this stuff, just sit back and enjoy the speakers.
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    Good Sound To You!

    David Fabrikant
    www.ascendacoustics.com

  7. #7
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    Default Re: Sierra 2 - Understanding REW Results

    Quote Originally Posted by Agd View Post
    I held the mic about three feet away centered between the tweeter and woofer, here are smoothed and an unsmoothed graphs.
    You physically held the microphone? If so, you can't do that...
    .
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    Good Sound To You!

    David Fabrikant
    www.ascendacoustics.com

  8. #8
    Join Date
    Apr 2019
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    Default Re: Sierra 2 - Understanding REW Results

    To Dave, this is super helpful, thank you for the input! It's reassuring to know that it's normal, I guess my fear is that I was missing out on "better" because of a compromised room that my umik mic showed in response graphs.

    I used the UMIK calibration and set it on it's tripod on my listening position (couch), grills on but nothing else in the way. Measured pure direct so no audyssey on the first chart without sub, then LR bypass on the one with sub (so no correction on LR)

    The clean bill of health is the reassurance I need to sit back and enjoy, so thanks again!!
    Last edited by Agd; 06-05-2019 at 06:36 PM.

  9. #9
    Join Date
    Apr 2019
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    27

    Default Re: Sierra 2 - Understanding REW Results

    Quote Originally Posted by Beave View Post
    Can you post a pic of your room and the speaker locations?

    REW frequency response measurements are good for subwoofer placement and EQ, and for bass response peaks, nulls, and subsequent ringing in the bass range. Above that, they don't necessarily tell you much about sound quality.
    Good to know, and welcome any recommendations about potential improvements. I needed to move the sub to the front as it was pressurizing one side of my head when in the back corner.

    Currently upgrading decor, so it's a bit mismatched, but with new decor I'll try and add acoustic treatments.
    Last edited by Agd; 06-12-2019 at 04:14 AM.

  10. #10
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    Default Re: Sierra 2 - Understanding REW Results

    Quote Originally Posted by Agd View Post
    To Dave, this is super helpful, thank you for the input! It's reassuring to know that it's normal, I guess my fear is that I was missing out on "better" because of a compromised room that my umik mic showed in response graphs.

    I used the UMIK calibration and set it on it's tripod on my listening position (couch), grills on but nothing else in the way. Measured pure direct so no audyssey on the first chart without sub, then LR bypass on the one with sub (so no correction on LR)

    The clean bill of health is the reassurance I need to sit back and enjoy, so thanks again!!
    You are very welcome!

    Also, when taking speaker response measurements, I do recommend removing the speaker grilles. However, when setting up Audyssey or for any auto-eq, if you plan on keeping the grilles on when using the system, the grilles should be kept on for setup procedures.
    .
    .
    .
    Good Sound To You!

    David Fabrikant
    www.ascendacoustics.com

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