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Thread: Sierra-2 output measurements in my room

  1. #1
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    Default Sierra-2 output measurements in my room

    Another thread here got me interested in doing some output tests on my Sierra-2s in my room. I have 5 Sierra-2s but I just tested the front right channel along with my 2 JL F112 subs. All running off my XMC-1 with Dirac and XPA-5 amp. I measured it with Room EQ Wizard and my Umik-1 microphone. Here's the results:



    I didn't see any compression until the 95dB sweep (orange line). That was at -8dB on my preamp. You can see a little compression above 10khz and a little more around 150-400hz. I have a wide suckout in my room at the 150-400hz area so that's partially to blame. My subs are 5dB hot and I'm glad to see no compression at all and extension down to 15hz. When you start seeing compression, it means you're getting pretty close to the max output of the speaker, at least at those frequencies. But this is just with a single speaker. If you're watching a movie or listening to music, you're going to have multiple speakers playing simultaneously, which will increase the volume.

    Since I have neighbors on the other side of the wall, I never listen louder than -13dB (purple line). Most of the time, it's more like -18dB (pink line). It's nice to see I still have some headroom available.

    Edit: Forget to mention, the mic was placed on a tripod by my couch about 9ft away from the speaker.
    Last edited by mikesiskav; 10-08-2017 at 11:12 PM.

  2. #2
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    Default Re: Sierra-2 output measurements in my room

    Quote Originally Posted by mikesiskav View Post
    Another thread here got me interested in doing some output tests on my Sierra-2s in my room. I have 5 Sierra-2s but I just tested the front right channel along with my 2 JL F112 subs. All running off my XMC-1 with Dirac and XPA-5 amp. I measured it with Room EQ Wizard and my Umik-1 microphone. Here's the results:



    I didn't see any compression until the 95dB sweep (orange line). That was at -8dB on my preamp. You can see a little compression above 10khz and a little more around 150-400hz. I have a wide suckout in my room at the 150-400hz area so that's partially to blame. My subs are 5dB hot and I'm glad to see no compression at all and extension down to 15hz. When you start seeing compression, it means you're getting pretty close to the max output of the speaker, at least at those frequencies. But this is just with a single speaker. If you're watching a movie or listening to music, you're going to have multiple speakers playing simultaneously, which will increase the volume.

    Since I have neighbors on the other side of the wall, I never listen louder than -13dB (purple line). Most of the time, it's more like -18dB (pink line). It's nice to see I still have some headroom available.

    Edit: Forget to mention, the mic was placed on a tripod by my couch about 9ft away from the speaker.
    Thanks Mike -- as I mentioned in the other post - these are ridiculously impressive in-room response measurements, and your even using a 5dB scale.

    Interesting that you are seeing a slight bit of compression at the higher tweeter frequencies. I would actually expect the opposite from the tweeter, with signs of compression starting in the lower ranges of the tweeter.

    Keep in mind, microphone elements also compress - in fact, mics have a much more difficult time at higher frequencies compared to mids and lows. What mic did you use for this? Still, this is quite good considering the levels you are reaching at your mic distance with only a single speaker.
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    David Fabrikant
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  3. #3
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    Default Re: Sierra-2 output measurements in my room

    Quote Originally Posted by davef View Post
    Thanks Mike -- as I mentioned in the other post - these are ridiculously impressive in-room response measurements, and your even using a 5dB scale.

    Interesting that you are seeing a slight bit of compression at the higher tweeter frequencies. I would actually expect the opposite from the tweeter, with signs of compression starting in the lower ranges of the tweeter.

    Keep in mind, microphone elements also compress - in fact, mics have a much more difficult time at higher frequencies compared to mids and lows. What mic did you use for this? Still, this is quite good considering the levels you are reaching at your mic distance with only a single speaker.
    Thanks Dave. I did these measurements with Dirac engaged, so that's the reason for the nearly flat response. I should probably redo them without Dirac. I'm also using 1/6th smoothing.

    The mic I'm using is the Umik-1 and I'm using a calibration file for it. The distance from the mic to the speaker was 9 ft.

    What you said about the tweeter compressing near the lower range makes sense to me since there's more excursion there and that's actually what I was expecting. But based on my measurements I don't see any compression at all between 2-4khz, which is very impressive. Now that I think about it, I know that Dirac was boosting the frequencies above 10khz so that may be why I'm seeing compression in that range.
    Last edited by mikesiskav; 10-09-2017 at 07:47 PM.

  4. #4
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    Default Re: Sierra-2 output measurements in my room

    Nice measurements. I have Sierra 2s as well, so it is nice to see how much they can do in terms of these long term output compression plots. I'm curious though, where did you set the crossover for the subs?

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    Default Re: Sierra-2 output measurements in my room

    Quote Originally Posted by N Boros View Post
    Nice measurements. I have Sierra 2s as well, so it is nice to see how much they can do in terms of these long term output compression plots. I'm curious though, where did you set the crossover for the subs?
    Thanks N Boros. My crossover is set to 80hz. That dip at 55hz is room induced. I might be able to fix it by experimenting with the subwoofers placement but I just haven't gotten around to it. The dip is fairly narrow so it doesn't bother me too much.

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    Default Re: Sierra-2 output measurements in my room

    Does Room EQ Wizard have a way of measuring short term peaks to see where compression would set in?

    I'm just curious because it seems like if someone was trying to play a movie at reference volume, that is 85 dB sustained and as much as 105 dB peaks. The 85 dB sustained appears to be fine in your room, but you started running into compression on the 95 dB sweep. That 95 dB sweep was more of a sustained measurement, than a short term burst though.

  7. #7
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    Default Re: Sierra-2 output measurements in my room

    Quote Originally Posted by N Boros View Post
    Does Room EQ Wizard have a way of measuring short term peaks to see where compression would set in?

    I'm just curious because it seems like if someone was trying to play a movie at reference volume, that is 85 dB sustained and as much as 105 dB peaks. The 85 dB sustained appears to be fine in your room, but you started running into compression on the 95 dB sweep. That 95 dB sweep was more of a sustained measurement, than a short term burst though.
    I failed to mention it in my original post, but these measurements were done with a fairly quick sweep (about 2 seconds in duration). These would probably be considered short term compression sweeps. I was worried that longer, sustained sweeps at high volume could damage my Sierra-2's and I didn't want to take that chance. I'm going to take some more measurements this weekend with Dirac disabled. I know for a fact that Dirac is boosting some frequencies and that is affecting the results.
    Last edited by mikesiskav; 10-20-2017 at 01:42 PM.

  8. #8
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    Default Re: Sierra-2 output measurements in my room

    Quote Originally Posted by mikesiskav View Post
    I failed to mention it in my original post, but these measurements were done with a fairly quick sweep (about 2 seconds in duration). These would probably be considered short term compression sweeps. I was worried that longer, sustained sweeps at high volume could damage my Sierra-2's and I didn't want to take that chance. I'm going to take some more measurements this weekend with Dirac disabled. I know for a fact that Dirac is boosting some frequencies and that is affecting the results.
    I could be wrong, but I think that short term peaks of 105 dB for reference volume are of shorter duration than 2 seconds. Probably a small fraction of a second.

  9. #9
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    Default Re: Sierra-2 output measurements in my room

    Quote Originally Posted by N Boros View Post
    I could be wrong, but I think that short term peaks of 105 dB for reference volume are of shorter duration than 2 seconds. Probably a small fraction of a second.
    This is correct, typically for measurement purposes, the duration of short term peaks is typically 30ms or shorter. However, there is really no set standard for this. I would consider a 2 second burst to be sustained, not short term. I am not really sure RoomEQ Wizard is appropriate software for calculating short term compression measurements.
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    David Fabrikant
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  10. #10
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    Default Re: Sierra-2 output measurements in my room

    I'll take a look at the options in REW this weekend. I believe the option I selected was the shortest possible. Then again, I'm not an expert in the software.

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