First off, Happy New Year! Those of us in the consumer electronics industry barely have any time to recover from the festivities before we race off to Las Vegas for the Consumer Electronics Show. In fact, as I write this I am on a flight to Denver, CO, for the CEDIA Expo, which focuses on the home theater and multi-room electronics version of the whacked-out world of car audio.
This is going to be a year of wild progress in the mobile electronics field if the past three months were any indication. I spent a larger than usual amount of time working as a consultant to manufacturers, distributors, retailers, agencies and government agencies as they look into ways to make the mobile experience so immersive that you never want to get out of your car. I wish I could tell you about it, but non-disclosure agreements are a matter of trust, and I take it seriously. Besides, I met their lawyers and they really scare me...
We wrapped up shooting the final episodes of the TV show we were featured in over the last two years and moved on to producing a weekly podcast based on this column that has appeared in Car Audio & Electronics for over eight years. I can't even remember when I started, since every issue is a new adrenalin rush for me. The podcast will resurrect the past columns, and by the time I catch up to this edition, we can go live, offering additional troubleshooting discussions as well as covering new and interesting topics of importance to anyone who bleeds car audio. My recording studio and production staff here at the Toronto training center had a bit of free time between other projects, so why not get the most out of it? Check out the "Cause Stock Sucks" podcast at www.mobiledynamics.ca/resources/podcast or on the iTunes Music Store and let me know what I can do to make it better for you. And be nice to me; I'm not a veteran podcaster, yet - that comes with experience...
Q: I am 14 and installed my first system in my 1975 Ford F150. I have a Duraband CD head unit that puts out 15 watts through four channels, which is wired to two Duraband 6 1/2" speakers and two Roadmaster 6 x 9 3-way speakers. I have two problems: One of the 6 x 9s rattled and I didn't know why. I turned the bass down and it still did it. I stuffed the area between the basket and the cone with foam and now it stopped. Why did it do that? My other problem is that I installed a free-air Roadmaster RSW80 8" subwoofer; it is a dual voice coil. I tapped into all four speakers and led two channels to each coil. My CD player goes up to 31 max and whenever I would turn it above 16, I would get no sound. I installed a 25-amp fuse instead of the 5-amp fuse. Then when I would turn it above 22, I would get no sound. I also noticed the lights on the radio would blink whenever the bass would hit, even after I installed the 25-amp fuse. Then I just tried tapping into just the 6 x 9s and led one channel to each coil. I can turn it all the way up to 31 now and it works fine. The light only blinks when I turn it above 25. My guess was that the subwoofer needs too much power and it would make the other speakers cut out. Is this right? I was planning on installing a VR3 2-channel amp and hooking up another 8" subwoofer and installing them in a ported box. Would it cut out or would the lights just blink like they would now? I plan on putting a bigger system in a 1990 Ford Aerostar and do not want the same problems I had with the 1975 Ford.Thank you for all of your help.Aaron Engel
A: I commend you for taking on the challenge of a self-installed system, but it shows me just why I teach new enthusiasts how to become professionals. You have the passion to go far, but dude - you need to start your education! There is some serious damage about to happen to your truck and your gear and maybe even your life!
You have a cascade of problems linked together. The head unit is cutting out due to the hookup, which is never the reason to increase the size of your fuse. Also, you probably wiped out the system's ability to produce stereo, or even a cohesive mono output. Although we use the flow of water as an analogy for how electricity works, you cannot just T-connect a couple of wires together without some form of summing device to properly accept the flow while isolating any backflow. That's why reverting to just tapping off one pair of speakers improved things.
When you connected the speakers to the subs, you essentially shorted out your channels in a partial way. Why your deck didn't cook, I don't know, but adding the 25-amp fuse was like tossing a match into a lake of gasoline. I would suspect that you have enough resistive connections that the current couldn't reach inferno level. That's another problem...
Your subs need a processed signal - just connecting the fullrange speaker outputs to the sub input allows fullrange into the subs. It won't harm them, but it will sound nasty. Adding the amp is the right approach, but you still need a crossover or dividing network if it is not already built into the amp.
Adding the amp will take the stress off of the head unit and will allow you to produce more output and even possibly limit the amount of blinking at high settings - you should note that full volume on almost all head units with a built-in power amplifier is about 3/4 of the numbering system. If your unit goes to 31, then about 22 is max volume. Anything above that is trading headroom and dynamic range for a bit more volume and a lot of distortion.
Next, we get to the subwoofer. Being free air, it is intended for use in the rear deck of a vehicle where a large volume of space (like a trunk) can act as some crude form of cabinet. In a pickup, either your sub isn't mounted or enclosed at all, or it is in a cabinet that it is not designed to work with. Adding a second sub will not do much other than double your problems. There are some free air speakers that are broad enough in design to actually function respectably in a box, but you wouldn't know without some math or testing.
As for your rattling 6 x 9, I suspect it is defective or damaged. Take it out of its mounting location and hit the back of the magnet with one hand while you hold the side of the magnet with your other hand. If you hear the rattle, it could be a loose part on the speaker. I often have found that tweeters riveted poorly in place would be the culprits. If you found there was no rattle, then it was either a problem with the strength of the mounting location, a door component rattle, or the speaker frame was twisting due to a mounting location that was not flat. The next test is to place the speaker face-up on a table and gently press down on the cone with equal force at several locations on the cone. This would reveal a rubbing voice coil, which would indicate that the speaker has been damaged through your actions rather than a manufacturing defect.
It's not my intention to trash your efforts - I went to MIT to learn about mobile electronics. You've heard of MIT, right? No, not the famed Massachusetts Institute of Technology, but rather "Mistakes I've Tried." Many industry veterans learned this way since there was no school in existence. Experience is a great teacher, but she charges a fortune! I get a bit freaked out when I hear about someone making the same mistakes I did when I was a 14-year-old experimenting in my garage, because there were no airbags and computers 30 years ago. My early rookie mistakes burnt a bit of insulation off the wiring, but it was never catastrophic. Vehicle design in the last 15 years has shifted to cheap materials and no room for error. Keep asking questions and learn the correct techniques. You can become a skilled specialist one day!
Q: I am about to install a new system in my 1992 Toyota 4Runner and need to know if my current battery and alternator will be up for the job. I am installing an MTX (Thunder) 1501D amplifier with an ought-gauge wiring kit and a 1-farad capacitor. I am going to be powering two Infinity Kappa perfect 12" single voice coil subs. Up front, I have an Alpine CDA-9813 and a separate 7-inch in-dash LCD connected to a stand-alone Blaupunkt DVD player under the dash. The Alpine is going to be running two JBL 3 1/2" speakers and four 4" Infinity speakers. So, I need to know if all of these components can be run with my stock 70-amp alternator and an Optima YellowTop battery. Any information or suggestions on the subject will be greatly appreciated.Ryan Koerner
I own an '02 Toyota Tacoma with a 70-amp alternator. I'm planning to install an Xtant 604 & 1001. The 604 will be driving a pair of Boston Z6's; the 1001 will be driving a Boston 555 subwoofer. What are some ways that can ensure that I have power to run the audio system and accessories?Thank you,Chris Fiorenzi
A: You both have basically the same concern, so I'll put them together and deal with the underlying methods. When it comes to predicting the ability of a stock electrical system to adequately feed your systems, there are a couple of guidelines to keep in mind. First, the carmaker had no intention of allowing anybody to add increased electrical loads to the vehicle. That means your audio system is a foreign virus as far as the car is concerned. Fortunately, there is often enough headroom in the electrical system to feed modest systems, provided it doesn't need to compete with aftermarket lighting and other devices. Once again, "stock sucks" and enthusiasts are left looking at whether or not you need to upgrade the charging system. When trying to predict the electrical support required, we often just look at the amplifiers since they draw the greatest electrical power by far. A simple rule of thumb is to add up the fuse sizes, since that is the maximum amount of current that your amplifiers can possibly draw. For example, two amplifiers with 30-amp fuses can draw a maximum of 60 amperes. Adding an additional 10 amps for the processors and head end is a good approximation. You are now sitting at 70 amps wondering if your 70-amp alternator has any hope of doing the job.
One of the main characteristics is that an audio system is dynamic, meaning that its current draw varies wildly. Most of the time, at half volume, the total current draw will be about 25 percent of the total, or about 17 amperes. As you turn up the volume control from that point, the current consumption really begins to skyrocket.
Also, the 25 percent is not constant, but rather dynamic, meaning current consumption will be spiking slightly higher on bass notes, but usually much lower the rest of the time. The higher spikes will often be pulled from the battery and stiffening capacitor (if you don't have one, get one). The alternator can handle that most of the time, providing you have periods that give your alternator time to refill the battery.
In terms of predicting the capacity you have, if the 25 percent of the fuse sizes in total adds up to more than half of your alternator rating, you can plan on some form of charging system upgrade. Less than that and you might be all right. In the past, I used slightly different numbers, but every year cars change either in the quality of the charging system or the amount of factory loads present. Last year introduced the "heated windshield washer fluid" feature, which is an electrical heater that draws its share of current (fortunately, only during washer usage). So, everything changes every year, and so do the methods we use to make our estimations.
Fortunately, car audio product also evolves, and with new classifications of amplifier design, we are seeing greater efficiency, with which amplifiers can put out just as much or more power while using less current. Most of the time this is a good thing. However, what form of charging system upgrade you perform is based more on experience. For now, your best bet is to discuss this with a trained custom installer who will have had experience with competition vehicles needing electrical reinforcement.
Q: I read in an issue of CA&E that you previously worked on the Alpine press fleet of F-bodies, so I was hoping you could give me some information about them and possibly a suggestion or two. I have a '94 Camaro that houses all Alpine components and I am in the process of updating my system. My top question is what did you (and everyone else) do to get some decent imaging and sound staging for the front passengers? Right now, I have Type-X components in the doors with the tweeters in pods near the side view mirrors. I am using a DSP so I can set the listening position. The soundstaging is OK, but it's nothing like I was hoping to get (i.e., home-audio quality). Also, did you build boxes for the door speakers or just mount them really well in the open door? Next question is what did you (and everyone else) do for the subs? I have and only want one sub, which is in a Stealthbox in the driver's-side trunk panel. A few people claim it's the best-sounding spot in the car. What do you think?Regards,Steve Hudson
A: Back in the mid-'90s, 3-way components were the rage, and to couple the drivers correctly, we would group the mid and tweeter together on a custom baffle plate in the factory 4" x 6" speaker openings. The path lengths were not really too bad, but with digital time correction, you can make it fairly easy to optimize the soundstage compared to today's cars. But to equal a home audio system is a very tall order. By this, I mean a real home audio system rather than a package system that sells for less than 1,000 bucks.
Other competitors obsessed with staging and imaging would build custom enclosures in the foot-well areas to increase the near-side path length to more closely match the far-side path length. A lot of voodoo started to appear as the surefire way to get a killer soundstage, but you can test things out for yourself. Remove your tweeters from their current mounting location and extend the wires so you can move them around the vehicle. Place them in different locations to audition the difference. Some ideas of positioning include various positions around the woofer, in the foot wells and on the dash top. As you move them, you will notice that the sonic character changes pretty drastically. Be sure to listen to software that has a wide frequency range so you can spot when the image seems to jump from one location to another as the music transitions from low notes to high notes. You may find that the best performance comes from a position where the woofer and tweeter are clustered, or in some very odd locations. The best position you find will dictate what you need to do to locate the speaker in that location.
As for subwoofers in an F-body, I agree that the best performance comes from the tail end of the vehicle. I have fabricated cabinets in the side panels where the 6 x 9 speakers normally sit, but it turned out to be a bad location for several acoustic reasons. In the rep fleet of Trans Ams, we would assemble a cabinet of MDF segments to utilize the maximum amount of volume in the rear storage tub. The predictable volume and rigid construction yielded a cabinet that could hammer pretty well. I became annoyed with always having to sacrifice volume and weight due to the thick MDF, so I made a casting of the tub using urethane foam and took a fiberglass print, or mold, of it. I then had the ability to pop out a fiberglass cabinet that wasted very little volume, weighed next to nothing and sounded great. Your Stealthbox is essentially the commercial version of what serious installers had to fabricate in the past.
Another key issue is the shape of the vehicle. Since the subs are in the tail end of the interior, there is little chance of cancellation that plagues so many sedans and coupes. Many referred to a "horn effect" since the rear window tapered from smaller to larger as you moved toward the front of the car, similar to a horn-loaded cabinet. This was in no way a true horn, since the shape did not follow the math of an exponential horn and didn't have the length or width to qualify. In reality, it just delivered a good "transfer function," such that the shape of the car and the characteristics of the cabinet in the end of it delivered a predictable combination.
For the doors, we rarely ever built specific enclosures since car audio speakers are typically designed to function best with the loose and leaky volume of the door cavity. In cases where I use home audio drivers, it becomes essential to build an enclosure of the correct volume, but that only happens on totally sick projects. One critical point is to seal the door from the interior as much as possible. Many installers will attach a layer of sound deadening material to the inner door skin, leaving allowances for mechanical items such as door lock rods and the door latch release handle. The rest they try to seal as much as possible to prevent the back wave of the speaker from coming through the door panel to cancel out the front wave. This is often referred to as an "acoustic short circuit" or just plain cancellation. The hot news is that GM is bringing back the Camaro Firebird in the near future. Will it still be called an F-body? I'm don't know, but all I really care about is how challenging it will be to upgrade the audio system of this popular car. My preference so far is the upcoming Dodge Challenger...