# Frequency Response Variables

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Hi,

Just a quick question. I'm just starting to research speakers seriously and I'm trying to compare specs etc... One thing I'm wondering about is what the decible rating after the frequency response indicates?

For example one pair that I'm looking at (JM Lab Chorus 705S) gives 65-28000Hz +/-3db and the Wharfedale Diamond 9.1 gives 50-24000 +/-6db. What is the significance of the 3 and 6 db? Can they be compared somehow?

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Quote:
 Originally Posted by advertguy2 Hi, Just a quick question. I'm just starting to research speakers seriously and I'm trying to compare specs etc... One thing I'm wondering about is what the decible rating after the frequency response indicates? For example one pair that I'm looking at (JM Lab Chorus 705S) gives 65-28000Hz +/-3db and the Wharfedale Diamond 9.1 gives 50-24000 +/-6db. What is the significance of the 3 and 6 db? Can they be compared somehow?
The +/- figure tells us how much the frequency response varies across the stated range, that is, how flat the curve is across the range. The typical reference is +/- 3dB, which is reasonably flat. (Without a tolerance, the frequency-response rating would tell us almost nothing.)

In this case, the JM Labs speaker is down 3 dB from flat at 65 Hz. The Wharfedale rating goes "lower," but it's down 6 dB at 50 Hz (and certainly down at 65 Hz as well), so it's hard to directly compare the two specs. If the Wharfedale spec also had a tolerance of +/- 3 dB, then its low-end cutoff would almost certainly have to be raised, or, conversely, the JM Labs' rating would go lower with a wider tolerance.

Anyway, frequency-response specs don't actually tell us a lot about how speakers sound (certainly when they're this similar), so you need to listen and decide what you like. I'm not familiar with these particular speakers, but I wouldn't be surprised if they sounded very different.
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In lay man's terms, the dB value tells you how loud the given frequency range will be heard. Without it, some manufacturers could claim that a speaker goes down to say 30 Hz, but what good is it, if at that frequency they are barely audible. The +/- 3dB says that there is no more than 3 dB variation in how loudly each frequency is reproduced. For comparison, to a human ear, a 10 dB differerence in sensitivity appears twice as loud (or as quiet).
Quote:
 Originally Posted by Pete7874 In lay man's terms, the dB value tells you how loud the given frequency range will be heard. Without it, some manufacturers could claim that a speaker goes down to say 30 Hz, but what good is it, if at that frequency they are barely audible. The +/- 3dB says that there is no more than 3 dB variation in how loudly each frequency is reproduced. For comparison, to a human ear, a 10 dB differerence in sensitivity appears twice as loud (or as quiet).
I agree in general, but there's an important distinction to be made here -- the frequency-response tolerance tells us about relative loudness, not loudness per se. Loudness is a measure of sensitivity.

If a speaker's response is down 3 dB at, say, 40 Hz, then its output at that frequency is 3 dB less than it is at other frequencies that fall on the baseline (and 6 dB less than a +3 dB peak that may occur elsewhere). Depending on a speaker's sensitivity, all the frequencies may be loud or quiet at a given input wattage. The +/- figure simply tells us the relative output levels across the stated range.
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Quote:
 Originally Posted by Mr. Brownstone I agree in general, but there's an important distinction to be made here -- the frequency-response tolerance tells us about relative loudness, not loudness per se.
Yes, of course. I worded my response imprecisely. Thanks for catching that.

The +/- dB is the variation from a reference sensitivity (ie. 90 dB for 1 Watt @ 1 meter) for a given speaker.
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