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  Topic Review (Newest First)
08-12-16 07:23 PM
AudiocRaver
Re: EQ Question

Quote:
matthijs87 wrote: View Post
Yes but lets say there's a dip on the left speaker at a certain frequencie which isnt visible on the right speaker.
That would mean there's naturaly already phasing going on becouse of diffrent timings and amplitude at those frequencies. So shouldnt equalizing then compensate for that diffrence ? The only thing i can think of which will change becouse of "it" are the (early) reflections that are cousing the natural phasing becouse there will be more pressure on it.
Phase itself is important to imaging between about 250 Hz and 1 kHz. Lower than 250, the wavelength is so long the ears don't detect the phase differential very well. Above 1 kH the wavelength is too short, so direction, and absolute timing become more important.
08-12-16 07:12 PM
AudiocRaver
Re: EQ Question

As others have said, a mismatch in frequency response between the L and R channels as measured at the LP can indicate an imaging problem.

Another thing to watch for is reflections. Early reflections that come from the wrong direction and/or at the wrong time can make or break imaging and soundstage performance.
08-08-16 08:06 AM
matthijs87
Re: EQ Question

Great stuff!, but what about Linear phase EQ ? Linear-phase filters only change the magnitude of the audio, while leaving the phase untouched.


Quote:
As you know, phase is also timing, so you can imagine what happens to the imaging when itís off in one speaker or the other at certain frequencies.
Yes but lets say there's a dip on the left speaker at a certain frequencie which isnt visible on the right speaker.
That would mean there's naturaly already phasing going on becouse of diffrent timings and amplitude at those frequencies. So shouldnt equalizing then compensate for that diffrence ? The only thing i can think of which will change becouse of "it" are the (early) reflections that are cousing the natural phasing becouse there will be more pressure on it.

Im happy to be wrong but i like to know how it works ) ,im learning allot here.
08-06-16 06:08 PM
Wayne A. Pflughaupt
Re: EQ Question


Quote:
Im still wondering though how the imaging exactly occurs.
What i learned from you guys is that EQing above 400 Hz can change the stereo image drasticly when not doing it with matched filters. But why ? is it becouse you could amplify that which is already out of phase ? or
is there another explaination ?
IMO it’s because equalizers actually work by introducing phase shift, as shown in this article. As you know, phase is also timing, so you can imagine what happens to the imaging when it’s off in one speaker or the other at certain frequencies.


Quote:
@ Wayne A.
Ah yes of course, thank you . What would be the reason it drops in the high frequency response ?
Not sure exactly why, but it has to do with the mic not being perfectly centered between the speakers.

Regards,
Wayne

08-06-16 02:49 PM
matthijs87
Re: EQ Question

@ tonyvdb
Yes you are right there are many variables but they all come down to either timing or frequencie related problems as far as i understand. The mic and speaker possition are time based and the room (acoustics) will determine how the frequencies respond to that.
So when found the most ideal spot "which i have" the only thing left is to either change the frequentie response by doing so with room acoustics or EQ if they are not to big dips/spikes.

Im still wondering though how the imaging exactly occurs.
What i learned from you guys is that EQing above 400 Hz can change the stereo image drasticly when not doing it with matched filters. But why ? is it becouse you could amplify that which is already out of phase ? or is there another explaination ?
The reason i ask is becouse from my point of logic doing filters individualy would get things more in time, so less phase coused by the timing when there is for example a dip on the left side at 100 hz (which you then treat) and on the right side its on spot(which you leave alone. What then would be responsible for the phasing in this case ? I like to know how it works

@ Wayne A.
Ah yes of course, thank you . What would be the reason it drops in the high frequency response ?
08-06-16 09:41 AM
Wayne A. Pflughaupt
Re: EQ Question


Quote:
Is there an option in REW to edit both left and right speakers at the same time ? At the EQ Menu i can only get a prediction of one file. For the matching filters it would realy come in handy to look how it affects both. I have searched for it but cant figgure it out.
REW can only generate a single graph at a time. If you want to EQ both channels simultaneously, you’ll have to take a measurement of both speakers running. This may show a droop in high frequency response compared to a single-speaker measurement; if so ignore that. You’re mainly looking for issues like significant peaks or depressions that need to be corrected.

Regards,
Wayne

08-06-16 02:09 AM
AudiocRaver
Re: EQ Question

Quote:
matthijs87 wrote: View Post
isn't phase the only thing responsible for diffrent stereo imaging in this case ? and thus the same thing, or better said the source for the diffrent stereo image ? What i learned is that the stereo image can only be changed by diffrent (left and right)frequenties and or diffrent timings in a nutshell. thus the phase and stereo imaging are the same things for "this" example becouse the timing wont be affected when eqing, is that true ? or am i missing something ?
Although in theory what you are saying is correct, it seems more accurate to think in terms of timing than phase, to me at least. Looking at typical phase plots between two channels does not give a clear idea at all what might be happening with imaging, but looking at impulse timing plots can be very informative.
08-05-16 12:27 PM
tonyvdb
Re: EQ Question

Quote:
matthijs87 wrote: View Post
@ tonyvdb : isn't phase the only thing responsible for diffrent stereo imaging in this case ? and thus the same thing, or better said the source for the diffrent stereo image ? What i learned is that the stereo image can only be changed by diffrent (left and right)frequenties and or diffrent timings in a nutshell. thus the phase and stereo imaging are the same things for "this" example becouse the timing wont be affected when eqing, is that true ? or am i missing something ?
Yes and no, there is not hard fast answer to this question as there are so many variables at play as speaker position can also play a part in the outcome.
08-05-16 11:38 AM
matthijs87
Re: EQ Question

Okay thanks,

Is there an option in REW to edit both left and right speakers at the same time ? At the EQ Menu i can only get a prediction of one file. For the matching filters it would realy come in handy to look how it affects both. I have searched for it but cant figgure it out.
08-03-16 08:08 AM
Wayne A. Pflughaupt
Re: EQ Question


Quote:
where would you say the danger zone starts approximately ?
Impossible to say. It all depends on available amplifier power and the efficiency of the speakers, which is different in every system. Fortunately with main-channel speakers itís not hard to tell when youíve gone over the line, as youíll hear audible distortion at the stressed frequency when you run out of headroom.

Regards,
Wayne A. Pflughaupt
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