You are here

Question About EQing Speakers and Frequency Response

For performing musicians and engineers: stagecraft, engineering and gear.

Question About EQing Speakers and Frequency Response

Postby GrayveRose » Mon Jan 20, 2020 2:09 pm

Hey, not sure if this is in the right section but I badly want this question answered so I made an account just to ask this lol.

I'm no audio engineer, mostly a hobbyist in search of decent sound and wanting to keep improving with my understanding, so I've been curious about something.

I recently bought some KRK Rokit G4's and have been adjusting their frequency response to my perception by using a 31 band EQ on my PC because they sound really inconsistent to me. I've done a lot of tweaks and have gotten the tone to sound phenomenal (as far as I can tell), but I want to make sure I'm doing the tweaks correctly which means my understanding of frequency response for speakers needs to be correct.

So my question is, is the general rule of thumb for flat response calibrated as simple as listening to the full range of frequencies like a sound test and listening for flatness across the spectrum, or is it based on some kind of other tests done by special equipment? I ask because the human ear hears audio on a different curve compared to the way the sound is actually being created. I've pushed some ranges of the sound spectrum as high as 10-15 db (after -15db pre-gain to compensate), and it sounds awesome to me but wanted to make sure I'm calibrating correctly; if it is as simple as listening to the spectrum being sweeped and making changes based on my hearing so every tone is as equal as possible.
GrayveRose
Posts: 2
Joined: Mon Jan 20, 2020 1:52 pm

Re: Question About EQing Speakers and Frequency Response

Postby Hugh Robjohns » Mon Jan 20, 2020 2:24 pm

There are plenty of 'room correction' software and hardware processors that essentially do what you have done, to modify the frequency response of the source signal in the hope of achieving a flat response in the room.

However, the basic problem with your approach is that our ears are rather more subjective than objective... so you may well find your results are a little variable. The room correction systems normally use calibration microphones for a more accurate and reliable measurement.

There's also the issue that a conventional 31 band EQ doesn't just change the amplitude at different frequencies, it alters the phase response too, and that can also alter the sound. Most of the room correction systems use linear-phase digital filters to avoid the phase-response issues, and with a lot more precision than your 31 bands can provide.

I'm a bit concerned that you've felt the need to introduce as much as 15dB of correction. Either you're trying to correct the response beyond the bandwidth that the speakers are intended to reproduce, or you're trying to correct for some pretty major local reflection/cancellation issues within the room due to a poor room acoustics.

It would be far better to address the acoustic conditions in the room first, using broadband absorbers and bass traps.

H
User avatar
Hugh Robjohns
Moderator
Posts: 25792
Joined: Fri Jul 25, 2003 12:00 am
Location: Worcestershire, UK
Technical Editor, Sound On Sound

Re: Question About EQing Speakers and Frequency Response

Postby GrayveRose » Mon Jan 20, 2020 2:55 pm

Oh hey, thanks for the fast and detailed reply.

About the 10-15 db increase, mostly used that to bring up some of the low-end bass because it drops significantly after 160-200hz and wanted it to be more even with how I hear the treble and mids. Some frequencies Im hearing are really inconsistent like 100hz so I was trying to boost them a bit, and the highs around 10-12khz are weak compared to 8khz and lower.

As far as "room correction systems", I'm actually glad I asked and why I wanted to post this question online because I didn't know that they existed but now I do. I know a random assortment of information on audio, Im a jack of all trades so I dont specialize in any one interest, but I try to pick up what I can as its relevant to what I'm doing. In this situation from what I've looked up on room correction it seems to be exactly what Im looking for and is a better method of what I'm basically arbitrarily doing by using the 31 band EQ and pre-gain.

You're absolutely right on it being subjective, I've made a lot of changes the past few days tweaking it slightly until I've finally got it where I like it. For sure though the 31 band is just splits along the spectrum and its more or less just trying to best improve that section of the spectrum split rather than notch correct problem areas or avoid other issues that could be caused. For my current setup and situation its kind of the best I can do, Ill be moving in the next few months and will do a better job setting up a more ideal environment, and will for sure get some kind of room correction system in place.

Aside from my situation, is it good enough lets say for a hobbyist to listen to the speaker sweeping the spectrum and check for flatness? Is that a loose standard?
GrayveRose
Posts: 2
Joined: Mon Jan 20, 2020 1:52 pm

Re: Question About EQing Speakers and Frequency Response

Postby CS70 » Mon Jan 20, 2020 3:43 pm

GrayveRose wrote:Aside from my situation, is it good enough lets say for a hobbyist to listen to the speaker sweeping the spectrum and check for flatness? Is that a loose standard?

If you just want to enjoy listening to music the way you like, it's exactly what the controls are for :)

On the other side, if you intend to use the monitors as guides to produce music that must work on other playback systems and listening spaces, it may be not a great idea.

The thing that it's easy to misunderstand is that the deficiencies of your room will actually destroy information. Even assuming that your have perfect ears, when you play back some audio, parts of it will simply not exist in a given position in a given room: the sense that the air won't vibrate because the energy that would make it vibrate is canceled by reflections (besides, nobody's ears are perfect, because the brain interprets and "changes" the perception a lot before it reaches your awareness and cognition).

A proper calibration system works against a known expected reference response and with a sensor (a microphone) that is made to be as flat as possible and whose characteristics are, also, well known. It also won't suffer from cognitive bias. That means that it has a baseline reference which is independent from the space you listen in. With your ears, you don't have that reference so the results are most likely inferior.
User avatar
CS70
Jedi Poster
Posts: 4766
Joined: Mon Nov 26, 2012 1:00 am
Location: Oslo, Norway
Silver Spoon - Check out our latest video and the FB page

Re: Question About EQing Speakers and Frequency Response

Postby Hugh Robjohns » Mon Jan 20, 2020 4:59 pm

GrayveRose wrote:About the 10-15 db increase, mostly used that to bring up some of the low-end bass because it drops significantly after 160-200hz and wanted it to be more even with how I hear the treble and mids...

I feared as much. I know you said you reduced the input gain by 15dB to compensate, but that's only going to avoid overloads in the EQ itself. As far as the speaker is concerned, you're asking the bass driver to produce 15dB more low end than it was designed to deliver, for any given listening level. That will inherently stress the bass driver more and will trigger the speaker's protection circuitry at a significantly lower overall listening level than intended. It's not necessarily a problem -- unless you listen at loud levels -- but is definitely something to bear in mind.

If you want a lot of extra bass from speakers that aren't designed to deliver it, you might be better off moving the speakers closer to the back wall, or even into the corners, to benefit from the low-frequency acoustic gain that comes for free from the proximity of boundary surfaces (half or quarter space).

Some frequencies Im hearing are really inconsistent like 100hz...

Yes -- that's a classic indication of typical room mode problems whereby the low frequencies are reflection off the walls and cancelling out or attenuating the direct sound from the speaker. Different frequencies will be cancelled or attenuated in different parts of the room, giving a very inconsistent overall response. In extreme cases, some bass notes can go missing completely!

H
User avatar
Hugh Robjohns
Moderator
Posts: 25792
Joined: Fri Jul 25, 2003 12:00 am
Location: Worcestershire, UK
Technical Editor, Sound On Sound