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#1
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If a room is small , we can't hear low frequency accurately? even if I use nearfield monitor
It is said that at least 28.5 feet length room is required for the
control room cuz I thought the wave length of 20hz is 56.6 feet then, I am using Mackie Hr824 monitor speaker in my room but my room is really small. most long length is just 12feet |
#2
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"bj" wrote in message
om... It is said that at least 28.5 feet length room is required for the control room cuz I thought the wave length of 20hz is 56.6 feet then, I am using Mackie Hr824 monitor speaker in my room but my room is really small. most long length is just 12feet My first lounge (with HiFi speakers) was very close to a 10 foot cube, and mains hum was a real problem when listening anywhere other than in the middle of the floor. Moved to a more modern place with a 19' x 15' x 8' lounge and the same system sounded so much better. (Mains frequency is 50Hz in the UK.) -- M Stewart Milton Keynes, UK http://www.megalith.freeserve.co.uk/oddimage.htm |
#3
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bj wrote:
It is said that at least 28.5 feet length room is required for the control room cuz I thought the wave length of 20hz is 56.6 feet then, I am using Mackie Hr824 monitor speaker in my room but my room is really small. most long length is just 12feet I'm not sure what you're asking. But if you play a sweep tone that goes from 20 to 100 Hz, you'll hear all kinds of things wrong with your room. Play the tone and see. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#4
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BJ,
It is said that at least 28.5 feet length room is required for the control room cuz I thought the wave length of 20hz is 56.6 feet That is a myth. If it were true, you wouldn't be able to hear anything below a few hundred Hz in a car! In fact, even a small room like yours can reproduce very low frequencies. However, the *flatness* of the low end response is undoubtedly way off. I am using Mackie Hr824 monitor speaker in my room but my room is really small. most long length is just 12feet Your speakers are fine, but your room is surely in need of bass traps and other acoustic treatment. For the complete story see the Acoustics FAQ, second in the list on my Articles page: www.ethanwiner.com/articles.html --Ethan |
#5
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Scott Dorsey wrote:
But if you play a sweep tone that goes from 20 to 100 Hz, you'll hear all kinds of things wrong with your room. Play the tone and see. I think the OP was asking if a sound wave can be accurately reproduced in a room whose longest dimension is *shorter* than half the wavelength of the frequency in question. (I assume here that "accurate" means without any form of distortion). You will still be able to perceive sounds at these low frequencies, however, it is physically impossible for any resonance to occur in this frequency range. The sound wave literally "does not fit" into the geometry of the room. However, the frequency of this sound will not be altered, therefore, you can still hear it "accurately". The longest dimension of a room X 2 defines the low frequency below which resonance simply *cannot* occur. This is known as the room's cut-off frequency. 1) Measure the longest dimension of your room 2a) If you measured in feet and inches then divide 1125 f/s by that value 2b) If you measured in metres then divide 343.4 m/s by that value 3) Divide by two again (because resonance occurs at half wavelength intervals). 4) Now you have the lowest frequency at which resonance can occur within that room. This does not mean that all sounds below this cut-off frequency simply disappear, they are still present, but are contained within a space too small to permit resonance - therefore, they die away very quickly. If you do as Scott suggested, then you will hear the volume of various pitches rise and fall as the sweep passes through the room's resonant frequencies. Below the cut-off frequency, the sound will appear very quiet for two reasons: Firstly, the room is not allowing *any* resonance to occur, therefore, the sound field that exists at that frequency lasts only for as longs as the sound wave's journey across the room (only a few milliseconds...) Secondly, the human ear is poorer at perceiving very low frequency sound (See the Fletcher-Munson curve of equal perceived volumes) HTH Chris W -- The voice of ignorance speaks loud and long, but the words of the wise are quiet and few. -- |
#6
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"bj" wrote in message
om It is said that at least 28.5 feet length room is required for the control room cuz I thought the wave length of 20hz is 56.6 feet The idea that small rooms can't support low bass is an old wive's tale. In fact its completely bass ackwards. Small rooms support bass better than large ones. In essence there is a 12 dB/octave boost that commences at some frequency inversely proportional to the size of the room. For a small room the boost starts at a higher frequency, while it starts at lower frequencies in larger rooms. This is one reason why bodacious bass is more feasible in automotive applictions - the listening room is effectively quite small. A synergistic match between speaker and room can be achieved when the speaker's bass extension starts cutting out just as the bass boost due to the size of the room starts cutting in. Of course some of this might get swamped by other room resonances. One thing that can happen is that the automatic bass boost due to a small room can cut in at such a high frequency that its not bass boost anymore - its midbass boost. Then things tend to sound thumpy or wooly. then, I am using Mackie Hr824 monitor speaker in my room but my room is really small. most long length is just 12feet. So how does it sound? |
#7
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"Chris Whealy" wrote in message
Scott Dorsey wrote: But if you play a sweep tone that goes from 20 to 100 Hz, you'll hear all kinds of things wrong with your room. Play the tone and see. I think the OP was asking if a sound wave can be accurately reproduced in a room whose longest dimension is *shorter* than half the wavelength of the frequency in question. (I assume here that "accurate" means without any form of distortion). You will still be able to perceive sounds at these low frequencies, however, it is physically impossible for any resonance to occur in this frequency range. Some rooms can be modelled as a Helmholtz resonator where the resonant frequency depends on the volume of the room and the size of its vent. |
#9
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Arny Krueger wrote:
Some rooms can be modelled as a Helmholtz resonator where the resonant frequency depends on the volume of the room and the size of its vent. ?? I'm afraid you lost me on that analogy Arny... A Helmholtz resonator is the acoustic analogue of a mass-spring system; it exhibits a single natural resonant frequency. Rooms on the other hand, exhibit multiple resonant frequencies due to the room have non-equal dimensions. (I assume your room is not a cube!) I think you would have to have a very particular shape of room before modelling it as a Helmholtz resonator would be appropriate. Chris W -- The voice of ignorance speaks loud and long, but the words of the wise are quiet and few. -- |
#10
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"Laurence Payne" wrote in message
... Can you hear booming bass in a car? A lot of youths have wasted a lot of money if you can't :-) And generally have even if you can. john |
#11
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In article ,
"John Hall" wrote: "Laurence Payne" wrote in message ... Can you hear booming bass in a car? A lot of youths have wasted a lot of money if you can't :-) And generally have even if you can. john Is it really wasted if you can annoy the neighbors? -Jay -- x------- Jay Kadis ------- x---- Jay's Attic Studio ------x x Lecturer, Audio Engineer x Dexter Records x x CCRMA, Stanford University x http://www.offbeats.com/ x x---------- http://ccrma.stanford.edu/~jay/ ------------x |
#12
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#13
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bj wrote:
It is said that at least 28.5 feet length room is required for the control room. IMO the reason is derived form which the wave length of 20hz is 56.6 feet As I and others have said, it is complete nonsense that you have to build a control room 28.5 feet long. A 20Hz sound wave will be heard fine in a small room. If you did build a control room 28.5 feet long, all you would be doing is creating a room in which bass resonance extends down to 20Hz! Chris W -- The voice of ignorance speaks loud and long, but the words of the wise are quiet and few. -- |
#14
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#15
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bluesjeon wrote:
It is said that at least 28.5 feet length room is required for the control room. in my opinion it is derived from which the wave length of 20hz is 56.6 feet There are a lot of reasons why you want a large control room. First of all, in a small room it IS difficult to get good and even low end, but it's possible to do. It doesn't require a room that is longer than a half wave in all directions, but having a larger room makes it easier. If you get the F. Alton Everest book, there is a nice introduction to room mode calculation in there. But also, in a larger room it's possible to get the speakers farther back and have a larger sweet spot. And it gives you a lot more options for placement if you need to worry aboout reflections off the console surface, or if you want to use planars. If you need to move the speakers around to get the low end evened out, it helps to have enough room to move them into a good position without them being on your lap. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#16
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"bj" wrote in message
om... It is said that at least 28.5 feet length room is required for the control room. IMO the reason is derived form which the wave length of 20hz is 56.6 feet Lots of urban mythology here. First, a room's acoustical size can be significantly greater at low frequencies than its dimensions due to the walls not being massive enough to reflect or even attenuate the sound. Soundproof, well isolated control rooms have little or nothing in common acoustically with most ordinary rooms. Second, if headphones can support low frequencies, certainly rooms of any size can do at least as good a job! -- Bob Olhsson Audio Mastery, Nashville TN Mastering, Audio for Picture, Mix Evaluation and Quality Control Over 40 years making people sound better than they ever imagined! 615.385.8051 http://www.hyperback.com |
#17
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On Tue, 01 Mar 2005 17:18:10 +0000, Chris Whealy
wrote: Arny Krueger wrote: Some rooms can be modelled as a Helmholtz resonator where the resonant frequency depends on the volume of the room and the size of its vent. ?? I'm afraid you lost me on that analogy Arny... You forgot Arny is moron. |
#18
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Chris Whealy wrote: Scott Dorsey wrote: But if you play a sweep tone that goes from 20 to 100 Hz, you'll hear all kinds of things wrong with your room. Play the tone and see. I think the OP was asking if a sound wave can be accurately reproduced in a room whose longest dimension is *shorter* than half the wavelength of the frequency in question. (I assume here that "accurate" means without any form of distortion). Seems to me that you would get phase cancellation at that frequency of which the room is half the distance of the wave length. Is this crazy? Mike http://www.mmeproductions.com |
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