Kick Panels

We have established some objectives, rules, and theories behind getting a great SQ setup in the car. As I stated earlier, the reason kick panels work so well is because of the more equal right and left pathlengths they offer. Recall that having identical pathlengths from the right and left main speakers is optimal for flawless staging and imaging. With kicks, we net a pathlength difference of only a few inches (6-10" at the most), whereas dash and door mounting could range from 6" differnces to more than a foot. This is bad. Of course, seating position affects this also, and moving the seats as far back as they can go helps further (this is the premise behind extending your seat rails for SQ). We won’t get into firewall mounting with a custom-built dash just yet (hehe!), but if you want it, I will deliver!

What speakers work well in the kicks? Any spkr will perform well in the kick area if installed properly. Some guys do subs or midbasses, but most often, it is the midrange and tweet combo that ends up there. Some guys even do a three-way kick panel setup with midbasses, mids, and tweets, and they can sound pretty darned good! As far as order of importance (like I said earlier), it is the midrange that benefits the most from near-equal pathlength. If you are considering a two way comp set for the kicks, and were wondering what to look for in terms of kick location compatibility and great results in terms of SQ, don’t look for any magical answers here. Fact is, there are many good quality speaker systems out there that can sound great! Now, if you want my own personal opinion as a reference, I can do that.

I like the sound of soft dome tweeters, and would indeed mount them in the kicks, but this is often at the expense of the “rainbow effect” due to the high freq roll-off of many soft domes. If I use softies, I usually ALWAYS use a second set of tweets up high (as mentioned in SQ3) but retain the kick tweets as the main ones. If the tweet is a metal dome, this is better suited to kick panel mounting b/c of the extended high end (tho it still will likely need a lot of EQ to smooth out the response), and will likely NOT require additional tweeters. As far as midranges, I hate paper cones. Even though paper is the material of choice in terms of sonic neutrality, they often are easily overdriven into distortion and can’t handle much power. Polypropylene and kevlar cones are usually all I deal with, and the new aluminum versions can sound impressive as well, if built properly. It is very important to understand that crossover quality is VERY important in high-end sound. If the crossover is a cheap, “throw-together-and-make-a-good-margin” design, that is exactly the sound you will get. Look for x/o’s with tweeter protection , Zobel impedence equalization networks, low-tolerance caps and coils, and quality connections. Air core coils are preferred as well, but not required. Of course, you must listen to the sets before you purchase them, but remember this----Listening on a sound board in an open room is VERY different than in a car, and ALL component sets will be affected by the vehicle’s interior in some capacity.

Also, I personally like to do two-way kicks rather than 3 way, b/c I get more room for enclosure space and wacky speaker angles.

Can I use Q-Forms and get good sound? Yes you can, but there are limitations. Q-Forms are vehicle-specific add-on kick panels made from injection-molded plastic that typically can hold a 5.25” midrange and 1” tweeter combo. They are meant to give good results with a variety of speakers and angled for best possible imaging using typical speakers. The problem lies in their construction and installation. Q-Forms are not enclosures, but rather just open-back panels meant to sit flush against your vehicle’s carpetting. The actual panel itself is a mere 1/8” thick and prone to serious resonation. If Q-Forms are something you’d like to try, be prepared to do two very important things: First, you won’t be able to get the proper amount of midbass out of them b/c they are open-backed, so you MUST use them for midrange and tweeters only, then install a dedicated pair of midbass drivers for the important range between about 75-150 Hz. Second, you must deaden the panels to combat resonations either by adding dynamat to the entire backside of them, OR by using fiberglass or Dynaglass (Bondo-fiberglass mix) to thicken them, adding more structural integrity. It should go without saying that they must be securely mounted as well, taking into consideration the need to seal them to the floor as good as possible. I have personaly used them in the past with both soft and hard dome tweeters, and they get good results in the imaging department, but do suffer from the “rainbow effect”, so I HAD to use additional tweeters to help combat this problem.

What if I want to build my own kickpanels? Well, with this article comes a pictorial “virtual install” documenting the construction of fiberglass kick panels for a 5.25/tweet combo. I will cover all aspects of construction with captions, etc. If you do want to build your own, some cars have little obstructions in their kick areas that must be removed or relocated to get the best use of the small space allowed. Case in point; many Honda vehicles have their computer modules mounted in the passenger’s kick panel area. Furthermore, they often have a large plastic footrest in the driver’s kick area. In order to free up some airspace area and get the kick enclosures as equal as possible in terms of air space (A MUST!), these will need to be removed and re-located. In my Civic, I took each computer wire one-by-one and extended it about 3 feet, so now the factroy computer resides under the passenger’s seat. The foot-rest was discarded altogether. This made the kick areas virtually the same shape, ensuring very close-to-even airspaces inside each kick.

Like we discussed earlier, when you design your own kicks, you must listen to the spkrs to find the best possible angle. In the install pictorial, you will see that the kick contains a speaker baffle that holds both the midrange and tweeter.

After I take the floor mold and trim it down, I use backstraps to hold the baffle to the floor mold, put the spkrs in the baffle, and use towels to surround the backside of the mid, simulating and enclosure. By using backstraps, you have a bendable attatchment that will allow you some flexibility in angling, and once you position them, the baffles will stay put. This way, they can go straigth from listening to molding and the angle wont change.

Now for more indepth discussion on spkr angling, we must discuss the “Path length/ Intensity trading” theory mentioned earlier. This again states that if the speaker path lengths are not identical, you can angle the near spkr off-axis so that the loudest section of the sound wave (the “directly on-axis” angle) is directed away from the near-side listener, decreasing the perceived volume of the nearer speaker and increasing the perceived volume of the farther spkr. This acts in similar fashion to a balance control, but has the opposite effect in the other seat. Since there will ALWAYS be a small difference in path lengths in cars due to not being able to sit directly in the center, we MUST angle the spkrs in kick panels. If you were to build direct On-axis kicks, the near side would seem way too loud, and it would draw almost the entire sound stage to it’s location sonically. This is very bad. Often times, kicks will sound best when built so that the direct “path” of sound crosses in front of the opposite seat listener’s face, but this is directly related to the dispersion pattern and off-axis frequency response of the drivers. There is no way to assess exactly how your drivers will sound off-axis in your particular car, so again, listening WHILE building is the key to proper kicks.

But what should I listen for, and what should I listen to? Well, the key to good tuning is to become intimately familiar with reference recordings where the sound stage characteristics are KNOWN, either by a stage map showing each musician’s location, or by learning the proper stage layout on a reference system in terms of imaging, staging, width, depth, etc. Many guys swear by an audiophile “near-field” (meaning you are in close proximity to the speakers, simulating a car set up) home system to set the mental reference when listening to a car. This topic is more important in the tuning section, but here you must find a CD with good imaging tracks when listening for spkr placement. The IASCA competition CD has three imaging tracks accompanied by a stage map in the liner notes for each song. Remember the 5 basic image locations are Left, left center, center, right center, and right. When listening to the tracks, you must try different spkr angles while trying to get these 5 locations as correct as possible. You should only worry about actual image location, NOT focus, not detail, not height, depth, or any other aspect. You are only listening for imaging. All these other aspects can be addressed later during tuning, and as such, we merely want the kicks built to give us the best “foundation” to work from.

Other source material can be used to determine the imaging. Autosound 2000 has a great set of 4 test and set-up CDs (101-104) that I highly recommend to anyone interested in absolute SQ or SQ competition. They include detailed liner notes explaining how to use each track as a tool for proper execution of your system. IASCA also has a 99 track Setup and Test CD with similar guides. The old USAC competition CD (which was the Sheffield/Coustic Design Reference Test Disc) is also great, containing a live tutorial; various test tones, polarity checks, imaging tracks, etc. I can’t take the time to name them all, but just getting your hands on one of these is of paramount importance for successful design and execution of your SQ system. Furthermore, these discs contain great tuning tracks to use during EQ adjustment, gain setting, and phase adjustments (which we will go into later, I promise.)

OK, first off, we will keep it simple and use a single baffle for both the mid and tweet. Keep in mind that better results can sometimes come from mids and tweets being positioned at different angles, but either way, it depends largely on the spkrs you choose and the vehicle you put them in. If the advanced guys want to experiment with this, simply cut out a midrange ring to use as the mid baffle and attatch the tweeter separately, either by a single backstrap screwed to the tweet base or with velcro, or both. For the rest of us, after we attatch our spkr baffle with the backstraps and dampen the rear wave of the mid, it is time to listen. NOTE---it is very important to make sure you set the balance at zero on the h/u, set the amp gains EQUAL from right to left using a voltmeter, the passive x/o and/or active x/o points are set identical from side to side and the x/o gains are even right to left, and there are NO eq circuits engaged at all>. Pop in an imaging track with a normally nice, tightly focused center image, and evaluate the center image location. Ideally, we want the image to be directly in the center of the dash. Sometimes, the image will be only slightly off to the near side, and may be low in the dash. Sometimes, the image will shift depending on frequency (could be a byproduct of not being in an enclosure). Whatever the case, begin adjusting the angles of the spkrs to find the best possible center image location, both in position from left to right AND height, regardless of all other aspects of the sound. Make sure you keep the angles as similar as possible on BOTH sides. Once you get the best possible center location, we can move on.

Next, play a track with well-defined left and right instruments. Sit back and listen to only those instruments and determine their apparent location in the car. Make references to the stage map for that particular track to see if the left and right information is where it is supposed to be. It will likely be low, but should be near correct. Sometimes, we will find the left and right images to be not quite as wide as the car.

While some of this can be corrected with tuning or added tweeters, etc., we may find that the mid-to-tweeter orientation may need to be changed. Before moving anything, take a mental note of the center image again. Try to associate an exact spot in the vehicle where the center image seems to be, and remember it. Then consider this; what would happen if I rotated the spkrs in the kicks? I have found that soft-dome tweeters like to be placed to the far outside corners, either evenly parallel with the mid, or slightly higher. Hard domes most often image and stage better when the tweeter is BELOW the mid or behind the mid, just slightly closer to the floor. Again, this depends largely on the actual spkrs you choose and their dispersion patterns. It also depends on the vehicle geometry and presence of reflective surfaces. So the results will vary widely. If you can’t seem to get a good center image height and location at first, or the left and right seem too far inward from the car’s sides, you should try rotating the spkrs to a different orientation, and repeat the above steps.

So, to summarize, we must listen to our kickpanel angles before building them, and we need to listen to image placement cues while doing this, making sure ALL balance and gain controls are equal in the left and right channels. So, what if you can’t get the center image to come from the center of the dash? Don’t sweat it! What you want to remember is that even kick panels aren’t perfect, and there WILL still be a difference in the physical pathlengths, so your goal is to get it as good as humanly possible to create a solid foundation to begin with. Also keep in mind that there are several things to address when tuning a system for SQ, and there are ways to “tune” the desired characteristics into your sound system, so long as a proper speaker setup is created to start with. to work from.

If you want to do a midrange-only kickpanel with the tweeters on the Apillars, the routine for listening and positioning is the exact same, though it may be a tougher task in an all-active system in terms of setting gains equally between the tweets and mids. And RTA would be helpful here. Passive systems are designed to compensate for volume differences between the tweet and mid, and this makes them a little easier to work with. One thing to consider when working with a single tweet pair in the pillars is that they will be a lot closer to the listener than the mids. A good way to help compensate is to wire the tweeters in reverse polarity (out of mechanical phase) at the x/o, thus initiating a mild time delay. As mentioned earlier, a “cross-firing” angle for Apillar tweets usually nets the best results, since the louder “direct” output is playing toward the opposite side, and the tweets are far enough off-axis to trade the “intensity-for-arrival time” phenomenon W/O an abundance of reflections bouncing off the windshield. Turn the tweeters too far forward, and watch your stage width collapse toward the near side, as the windshield reflections become too great to overcome.

These windshield reflections are what also badly affect factory dash spkr locations in most cars, where the speakers fire straight up from dash cutouts, giving you poor imaging with a large “sonic hole” in the center of the soundstage.

So, let’s say you have found the best possible kickpanel baffle angle for your car, and you are ready to build. There are several fabrication techniques to choose from, you just need to find the one that best suies your skill level. The pictorial included here is a step-by-step fiberglass process using a floor mold as the base. I will be happy to answer any questions you may have concerning any technique you wish to use, just post them here.

Remember in the previous articles that enclosure resonation and standing waves destroy good sound quality. You should keep this in mind during construction. Make the baffles as solid as possible, make the enclosure walls thick enough to avoid flexing, and make sure the kicks can be very securely mounted to the car. Damping the kicks during installation is a very good idea (as discussed previously), and the use of DeFlex pads or polyfill will help control the standing waves and reflections inside the kicks. Even a form of absorptive damping material can help dramatically.

In the pictorial, you will see that I begin with a “negative” mold of the floor that is an exact form-fit. Because the shape is exactly the same as the kick area, it can only be mounted properly ONE way. Often times, I find that a single coarse-thread screw into the vehicle frame through the midrange opening is all that is needed to securely mount the kick pods. You can grab the kicks and try to yank them out, but you will end up moving the car! This is something you cannot do with Qforms.

Should I go sealed or vented? This is the topic of many debates. Tons of guys do their midranges in completely sealed kicks. Sometimes they sound good, sometimes not at all. What I have found is that a typical kick enclosure ranges from .1 cubic foot to about .3 cubes. When the maidranges are playing 200Hz and up, this could work fine. But when the mids are directed to play down to 150 or so (like they should!), there simply isn’t enough air space for them to reproduce the upper midbass without some form of sonic coloration. Many times I have tried to use totally sealed kicks, and many times I got a nasty resonance peak in the lower notes, requiring so much EQ to correct that I end up with very thin midbass output. Even stuffing the kick with polyfill won’t help matters all that much. So, what do I do?

Well, in a good SQ system, the midrange in a kickpanel needs to do 3 important things. First, it must play a wide range of frequencies, including the upper midbass notes, thus serving as a point source for all imaging cues. Second, it must reproduce coloration-free sound, absent of resonations and nasty peaks. Third, it must be in a large enough airspace to avoid frequency response peaks, cone flexing, and distortion (in essence, it must be able to breathe in a tiny enclosure).

We have already gotten a handle on #1, will address #2 more vividly in the Tuning section but proper fabrication already has us on-track, and here is what I do for #3. Since my kicks use a floor mold, which is made to rest right on top of the vehicle’s carpet, I make up for the lack of proper airspaceby allowing the midrange to vent INTO the carpet on the backside of the kick pod. After the pod is built, this is usually done by using a 2-3” hole saw right through the floor mold base. You will see it in the photos. And no, this does not defeat the purpose of building an enclosure, as the enclosure will still provide unaffected midbass reinforcement and sonics. What it Does do however is it allows the midrange to breathe into the carpet slightly, and works in a similar fashoin as “resistive damping” in ported and Aperiodic enclosures. This simulates the performance of a larger enclosure and usually alleviates nasty resonant peaks and reduces cone distortion by allowing the midrange cone to move without any undue forces being exerted on it. Please note, that I am not saying this is a must, but in my experience, it seemingly ALWAYS gives good results, so try it!

We have discussed kick panels and I have provided a pictorial to use as a guide for construction. I know you guys will have specific Q’s about kicks and other design variants, so post them on the Q&A Page (link below). Hang tight for the tuning section, as it will be LARGE, encomapassing kick panels, HLCD set ups, as well as dash pods. The next article is HLCD systems design, installation, and theories.