Alpine 9887/KTX-100 EQ Tuning Notes
I think I understand how to get consistent results tuning my Alpine 9887. I’ve been fighting with it for some time, but the results were sometimes disappointing. Now, I think I have a recipe that works.
For my own future reference and the benefit of insane car stereo geeks, here is what I did that actually seems to work consistently. This process is tested for the front seats (the rear seats in my car are vestigal), with the head unit switched into three-way mode. I did not tune just for the driver, but this should work equally well.
Notes:
- I measure at the driver’s ear level vertically
- Take measurements slightly behind the normal ear location. This tends to focus the sound image forward, and allows for moving the seats back a bit. For example, I measure at the driver’s headrest and the front of the driver’s head, instead of center of the driver’s head and center of the seat.
- Do not change your EQ, crossover, and timing settings after calibration, unless you want to run IMPRINT again.
Procedure:
- Remove headrests
- Turn off MultEQ
- Set all EQ settings flat
- Set all timing compensation to 0
- Set the subwoofer to 1 or 5 (doesn’t seem to matter much).
- Set up the crossover where you like it, but with all levels at 0. I crossed over at 80 and 200 Hz, using the rear deck as mid-bass.
- Play music, and set the amplifier gains for the low/mid/high so that it is approximately flat response. Leave room to boost the subwoofer level, depending on personal taste
- Run the IMPRINT software, and measure position 1 to detect speakers and get a quick measurement, but don’t do more unless you have time to kill
- Here’s the trick! Click “Go to results” (or whatever it is called) and look at the measured frequency curve. Does it look roughly like the “reference curve” or the “linear curve” (I use linear myself). Adjust sub/lo/high amp levels and repeat the first measurement until it is close.
- When you like the initial curve, go back and make all measurements and load the curves.
- Listen to the result and adjust your subwoofer level to taste.
- You may wish to change your mic locations or crossover points and start over. If not, you are done!
If the rough levels of the low/mid/high are close to the final desired slope, IMPRINT will not waste EQ fixing the overall balance, and can focus on smaller peaks. I find that IMPRINT can not compensate for large offsets, and will generally give up.
If the mid-bass speakers are much louder than the tops, IMPRINT can not adjust this–it will try to fix it with EQ! So it will crank up the high mids and treble, causing your mid-bass speakers to blast honky high mids from the rear deck. This is not what you want! This also applies to the subs/midbass crossover point.
This discovery has left me wondering how much adjustment we are expected or allowed to do before running the IMPRINT measurements. Should we be EQ-ing obvious problems? Is it OK to change the levels in the crossover?
Once again, the trick is to use IMPRINTs “measured” curve to check your amplifier gains. Or, if you have it, a real analyzer and reference mic. But hey, if you have that you probably aren’t fighting with IMPRINT, right? :)
