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Thread: Sierra-2 output measurements in my room

  1. #11
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    Default Re: Sierra-2 output measurements in my room

    I took some new measurements today, this time with Dirac turned off. And I have to say, the results are impressive. Doing the same 70-95dB sweeps in 5dB increments, I see almost no compression at all with the Sierra-2 at this level. I probably could have done a sweep at 100dB but I decided not to since it was already very loud and I didn't want to take any chances of breaking something. This is really impressive performance from a single bookshelf speaker. Again, this is measured at 9ft from the speaker.

    For my subwoofers, without EQ, there's a broad hump around 20-30hz. I'm reaching 115dB in this area with my two JL F112s before compression sets in.

    Last edited by mikesiskav; 10-22-2017 at 12:31 PM.

  2. #12
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    Default Re: Sierra-2 output measurements in my room

    Quote Originally Posted by mikesiskav View Post
    I took some new measurements today, this time with Dirac turned off. And I have to say, the results are impressive. Doing the same 70-95dB sweeps in 5dB increments, I see almost no compression at all with the Sierra-2 at this level. I probably could have done a sweep at 100dB but I decided not to since it was already very loud and I didn't want to take any chances of breaking something. This is really impressive performance from a single bookshelf speaker. Again, this is measured at 9ft from the speaker.

    For my subwoofers, without EQ, there's a broad hump around 20-30hz. I'm reaching 115dB in this area with my two JL F112s before compression sets in.

    These look great - really not too much correction and, at your listening distance, we are seeing the SPL's I would expect. Looks like there was about 3-4dB of HF boost being applied when Dirac was enabled, which cuts the headroom of your amp in half at the frequencies.
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    David Fabrikant
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  3. #13
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    Default Re: Sierra-2 output measurements in my room

    Thanks Dave. I suspect the high frequency roll-off may be caused by my extensive room treatments. I've got a total of 18 acoustic panels and a large, thick rug on the floor.

  4. #14
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    Default Re: Sierra-2 output measurements in my room

    Quote Originally Posted by mikesiskav View Post
    Thanks Dave. I suspect the high frequency roll-off may be caused by my extensive room treatments. I've got a total of 18 acoustic panels and a large, thick rug on the floor.
    Were you measuring with the mic directly on axis with the tweeter? If not, this would cause the rather mild HF roll off. In addition, all rooms have HF losses - and since room EQ wizard uses swept sine waves for measurements, you can't effectively isolate the speaker's response from the room response so you are measuring reflections as well, which bounce back to the mic out-of-phase from the direct sound which causes cancellations.

    That said, this is a very mild rolloff and is probably not worth correcting for using Dirac (if possible to avoid EQ at the upper range).

    Even without Dirac engaged, the speaker's + room response looks fantastic and the big dip you see at 180Hz is just floor bounce.
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    Good Sound To You!

    David Fabrikant
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  5. #15
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    Default Re: Sierra-2 output measurements in my room

    Quote Originally Posted by davef View Post
    Were you measuring with the mic directly on axis with the tweeter? If not, this would cause the rather mild HF roll off. In addition, all rooms have HF losses - and since room EQ wizard uses swept sine waves for measurements, you can't effectively isolate the speaker's response from the room response so you are measuring reflections as well, which bounce back to the mic out-of-phase from the direct sound which causes cancellations.

    That said, this is a very mild rolloff and is probably not worth correcting for using Dirac (if possible to avoid EQ at the upper range).

    Even without Dirac engaged, the speaker's + room response looks fantastic and the big dip you see at 180Hz is just floor bounce.
    Yes, the microphone was pointed straight ahead at my TV, although my speakers are toed in quite a bit. Any way to fix the floor bounce dip? Bass traps on the floor?

  6. #16
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    Default Re: Sierra-2 output measurements in my room

    Quote Originally Posted by mikesiskav View Post
    Yes, the microphone was pointed straight ahead at my TV, although my speakers are toed in quite a bit. Any way to fix the floor bounce dip? Bass traps on the floor?
    Put a whole bunch of thick blankets and comforters, so that you donít have to take down the panels to check. Maybe it will make a difference or maybe not. If it does make a difference, then you might be able to look into a thick carpet pad.

  7. #17

    Default Re: Sierra-2 output measurements in my room

    A lot of variables come into play mostly room related. Kinda looks like it is bass management related but you said its at 80. Make sure any listening mode is disabled. Do you see the bounce if you measure just the fronts or just the subs? If you do it's a bounce or reflection. If you don't, you may be able to adjust the phase first on each sub to get them to their loudest/smoothest combined output with the mains. Then try adjusting the distance on each sub independantly to see if that helps the dip. Also if the tip of mic is pointed straight at the speakers make sure you use the 0 degree axis microphone calibration file otherwise most of the time you'd use the 90 axis for room measurements with it pointed straight towards the ceiling.
    Ascend Sierra Towers RAAL | Ascend Sierra Horizon RAAL | Ascend HTM-200SE | Rythmik F15HP | Anthem MRX-520 | Schiit Modi Multibit

  8. #18
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    Default Re: Sierra-2 output measurements in my room

    Thanks for the tips guys. I'm going to play around with it some more this weekend. I'll measure the subs and speakers separately. Also, I just realized the distance from my speaker to the side wall is almost the same as the speaker to the floor which could be causing a dip in the FR.

  9. #19
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    Default Re: Sierra-2 output measurements in my room

    Quote Originally Posted by mikesiskav View Post
    Yes, the microphone was pointed straight ahead at my TV, although my speakers are toed in quite a bit. Any way to fix the floor bounce dip? Bass traps on the floor?
    To reduce floor bounce you are going to need put down some extremely thick absorption -- about 3 feet thick. I have attached a pic of what we do at our production line testing area. Obviously, this isn't appropriate for a home environment

    Floor bounce is unavoidable and is usually a high q dip - meaning steep but of small bandwidth. Since the average listener typically hears at 1/3 octave smoothing (at best 1/6th octave) -- the dip looks bad in measurements but is likely not audible.

    The simplest way to confirm if this is floor bounce is to take the measurement, mark the frequency of the steepest point of the notch, then raise (or lower) the speaker by a foot and then retake the measurement. Did the frequency of the dip change? If yes, definitely floor bounce.

    Also note that if you have a solid ceiling and the speaker is halfway between the floor and the ceiling - the "bounce" will be worse.

    I need to stress this though -- it all gets averaged into the overall room response and isn't something anyone should be concerned with.
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    Good Sound To You!

    David Fabrikant
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