Lots of folks have an EQ in their system, but fewer actually have access to an RTA or PC based RTA system, however this does not mean your sound stage has to wander all over your dash and seem incoherent! I'm going to illustrate a method I use to get my sound stage centered and sounding spectacular in less than an hour.

1) I'm not going to cover speaker placement, install, time alignment, phasing, level matching etc. These are all very important subjects but are outside the scope of what I'm presenting here. Remember that all of the above should be optimised before you go nuts with your EQ. The EQ should always be the last step in the process.

2) You must have an EQ that works on both the right and left channels separately. If you just have an in-dash deal that works on both channels at the same time, you're SOL. For the following I will be using the Autosound 2000 test CD number 103 "My Disk" which is available from Crutchfield among others.

Here's how to do it:

Start by zeroing your fader left/right balance if it's not already. I'll then set a general listening volume using the reference tracks at the beginning of the CD, this is not critical, you just want to do your evaluation at a general listening volume that is somewhat close to how you like to listen to your music. Don't blast it ridiculously loud, but don't keep it too quiet either, your results may vary depending on volume because of reflection intensity (which by the way, means you need the doors closed and windows up to simulate a true driving condition).

Once you have a volume level set, you'll want to skip ahead to tracks 47 - 56 which contain band-limited pink noise in 1/3 octave steps starting at 25hz and ending at 20khz. These are the same frequency ranges you would see on a standard 1/3 octave RTA and may correspond with your EQ frequencies (as it does on my Audiocontrol unit).

The next step will be to sit in the seat you will be EQ'ing for and listen to each track segment while noting the position of the phantom image on your sound stage for that frequency band. For instance:

Tracks 47 and 48 are interesting, but at these frequencies, positioning is phase dependent rather than volume dependent, so you won't be able to shift the focus of the phantom image with your EQ in these frequencies. If that did work for you, it's probably because the speakers are resonating (in your doors, or whatever) and causing some higher frequencies to give away their location. Either way, I skip these two tracks and head straight to track number 49 which begins at 100hz and ends at 160hz.

While listening to track 49, I'll pick a point on the windshield, dash or horizon where the sound seems to be emanating from for each of the three frequencies. The 100hz frequency should sound really centered, because again 100hz isn't very volume dependent. Then at 125hz you might notice a shift (again somewhat unlikely) however the final segment of this track at 160hz may have shifted somewhat. If so, note where it seems to be coming from, say the right side of the steering wheel. We now know that 160hz needs to shift to our left very slightly.

I have the ability to EQ right from the driver's seat and that allows me to tune as I listen (from that location), however not everyone has that ability. If you're EQ/s are in the trunk, then you'll need to make a note on some scratch paper for making the adjustments, or have a buddy tweak it while you point left or right.

While tweaking in real time, I'll stop right there and adjust 160hz until it sounds perfectly centered to me, before moving on. If you can't do that however, just make notes as you progress from track to track. I like to cut and boost equally while doing this, so I might raise one side by +2db and lower the other by -2db. This way the difference is 4db but the sum is still 0db total cut or boost at this stage (Understand that levels might need resetting later, but again that's not part of this tutorial).

As you move your way up the frequency range you will find that it becomes increasingly easy to note differences and adjust them precisely. This is because your ears are more sensitive to volume differences the higher the frequency, rather than phase relationships as with lower frequencies. You should get a feel for how much difference between left/right you'll need for a given movement of the phantom image (total of 2db, 4db, 6db, etc.).

After going from track 49 all the way to track 56 and making your adjustments, listen to those tracks again in succession and try to see if the phantom image (focal point of the sound) shifts at all. You might note that it moves up and down at times depending on frequency and that's OK, but it should not be shifting right and left, you'd like it to always sound as though it's directly in front of you.

Once you've successfully achieved a perfectly centered image for all of the pink noise tracks, you're ready to go back to some reference music and see how your system sounds!

If your image shifted around at all during the process outlined above prior to setting your left/right EQ, you should find that the imaging of your music has vastly improved. Left and right imaging should sound more equal (rather than nearside too close to being in front of you and far side WAY far away, for instance). Additionally, you might get a greater sense of depth and ambiance. This is the kind of EQing that will make the difference between a "pretty good" sound system and one that sounds "spectacular."

If you choose to do further EQ work to adjust your frequency response, you need only to keep the relative left/right balance in mind for each frequency and you will always enjoy your perfect sound stage imaging.

Good luck and have fun!


for the rest of the thread
please click --> How To EQ For Better Sound Staging Without an RTA - DIYMA.com - Scientific Car Audio - Truth in Sound Quality