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Thread: Luna specifications and measurements

  1. #1
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    Default Luna specifications and measurements

    Sierra Luna Specifications and Measurements


    lunaspecs.gif


    *All measurements taken using DRA Lab’s MLSSA system with RCAI, calibrated ACO Pacific 7012 ½” free field measurement microphone with associated pre-amp and power supply and an automated Outline turntable.

    Full-range quasi-anechoic on-axis frequency response

    Microphone distance is 1 meter with calibrated sensitivity

    lunafull.gif


    Horizontal and vertical off-axis graphs plus listening window

    Listening window is the averaged response of 5 separate measurements, on-axis, +/- 15 degrees horizontal and +/- 15 degrees vertical. Note: due to the measurement technique, the response below 250Hz is invalid, as represented by the above and below horizontal green bars.

    lunaoffaxis.gif


    Polar Response

    5 degree increments from 0 degs to a full 90 degs off-axis. Note how the critical midrange response remains linear and consistent with uniformly decreasing spl as frequency increases. This represents an exceptionally wide off-axis response.

    lunapolar.gif


    Impedance and electrical phase

    Note the extremely clean impedance response (free from wrinkles which would represent various forms of resonances) and linear phase with minimal phase angles. The mild phase angles ensure that this speaker is an easy load for even basic receivers.

    lunabode.gif


    Energy Time Curve

    This measurement is a good indication of overall transient accuracy and stored energy. The graph displays the decay time of a full range impulse. The impulse occurs at 3ms and decreases uniformly to the noise floor (-45db) by 4ms. This represents a decay time of 1ms, which is superb. Large diameter woofer cones, woofers and tweeters with poorly designed motor systems and/or heavy mass and poorly constructed cabinets will often contribute to far greater decay times which damage transient accuracy, coherency and overall resolution.

    lunaetc.gif


    Cumulative Spectral Decay

    This measurement is similar to the energy time curve but displays a 3 dimensional view such that we can examine the decay time with reference to frequency. It is an exceptional tool to reveal transient accuracy and indicate various problem areas with respect to resonance and stored energy. The CSD of the Luna is exceptionally clean with good uniformity

    lunacsd.gif
    Last edited by davef; 03-26-2017 at 06:33 PM.
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    David Fabrikant
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    Default Re: Luna specifications and measurements

    Dave, those specifications look awesome!! I have a customer who asked me about putting the Lunas in-wall and/or in-ceiling. I told him to contact you. My guess is if you can flush mount it, in wall should be possible as well, right?
    Enrico Castagnetti @ Rythmik Audio
    Media Room: Ascend Acoustics Sierra Towers w/ RAAL, Horizon w/ RAAL & Sierra 2s | Rythmik F12SE (x2) | Marantz SR7008 | Parasound Halo P5 | Emotiva XPA-3 & XPA-200 | Oppo 105D | Sony HW40ES |
    Desktop: Dynaudio BM5 mkIII | Rythmik L22 | Apogee Quartet | 27" iMac|
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    Default Re: Luna specifications and measurements

    Quote Originally Posted by enricoclaudio View Post
    Dave, those specifications look awesome!! I have a customer who asked me about putting the Lunas in-wall and/or in-ceiling. I told him to contact you. My guess is if you can flush mount it, in wall should be possible as well, right?
    By doing that, it increases the size of the front baffle, so it will change the sound a bit.
    It will still sound good, but it is the reason Dave created the EXBAC circuit for the CMT-340 center.
    -curtis

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    Default Re: Luna specifications and measurements

    Quote Originally Posted by enricoclaudio View Post
    Dave, those specifications look awesome!! I have a customer who asked me about putting the Lunas in-wall and/or in-ceiling. I told him to contact you. My guess is if you can flush mount it, in wall should be possible as well, right?
    Yes - there will be a slight midbass boost, but that is not a bad thing at all. These guys will crush typical in-wall speakers.
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    David Fabrikant
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    Default Re: Luna specifications and measurements

    I'll be mounting these to the sides of my couch as surrounds. The room is 15 ft wide. The speakers will be flush mounted. How much higher can I go than ear height and still be within a good listening window?

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    Default Re: Luna specifications and measurements

    Those measurements are incredible. In just about every area you get an improvement over the Sierra 2, from the smaller size. Look back at the Sierra 2 at how there was maybe only a 5 dB difference when going horizontally 45 degrees off axis and that was the biggest difference. This was already an excellent result for the Sierra 2s. Now it is down to around 2 to 3 dB with the Lunas. Look at the cumulative spectral decay plots. Again, it improves upon the already exceptional Sierra 2. There is so much flexibility with the Lunas that you can even flush mount them on the wall.

    The only downside you get with the Lunas us just because of the physics of the situation. With a smaller bass driver and cabinet, they will have less output and a bit less bass extension. The less bass extension is not much an issue by using a subwoofer. Some might be torn about going with the Lunas or the Sierra 2s for mains, but if one has a small room, the Lunas seem to have the advantage in most areas if they have enough output.

    For using these as surrounds, there is almost no question about going with the Lunas. That small size, flush mounting ability and even better off axis response makes they ideal choices for surrounds. Excellent work Dave!


    Dave, one suggestion though. You might consider looking into getting accurate measurements for below 250 Hz, if it isn't an expensive undertaking. Some might be misled into thinking that is actually the response, due to the size of this speaker. You might be selling yourself short by not showing the true measurements that resulted from all that hard work. I'm definitely convinced though and you do say clearly in the "specifications" page that they extend down to 65Hz. I'll be picking some up for side surround speakers to match my Sierra 2s up front.
    Last edited by N Boros; 03-27-2017 at 01:38 PM.

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    Default Re: Luna specifications and measurements

    Quote Originally Posted by natetg57 View Post
    I'll be mounting these to the sides of my couch as surrounds. The room is 15 ft wide. The speakers will be flush mounted. How much higher can I go than ear height and still be within a good listening window?
    I have not heard these speakers and tried this, obviously. But, looking at how there is very little difference going 10 degrees vertically from what you see at 5 degrees and how you do begin to see differences at 15 degrees... I would say that 10 to 12 degrees vertically above would probably be safe in not changing the character of the sound too much. If your seat is 7 feet from the surrounds (taking into account they are about 6 inches deep), then you can go from 1.25 to 1.5 feet above your seated ear level and have them flush mounted. Beyond that you might look into getting mounts that you can angle down to the ear height.

    That is what I'm thinking when I actually get mine at some point. I would be interested to hear what others do though and how it sounds.

  8. #8
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    Default Re: Luna specifications and measurements

    Quote Originally Posted by N Boros View Post
    Those measurements are incredible. In just about every area you get an improvement over the Sierra 2, from the smaller size. Look back at the Sierra 2 at how there was maybe only a 5 dB difference when going horizontally 45 degrees off axis and that was the biggest difference. This was already an excellent result for the Sierra 2s. Now it is down to around 2 to 3 dB with the Lunas. Look at the cumulative spectral decay plots. Again, it improves upon the already exceptional Sierra 2. There is so much flexibility with the Lunas that you can even flush mount them on the wall.

    The only downside you get with the Lunas us just because of the physics of the situation. With a smaller bass driver and cabinet, they will have less output and a bit less bass extension. The less bass extension is not much an issue by using a subwoofer. Some might be torn about going with the Lunas or the Sierra 2s for mains, but if one has a small room, the Lunas seem to have the advantage in most areas if they have enough output.

    For using these as surrounds, there is almost no question about going with the Lunas. That small size, flush mounting ability and even better off axis response makes they ideal choices for surrounds. Excellent work Dave!


    Dave, one suggestion though. You might consider looking into getting accurate measurements for below 250 Hz, if it isn't an expensive undertaking. Some might be misled into thinking that is actually the response, due to the size of this speaker. You might be selling yourself short by not showing the true measurements that resulted from all that hard work. I'm definitely convinced though and you do say clearly in the "specifications" page that they extend down to 65Hz. I'll be picking some up for side surround speakers to match my Sierra 2s up front.

    Hi Nick,

    I am happy to see your excitement with the new Luna's - we too are excited I wouldn't actually go as far as to say the Luna is an improvement over the Sierra-2 -- the Sierra-2, without question, is the better overall speaker - its response is more linear overall but the smaller woofer of the Luna does provide a bit wider dispersion (both horizontally and vertically) Hard to say if that slightly wider dispersion is audible when comparing with the Sierra-2 - both speakers already have such wide horizontal dispersion that you would likely need an extremely wide room to hear any perceived difference in this as room reflections would dominate at these wide angles.

    With regard to the improvements you see in the CSD, this is also due to having the smaller woofer. This unique 4.5" woofer uses essentially the same absurdly powerful motor system as the 6" woofer in the Sierra-2 - but the lower mass of the cone compared to the S2 woofer gives it slightly faster decay times - which was to be expected.

    Dave, one suggestion though. You might consider looking into getting accurate measurements for below 250 Hz, if it isn't an expensive undertaking. Some might be misled into thinking that is actually the response, due to the size of this speaker. You might be selling yourself short by not showing the true measurements that resulted from all that hard work.
    I am not sure if you are aware of the inherent limitations in measuring a speaker's response below ~250Hz. Essentially, without a true anechoic chamber tuned to 20Hz (only a very limited number of these exist throughout the world) - one must compensate by taking complex close mic measurements of both the woofer and port, and using weighted averages to combine the two. This measurement than gets spliced into the response above 250Hz. We post the full range on-axis response of the speaker (we do for all of our speakers). With this in mind, there is no reason to include the low frequency response in the other measurements since it will not change due to being off-axis. To add this in to every measurement taken would be a huge undertaking for really no reason at all.

    For example, if you look at any of the excellent measurements Stereophile takes when they review speakers, you will see the exact same limitations (although they seem to stop at about 400Hz). The low frequency limit is not established by us, it is a factor of at what frequency the first reflection starts at - everything from the first reflection and below becomes inaccurate.

    Be wary of any published speaker measurements without this limitation. A few of the very large speaker companies do have a true anechoic chamber available (but very few are actually tuned to as low as 20Hz - most are tuned somewhere between 60-40Hz) These days though, with advanced maximum length sequence measurement systems - anechoic chambers are really no longer needed and the huge expense in building and maintaining one would just add to the retail cost of the speakers...

    Again, check out the full range frequency response of the Luna, it is called the quasi-anechoic response because it accurately simulates what the full range response would be if taken in a true anechoic chamber.

    Hope this makes sense!
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    David Fabrikant
    www.ascendacoustics.com

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    Default Re: Luna specifications and measurements

    Quote Originally Posted by natetg57 View Post
    I'll be mounting these to the sides of my couch as surrounds. The room is 15 ft wide. The speakers will be flush mounted. How much higher can I go than ear height and still be within a good listening window?
    What is the distance between the surround speakers and the main listening position? Basically, you will want to try and keep the vertical listening angle at 15 degs or less.
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    Good Sound To You!

    David Fabrikant
    www.ascendacoustics.com

  10. #10
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    Default Re: Luna specifications and measurements

    Quote Originally Posted by davef View Post
    Again, check out the full range frequency response of the Luna, it is called the quasi-anechoic response because it accurately simulates what the full range response would be if taken in a true anechoic chamber.

    Hope this makes sense!

    Yes, that makes sense. Its funny. I spent all of the time comparing all other graphs with the Sierra 2 and Sierra tower, than I didn't look carefully at the first plot to see that you have what I thought others and myself would like to see. Yes, the quasi-anechoic response, which you have first, is what I thought most would find helpful. Especially since it is possible to get this much extension out of such a small speaker with such a small woofer.



    Quote Originally Posted by davef View Post
    With regard to the improvements you see in the CSD, this is also due to having the smaller woofer. This unique 4.5" woofer uses essentially the same absurdly powerful motor system as the 6" woofer in the Sierra-2 - but the lower mass of the cone compared to the S2 woofer gives it slightly faster decay times - which was to be expected.
    You mentioned above that the wider dispersion of the Luna is not big enough to be noticeable over the Sierra 2, in most cases. Do you find that the faster transient response in the Luna is also something that is also not really audible compared with the Sierra 2?

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