Question concerning EQs

Violoncello · Jun 18, 2011, 11:42 AM

Hi all!
I'm quite new to these KX things, furthermore I'm no native speaker, so please excuse if I mistake something

.

Firstly I wonna thank everybody who has contributed to this awesome Software! It's exactly what I need.

But something is unclear for me in the EQ Plugins for the DSP. Take for example the peaking EQ, which should be great for parametric equalizing. You can adjust a value named "Width (Q)". This seems contradictory for me, so my question is: Does this value stand for:
a) a Bandwidth as in Bandwidth (signal processing) - Wikipedia, the free encyclopedia which would cause higher values to result in a wider influence area
b) a Q factor as in Q factor - Wikipedia, the free encyclopedia which would cause higher values to result in a smaller influence area

Maybe this question has been answered somewhere else, however the forum search has returend some threads in russian, but this doesn't help for me

.

Thanks for your help, greetings from Germany

Russ · Jun 18, 2011, 08:31 PM

IIRC, they (currently) all use Q (except the shelf filters which use shelf slope).

Violoncello · Jun 18, 2011, 08:45 PM

Ok I almost thought so. What made me doubt was the fact that the default value is set to 1.20, which results in an "overshooting" (do you say so in english? I don't know) filter function in case of high/low passes.

Russ · Jun 18, 2011, 09:57 PM

Yeah, I am not sure why that was chosen as the default value, but the overshoot makes sense as (IIRC) for these lowpass/highpass filters, Q would be approx. equal to gain at the cutoff frequency (e.g. 1.2 Q = @1.58 dB Gain ( 20*Log10(1.2) ) at cutoff).

Violoncello · Jun 19, 2011, 09:28 AM

Yeah, sure, an overshooting filter CAN make sense, for example for Bass Boost via subsonic. But in most cases you will use Butterworth filters (Q 0,707), cause they give you a "clean" filter function without overshoot and ripple.

But, of course, it does not matter what is set by default if you know that actually the Q factor is meant

.

Russ · Jun 19, 2011, 08:45 PM

Right, so you understand

I guess I misunderstood your previous reply...

silvertones · Jun 19, 2011, 10:07 PM

Don't know if this adds to the discussion or not however "Q" is the bandwidth of the signal 3Db down from peak. For a given Q at 0 Db as the gain is increased the Q actually gets smaller.

Jun 18, 2011, 11:42 AM	#1
Violoncello HardwareHeaven Newbie Join Date: Jun 2011 Posts: 10 Rep Power: 0	Question concerning EQs Hi all! I'm quite new to these KX things, furthermore I'm no native speaker, so please excuse if I mistake something . Firstly I wonna thank everybody who has contributed to this awesome Software! It's exactly what I need. But something is unclear for me in the EQ Plugins for the DSP. Take for example the peaking EQ, which should be great for parametric equalizing. You can adjust a value named "Width (Q)". This seems contradictory for me, so my question is: Does this value stand for: a) a Bandwidth as in Bandwidth (signal processing) - Wikipedia, the free encyclopedia which would cause higher values to result in a wider influence area b) a Q factor as in Q factor - Wikipedia, the free encyclopedia which would cause higher values to result in a smaller influence area Maybe this question has been answered somewhere else, however the forum search has returend some threads in russian, but this doesn't help for me . Thanks for your help, greetings from Germany

Jun 18, 2011, 08:31 PM	#2
Russ HardwareHeaven Extreme Member Join Date: Jan 2005 Posts: 5,563 Rep Power: 62	Re: Question concerning EQs IIRC, they (currently) all use Q (except the shelf filters which use shelf slope).

Jun 18, 2011, 08:45 PM	Thread Starter #3
Violoncello HardwareHeaven Newbie Join Date: Jun 2011 Posts: 10 Rep Power: 0	AW: Question concerning EQs Ok I almost thought so. What made me doubt was the fact that the default value is set to 1.20, which results in an "overshooting" (do you say so in english? I don't know) filter function in case of high/low passes.

Jun 18, 2011, 09:57 PM	#4
Russ HardwareHeaven Extreme Member Join Date: Jan 2005 Posts: 5,563 Rep Power: 62	Re: Question concerning EQs Yeah, I am not sure why that was chosen as the default value, but the overshoot makes sense as (IIRC) for these lowpass/highpass filters, Q would be approx. equal to gain at the cutoff frequency (e.g. 1.2 Q = @1.58 dB Gain ( 20Log10(1.2) )* at cutoff). Last edited by Russ; Jun 19, 2011 at 05:39 AM.

Jun 19, 2011, 09:28 AM	Thread Starter #5
Violoncello HardwareHeaven Newbie Join Date: Jun 2011 Posts: 10 Rep Power: 0	AW: Question concerning EQs Yeah, sure, an overshooting filter CAN make sense, for example for Bass Boost via subsonic. But in most cases you will use Butterworth filters (Q 0,707), cause they give you a "clean" filter function without overshoot and ripple. But, of course, it does not matter what is set by default if you know that actually the Q factor is meant .

Jun 19, 2011, 08:45 PM	#6
Russ HardwareHeaven Extreme Member Join Date: Jan 2005 Posts: 5,563 Rep Power: 62	Re: Question concerning EQs Right, so you understand I guess I misunderstood your previous reply...

Jun 19, 2011, 10:07 PM	#7
silvertones HardwareHeaven Addict Join Date: Jul 2006 Posts: 283 Rep Power: 39	Re: Question concerning EQs Don't know if this adds to the discussion or not however "Q" is the bandwidth of the signal 3Db down from peak. For a given Q at 0 Db as the gain is increased the Q actually gets smaller.