Speakers specifications

[power]

I have a question about speakers specs. I fully understand what the frequency response means but I dont really understand the meaning of the frequency range. Which between the frequency response and range is more useful in setting the low pass filter.

I have B&W CM8 and their specs are as follows:
Frequency response 69Hz - 22kHz ±3dB on reference axis
Frequency range -6dB at 43Hz and 50kHz

Can someone explain to me the meaning and implication of this specs?

 

[power]

Please help

 

[Jhotopf]

Frequency range is like frequency response except it is tells you what what point the frequency drops below 6bd output from ideal. More meaningful would be to have a graphical representation of frequency against output. The frequency response is made in an echo free chamber, actual response in your own room would change the frequency response.

 

[Covenanter]

6dB is half as loud, so if you plot the output of a speaker across a frequency range for a constant level of input you will get some sort of curve which will fall away at the ends, ie low and high frequencies, and the 6dB points are where the output has fallen by half. (The decibel scale is logarithmic hence the unusual number.)

Chris

PS If the output doubled it would be 6dB up.

 

[Covenanter]

Of course if you are an old fogey like me, or even a not so old fogey, you might not worry about the high end too much:

http://www.roger-russell.com/hearing/hearing.htm

Chris

PS There are lots of hearing level tests on the net. Try one, you might be surprised. (I'm not as my annual BUPA medical has been showing a large but normal decline in high frequency hearing for a number of years.) Even a 30 year old will have lost large amounts of their hearing. It's much worse for men than women which is why the ladies will turn the hifi down!

 

[busb]

It's 3dB for half the power:

http://en.wikipedia.org/wiki/3dB-point

 

[gregvet]

I have a question about speakers specs. I fully understand what the frequency response means but I dont really understand the meaning of the frequency range. Which between the frequency response and range is more useful in setting the low pass filter. I have B&W CM8 and their specs are as follows: Frequency response 69Hz - 22kHz ±3dB on reference axis Frequency range -6dB at 43Hz and 50kHz Can someone explain to me the meaning and implication of this specs?

My understanding as to the significance of the two different ranges is as follows:

The frequency response figures (+/-3db) signifies the accurate range, beyond which any frequencies produced will be audibly quieter than those within the range, ie in your example frequencies below 69Hz or above 22kHz will be significantly quieter and therefore not accurate to the original fecording, compared to those within the 69Hz - 22kHz range. There may also be more distortion to frequencies produced outside of this quoted range, due to the drivers reaching the limits of their frequency capabilities.

The frequency range signifies the absolute range of frequencies produced by the speaker, audible to any significant extent. Once they get more than 6dB quieter than the other frequencies, there is considered to be an insufficient response. So in your example frequencies below 43Hz or above 50kHz are not produced at all to any significant degree.

The above may not be textbook accurate, but explains in laymans terms my understanding (being a layman myself )

 

[andyjm]

Like most spec's in hifi, its all about marketing. 3dB, 6dB or whatever points are arbitrary levels chosen to put in a spec sheet. By choosing a 6 dB point, they get to print a wider frequency range.

Just think about the number on the frequency response - 3dB is half, or twice the power - so the frequency response is 'flat' within half or twice the power?? that can't be good. Just goes to show that the largest random factor in hifi is the speaker itself.

In answer to your OP, (assuming you are trying to incorporate a sub into your system) if you set the -3dB point of your sub and your mains to the same frequency, then half the power (-3dB sub) plus half the power (-3dB mains) should equate to a flat transition from sub to main. Put the room in the mix and it never works out like that, but its a good starting point.

 

[Thompsonuxb]

gregvet is THE best explanation..... :rofl:

 

[gregvet]

Why thankyou kind sir

..... I'll get my coat

 

[power]

I have a question about speakers specs. I fully understand what the frequency response means but I dont really understand the meaning of the frequency range. Which between the frequency response and range is more useful in setting the low pass filter. I have B&W CM8 and their specs are as follows: Frequency response 69Hz - 22kHz ±3dB on reference axis Frequency range -6dB at 43Hz and 50kHz Can someone explain to me the meaning and implication of this specs?

My understanding as to the significance of the two different ranges is as follows:

The frequency response figures (+/-3db) signifies the accurate range, beyond which any frequencies produced will be audibly quieter than those within the range, ie in your example frequencies below 69Hz or above 22kHz will be significantly quieter and therefore not accurate to the original fecording, compared to those within the 69Hz - 22kHz range. There may also be more distortion to frequencies produced outside of this quoted range, due to the drivers reaching the limits of their frequency capabilities.

Gregvet's explanation sounds very clear to me.Thanks a lot to explaining it like that. . Like i said in my 1st thread that my speakers specs frequency response is 69Hz-22kHz at +-3db and frequency range is 43Hz and 50kHz at -6d. I realise that Most people in the forums seems to feel 80Hz is the gold standard for setting the receiver's low pass filter. I tried setting my low pass filter for the mains at 80Hz but i find the sub to be too audible. I found 60Hz to be the best sounding. The question then is do I loose out on some frequencies considering my speakers specs and how I set the low pass filter on my receiver?

The frequency range signifies the absolute range of frequencies produced by the speaker, audible to any significant extent. Once they get more than 6dB quieter than the other frequencies, there is considered to be an insufficient response. So in your example frequencies below 43Hz or above 50kHz are not produced at all to any significant degree.

The above may not be textbook accurate, but explains in laymans terms my understanding (being a layman myself )

 

[power]

I have a question about speakers specs. I fully understand what the frequency response means but I dont really understand the meaning of the frequency range. Which between the frequency response and range is more useful in setting the low pass filter. I have B&W CM8 and their specs are as follows: Frequency response 69Hz - 22kHz ±3dB on reference axis Frequency range -6dB at 43Hz and 50kHz Can someone explain to me the meaning and implication of this specs?

My understanding as to the significance of the two different ranges is as follows:

The frequency response figures (+/-3db) signifies the accurate range, beyond which any frequencies produced will be audibly quieter than those within the range, ie in your example frequencies below 69Hz or above 22kHz will be significantly quieter and therefore not accurate to the original fecording, compared to those within the 69Hz - 22kHz range. There may also be more distortion to frequencies produced outside of this quoted range, due to the drivers reaching the limits of their frequency capabilities.

Gregvet's explanation sounds very clear to me.Thanks a lot to explaining it like that. . Like i said in my 1st thread that my speakers specs frequency response is 69Hz-22kHz at +-3db and frequency range is 43Hz and 50kHz at -6d. I realise that Most people in the forums seems to feel 80Hz is the gold standard for setting the receiver's low pass filter. I tried setting my low pass filter for the mains at 80Hz but i find the sub to be too audible. I found 60Hz to be the best sounding. The question then is do I loose out on some frequencies considering my speakers specs and how I set the low pass filter on my receiver?

The frequency range signifies the absolute range of frequencies produced by the speaker, audible to any significant extent. Once they get more than 6dB quieter than the other frequencies, there is considered to be an insufficient response. So in your example frequencies below 43Hz or above 50kHz are not produced at all to any significant degree.

The above may not be textbook accurate, but explains in laymans terms my understanding (being a layman myself )

 

[power]

Gregvet's explanation sounds very clear to me.Thanks a lot to explaining it like that. . Like i said in my 1st thread that my speakers specs frequency response is 69Hz-22kHz at +-3db and frequency range is 43Hz and 50kHz at -6d. I realise that Most people in the forums seems to feel 80Hz is the gold standard for setting the receiver's low pass filter. I tried setting my low pass filter for the mains at 80Hz but i find the sub to be too audible. I found 60Hz to be the best sounding. The question then is do I loose out on some frequencies considering my speakers specs and how I set the low pass filter on my receiver?

 

[Covenanter]

Decibels are tricky beasts! If the thing you are measuring is power then -3bd is indeed 1/2 (well roughly as log10(2) =0.3010) and the formula for dBs is 10log10(x) so where x=2 then this is 3.010dB which is close enough to 3 for everybody to use it.

If you are measuring amplitudes then the formula is 20log10(x) so 1/2 is -6dB. The formulae are different to keep the two measurements in line, power being related to the square of the amplitude.

Anyway the key point is that beyond the 6dB points the output from the speaker is very small.

Why anyone would need a speaker with a frequency range up to 50kHz is beyond me as most of us adults won't be able to hear anything above 10kHz. Perhaps people like annoying their dogs? :?

 

[lindsayt]

Something else to bear in mind is the -3db or -6db figure in the bass region may be "anechoic" or "in-room."

Anechoic measurements are supposed to be done on tall stands in special non-echoey rooms. In room measurement are done with some room echoes reinforcing the bass. Sometimes looking at anechoic ferequency plots and manufacturer's quoted bass extension figures makes me wonder if they measured their speakers sitting in the bottom corner of a very echoey room.

Also there's a bit of room for manipulating where you set the +/- 0 db figure, with a tendency to set it a bit on the low side to give more extended +/- 3 or 6 db figures.

In other words there is scope for marketing exageration of these +/- 3db or 6 db figures.

I do find full frequency response curves useful for predicting the tonal balance of speakers and cartridges. More useful than +/- 3 or 6 db figures.