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<blockquote data-quote="req" data-source="post: 762243" data-attributes="member: 555713"><p>if this is a LOW PASS FILER (filters out EVERYTHING but the LOW frequencies), it will cut off everything ABOVE 75hz. and at that point, the volume of everything above that point will decline and 12db PER octave (octave = 1\2 lower, or 2x higher)</p><p></p><p>[see the black graph above, and look at the white line. this is a subwoofer with an 80hz low pass filter]</p><p></p><p></p><p>as its a LOW PASS FILTER, and it will filter everything ABOVE that point out of the speaker. so in order to hear MORE and play HIGHER frequencies, you will need to turn it UP say to 80hz, or 85hz - not down.</p><p></p><p>but as said, it wont completly cut off at 75 or 80hz, it will decrease in volume after that at the rate of (as you said) 12db per octave. in this case, at 150~160hz, it will be 12 decibles lower - so you will still be able to hear it. this is how music 'blends' together via different speakers.</p><p></p><p></p><p>as stated above, it would filter out EVERYTHING above 0decibles - if its a LOW PASS FILTER.</p><p></p><p></p><p>no problem patrick. hopefully your questions will help many more to come.</p><p></p><p><strong>furthermore</strong> i feel that some people might take my whole article about refrence levels a little askew - there are two kinds of 'decibles' that we look at. we look at <strong>spectrum response</strong> and <strong>speaker frequecny response</strong>. both are listed as the same graph. HZ on one side, and DB on the other (as seen in the above graphs). <strong>spectrum response</strong> however, is meant to tell us how loud the entire spectrum of sound is in our current setup. this is done by an insturment called a <strong>RTA, or Real Time Anaylazer</strong>. it analyzes EACH frequecny, and it will show a graph (seen in the white graphs above, peaky vs flat) the loudness of each frequecny. this is useful so we know if our high frequencies are overpowering our low frequencies, or vice versa. most people will never use an RTA, but that is beside the point. our second kind of reading is <strong>speaker frequecny response</strong>. frequency response is the physical response a speaker can produce at whatever loudness (db). the speaker company will send the speaker 1 watt, and put a microphone 1 meter away from the speaker, and play a sweep of the entire frequency band. it will record how loud each individual note is, and we will see a graph like this;</p><p></p><p><img src="http://www.adireaudio.com/images/Koda8FR.gif" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p>this is an adire koda 8" midbass speaker, recorded as i described above. notice how it can ONLY PLAY 22-2300hz down to about 50hz - this is the PHYSICAL LIMIT of the speaker... and this is why our stereo's need multiple speakers to play every note. BUT - each speaker CAN NOT play EVERY note in theie PHYSICAL SPECTRUM at the same volume. this is why there are peaks and valleys. this graph is a real-world application. it is the actual measurements of that actual speaker. and to be honest, it is quite a flat response between 1000hz, even though 1000hz is -7db from 100hz.</p><p></p><p>i cant really think of anything else to put in here. so please post any and all questions for us to awnser. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif</p></blockquote><p></p>
[QUOTE="req, post: 762243, member: 555713"] if this is a LOW PASS FILER (filters out EVERYTHING but the LOW frequencies), it will cut off everything ABOVE 75hz. and at that point, the volume of everything above that point will decline and 12db PER octave (octave = 1\2 lower, or 2x higher) [see the black graph above, and look at the white line. this is a subwoofer with an 80hz low pass filter] as its a LOW PASS FILTER, and it will filter everything ABOVE that point out of the speaker. so in order to hear MORE and play HIGHER frequencies, you will need to turn it UP say to 80hz, or 85hz - not down. but as said, it wont completly cut off at 75 or 80hz, it will decrease in volume after that at the rate of (as you said) 12db per octave. in this case, at 150~160hz, it will be 12 decibles lower - so you will still be able to hear it. this is how music 'blends' together via different speakers. as stated above, it would filter out EVERYTHING above 0decibles - if its a LOW PASS FILTER. no problem patrick. hopefully your questions will help many more to come. [B]furthermore[/B] i feel that some people might take my whole article about refrence levels a little askew - there are two kinds of 'decibles' that we look at. we look at [B]spectrum response[/B] and [B]speaker frequecny response[/B]. both are listed as the same graph. HZ on one side, and DB on the other (as seen in the above graphs). [B]spectrum response[/B] however, is meant to tell us how loud the entire spectrum of sound is in our current setup. this is done by an insturment called a [B]RTA, or Real Time Anaylazer[/B]. it analyzes EACH frequecny, and it will show a graph (seen in the white graphs above, peaky vs flat) the loudness of each frequecny. this is useful so we know if our high frequencies are overpowering our low frequencies, or vice versa. most people will never use an RTA, but that is beside the point. our second kind of reading is [B]speaker frequecny response[/B]. frequency response is the physical response a speaker can produce at whatever loudness (db). the speaker company will send the speaker 1 watt, and put a microphone 1 meter away from the speaker, and play a sweep of the entire frequency band. it will record how loud each individual note is, and we will see a graph like this; [IMG]http://www.adireaudio.com/images/Koda8FR.gif[/IMG] this is an adire koda 8" midbass speaker, recorded as i described above. notice how it can ONLY PLAY 22-2300hz down to about 50hz - this is the PHYSICAL LIMIT of the speaker... and this is why our stereo's need multiple speakers to play every note. BUT - each speaker CAN NOT play EVERY note in theie PHYSICAL SPECTRUM at the same volume. this is why there are peaks and valleys. this graph is a real-world application. it is the actual measurements of that actual speaker. and to be honest, it is quite a flat response between 1000hz, even though 1000hz is -7db from 100hz. i cant really think of anything else to put in here. so please post any and all questions for us to awnser. [IMG]//content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif[/IMG] [/QUOTE]
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