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what is flat response?

Discussion in 'Home Cinema Speakers' started by cribeiro, Jan 14, 2004.

  1. cribeiro

    cribeiro
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    Hi!
    Well, I know the theory about it, but I'd like to put it in numbers... I have heard that Magnat speakers are not flat at all, and I decided to see some measurements. Without details about the measurement, between 60 Hz and 20 kHz the variation was 3 dB maximum, specially given by peaks in the 100 Hz and 15 kHz range. Good. They are not "flat"... Now then, what is flat? I know there are always variations, but what is the limit?
    I hope you can help, greetings.
     
  2. buns

    buns
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    well if i had speaker which were no worse than plus or minus 3db from 60Hz to 20kHz..... id be quite likely to call them flat!!!

    How did you sample? How many samples and spaced in what fashion?

    edit
    oh and im stupid..... unless you went to incredible lengths, alot of the measurement is characteristic of your room. So if you were getting them this flat in your room, it is unlikely that they would have been the same in an anechoic envbironment (where the manugfacturer should have measured them). The fact that any discrepancies the speaker may have in anechoic environment seem to be balanced by your room is the most incredible thing of all..... hmmmmm

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  3. alexs2

    alexs2
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    Room variations etc aside,if my speakers were +/- 3dB from 60Hz to 20kHz I'd be surprised if they sounded flat,....given that a lot of people can hear +/- 1dB variations in response,and that +/- 3dB equates to a 4 fold change in SPL at any given frequency,it could easily make a speaker sound very bright,or recessed etc.

    The thing is though,as you said,that it's the in-room response that matters,and a speaker that measures perfectly in a lab can sound awful in the wrong room(my Keltiks sounded superb in our previous house,and had to be sold due to incurable room interaction probs in the next house...and they do measure very well in the lab,going down to -2dB @ 20Hz...that was the problem!).
     
  4. cribeiro

    cribeiro
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    I am terribly sorry for the misunderstanding...
    I didn't mean I did any measurement, but I saw them... I checked, and yes, I said "I decided to see some measurements"... But you are right, it can be misunderstood.
    No, the measurements I talk about where made in a review... I want to buy an spl meter and some test dvd in order to do it at home... But I take it easy :)
    Anyway, I wanted to compare some numbers, and this is why I ask... Good to know there is so much dependence on the room... Mine is 6x4x2.5 meters (long x wide x high). Rather standard? BTW, I'd like to know how should I furnish the room and walls if I want to optimize the acustics... Any hint?
    Of course, also the angle dispersion plays a role, etc, etc... Uf! Too much. And, in the end, it is your ear what matters... :) But I think these details can at least help by disregarding stuff that doesn't satisfy some basic requirements... Or not?
    BTW, cheapest spl meter in the market? Specially Germany...
     
  5. alexs2

    alexs2
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    There's an Excel spreadsheet here ( http://cgi.guidetohometheater.com/cgi-bin/showoldnews.cgi?388 ) for calculating your room characteristics,which may help.

    As for furnishings etc....essentially the more absorbent surfaces you place in the room,especially near reflective surfaces such as walls,the duller the overall sound is going to be,and this can be helpful in taming the excesses of some loudspeakers.

    Obviously you have to factor into that what you need in terms of furnishings,and work from there to get a room that works reasonably well,in the absence of digital room correction software in your processor.
     

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