Kicker Technical Tips
Page 29
Greg cont.
Now that we have the disclaimers out of the way, Dr. K, let’s get serious about a systematic approach to a
winning tune. Remember the scientific method from grade school? There is a reason that it has stood the
test of time. Keep that in mind when you get the urge to jump in and start manhandling the EQ’s.
Dr. K: Can I just replace my factory speaker and expect to win?
Greg: No way Beavis! There are a couple of of things to keep in mind with speaker placement.
1.) Minimize the difference of the pathlengths ( distance from the right speaker to your right ear and left
speaker to left ear) and B.) Control dispersion. Dr. K let me save you some time. Using a set temporary
enclosures (PVC pipe is quick and inexpensive) you can experiment with setting up the angles of the drivers
in your front stage. I usually start with just the mids. Fine-tune the angles of the drivers before you build
the kick panels. You may find that one side needs to be drastically different than the other. Use the seven
drumbeats on the IASCA disc and the recording of the three spoken voices to check for imaging.
Autosound 2000’s CD102 is also a must here. Try tracks 1-24. You can use double stick tape for trying differ-
ent locations for the tweeters. Make a jig or take a series of measurements to replicate your findings. Here
is a cool trick you can use even if you have already built kicks. Make a ring that tapers from one quarter of
an inch to an inch on which to mount the mids. By rotating the ring you can fine-tune the angle of the
driver. Subtle changes can have a pronounced effect on the image location. It may take you several days,
but nail the driver locations before you proceed.
Dr. K: How about loaning me some of these capacitors on your desk for my crossovers?
Greg: Dr. K, no offense, but your vest is a little tight. So let’s get active! From my perspective, I would
highly recommend that you use active crossovers whenever you can. Experience has taught me that the
advantages afforded by 24 dB per octave slopes are the way to go in a car. The fast slopes in this design
provide the necessary control to tackle the problems in the mid-bass region generated by most vehicles’
interior dimensions without adding phase shift problems. Sure you can use passive networks, but be ready
for massive trial and error. The charts designed for fixed resistance in many manuals do not take into
account the changing impedance of the speaker over the course of its operating range. They are helpful to
get generally a good sound, they just are not as accurate for serious competition. Why make things diffi-
cult? Do not be afraid to overlap crossover points. This technique can be very useful in the sub-bass to
mid-bass transition and the mid-bass to midrange area. If price or power class consideration prevents using
all active crossovers, my advice is to use the active on the mid-bass to sub-bass section of your system.
Speaking of mid-bass, many competitors miss the boat by crossing over the front stage too high. If you
had point deductions for not having bass up-front, try using a 24 dB per octave crossover at 60Hz on the
front stage (provided the speakers are up to the task).
(Greg takes a drink of water)
One final advantage to an active crossover is the ability to quickly change the subwoofer’s crossover point
to improve you SPL score. You can also vary your crossover points between the mid and tweet to optimize
imaging. The dispersion patterns of these two drivers can be quite different, so this is a big plus to fine-
tune the soundstage. Vocals and instruments such as a piano that feature a wide frequency range should
be used to evaluate this area. this will help you to minimize the frequency dependent shift quite common
in many competition vehicles.
Greg: Have you eaten yet?
Dr. K: No, let’s order some food?
Greg: How about Thai?
Dr. K: Ahh, Jack talk Thai very well! Sounds great.
Vol. 1
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