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Raw 1m Measurements of a Gedlee NS15?
- Thread starter DRNNOO
- Start date
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solderdude
Grand Contributor
In room measurements are pointless unless they were taken in your room at your listening position.
Posting those plots thus is pointless unless one wants some hints on how to EQ... but if one can measure it I am sure one can also EQ it.
Posting those plots thus is pointless unless one wants some hints on how to EQ... but if one can measure it I am sure one can also EQ it.
- Thread Starter
- #4
Well I listen at 1m so it would help me compare to my inroom measurements. The Mdat to an outside measurement at 1m would be great.
I doubt there is a decent summing of CD horn and woofer at only a 1m distance.
solderdude
Grand Contributor
Is the info on the website not enough ?
- Thread Starter
- #8
Is what it is...
Not even close. A outdoor measurement at 1m, is standard practice anyway. Professionals use Anechoic chamber but everyone else just goes outdoors.
solderdude
Grand Contributor
Can you post your indoor measurements ?
D
Deleted member 21219
Guest
From the Audio Precision AppNotes:
Application Note:
Loudspeaker Electroacoustic Measurements
Near Field/Far Field
"Another important concept in acoustics is the near field and far field. Far away
from a source (relative to its size), the inverse square law (or 6 dB/dd rule)
applies. At this distance the sound field has become stable and radiates from
the source in a predictable way. Close to the source, however, sound waves
behave in a much more complex fashion and there is no fixed relationship
between pressure and distance. In this near field, the sound level is uncertain.
Therefore, measurements should be conducted in the far field. The distance
from the source to the far field depends on the size of the source. As a rule of
thumb, the far field is typically considered to begin at a distance of 3 times the
largest dimension of the sound source [5]. However, it has been suggested that
the far field begins at 3 to 10 times the largest dimension of the source [6] .
Free-field Measurements
To achieve free-field conditions, two options are available: testing outdoors or
in an anechoic chamber.
Outdoors
To achieve free-field conditions outdoors, a loudspeaker and microphone must be
elevated high above the ground to minimize the influence of ground reflections.
For example, the loudspeaker could be mounted on a tall tower, suspended from
a crane or on a boom projecting from the corner of a building’s roof. The required
height depends on the size of the loudspeaker, which in turn determines the
required distance for the microphone to be in the far field. For example, consider
a bookshelf-sized loudspeaker cabinet whose largest dimension is 0.33 m (13″).
Using the lowest rule-of-thumb value for the far-field distance of three times the
largest dimension of the source would require the microphone to be 1 m (3.28′)
away from the loudspeaker. Based on the 6 dB/dd rule, to reduce the level of
reflected sound to 20 dB less than the direct sound would require a height of 5 m
(16.4′) above the ground. Doubling the size of this bookshelf speaker would double
the height required to get the same 20 dB reduction of reflected to direct sound"
As you can see, the absolute minimum distance from the mic to the speaker is 3X the largest dimension of the speaker. In the example quoted above, the 1 meter distance would apply only to a bookshelf speaker having a maximum dimension of 13".
The GedLee speakers have a maximum dimension of 35" ( http://www.gedlee.com/Loudspeakers/NS15.aspx ) so the absolute minimum distance for mic placement would be 105" away, or 8'-09".
Note that not only is this the absolute minimum, but that some disagreement exists as to whether 3X the largest dimension is sufficient. The notes above state that in some cases, the distance needed may be as much as 10X.
Jim
Application Note:
Loudspeaker Electroacoustic Measurements
Near Field/Far Field
"Another important concept in acoustics is the near field and far field. Far away
from a source (relative to its size), the inverse square law (or 6 dB/dd rule)
applies. At this distance the sound field has become stable and radiates from
the source in a predictable way. Close to the source, however, sound waves
behave in a much more complex fashion and there is no fixed relationship
between pressure and distance. In this near field, the sound level is uncertain.
Therefore, measurements should be conducted in the far field. The distance
from the source to the far field depends on the size of the source. As a rule of
thumb, the far field is typically considered to begin at a distance of 3 times the
largest dimension of the sound source [5]. However, it has been suggested that
the far field begins at 3 to 10 times the largest dimension of the source [6] .
Free-field Measurements
To achieve free-field conditions, two options are available: testing outdoors or
in an anechoic chamber.
Outdoors
To achieve free-field conditions outdoors, a loudspeaker and microphone must be
elevated high above the ground to minimize the influence of ground reflections.
For example, the loudspeaker could be mounted on a tall tower, suspended from
a crane or on a boom projecting from the corner of a building’s roof. The required
height depends on the size of the loudspeaker, which in turn determines the
required distance for the microphone to be in the far field. For example, consider
a bookshelf-sized loudspeaker cabinet whose largest dimension is 0.33 m (13″).
Using the lowest rule-of-thumb value for the far-field distance of three times the
largest dimension of the source would require the microphone to be 1 m (3.28′)
away from the loudspeaker. Based on the 6 dB/dd rule, to reduce the level of
reflected sound to 20 dB less than the direct sound would require a height of 5 m
(16.4′) above the ground. Doubling the size of this bookshelf speaker would double
the height required to get the same 20 dB reduction of reflected to direct sound"
As you can see, the absolute minimum distance from the mic to the speaker is 3X the largest dimension of the speaker. In the example quoted above, the 1 meter distance would apply only to a bookshelf speaker having a maximum dimension of 13".
The GedLee speakers have a maximum dimension of 35" ( http://www.gedlee.com/Loudspeakers/NS15.aspx ) so the absolute minimum distance for mic placement would be 105" away, or 8'-09".
Note that not only is this the absolute minimum, but that some disagreement exists as to whether 3X the largest dimension is sufficient. The notes above state that in some cases, the distance needed may be as much as 10X.
Jim
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I got the Abbeys in 2012. They were passive. Had them placed in two different rooms with many different positions.
First some pictures.
I also had the smaller Harpers, which I used as surrounds. And yup, I did experiment a heck of alot with acoustic treatment back then and it didn't look nice.
First some pictures.
I also had the smaller Harpers, which I used as surrounds. And yup, I did experiment a heck of alot with acoustic treatment back then and it didn't look nice.
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A few more pics.
I had one Abbey behind a transparent screen for a while as a center speaker. But I had a major cancellation in the midbass from it, so there were no weight or foundation to the sound. Sounded like a clock radio. So I ended selling it and ran phantom center instead.
Here's you see the chair behing the screen with the Abbey.
I had one Abbey behind a transparent screen for a while as a center speaker. But I had a major cancellation in the midbass from it, so there were no weight or foundation to the sound. Sounded like a clock radio. So I ended selling it and ran phantom center instead.
Here's you see the chair behing the screen with the Abbey.
Over to meausurements. Let's start with some fairly close up measurement of the Abbey. All of these are with 1/24 Oct smoothing unless otherwise is stated.
50-55 cm distance:
70-75 cm distance:
2m distance. Might have been in a different room this one (not sure).
50-55 cm distance:
70-75 cm distance:
2m distance. Might have been in a different room this one (not sure).
Here's a measurement of the Harper at 61 cm distance:
The Harper was a really poor design IMO due to the lack of extension of lows. It needed to be crossed over very high to a sub, something that's not ideal for a surround speaker. With a lot of distance between the surrounds and the subwoofer(s), a crossover not much higher than 80 Hz is preferable.
The Harper was a really poor design IMO due to the lack of extension of lows. It needed to be crossed over very high to a sub, something that's not ideal for a surround speaker. With a lot of distance between the surrounds and the subwoofer(s), a crossover not much higher than 80 Hz is preferable.
Let's move on to some frequency measurements of the Abbey in the listening position. Measurements are from two rooms and with placement both on short walls and in front of long walls. 1/24 octave smoothing here as well.
Left and right channel with Abbey placed in front of corners.
Left and right with a different position.
Left and right channel with Abbey placed in front of corners.
Left and right with a different position.
And here's a measurement where a lot of treatment had been added to the room. It's possible placement of speaker were optimized better.
Left and right channel.
I had the CBT36 speakers at the same time. They measured generally much more even in both rooms and with different positions, which is no surprise considering the design. People who came and listened to both, greatly preferred the CBT36. They not only had a more correct tonality, but sounded much more open and detailed with greater clarity. Here's a meausurement of one CBT36 channel.
Left and right channel.
I had the CBT36 speakers at the same time. They measured generally much more even in both rooms and with different positions, which is no surprise considering the design. People who came and listened to both, greatly preferred the CBT36. They not only had a more correct tonality, but sounded much more open and detailed with greater clarity. Here's a meausurement of one CBT36 channel.
If there are any questions or you want to look at other measurements, let me know.
I went from Gradient Revolution to Abbey. In retrospect I would say that wasn't overall better. The Abbey sounded more dynamic, but coherence was better with the Gradient. The Gradient also measured flatter in the room, but I should have added some shelving to the Gradients that were a bit too flat (didn't fall enough towards he treble).
Funny to look back on this. Here's the Gradient with Adam Classic Column Mk3 on the inside and a XTZ speaker used a surround in the back.
Talk about extensive treatment in a small space!
And treatment got thicker and thicker over time!
I went from Gradient Revolution to Abbey. In retrospect I would say that wasn't overall better. The Abbey sounded more dynamic, but coherence was better with the Gradient. The Gradient also measured flatter in the room, but I should have added some shelving to the Gradients that were a bit too flat (didn't fall enough towards he treble).
Funny to look back on this. Here's the Gradient with Adam Classic Column Mk3 on the inside and a XTZ speaker used a surround in the back.
Talk about extensive treatment in a small space!
And treatment got thicker and thicker over time!
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- Thread Starter
- #20
Hello again and thank you so much for sharing these. There is a lot of philosophy going into this loudspeaker but what matters most is how things play out in the room.
If you can share the mdat files with me that would be awesome. I sent you a PM about it.
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