For many people the best knob on their A/V receiver is the one labeled “bass”. When I was a kid I loved to crank that thing all the way up on my dad’s shiny Denon receiver. I would also push in the “loudness” button for that extra kick.
As I got older I realized that the sound I was hearing when I did that was far from accurate. There is a purpose to the mid-range of the music and I was completely blasting it away with my knob-tweaking. So how do you figure out which way to turn the knobs? What’s the correct EQ (equalization) for your system?
Before we dive into the answers to those questions you need to be sure that your system already has the basic setup done. Read through these 3 posts if you haven’t already, they will help make sure that you’re ready to start EQing:
- How To Optimize Your Stereo Speaker Placement
- How To Optimize Your 5.1 Surround Sound Speaker Placement
- Audio Tweaking And Tuning – Speaker Settings
Now that you’re ready to EQ you first need to figure out what EQ tools you have to work with. Many receivers now have built-in auto-EQ. To use those systems you simply place the included measurement microphone at your listening position, press a few buttons, and magically the system is EQ’d. Since that process works fairly well, and is completely automated, I’m going to skip it. If you have that type of system then you can still read my suggestions and play around with some manual adjustments, but the auto-EQ should get things pretty close to accurate.
Bass and Treble Controls
The classic bass and treble knobs usually operate what are called “shelf” EQs. These shelf EQs have a certain frequency where they begin acting, and they create a shelf from that frequency out to that end of the audible spectrum. For example, many bass knobs are a shelf EQ at 80Hz. So when you crank up the bass knob you are creating a “shelf” of increased volume from 80Hz all the way down to 20Hz or below. The treble knob works the same way. If you crank that up you are creating a shelf from approx 10KHz all the up to 20KHz.
The amount that you turn the knob varies the gain that is applied to sound within that specific frequency range. Most bass and treble controls allow around 12dB of variation, which is quite a bit.
The best use of the bass and treble controls is for subtle tone adjustments. Start with them both at zero, then listen carefully with some varied material. Here are some examples of good use of these controls:
- Your speakers are a bit weak in the low-bass region because they’re small – Turn up the bass by just a bit until the sound seems more balanced. Be careful though, you should limit your listening volume so you don’t damage the speakers by asking them to create more bass than they can. Listen for distortion and if you hear any then turn the volume or the bass down.
- You had to place the speakers close to the wall and now the bass seems too loud – Turn the bass down a little bit until the bass and midrange seem to be the same volume.
- Your speaker-mounts don’t adjust enough so your speakers are not pointed at your head and the sound seems undefined – Turn the treble up a bit until the high-end of the frequency range sounds clear and distinct, but not harsh or exaggerated.
- You just have crappy speakers with no bass or treble – In this case you might have to use more drastic changes to get some decent sound. Try various settings until you get a smooth and even sound with decent bass and treble extension, but don’t bury the midrange by just cranking the knobs up all the way.
The Loudness Setting
The loudness control is not what it sounds like. You’re supposed to use it when you have the volume of the system turned down low. What the loudness control does is it applies a bass AND treble shelf EQ boost. The reason you would want to use that when the system is turned down low is because at low volumes your ears are less sensitive to those extreme high and low frequencies. The loudness button makes up for that change in your hearing by increasing the volume of the frequencies that you perceive as being quieter.
Try this test to see how it works: Play some music at a medium-loud volume, then turn the volume way down to just above a whisper. Notice how the bass and treble seem to drop off so you can’t even hear them? Now turn the loudness control on. If it was designed well, the bass and treble should pop back to the same general level they were at when you were listening at the loud volume.
When I’m listening I tend to not use any loudness boost because I feel that the effect is too drastic. Use it if you like it, but just remember to turn it off when you turn it up.
Graphical EQ
Graphical EQs come in many versions. My first one was the 3-band graphical EQ on the boom-box I got for Christmas one year. I had a blast with that thing, tweaking it for hours on end until I thought it was perfect. They also come in 5-band, 12-band, 31-band, and other variations. They common denominator is that there are 2 or more sliders that can be adjusted up and down to increase or reduce volume within a specific frequency band.
Each slider represents its own frequency band. The width of the band, or how much of the frequency range that it adjusts, depends on how many bands there are. If there are only 3 then the width of each band is rather large so any adjustments will affect a large range of frequencies, just like the classic bass and treble knobs. If there are a bunch of bands, such as with a professional 31-band EQ, then each band is very narrow and is designed to filter out certain problem frequencies or boost narrow gaps in the frequency response.
Whatever you do with a graphical EQ, DO NOT JUST MAKE A HAPPY FACE!! If you don’t know what to do then just leave the EQ flat (no boost or reduction in any bands), the sound will be much more accurate. Making a happy face is similar to just cranking the bass and treble knobs up all the way, a big no-no.
To properly use a 3-band EQ you basically want to use some of the methods I mentioned in the bass and treble section. Since the bands are so wide, there is not much difference as compared to standard bass and treble knobs. The only real change is that there is now an adjustment for the midrange. The midrange control should be used sparingly. Most speakers have plenty of response in the midrange, so you probably won’t need to boost there. You might need to make a slight cut (2-3dB) if there is some harshness from the speakers at higher volume. Just be sure you don’t cut too much or you’ll be taking away a bunch of useful audio information from what you hear.
If you have an EQ with narrow bands, more than 5, then you’re going to have to be very careful about how you go about things. It’s easy to get overwhelmed and feel like you don’t know what you’re doing. You’re goal is to filter out the peaks and valleys in your system’s response so that it’s as accurate as possible. Refer to the tuning tips below for some suggestions. When you’re listening you should adjust one slider at a time, in amounts no more than 2dB at a time, then listen and see how that frequency range compares with the ones around it. Keep adjusting until the sound is even over all frequencies.
Parametric EQ
The ultimate EQ is the parametric EQ. It allows you full flexibility in the frequency affected, how wide of a swath of frequency is affected, and the gain or volume change that is applied. There are three controls for those three parameters in each band of the EQ. The first would be labeled “frequency”, the second would be “Q” or “width”, and the third would be called “gain” or “level”. If you have a parametric EQ then you hopefully know how to use it, or your device performs some auto-EQ functions, because they can be very hard to use properly. When in doubt leave them flat (gain at zero).
To best set up a system with a parametric EQ you should have an expert do it, someone with a trained ear. There is an infinite amount of variation available, so a written guide like this blog can’t really tell you what to listen for when you’re using that specific of a tool. If you have a parametric EQ and you’re not sure how to tune it then ask a musician friend who is also a geek, or the sound-guy at your church to come help you tune your system.
Tuning Tips
Now that we’ve discussed the basic types of EQ here are some tips to use in your tuning session.
- Make sure you have a quiet atmosphere. No kids around, noisy dogs, the bathroom vent fan should be off, etc. The variations in sound that you’re listening for are very small, so you need a low noise-floor.
- Treat your ears nice prior to your tuning session. Don’t listen to loud music that day, leave the TV off, etc. You’re ears do something called “threshold shift” where they adjust to loud or constant sound, causing your ears to block out quieter sounds. You don’t want them to be in a state of threshold shift when you’re trying to tune your system
- Pick out some media that you know, and that has some vocals, acoustic instruments, and frequency extension. I like to use the first track from the Dave Matthews Band “Crash” CD. I know the track well, and it starts out with just an acoustic guitar, then builds to a full rockin’ band. The beginning of the track helps me hear if the mid-bass frequency response has any funny peaks because the acoustic guitar really brings that out. Any issues in the midrange tend to show up with the horns and the vocal. Bass and treble extension and smoothness are very evident when the drum kit comes in due to the kick drum and the cymbals. The most important thing to keep in mind when choosing test media is that you should know how the overall tone of the song sounds on an accurate system.
- Play the same song over and over again. Tweak a bunch. Take short breaks occasionally to reset your ears.
- If you just have 2 or 3 bands of control then focus on general tone adjustments. They should be fairly small and they are usually in a positive direction–adding volume.
- If you have a graphic EQ with 5 or more bands then you should focus on downward direction adjustments. You should first identify where unnatural peaks in the speaker response exist. Listen for them and then find out which slider is the correct band by momentarily popping sliders UP all the way, one at a time. When the problem that you hear gets a lot worse you know you found the right band. Now set that band back to zero to “reset” your ears, listen for the problem again, then move the slider slightly down to reduce the volume of that band. Listen again, then reduce as needed until the problem peak you heard has blended in with the rest of the sound.
- Once you think you’ve got the sound pretty good on that song then switch to another type of music. Throw in a classical CD or some jazz. See if the tonal changes you made still seem natural, or if you need to revise them. Listen for any peaks or valleys that you might have fixed with the graphic EQ, are there any new problems that you can identify, or do your “fixes” now sound too drastic? Adjust some more until you’re happy, then go back to your first media and see how things sound.
- You’ll likely end up compromising some to get a sound that works well for all media that you listen to. Just try to get the response as accurate as possible, and remember to enjoy the process!
Related posts:
