1. Join Now

    AVForums.com uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Lots of daft questions about frequencies and stuff!

Discussion in 'Home Cinema Speakers' started by ollie501, Aug 27, 2003.

  1. ollie501

    ollie501
    Active Member

    Joined:
    Jul 14, 2003
    Messages:
    998
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    31
    Location:
    Dorset, UK
    Ratings:
    +25
    Hi,

    I have some questions that hopefully someone can answer in plain English, without confusing the hell out of me, as most websites appear to do. Most give so much information that I can't see the wood for the trees! The questions are mainly speaker related, although a couple of amp questions do pop up - I am guessing they are more or less the same on all amps. Ok, here goes

    Speakers themselves have frequency response eg 50-20,000k - does the lower the first figure mean better, or more bass, and the latter figure better, or higher treble range - ie, would a set of 50-20000 speakers be "better" than 60-20000, or 55-22000

    My amp has frequency settings for speakers eg each speaker (front centre and rear) has settings for bass, treble and in the case of the front, mid.

    At present my rears are set with :

    bass has range of 99hz to 1khz - what should it be set to (is currently at 250hz)
    treble is 2.5khz (range is 1khz to 10 khz)

    fronts are same, set on amp at 250hz bass (range as above) 2.0khz mid (range 198hz-10khz) and a "slope" set to wide. What is a slope?

    treble is at 1.4khz (range is 1.0khz-10khz)

    Speakers are set to large, crossover frequency in setup is greyed out and only able

    to be set when speakers are "small" - what does this mean - how do I know which is the better setting - does one give more control, and how does one determine whether speakers are "large" or "small"?

    On my subwoofers, volume (obvious, even to me!), crossover (or low pass frequency) 50-250 and phase, switchable between 0 and 180. What is crossover, how do I set it correctly, and what on earth is "phase"

    Other speaker related questions I have are -

    sensitivity (90db) - is higher or lower better - what is it?

    impedance - is it particularly relevant?

    Should all these various things be set according to the speakers you have, and how?


    If it is of any help, my amp is a Sony STR-VA555ES, front's are Acoustic Energy Evo3, Rears Eltax HT-2 Bipolar, Centre is Eltax HT-2, and subs are both Eltax, although not sure what model.

    I really appreciate any plain speaking advice on this lot!

    Many thanks

    Ollie :confused:
     
  2. hornydragon

    hornydragon
    Well-known Member

    Joined:
    Dec 19, 2001
    Messages:
    28,293
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    136
    Location:
    Somewhere near the M4 most of the time......
    Ratings:
    +1,215
    Err your asking alot there mate.............
    I can be arsed to answer it all at once so break it up a bit please...
     
  3. ollie501

    ollie501
    Active Member

    Joined:
    Jul 14, 2003
    Messages:
    998
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    31
    Location:
    Dorset, UK
    Ratings:
    +25
    I don't really know how you want me to break it down? I am guessing that they are all related to each other which is why I lumped them all in to one post. I did try and separate it up a bit, but couldn't really see how to without confusing things (even more than they are!)

    Thanks

    Ollie
     
  4. Dominic

    Dominic
    Active Member

    Joined:
    Mar 2, 2001
    Messages:
    288
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    21
    Location:
    Essex
    Ratings:
    +6
    to be set when speakers are "small" - what does this mean - how do I know which is the better setting - does one give more control, and how does one determine whether speakers are "large" or "small"?
    Small is generally a bass driver les than 6" (165mm) diameter, its best to set to small for Regards HT2 are small not sure on centre and front, if you set to small then the AMP will send the intended BASS for those speakers to your sub/subs


    On my subwoofers, volume (obvious, even to me!), crossover (or low pass frequency) 50-250 and phase, switchable between 0 and 180. What is crossover, how do I set it correctly, and what on earth is "phase"
    Phase is refered to what direction the sub is moving in with relation to your main speakers, either 0 degrees ( ie at the same time the main speakers move out so does the sub, at 180 degrees the sub is moving in when the main are moving out. ( and vice versa) If this means nothing to you then leave it alone, the benifit could be enhanced base in certain situations, but experimentation is the key

    Other speaker related questions I have are -

    sensitivity (90db) - is higher or lower better - what is it?
    sensitivity is the given output at 1metre for 1Watt of power, the higher the more easily the cone moves so in theory the louder. but louder doesnt always mean more powerfull.

    impedance - is it particularly relevant?
    impedance is the resistance of the driver, in an ideal world for maximum power transfer you need to match the impedance of the AMP and the speaker. So an amp that can drive 6-16ohm speakers will cope with what you have. there is loads of info on ohmms law if you want to waste many hours of your life
    Should all these various things be set according to the speakers you have, and how?


    As for the test of it, my method would be to set all speakers to small and then adjust the sub crossover to around 80hz, that way main speakers handle above 80Hz and the sub handles everthing below. The crossover slope is how quickley the frequency Rolls or drops off for a given output. 12db/octive is a 12db decay for every double in frequency. i think someone may correct me if thats wrong
     
  5. ollie501

    ollie501
    Active Member

    Joined:
    Jul 14, 2003
    Messages:
    998
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    31
    Location:
    Dorset, UK
    Ratings:
    +25
    Hi Dominic,

    Thanks. That all seems to make sense - only thing I'm not sure about is setting the amp, presumably if I set the bass to 80hz, the speakers handle everything above that - so from there what would be the optimal settings for midrange and treble.

    I am guessing that one should take over from the other at some point, so it would it be something along the lines of:
    80hz- A A-B for the midrange B-C for the treble. If I am right in that assumption, how do I work out what points to set A, B, and C at. Hopefully that made sense! Are they precise, in as much as if for example the midrange ended at 120, would the treble be set to 120 to take over from there?

    Thanks for the help so far!

    Cheers

    Ollie
     
  6. Reiner

    Reiner
    Active Member

    Joined:
    Jul 16, 2000
    Messages:
    3,315
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    61
    Location:
    Germany
    Ratings:
    +13
    Frequencies are measured in Hertz (Hz) = cycles per second.
    A low number means a low frequency, so 50Hz is low and in terms of audio/hifi considered bass. The lower the number the lower the bass frequency (not more or better though). Treble is made of higher frequencies.
    The human hearing goes from 20Hz to 20kHz (20000Hz), speech is within the range of 300-3400Hz (not considering extremes or singing ;) ).

    As for speakers be carefull with the lower numbers, the entire frequency thing depends on the level it's quoted at (measured in dB) - if it's 50Hz @ -10dB it's a trick (to use a nice word).
    A speaker should have a linear frequency response, dropping of at either end which would define the range of that particular speaker.
    Even subwoofers struggle to reach down to 20Hz let alone normal speakers.

    It says how much power is needed to produce a certain level of output (1W/m). The higher, the better as the speaker then is easier to drive and produces less load to the amp. This is measured in Dezibel (dB).

    Yes and no. For normal use probably not, but if you want to run a disco or you have a weak amplifier this might matter.
    Usually speakers are called 4 or 8 Ohm speakers. This is a nominal value. Typically a 8 Ohm speaker presents less load to an amplifier than a 4 Ohm speaker, though as explained above the sensitivity might also influence that. (If they have the same sensitivity than the 4 Ohm speaker is definetely the tougher load).
    Impedance itself is not a static value, it changes with the frequency applied. In simple terms bass causes a low impedance (and thus a higher load) while treble causes a high impedance (less load).
    A speaker can e.g. have an impedance from 3.5 - 14.4 Ohm (Dynaudio Contour 1.3MkII). This model is considered a 4 Ohm speaker.

    In normal use the whole thing is not much of an issue, most amps / receivers should be able to handle 4 Ohm loads even though the amp manufacturer states "for speakers from 6-16 Ohms only" as they are playing safe. Then again most amps have a protection circuit to prevent damage to the amp (but not the speaker).
    If your requirements exceed normal listening levels and you have tough speakers to drive (low sensitivity, low impedance) than you should look at (external) power amps.
     

Share This Page

Loading...