Bass frequency limit no LFE

Discussion in 'Effects and the DSP' started by blitter2, Jan 15, 2011.

  1. blitter2

    blitter2 New Member

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    Hi and happy new year.

    My Logitech speaker set's subwoofer has no LFE.

    Is there any way to make my subwoofer only play frequencies under 80Hz?

    With kxproject and the use of kx DSP.

    I currently use a Profx setup at kx DSP.
     
    Last edited: Jan 15, 2011
  2. Russ

    Russ Well-Known Member

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    Hmm, I do not completely understand what you are asking...

    What exactly do you mean when you say "My Logitech speaker set's subwoofer has no LFE."?
    Do you mean that you are getting no output from the subwoofer at all?

    Does your speaker set utilize the sound card's LFE output (i.e. does the subwoofer have it's own connection to the sound card)?
    Does your speaker set have a built-in crossover that limits (or redirects) the frequencies that are sent to each speaker and/or the subwoofer?
     
    Last edited: Jan 26, 2011
  3. blitter2

    blitter2 New Member

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    The speaker set has only one green stereo connector in total.

    The subwoofer has a bass volume knob on it, and that's all.

    From what I understood that my speaker set has no LFE channel, was when I seted Out2L and Out2R on k1lt to Digital Center/LFE Out and whatever I was connecting there was having no sound output from the subwoofer.

    Its is the Logitech Z3 speaker set.
     
  4. Russ

    Russ Well-Known Member

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    Since there is no connection between the sound card and the subwoofer, there is no way for kX to be able to control it at all. The hardware in your speaker set determines on it's own what frequencies to send to the subwoofer (redirected from the other 2 speakers). The best you can do in the DSP, is to use EQ plugins to maybe boost the lower frequencies, etc (or maybe try a bass booster plugin, which can give the impression of more bass, etc).
     
  5. blitter2

    blitter2 New Member

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    Thank you Russ.
     
  6. Russ

    Russ Well-Known Member

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    Glad to help.

    BTW: (In case it is not clear) You will not get any output using Center/LFE unless you have something connected to the Center/LFE jack on the sound card. Also, there is nothing special about the Center/LFE output. It is exactly the same as the other analog outputs on the card. If you feed the same signal to any of the analog outputs, and connect the same speakers to the corresponding jack, the resulting audio will be the same.
     
    Last edited: Jan 17, 2011
  7. blitter2

    blitter2 New Member

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    I think there is a special thing about the Center/LFE output.

    Using a crossover plug-in and kx you can command the subwoofer to output only frequencies up to 80hz for example, and send the rest beyond frequencies to the satelite speakers for output. That is because you use 2 jacks and gives you an extra OUT to wire on kx DSP for k1LT.

    I think I can't do a frequency redirection like that with my sound system because as said my system decides from its own what to send to the satelite speakers and what to the subwoofer because it uses just a green jack.

    Is there any way I would be able to do this on my setup?

    I use a 2nd order crossover plug-in to proccess frequencies under 80hz my way.
    Is it dangerous for the sound system which from what I can understand has a built-in crossover as well? Or is it any kind of frequency redirection funtion?

    Please any hint for a crossover Hz value for my 2nd order crossover plug-in to match my sound system's built-in crossover, if any? I own the Logitech Z3.
     
    Last edited: Jan 24, 2011
  8. blitter2

    blitter2 New Member

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    They say on the net that crossover frequency goes according with the inches of the subwoofer, and for mine which is 8 inches, the crossover should be 60-80Hz.

    Paste from Subwoofer Setup Guide | The Audiophiliac - CNET News :

    You'll find the receiver's crossover setting in the speaker setup menu, and on some receivers you'll be presented with a wide range of settings from 40 Hertz up to as high as 200 Hz. Your speaker and/or subwoofer's user manual may offer specific guidance in this area; otherwise use the Audiophiliac's crossover recommendations--for small speakers with 2 or 3 inch woofers, try between 150 and 200 Hz; for midsize speakers with 4 or 5 inch woofers, use 80 or 100 Hz; and with large bookshelf speakers or skinny floorstanding speakers, try a 60 or 80 Hz crossover.

     
    Last edited: Jan 24, 2011
  9. Russ

    Russ Well-Known Member

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    Of course, but that is only because that is where a subwoofer would normally be connected. There is no reason that you could not connect a subwoofer to any of the other outputs and do the same thing.

    Right, your cannot do this with your speaker system (unless your speaker system itself allows for such adjustments) because the subwoofer is not directly connected to the sound card.

    Sorry, I am not sure what you are asking, and you did not state what it is that you are are doing with the crossover plugin in the DSP (I am not sure how using a crossover plugin in the DSP would hurt your speaker system (unless you were using it to send frequencies to speakers that cannot handle those frequencies, but with your speaker system, that should not be an issue)).

    You would have to refer to the documentation for your speaker system.
     
    Last edited: Jan 24, 2011
  10. blitter2

    blitter2 New Member

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    I am feeding l1 and l2 of 2nd order crossover to EQ peaking that uses Q= 0.70 and Gain= -3.0.

    Then just mixing EQ peaking output with h1 and h2 of 2nd order crossover and connect to OUT1L and OUT1R of k1lt.

    I have read about this method on the forum and it sounds nice. Is it for better bass than using no crossover?
     
    Last edited: Jan 24, 2011
  11. Russ

    Russ Well-Known Member

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    What are you trying to accomplish with that config? With negative gain, you are reducing some of the lower frequencies... Is that what you want? Also, I am not sure why a crossover is necessary there. In any case, such a config should not hurt your speaker system.

    BTW: You might try using a low shelf filter.
     
    Last edited: Jan 24, 2011
  12. blitter2

    blitter2 New Member

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    What the slope value of low shelf filter is for please?

    Is low shelf filter an 1st or 2nd order plug-in?
     
    Last edited: Jan 24, 2011
  13. Russ

    Russ Well-Known Member

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    Low Shelf is 2nd order (same as Peaking).
     
  14. Russ

    Russ Well-Known Member

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    BTW: You might take a look at this: http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt for a description of the parameters as most of the bundled EQ <type> plugins (e.g. EQ Lowpass, EQ Peaking, EQ Low Shelf, etc) are based on it.

    Also, if you are able to use UFX, I suggest trying out EQP1 and EQP5.... as you will basically be able to see (on it's graph display) how each filter and setting effects the frequency spectrum, etc.
     
    Last edited: Jan 24, 2011
  15. blitter2

    blitter2 New Member

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    If I insert a low shelf filter or EQ peaking and change the Frequency in Hz the sound doesn't changes.

    Are it supposed to be after a crossover plug-in so the Frequency can be controled from the crossover plug-in? But if it was like it why does the Frequency slider on those 2 EQ filters exists?

    Russ can you explain please.
     
  16. Russ

    Russ Well-Known Member

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    You will not hear any difference unless you apply gain (boost or cut), and of course you will not hear any difference if the audio signal does not contain any frequencies in the range where the gain is applied.

    Apply gain (using plugin's gain parameter), and then adjust the frequency parameter.

    (crossover is not necessary)
     
    Last edited: Jan 24, 2011
  17. blitter2

    blitter2 New Member

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    Yes you are right Russ. It works that way.
     
    Last edited: Jan 24, 2011
  18. Russ

    Russ Well-Known Member

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    The term "center frequency" only applies to certain filter types. A 2-Way crossover is typically made up of a lowpass filter and a highpass filter (though IIRC, kX crossovers use allpass filters). These filters typically use the term "cutoff frequency" (or "corner frequency", etc). The frequency parameter used in a 2-way crossover basically adjusts this cutoff frequency for both filters (lowpass/highpass) at the same time, but is (AFAIK) just called "crossover frequency" (or "crossover point", etc).

    Regardless of the term used, it is really just about what frequency is relevant with each filter type (as described in the Audio EQ Cookbook (with f0)). Your best bet is to probably search for each filter type (low-pass/high-pass, low-shelf/high-shelf, band-pass, peaking, etc) to get an understanding of what each type of filter does, and what the frequency parameter means for each filter, etc.

    BTW: I am not an expert on the subject, just trying to answer as best I can...

    [edit: oops, I guess you deleted that question... never mind then, hehe :D)

    ...and again, if you are able to use UFX EQP1...
     
    Last edited: Mar 5, 2011
  19. blitter2

    blitter2 New Member

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    I have found a very nice low shelf preset on EQP1 called "SubBass Boost"

    But it uses 6.0db gain.

    Doesn't anything more from 0db introduces distorsion?
     
    Last edited: Jan 24, 2011
  20. Russ

    Russ Well-Known Member

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    It is nice being able to see what each filter is doing, right? With EQP5 you can also see how different filters interact with each other.

    Applying gain is not necessarily going to introduce distortion (changing the volume level applies gain to the signal). You are changing the signal of course, so in that sense... but unless you go overboard, and cause the signal to clip (check with a peak meter) it should be OK. Of course, it all comes down to personal taste (i.e. does it sound good to you?).
     
    Last edited: Jan 24, 2011

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