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  1. #1
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    Frequency Response

    Hi :


    I usually see speaker description as Freq Response : 60Hz - 22kHz 3dB
    What does this number indicate ?

    Will 60Hz - 28Khz sound better (more treble, more bass, more vocal) than
    60Hz - 22kHz ? Can you guys help ?

    Thanks

  2. #2
    Loving This kexodusc's Avatar
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    Don't rely on Frequency Response for too much...it is a good measure, but it doesn't tell you nearly as much as the variablility within the frequency response...ie, how smooth/flat the curve is.

    First, you probably can't hear much above 15 kHz anyway...some people don't hear much past 13 kHz...those are the pretty high frequencies you'd associate with treble. 20 kHz is generally accepted as the highest you have to worry about.

    60Hz, is in the bass region, but not very deep. Human hearing bottoms out somewhere around 20 Hz...
    for more infor on frequencies of instruments, look here:
    http://psbspeakers.com/FrequenciesOfMusic.html


    The +/- 3 dB is pretty much an industry standard for measurements, and qualifies under what volume differential the listed response was measured. Say the average volume in which a speaker was to emit sound with 1 watt of power was 90 dB. The loudest frequency would be 93 dB and the softest or most quiet frequency would be 87 dB...hence, a total difference of 6dB between the loudest and quietest frequencies. A speaker's job is to remain neutral to the recording, so you can see why you'd ideally want this figure to be +/- 0 dB. But don't put too much stock in that.

    Finally, you can probably expect these speakers to still emit sound below 60Hz, but at this point the response (loudness) of these frequencies likely drops off or gets to erratic and no longer falls within the respectable +/- 3 dB range.

    These speaker measurements you are looking at in particular (if they are real and not hypothetical) tell you nothing about the vocal, or treble capabilities (ie: tonal properties) of the speakers. And really, not even a whole lot about the bass response.

    And this doesn't even touch whether the measurements were done on axis or off axis by 30 degrees etc...in an anechoic chamber or in some arbitrary room that may not be indicative of your listening area.

    Best bet is to rely on your ears more than measurements...though they can be useful in helping you identify what to listen for.

  3. #3
    RGA
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    Something to add is that at one frequency say 500hz the speaker may be -3db and at 3khz the speaker may have a boost of +3db - that is now a very noticeable 6db swing which would proably leave you thinking there was a suckout and bright treble. +/-0db from 20hz to 20khz is considered flat - again though rooms change these figures dramatically very noticably in the bass (below about 80hz). Then you have to be careful how it was tested - some use anechoic chambers which don;t say zilch unfortunately about real world listening - on the other hand it does tell you how they do against others tested in the chamber which can maybe be usefull.

    If a figure is not given then it could be +/- 10db or more - even that in itself doesn't necessarly mean it will sound bad in a real room because it depends where the dips and doodles are. Plus looking at a lot of graphs over the years very few have a smooth response - which may in fact be more important - a lot of them even some +/- 1-2db look a lot like a polygraph up and down as opposed to one which has gentle rise and fall - I am looking at a number of speakers that I personally don;t think sound very good and noticing a peaky response versus some others that sound much better in real life rooms with a greater frequency swing but a much smoother non peaky response - Ideally from 200hz to about 5khz you don;t want to see any jagged peaks and dips even if just 2 db but I have only been looking at a few so far so correlating it won't be for a while.

    In other words you have to listen period.

  4. #4
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    Quote Originally Posted by RGA
    at one frequency say 500hz the speaker may be -3db and at 3khz the speaker may have a boost of +3db - that is now a very noticeable 6db swing which would proably leave you thinking there was a suckout and bright treble
    That's really too large a range for a +/- 6 dB to cause a suckout, but I know what you're getting at here...from what I've seen, it's usually the other way around as you reach the limit of the woofer's upper response and begin the transition to the tweeter you find a +3 dB peak at 500-800Hz where roll-off begins and the suck out at 3kHz...Then the super steep rise in treble back up to 5 kHz or so, and another hump around 10 kHz and again at 15 kHz. This is common in metal tweeters which are great for low distortion and accuracy, but known for having a few steps or plateaus in response you have to compensate for.

    I secretly suspect your beef with metal tweeters isn't really with the tweeters themselves but with the cheap stock crossovers the speakers use that don't address this. But that's a discussion for another day.

    Quote Originally Posted by RGA
    Plus looking at a lot of graphs over the years very few have a smooth response - which may in fact be more important - a lot of them even some +/- 1-2db look a lot like a polygraph up and down as opposed to one which has gentle rise and fall - I am looking at a number of speakers that I personally don;t think sound very good and noticing a peaky response versus some others that sound much better in real life rooms with a greater frequency swing but a much smoother non peaky response - Ideally from 200hz to about 5khz you don;t want to see any jagged peaks and dips even if just 2 db but I have only been looking at a few so far so correlating it won't be for a while.
    I completely agree with that...alot of spikes and dips between 13 kHz and 20 khz probably isn't going to bother people as much as if you moved in to the midrange or bass area.
    Some gradual and wide dips actually add a very pleasing sound in the midrange, and designers will intentionally incorporate these to add "depth" to the soundstage...It can be quite pleasant, or unbearable depending on your tastes. But it's pretty hard to pull off well.

    Just about everybookshelf I've heard under $1000 has that mid-bass dip where the baffle step rise begins to occur, usually between 2 and 4 kHz. That can get annoying.

  5. #5
    Forum Regular Woochifer's Avatar
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    The specs by themselves don't really tell you much. You have no idea how the response was measured (in-room or anecholic?), and you don't have any idea where the inaccuracies occur. You need to actually look at the graph and see how the speaker behaves at different parts of the frequency range. And you need to make sure that the measurements were all done the same way, when comparing speaker frequency response charts. That will BEGIN to tell you how a speaker might sound. A speaker with a choppy inconsistent response in the midrange will rate the same as something with more gradual shifts in frequency response, but the sound quality will be quite different.

    High end extensions beyond 20 kHz are not audible, and I've yet to see anything definitive that would tell me that going beyond that level by itself makes a speaker sound better. The low end extension down to 60 Hz might give you slightly fuller sounding bass, but you really need to give it a listen for yourself to get a feel for what the speaker actually sounds like. Keep in mind that the room and placement are also huge determinants of what you hear.

  6. #6
    Dustin Broke is hot!!! SpankingVanillaice's Avatar
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    I can say I try to get speakers that have the flattest response since they play very realistic sounds and percise too. Like the Studio Series from JBL is pretty flat. I can say that the higher the speakers cost the more flatter response they are. Like the JBL LSR series from the pro they have very flat response like +1, -1.5db.
    Last edited by SpankingVanillaice; 12-14-2004 at 07:09 PM.

  7. #7
    Forum Regular Woochifer's Avatar
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    Quote Originally Posted by SpankingVanillaice
    I can say I try to get speakers that have the flattest response since they play very realistic sounds and percise too. Like the Studio Series from JBL is pretty flat. I can say that the higher the speakers cost the more flatter response they are. Like the JBL LSR series from the pro they have very flat response like +1, -1.5db.
    In-room response will vary a LOT from anecholic measurements, as will the off-axis response. JBL's pro studio monitors are designed to have a flat frequency response from the near-field position (i.e. on top of a recording studio mixing board), which is not how speakers are typically positioned at home. If you measure a nearfield monitor from a typical home listening position several feet away, its specs can look very different, especially in the off-axis positions since nearfield monitors are normally designed with a narrow dispersion pattern in order to minimize interaction with adjacent walls.

    And higher priced speakers DO NOT necessarily have flatter frequency response. Plenty of expensive speakers are very accurate, but others are not, and this is intentional. Sometimes, the expensive audiophile speakers are designed with a bulge in the midrange or a rolloff in the highs in order to highlight acoustic music. This is not necessarily more accurate, but it reflects the sound preference for a specific audience. Not all that different from how a lot of JBL speakers have a rise in the midbass and a boost in the highs.

  8. #8
    Dustin Broke is hot!!! SpankingVanillaice's Avatar
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    I did noticed that the more expensive speakers are the more flatter they are on lots of studio monitors. Most monitors that are like $300 pair or less are rated +-3db.

  9. #9
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    The +/- 3 dB or 1dB isn't nearly as important as the variations in amplitude of the frequency plot. You could have a plot that is within +/- 1 dB but is constantly zigging and zagging up and down. This could sound a lot worse than another speaker that plots a +/- 3dB response, but with smooth, slow, gradual peaks and dips, so there are no radical changes in response from one frequency to the next.

    The convention of using +/- 3dB has nothing to do with a speaker costing $300 or less...Most companies will try to fit as wide a response within a given +/- 3dB parameter to give you some idea of the usuable bass response. It could very well be that the $300 that measures +/- 3dB from 45 Hz to 20 kHz also measures +/- 2 dB from 80 Hz to 20 kHz...and again, this still won't tell you if it sounds good.

    Alot of very, good, very expensive speakers would measure +/- 1dB from 30 Hz to 20 kHz or less, with the exception of 1 small dip or spike, so naturally they include the amplitude of the spike, and the spec reads +/- 3 dB.

    You really have to look at the shape of the curve more than the range of variance to infer much from it.

  10. #10
    Big science. Hallelujah. noddin0ff's Avatar
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    Quote Originally Posted by SAPSEC
    Hi :


    I usually see speaker description as Freq Response : 60Hz - 22kHz 3dB
    What does this number indicate ?

    Will 60Hz - 28Khz sound better (more treble, more bass, more vocal) than
    60Hz - 22kHz ? Can you guys help ?

    Thanks
    SAPSEC-

    Just in case you need a total breakdown on what the frequency numbers mean... Hz is a unit of frequency called a Hertz. Its units are cycles/second. the 'k' is kilo for 'thousand'. A high pitch noise has shorter wavelenth but higher frequency. 22 kilohertz is a pretty high frequence, higher than most people can hear. 60Hz is a low note.

    The low key (A) on a piano is 27.5Hz
    the high key (C) on a piano is 4.186kHz
    Middle C is 261.63Hz

    If you go up one octave, you double the the frequency and shorten the wavelength by one-half.


    noddin0ff

  11. #11
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    Quote Originally Posted by SAPSEC
    Hi :


    I usually see speaker description as Freq Response : 60Hz - 22kHz 3dB
    What does this number indicate ?

    Will 60Hz - 28Khz sound better (more treble, more bass, more vocal) than
    60Hz - 22kHz ? Can you guys help ?

    Thanks
    Frequency response is not simple. It is best represented by sets of curves which indicate the dispersion pattern. Soundstage, Stereophile, and Audio Ideas Guide show such measurements, but they all use different methodologies so they are not directly comparable. Here is a link to the speaker measurements done by Soundstage:

    http://www.soundstagemagazine.com/speakermeasurements/
    "Opposition brings concord. Out of discord comes the fairest harmony."
    ------Heraclitus of Ephesis (fl. 504-500 BC), trans. Wheelwright.

  12. #12
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    I also question the accuracy of most specs published by manufacturers.

  13. #13
    RGA
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    stuartlittle

    Quite right. I have seen a number of standmounts claim ~35-40hz +/- 2db. Yet you listen to that 40hz versus the 40hz from Wharfedale Vanguards. One sounds like bass(the Wharfedales) the other sounds like an utter joke. At what volume - even then they claim at their sensitivity rating so around 90db - still somehting is very very missing.

    You simply don't need to get bogged down by it. Listen to a piano and the female voice on good high quality systems - it may cost a lot but I can't go back to anything less when I have to scarifice half the piano and listen to spitty female vocals due to horrid integration of drivers. And it sad that most of the big companies I've heard are totally out to lunch at reproducing piano(just one instrument at one time - heaven help them if the piano is actually being played at the SAME time as some other instrument). Better just stick with AC/DC and play it real loud so it doesn't matter.

  14. #14
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    I don't doubt speaker stats at all, you just have to be careful not to read more into the numbers than what's there. If memory serves, ratings "audited" to some extent on these type of things, aren't they?

    I think the real issue Stuart Little and RGA are getting at is how much these stated specs really tell you...40 Hz ratings +/-3dB might look good on paper, but in what type of room setup? What does the response curve look like, up one frequency, down the next? Consistently down 3 db or up 3 dB from the average? Two speakers with identical numerical specs can sound completely different from each other.
    I would argue we need more relevant specs, or at least better qualification to infer too much from them.

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