SECRETS of CAR AUDIO

Here's what people are saying...

"This is the best book I've read on car audio!"

SECRETS OF CAR AUDIO
by
STEVE DECKERT

CHAPTER 1

You find yourself at that point when you realize it's a done deal, you have decided to buy a car stereo.  You're feeling pretty good right about now and the best part still awaits....  spending some money!  What a great rush it is to know that you are going to go to the stereo store and buy some brand new stuff!          

You arrive at the front door.  You can see inside and the place looks like it's packed with stuff.  There are three or four sales people running around, a guy standing at the counter and half a dozen people scattered throughout the various rooms.  You walk inside and one of the sales people (who has been watching you from the time you pulled up in the parking lot) comes darting around from behind the sub woofer display and greets you with a great big smile.  "What can I help you find today?" he exclaims!  You reply, "Oh... just looking, thanks" as you shift your look to anywhere else but at him, at least until he leaves.  He smiles  and tells you to take your time, and hopes you will feel free to ask for him if you have any questions.   A programmed greeting followed by a programmed response. Now if the rest of this  buying experience could only be so easy.         

You begin to look around you and notice some BIG woofers over to your left.  Yea, there we go... BIG woofers, lots of 'em too.  You think to yourself, "I'll surely need some of those, 'cause everyone has those!"  You arrive at the display, and square off with it. 

There they are, woofers.  Woofers in a display that seems to tower over your head.  The boxes stacked on top just grazing the ceiling.  Damn, there are a lot of speakers here.  Lets see now, there are 18" woofers on the bottom, 15"  woofers above those, 12" woofers above those, 10" woofers above those, 8" woofers above those, 6" woofers above those, 5-1/4" woofers above those!  Over here we have some 4" woofers, some 3- 1/2" woofers next to them and just above there are a bunch of little ones. I guess they're tweeters, too many different ones to think about right now. 

You turn around and see another display almost as big with just as many speakers in it, only they're all blue instead of black.  To your right, in stacks on the floor are  boxes of more woofers.  They are gray ones.  A little overwhelmed, you draw the conclusion that at least there are  plenty of them, and with some help you'll be able to figure out which ones you want, and maybe even the inside scoop on which color sounds better.          

OK, you browse over to your left and walk around the corner.   Hey what's this?  Stacked up to cover an entire wall, and most of the floor in front of it, are boxes.  I've never seen so many  boxes.  There are boxes of every shape and size, and speakers in the boxes.  Some black ones, some green ones, some red ones, and some blue ones.  You step back a little to take in the whole view, and crash! "Shit, I knocked something over."  Some kind of round tube... hmmm... is there a speaker in here?  What in the world are these?  Bass Cannons!  At least that's what the sign  says. Over here, another sign with a picture of some weird thing shaped like a teardrop with holes in it and fire coming out of the holes!  You stop for a minute, you spin around slowly and realize all of these boxes have holes in them.  You back away, slowly, and find yourself standing kind of out in the middle of nowhere.          

You quickly realize that the dazed look on your face in this open area makes you a prime target for another programmed encounter with the sales person and you haven't finished looking at everything yet.  You spot a little room on the other side of the counter, and make your way into it's safe haven.  Here you see a wall completely filled with radio's and cassette decks, amplifiers ranging in size from about that of a cigarette pack to  a large box of Cheerios.  Behind you a wall of speakers, 6x9's,  4x10's, 6-1/2's, more 5-1/4's, every size imaginable all a little  differently shaped.  Some are full-range, some are 2-ways, some are 3-ways.  You wonder which size fits in your doors, and narrow it down to possibly... twenty.         

Over to the right are three displays with the word "SEPARATES" above them.  Yep, there they are, filled with lots of separate individual little speakers.  The small ones at eye level are playing some new age jazz or something, but there is bass coming out of them.  Crap, they are making the whole room shake!   Well, these are obviously going to be contenders for my car!  You make a mental note to ask the sales person how those little speakers can have so much bass and suddenly what are these down  here?  You kneel down and see a cluster of neat little flat  things with fancy little lights on each knob.  Wow, equalizers!    "Probably if I have some extra money one of these would be the thing to get, you think?", you say to yourself.  You're sure that would be like icing on the cake... you think...          

Soon you stand back up and some shinny stuff catches your eye from the other corner.  You go over there and see coils and coils of speaker wire and red power wire.  Perhaps if I get some of those BIG woofers I saw, I should use this fat red POWER wire to hook them up so I can get more power.  You ponder about wire for a moment realizing that you obviously will need some wire to hook every thing up.  You see more stuff in the distance, wire stuff.  Another wall of "Accessories" awaits your inspection with over 300 separate individual little things like oh lets see...  here's some noise filters, 6 different kinds too.  Hey, your  buddy's car buzzes when the engine runs so he always has to listen to it in his driveway.  In fact, he always runs his battery down too.  If he would have bought one of these, and maybe some of that POWER wire, he wouldn't have these problems.          

Well, now you feel like your getting somewhere.  You have a plan.  So far it includes a noise filter, some of those BIG woofers and some wire.  You know your stereo will be better than your buddy's right off because you're going to have a noise filter to eliminate engine noise, and your going to buy the BIG woofers which are bigger than his.  With that thought, you wonder how much this is all going to cost, so you decide to pick out a hypothetical system and tally it up. That way when the sales person comes back you'll know ahead of time approximately what you want to spend.  You go back to the woofers, then the cassette  decks.  Hey, you wonder if you should get a CD player instead.  You know they sound better but you have a bunch of tapes already.  You see that there is a cassette player that offers a CD CHANGER as an option. It's more expensive than the some of the in-dash CD players, but oh well, let see.          

At this time the sales person feels he has let you flounder around long enough, and the nice couple he was waiting on have left.  He arrives, and you now take the poise of a person who knows what he likes, and wants what he needs...  or something like that.  You ask him how much is this cassette deck, and those BIG woofers across the way and what kind of amp you should get to run everything.  He starts asking you questions regarding what you already have, and finishes 25 minutes later with what type of crossover do you want.  That's one of those things that crosses  every thing over to the car, or no, makes bass come out of the BIG speakers, or ugh no the amp does that.  Frankly you got lost somewhere between "active" and "passive", and too confused to think anymore.          

You thank him, Joe, for his time. You know his name is Joe because it's the last thing you heard as you were walking out the front door.  Eight hundred and fifty bucks, you think as you walk out to your car, holy crap.  Suddenly a mild stress head ache begins to grip you as you pull out of the parking lot and realize that car stereo has become an ultra complicated and potentially super expensive proposition.  The guy (Joe) said he has people spend five grand on systems all the time and those really sound good!        

It takes about a week of asking all your friends what they have before you understand they don't know any more than you do. All seven have different things and different ideas about what is the best, but all agree that theirs are the best.  You begin to realize that it seems as equally important to have certain BRANDS as it does to have good sound.  As a matter of fact, most of your friend's systems didn't actually sound all that wonderful.  Certainly nothing like Dad's old tube stereo on those black speakers in the living room.  Oh sure there's more bass, but  nothing else sounds better.          

You pick up a mail order catalogue and find page after page of the same or similar stuff but with better prices than those you saw at the stereo store.  You spend the next evening circling things in the catalogue, and try to decide if you should order everything.  Problem is, who will install it when it gets here and do we want to wait that long... not me, and hell no!  By now you are about half tempted to forget the whole thing but all this activity in your brain about car stereos is about ready to make you burst!  If you don't spend some money soon on something related to stereo the whole concept could just fade away, so you head to Everything World to get a cassette tape.        

While in Everything World looking for a tape, you observe that they have a Car Audio Department so you wonder over there.  Right in the archway sits a display containing a tape deck, separates (which you know are better since you saw they cost more at the stereo shop) and a sub woofer box complete with amplifier.  A whole system for six hundred bucks!  You turn it on and it actually played!  It doesn't sound too bad either!  Wonder what happens when you turn it up...  Oh look, two sales people are running towards you!  Sounded really bad when you did that.  The  first salesperson to arrive exclaims that someone turned the bass all the way up and that's what made it distort so badly.  The second sales person adds that it only sounds good inside my car, since after all my car is much smaller than the inside of this store.        

At the check out counter you modestly hoist up this giant box full of your complete car stereo system.  That's right, you bought it.  If the other place would have made it this simple you wouldn't be here! The girl hands you a receipt not unlike the kind you get at McDonnalds and tells you to drive around back and set an appointment with the installation department.  Your friendly installation department exclaims that they could get you in tomorrow if you had only a cassette deck but since you want an ENTIRE system installed, it will have to be in 9 days at 2:30  P.M.  And lets see, you'll need one of these amp install kits,  and a GM kit for your dashboard to accommodate the new cassette deck.  That's another 40 bucks, and the labor to install all this will be a mere 178 bucks.  Boy, you never even thought about this.  The good news is that you only have to pay half now.  The rest is due when they put your stuff in.        

Well, minus the minor unplanned financial upset at the install department, you didn't do too bad.  You drive home with your giant box in the back seat signifying your triumphant decision making abilities, a genuine celebration of your independence and your ability to provide... kinda like Daniel Boon after a 3 day hunt walking back home with the big black bear over his shoulder.  Actually you never saw him do that, but why spoil the moment!  You pull in the driveway and drag your kill into the house where you allow it to set in the middle of the floor.  You take a rest and from the safety of your couch, you study it trying to determine the best procedure for skinning it.   Eventually you can't stand the suspense any more, and unpack EVERYTHING. This is the best part of spending money on stuff isn't it?          

After attempting to install various parts of the ominous system in your car, you pull into the installation department for your scheduled install.  The installer takes your keys and grumbles because you just HAD to open EVERYTHING making his job even more joyful than it already is, and your ride takes you away.  You decide to stop for something to eat with your ride to help kill time, and end up telling the waitress all about your awesome stereo being installed at this very moment.  She smiles and pats you on the back asking again what you would like to eat.  Suddenly you hear, no feel, a small bass note coming from the parking lot.  Yes, it is, someone else has a car stereo.  You just smile.        

Six o'clock rolls around and your car is finished.  You anxiously drive back to the install department, and you see your car sitting in the lot behind the install bay.  You go in and ask how everything went?  The installer smiles and says just fine, minus a few missing screws, but he had some more so he just added them to the bill.  You pay the man and almost run out to your car.  You hop in and turn it on.  WOW, not bad!  You find the bass knob on the cassette deck, and crank it up.  Hey there is a loudness button too, to you engage it.  Thank God, bass!  For a  second you weren't sure if there was any or not.  You now begin to rotate the volume control to max.  Approximately half way there, everything begins to sound just like it did in the store when the two sales guys came running.  You quickly turn it down,  and decided to listen to it at a normal level for now.  You can wonder about the rest later, and drive away listening to the radio because you forgot to buy the cassette tape you originally went to Everything World for.

CHAPTER 2

You know, in chapter one we see a hypothetical but also very typical circumstance.  The first car stereo purchase by a person of average intelligence and equipped with average knowledge about car stereo.  I know the story to be accurate because I was that person once, and remember my first experiences.  I have since that time also been the other person, the salesman.  I specialized in car audio sales for several years and watched thousands of people go though the same experience.

I am still learning new things about audio almost every week, and I own a loudspeaker company where we design and manufacture high end home speakers and high performance sub woofer enclosures for car audio.  If after all these years of experience I can admit that there's more to learn, you should feel more comfortable doing the same

First of all, to finish our story in chapter one, a sequence of events takes place which is all too common for the average car audio consumer.  Lets call our character in chapter one Fred. After about 3 weeks, Fred becomes somewhat displacement about his stereo.  He has taken several critical listens to everyone else's stereos, and while better than 2 he heard, his system just doesn't measure up.  The biggest problem is the bass and distortion.  Not enough of one and too much of the other.  Had Fred purchased his stereo from the stereo store he went to instead of Wally World (or whatever), it is probable that he would have received a better system for around the same money. However probable is not to say always, it could have been the same and in some instances worse.  It really depends on the credibility of the store you deal with and the expertise and experience of their staff.

Trust me, it is better to pay more money for something if it comes with a knowledgeable human to help you use it, and to fix it if it breaks.  Saving 15 or 20 dollars on a car stereo component is usually the same thing as spending twice that if it means being on you own vs. having a store with people you can depend on to help you.  If money is a concern but not a serious deal, than my advise would be to find a small to medium size specialty shop that carries a good reputation with custom work. If they don't do custom work, find another shop.  Find a sales person you are comfortable with and give him a very GENERAL idea of what you want, let him know you trust him, and tell him to do whatever he wants.  Give him a reasonable spending limit, between 1500 and 5000 dollars, and have them call you when they are done. In a specialty shop with a competent reputation, their personal pride will guarantee you get more than your moneys worth, and the system will sound good.

For some of us however, it's the hands on that makes car audio so exciting.  There is a great feeling in listening to a system that you've worked on and as a result of, increased your education in audio by leaps and bounds.  For others it's just being in charge of deciding what goes in and where it goes.  This book will explain some fundamental truths about audio and cars, truths which are not always parallel with everything you read and see in the stereo shops.  Marketing and its necessity for "Buzzwords" does not always display information in an accurate light.

Back to Fred.  Fred's problem is that the bass only sounds good at low levels.  When he turns up the volume everything sounds crappie.  Since Fred likes to party, Fred on several occasions has elected to ignore the fact that it sounds crappie and play it as loud as he could.  Fred simply wants to enjoy his stereo.  The last time Fred did this, one of his speakers blew up.  Fred can't understand how a speaker rated at 150 watts could get blown up by an amp that only puts out 100 watts!  Fred knows he can probably get the speaker replaced but is so frustrated that he now has the urge to go back to the stereo shop and complain about his situation.  Unfortunately the sales people at the stereo shop couldn't find much sympathy for Fred since he took an hour of their time and than bought his stereo somewhere else.

"Fred" was my stereotype customer who was sent over hearing that I was sort of a Maverick in the local audio industry.  I spent hundreds of hours talking to hundreds of Fred's.  In each case it took a crash course in car audio, an injection of knowledge before I could really help them.  Sometimes the injections were too big and I lost a few, and sometimes the injections had no effect at all.  But for those with a strong common sense, the reward was great, they got their stereo sounding great and did it without being sucked into the marketing hype and spending more money than they should have.

Lets just bring Fred over and see what we can do for him. There is a knock on the door.  Guess who it is?  Yup, its Fred. "Hello, are you Steve?" he asks.  We walk out to his car.  It's a 1979 Chevy Nova with a little rust on the drivers door.  The first thing I do is ask him to open the trunk.  He wants me to listen to it first.  I tell him to turn it on and proceed to listen to it.  The first thing I do is turn all of the adjustments on the cassette deck to flat.  Set the balance to the center position, and do the same with the Fader.  I felt sorry for him right away.  The sound was thin, there were no highs, bass was barely there and when you turned it up the sub woofer got muddy.  Fred exclaims that you have to turn the bass up to make it sound bad.  Knowing full well what he meant I asked him why he would want to make it sound bad!  He returns with a dumfounded look and says "Yea but there is no bass."  OK, go ahead and show me I said as he turned the bass up and demonstrated the distortion.  Fred also mentions that this is a lot better than it was before because some guy put the dash speakers on their own amplifier.  Before he did that they were hooked up to the cassette deck and distorted real bad when you turned the bass up.

I asked Fred what kind of amp did he buy for the dash speakers, and he took me back to the now open trunk and showed me.  It was a little tiny thing that used a 5 AMP fuse.  On the case was written 40 x 2 max. power.  He boasted "Yea, and it was only 39.00!"  Fred's system consists of the following: Cassette deck - valued at 219.00 with RCA outputs for rear out. 5.25 Coaxial Door speakers located in the doors.   Value 79.00. A band pass box using 2 10" woofers, value 179.00. An amplifier claiming 200 x 2 max. power, value 179.00. An amplifier claiming 40 x 2 max. power, value  29.00. A 2-way electronic crossover, value  59.00.

Fred, I said, come in here for a minute and sit down.  We need to talk... Fred followed me inside and sat down.  He made himself comfortable and we proceeded to talk.

First of all you don't have anywhere near enough bass, right?  His eyes lit up, and he nods his head while scooting to the edge of his seat.  Amazing how bass effects people isn't it? Your system is letting you down.  Think of it like a car that only goes 56 miles an hour.  Everyone wants to pass it on the highway, and since you have to floor it to go 56 miles an hour your car is always breaking.  I'll bet you've blown a speaker haven't you.  Fred sits up and admits that its happened twice. He continued that someone told him he needed a crossover so that the dash speakers wouldn't pop and crackle with every bass note. He then added that he also had to buy a little amp which he did. So you bought an active crossover and a second little amp to run your dash speakers right?  He nodded.

Fred stops me and insists "What is wrong with it anyway?" Well, I said, your sub woofer is a little under powered, your power cable running from the battery to the amp is barely big enough to service the sub amp.  Adding the second amplifier increased this problem.  The second amplifier isn't any good at all.  The door speakers are crossed over a little high, and could be reinstalled to sound twice as good in the same door.  The frequency response on the tape head in your cassette deck only goes down to 50 cycles. Your box is tuned at 40 Hz and in an effort to hear base you're increasing the gain at 80hz with the bass control which makes the 50hz notes play half as loud which means you really can barely hear them. The small amplifier has poorer specs than the amplifier in your cassette deck, and about the same power.  The gain control on the small amp is set too high, and the gain on the sub amp is also set too high.  The efficiency of the front speakers are 91db at 1 watt, and the sub woofer has an efficiency of 87db (typical in cheaper sub woofer packages).  That means to play at the same loudness the sub woofer needs over twice the power.  The smaller amp has a total of about 30 watts clean, and the bigger amp is only about 90 watts clean.  So you see they play at the same volume.  What you want is for the sub woofer to play at a level 3 to 9 dB louder than the front speakers.  To do that you could double the power of your sub amp 3 times, or get a better sub woofer.  I recommend the later.

The simplified secret to good audio is balance.  You want to hear each note in the music without coloration.  If your system exhibits real peaky frequency response that is coloration.  In Fig. 1 we show a graph of each frequency our ears can hear. The lowest note is 20 cycles per second.  If take the speed of sound and do the math you will see that the sound wave travels over 40 feet before the next wave follows it.  So a 20 cycle note would be 20 waves spaced around 40 feet apart in one second.  The highest note we can hear is 20,000 cycles.  Most music does not exceed 16,000 cycles.  Some people can't hear past 12,000 cycles, and if for example you were to continue to listen to your car stereo when it is distorting for another year your will be one of them.  Fred has now taken the poise of a tree stump, motionless on the couch and in some sort of a daze.   The bomb has been dropped.  Poor Fred, all he ever did is try to buy a car stereo.

FIG. 1

If you examine fig 1 again, you see a solid line and a dashed line. At the far left the graph represents 20 cycles. At the far right the graph represents 20,000 cycles.  The solid line lays fairly flat.  That means all the notes will play at the same volume.  This way you can hear all of the notes.  If you look at the dashed line you will see it is very peaky.  The peaks represent notes that are way too loud.  The dips are notes that are way to soft.  When dips and peaks are close together you cannot hear any of the notes in the dips.  In Fred's case, his bass response sounds like it only goes down to about 75 cycles, in other words no bass, when in fact it can reproduce 50 cycles. Fred created a large peak at 80 cycles with his bass control, and than another one at 120 cycles.  The dashed line is an accurate representation of the average frequency response found in cars. Cars have very different acoustics than houses.

Cars are different than living rooms in two ways where stereo is concerned.  The first is that the noise floor (noise around you) is bass heavy and fairly high, around 80db.  A living room can reach a noise floor as low as 40 dB in the evenings. This means car stereos must have more power than home stereos just to sound like home stereos.  The second is that rooms effect dramatically how the frequency response will balance out.  A car is so small that we're not sure if we should treat it like a room or another box.  When you put a box inside of another larger box, an interesting thing happens.  The low bass is amplified. This is referred to as "cabin gain".  So it should be easier to get bass in a car than in a living room you ask?  If you consider only the two different types of rooms, yes.  To make a long story short Fred, what you need to do is leave me your car, and come back outside so I can show you some things about your sub woofer box.

Fred, now carrying the weight of the world on his shoulders slumps a little and than pops up to his feet.  He follows as we go back outside.  At the trunk, we look at his box.  It is about 4 feet wide and 13" tall.  It is crammed as close to the back seat as possible.  The trunk is full of rattles, and the box itself is so thin that it too is creating a very annoying peak at around 400 cycles.  Fred given your two options of doubling your amplifier power 3 times or getting a new sub woofer, I would recommend getting a new sub woofer.  Fred thinks for a minute and asks how much power would that be.  I pointed out that at a rating of 200 x 2 max. power he should get one that is 3200 watts. Fred hits his head on the trunk lid and starts to turn a little white.  Then he realizes they don't make an amplifier that big. If they did, and if Fred could afford it, the cheap sub woofer wouldn't handle the power anyway.

I think its time to let Fred off the hook, before he melts. But not until we bring him back up with a little tease.  I unhook his box and take it into the shop.  In there I have 20 or so different sub woofers on a switcher for demonstration and testing reasons.  I hooked up his box to switch one.  His box has two tens, with an efficiency of 87db.  I demonstrated his box on a good flat CD source on an amplifier similar to his own.  His eyes got big when for the first time he heard 50 cycle notes from his box.  He starts to speak... I hold up my hand and tell him to hold on, and let me finish.  This I said is what your box should sound like.  This is as good as your box can sound.  If you buy an indash CD player you can achieve this sound, if you only listen to your box in this show room.  Fred, your box is a little large for your trunk.  In fact it is so large that it obstructs the air flow in your trunk and does not breath properly.  Fred is amazed.  I then hook up a properly and professionally built box, also a band pass, about 1/2 the size using only one 10 inch woofer.  I let Fred hold the button and tell him to wait till the music plays and then flip the switch.  I explained that what will happen is that the smaller sub woofer will start playing instead of his, all without changing the signal going to the box.  Fred lets the music play for a bit.  I choose Mariah Carey, because there is a rich harmonic bass line centered around 35 Hz. Fred's box begins to roll off at 45hz, and at 35hz is playing only half as loud.  The smaller sub woofer has a reference efficiency of 91db and is ported to achieve 12 dB of gain centered at 38hz.  That makes it well over twice as loud as Fred's box on 35hz frequencies.  Fred flips the switch, and a bass note straight from hell rips through our pant legs.  Fred almost knocked over a speaker setting on the bench just behind him.  Fred was flabbergasted.  It took about 15 minutes for Fred to wind back down and he realized the story about his grandma's bird bath which he was somehow in the middle of telling...  oh well.  Twice as loud with half as much.  This is the difference between a good box and a bad box.  What makes a good box good is design and craftsmanship, and the proper materials.

Just for kicks, and since he asked, I decided to let Fred hear the 28 cubic foot folded horn over in the corner.  He walked over to it and stood directly in front of the horn throat.  I suggested he get over here across the room with me where its safe.  He laughed, and then realized I might actually not be kidding and came over.  "OK," I said, "Now your going to hear all the notes we've been talking about for the past hour."  I reached around behind me and flipped on my vacuum tube frequency generator and let it warm up.  I switched the signal back to Fred's box, and adjusted the dial for 100 cycles.  I turned it up until the box started to hack, and backed it off a little.  "This is 100 cycles," I said.  I then slowly rolled the dial down until the bass reached 45 cycles.  The box was starting to get quieter fast.  I continued to turn the dial until I reached 30 cycles. Now the box was just making a soft puffing sound.  I continued to turn the dial until I reached 20 cycles and either of us heard anything at all. 

A short discussion followed, and then without adjusting the volume, I returned the dial to 100 cycles.  I pointed to the switch and Fred knew what to do.  Pow!  On came the Imperial which was using one 12" woofer at the time.  It was about 15 dB louder than Fred's box.  We had to turn it down. Arriving at the same level that we heard on Fred's box, I continued.  As I turned the dial down the bass kept increasing until at 50 cycles we had to turn it down again. Finally I finished at 12 cycles and you could feel the concrete floor resonate, and when we talked our voices went up and down.  It was a unique twist on the Doppler effect. 

The folded horn had a sweet spot at 28.5 cycles in this particular room so I turned the volume down and adjusted the dial to that frequency.  I then turned to Fred to see if he was ready.  Grinning with anticipation, I turned the volume up to one quarter.  The bass was so deep and so strong that the cabinet doors on the wall started to open.  I increased the volume to one half and the experience started resembling an elephant sitting on your chest 28 times a second.  I held it there until a multitude of things started falling off the shelves, and then backed it off, and shut it down.  Fred was no longer carrying the weight of the world on his shoulders.  If bass were like drugs, and it is, Fred just  about had an overdose!

On the way back out to his car Fred asked me if I could make him a box, and he would sell the one he has.  I told him to sell the small amplifier as well, and come back with two tweeters, and some better power wire.  An hour latter Fred returned with two tweeters and some of the fat red power wire, and a noise filter.        

Pretty soon we are going to take Fred's car stereo and re- install it but before we do that, we need to go over some of the basic facts about car stereo components.  One of the most miss- understood things is BASS and how to achieve it efficiently.  The next chapter will clue you in on how bass works and the most common problem found in car stereo systems, cancellation.  If BASS is Superman, than Cancellation is Kryptonite

 CHAPTER 3

The largest misconception that I run into regarding bass is that free-air sub woofers do not need any enclosures.  If we start there we should be at the heart of the matter.        

If you take a "free-air" sub woofer hanging from a string in free air and play it there will be NO bass.  The industry term  "Free-Air" is obviously... misleading.  To understand exactly why this is let's take a deeper look at how speakers generate bass.  In Fig. 2 we show you representation of a sound wave as seen on an oscilloscope.

FIG. 2

Sound waves (or any type of radiation) consist of 2 main parts.   A positive section and a negative section.  When a woofer cone moves OUT the POSITIVE part of the sound wave is made.  When a woofer moves IN the NEGATIVE section of the sound wave is made.  These two steps complete the cycle, and the process is repeated.  If for example the cycle repeats 60 times in one second, you will hear a high bass note.  If the process is slowed down, and the cycle repeats itself only 25 times in one second, you will hear a very low bass note.  This process is often referred to as "cycles per second" or "Hz" which stands for "Hertz" which is the same thing.  Remember the human ear can detect sounds as low as 20 Hz,  and as high as 20 KHz (Kilo Hertz).           

In Fig. 3 we have shown how the process of cycles are related to a speaker.  The front of the woofer creates a positive wave front and the back side of the woofer creates a negative  wave front.  BASS only happens when these two wave fronts are kept apart.  If the two wave fronts are allowed to collide, there will be no bass.  This is called CANCELLATION.

FIG. 3

To help you better understand cancellation, let me compare  the cycle process to digging holes.  Lets get Fred to dig the holes!   We are going to compare the lowest bass note we can hear, 20 cycles, to hole digging.  We have assigned Fred the task of digging 20 holes.  Each hole is to be dug in a straight line some 40 feet apart.  Fred begins to dig.  Are you digging yet Fred? He responds; Uh-huh...  Are you positive?  Yes I am positive!  Yes, you are!  And we will be negative.  So Fred is  digging holes which represent the wave fronts coming off the front of the speaker, the positive half.  If Fred gets all 20 holes dug he gets to hear a great big bass note! 

Fred finishes the first hole and looks at us funny.  "Aren't you going to do anything?" he exclaims.  "Yea, Fred, we also have to dig 20 holes, but we can't start until you finish!"  That's the way the cycle works.  "Go down there and get by the spot where you're going to dig the second hole... you can start digging again as soon as we're finished!"  Fred takes off walking... Quick, help me start shoveling this pile of dirt back into Fred's hole!  Hurry up, he's almost there.  With great finesse we managed to fill the hole Fred just dug clear back up to the top.  You can't even tell there was a hole!  This is great isn't it?  Fred stops and yells back to us that he is ready so we walk over to meet  him.  Stopping a few feet away, there is a pause and Fred starts digging his second hole. 

By this point it's getting hard not to crack a smile, but somehow we manage.  Fred finishes the second hole, and leaves to start the third one.  We fill the hole again while he is not looking.  About an hour later Fred completes his last hole, and sits down on the grass.  "Well, let me hear the bass note you promised!" demanded Fred. Sorry Fred, it only works when you have 20 holes straight in a line, and I only see one hole here. "What?", he shouts!  Yea, take a look!  We filled in all of the holes one at a time right after you dug them!   That's because we're Negative today, and what you've just experienced is called CANCELLATION!          

Fred didn't get off on our little joke very much. Bound and determined to hear that giant bass note we promised him, and wanting to even the score a little, Fred returned with a large wooden box.  Fred put us in the box, and sealed it up real good!  He then began digging 20 new holes.  When he finished he was over joyed to look back and see 20 holes in a straight line.  He shouted from the other end "Well where is the note?"  Come back here and let us out Fred, then I'll tell you...  "You won't try to fill in my holes will you?" he asked.  No Fred, just open the door please.  Fred unlocks the door, and we exit.  Anxiously Fred asks about the note.  Come on Fred, it was just an illustration! Poor Fred.        

The technical explanation for cancellation may be phrased like: "Your woofers are 180 degrees out of phase!"  That means we were 180 degrees out of phase with Fred.  You see, I didn't mention that we were required to move the exact amount of dirt as red, and each time the same distance apart.  If we had only filled each hole 1/2 way with dirt, and shoveled the rest onto the grass, we would have been only 90 degrees out of phase with  Fred.  Fred could have heard his bass note half as loud, since all his holes are half full. 

By putting us in a box, Fred was able to TRAP us a keep us from canceling his holes.  Therefor the purpose for a box is to eliminate cancellation and thereby permit low frequency information (bass) to exist.  The moral of this story is that for a speaker to have bass, it must be in a box, or in some kind of baffle that is large enough to delay the back- wave so as not to be out of phase with the front wave.  "Boxless"  woofers do not exist. The term Free-air & Boxless was meant to mean you can mount woofers in a baffle board located against the  back seat inside your trunk rather than in a box placed in your trunk.  If done correctly, your trunk becomes the box and traps the back waves of the woofers, while the front waves come through your back seat.        

The difference between a "Free-Air" woofer and any other kind is a rather gray area.  In general a Free-air woofer will be lower compliance than usual which means it is stiffer.  Since it will not have a tightly sealed box to push against, the suspension system which controls how the cone moves in and out, must be tighter.  If it were not, the speaker would do something not unlike a fish out of water every time you turned it up loud.        

7 out of 10 "Free-Air" installations that I have seen are done incorrectly. These installs use a board with two holes in it and screw it to the back seat from the trunk.  All around the  board are gapping holes from which cancellation can occur.  These installs perform about like Fred's holes when they're 1/2 full of  dirt.

In this chapter you will find out the truths about car audio components, and their ratings.  You will find out what you do and don't need.  In the car audio industry there are a wide variety of manufactures, hence a large selection of similar products. How do you know which one to buy when there are 6 variations of the same thing?  By the end of this chapter you should know.

AMPS        

We will start with amplifiers since they are the most common ingredient found in after market car stereos.  Amplifiers for cars all share the following similarities:  They all run on 12 volts DC and they all amplify a single and send it to your speakers.  90% of all car amplifiers will put out more power and or less distortion when the car is running.  The reason for this is because your car's alternator raises the voltage from 12 VDC to 13.8 VDC. This concludes the similarities between car amplifiers.  Amplifiers range in size from 12 watts per channel to around 200 watts.  Smaller amplifiers are often called "Power Boosters", some even have equalizers built in. Larger amplifiers are often referred to as "Big Amps", although you probably could have got that one.

Amplifiers can be divided into two main groups and they are Group 1 - DECENT and Group 2 - CRAPPIE.  What is it that decides which is which?  Is it size? No.  Is it price? No.  Is it how much power it claims to have? No. Ahhh, is it the color?  ...No. In fact it can be difficult if not impossible to tell if you don't know ahead of time.  The answer is: How it is marketed.

WATTS        

Amplifiers that are mass marketed through large electronics supermarkets, and mail order catalogues are designed to make their manufactures and dealers money, not to necessarily sound good.  In this market price is what sells product, and the reason for that is simple enough.  If your product sits on a shelf in a mass merchants store next to 4 or 5 other products just like it, what is going to make the customer choose yours?  What you print on the box. Since there are no qualified salespeople to help you choose the right one, you are left to read each box carefully and decide.  The combination of what you read and the asking price are the determining factors.  A crappy amp and a decent amp are rarely sold in the same place and here is an example of why.  A crappy amp and a decent amp both sit on a shelf side by side. Both amps are the same physical size.  The crappy amp has the following specs printed on the box:        

200WATTS X 200WATTS MAX POWER  Frequency Response 20-20K Not more than .7% total harmonic distortion @ 1 watt both channels driven.  
REGULAR EVERYDAY LOW PRICE $179.00 
NOW $99.95 with 90 day warranty.

The decent amp has the following specs printed on the box:

        40WATTS X 40WATTS  RMS From 20 - 20K @ .07% THD.  $249.00

Now judging from this information you would choose the crappy amp.  It has more power (way more power) and cost less, plus it's on sale.  FRED fell into this trap too, and so do about 500 people every day just in this city.  The truth is that the bottom amp, the decent one, is FAR better than the crappy amp.  It has FAR more power, and the difference in sound quality cannot even be compared.  How can this be you wonder?  Both manufactures have listed specifications for their amplifiers that are within the boundaries of the law.  One has stretched it to the limits of the law, and one has slightly under rated theirs.  This is the difference between the two types of amplifiers.  It is easy to see why the better of the two products are not sold in mass merchandise marts, and why the others are not sold in specialty shops. 

A simple guideline to remember is the "DOLLAR PER WATT" theory.  A decent amplifier should cost MORE than one dollar per watt.  If you find an amplifier like the one in the sample above, that is less than a dollar per watt, don't buy it.  The sample above calculates out to 25 cents per watt.  The irony of this is that the second amp is actually LESS money per watt than the first.  If you take the REAL watts that each puts out the figures are like this:  First amp total REAL watts is 50.  That's $2.00 per watt.  The second amp total REAL watts is 160.  That's a $1.55 per watt.

RATINGS        

For those of you who demand more of an explanation on why ratings vary so much, the law does not require enough information to be printed on the products rating.  And what information the law does require most people don't understand anyway.  The first of the two amplifiers was rated under NON-REAL conditions in a test lab connected to a "dummy load" rather than a real speaker. In the lab, under ideal conditions, the amplifier was tested to have 50 watts.  Then they found if they use a tone rather than music the power doubled,  easy to understand since the amp is only playing one note instead of combinations of 20,000 notes. Then they discovered that if they raise the voltage to 15 or 16 volts the power doubled again.  Then they discovered that if you let the amp sit with no signal going to it, and than burst it with one note for a millisecond, the peak (MAX) measured higher still!  Now the power supply and most of the other parts in the amplifier are getting so hot that the amp is starting to smell, so they found out that if you spray freon on the amplifier and keep it cold, the voltage could be increased to 19 volts before smoke rolls out of it.  So that's what they so, and however high the power meter says just before the amp smokes is what they print on the box.  The second of the two amplifiers was rated under simulated worst case conditions with low voltage (12 VDC) across the entire musical spectrum with no distortion.  A rating that will be accurate for the life of the amplifier even if it is never shut off.  That's the difference.

FANCY WIRE        

So does all this fancy 1.00 per foot speaker wire make a difference?  Yes and No.  Yes it makes a difference, and No, you probably won't hear it.  On a audiophile grade system you can hear a difference and the investment in premium wire is usually worth it.  In a car, however, the noise floor will mask any of the additional detail gained from the use of fancy wire.  And, most car stereos, unless someone like myself does it, aren't up to par enough to benefit from it.        

You can think of fancy wire like buying fancy high performance spark plugs for your car.  Only your car has worn valves which leak oil down onto the plugs and keep them about half fouled out.  You car runs exactly the same as it did with the stock plugs.  Point being, if your just throwing together an inexpensive car stereo you wont hear any difference from that 5 foot piece of monster size wire you hooked to your sub woofer.        

Why is there so many sizes and types of wire available? Because people are buying it.  Basic speaker wire consists of between 12 and 16 gauge stranded copper.  It is always "Polarized" or labeled for plus and minus.  The next step up from this would be oxygen free copper wire, with more strands.  When an amplifier is hooked to a speaker via a piece of speaker wire, the speaker AND the wire become the load.  Long lengths of thin wire can actually add resistance to a speaker and increase the load to the amplifier.  This is not good.  The longer the distance between the amplifier and speaker, the bigger the wire.        

Usually it is hard to get a speaker very far away from an amplifier in a car, which is why 12 gauge wire is acceptable for any car stereo system.  High performance speaker cable will have more strands than basic speaker wire, which means it will have less resistance.  If you use a high performance speaker wire, it is acceptable to use 14 gauge throughout.  14 gauge wire is smaller than 12 gauge.  The numbering system is backwards.        

In a high end stereo system, high performance cable sounds better for a couple reasons.  The increased number of strands in the wire decrease the resistance and allow more current to hit the speaker.  The audible difference is a tighter, stronger bass. The insulation that is found in most high performance cable is also different.  A typical material used is Teflon.  When you place an insulator directly on a conductor, such as wire, the magnetic fields created as the voltages change create capacitance.  The capacitance or interaction between the conductor and insulator will have a audible effect found in the higher frequencies.  The audible effect is said to add harshness to the music.  High performance speaker wire and cable minimize this effect.        

The same principle applies to patch cords (RCA CABLES) as well.  Primarily due to the added shielding, premium patch cords are almost always an audible improvement in a car stereo system. The higher quality means better connectors, and stronger thicker jackets.  I recommend that no one uses the very cheapest patch cords available.  One pull and the wire inside stretches where you can't see it and you're stereo will intermittently sound bad from that point on.  The difference between a 6' generic patch cable at 5.00, and a high performance cable at 25.00 is money well spent.

FANCY SPEAKERS        

When purchasing car speakers i.e. 6x9's, door and dash speakers, there are two options.  One is to use speakers designed to replace the original factory speakers in the factory locations.  The second is to use separates, and have them custom installed in your doors, dash, or where ever needed.  The later will not necessarily sound better, because it relies completely on who does the custom install, and how they do it.        

The most common difference between a factory car speaker and an after market one is that the after market speaker will usually have a separate tweeter.  This is referred to as a two-way speaker.  There are 3 and even 4 way speakers available also, but whether they sound better than a two way depends on your ears, and personal taste.  Just remember that MORE is not BETTER in audio, its just more complicated.  I personally lean towards a two way speaker because I like the sound better.        

The point I want to make about fancy speakers is that while they are great and everything they do not automatically improve the sound quality.  The way they are installed, particularly in a custom job, is in my opinion responsible for 75% of the sound quality that they will produce.  A PROPERLY INSTALLED FACTORY OR INEXPENSIVE SPEAKER will ALWAYS sound better, distort less, and get louder than an IMPROPERLY INSTALLED 200.00 after market model.  That is the real secret to good sound, so place your emphasis on getting a speaker that fits properly and have it installed properly.  Later on when we reinstall Fred's stereo, I will show you in detail how to properly install one. SUB WOOFERS        

At this time, lets apply the same general gist of what I said about fancy speakers, and add that BIGGER IS NOT USUALLY BETTER.  I consistently get MORE bass IN THE CAR with one ten inch (properly installed) sub woofer than the car came in with when it had two fifteen's in a huge box.  Implementation accounts for 95% of the bass a woofer delivers, not the woofer itself. In a later chapter we will discuss how real good sub woofers are built, and the many differences between good boxes and bad boxes.

HEAD UNITS        

A head unit is the industry nick name for a AM/FM Stereo cassette deck or CD player.  It is possible to obtain reasonable to very good sound from the FM section of most head units. Typical Frequency Response on FM is 30Hz to 16KHz or so.  What makes a head unit start costing money is the cassette deck portion of it.  There are only a few ways to make an FM tuner, but there are dozens of gadgets and features in cassette deck mechanisms.  The most crucial to the sound quality is the cassette head.  This is commonly the most expensive part of any cassette deck mechanism.  In addition to sound quality, a cassette head is also responsible for the frequency response when you listen to taps.  The inexpensive decks only go down to 50 Hz, so there is NO deep bass at all.  Mid priced cassette head units will usually go down to 30Hz which is adequate for good bass response in a car.  Some high priced cassette decks go down to 20 Hz.  Most store bought cassette tapes do not have the fidelity to take advantage of the high priced decks.  If, however, you properly record CD or LP's onto high quality metal cassette tapes, you probably will be pleased to know your tape deck sounds like a CD player.        

The best value sonically and in every other aspect is the in-dash CD player.  Even an inexpensive model which cost less than a mid priced cassette deck, will sound superior.  It's almost hard to get real carried away on a sub woofer design unless you have a CD player.  In general a CD player will have LOWER and TIGHTER bass than a cassette deck. That's what you want.  It has always been easier for me to get great performance from a sub woofer when the source is a CD player.

CROSSOVERS        

Generally a confusing topic that complicates the buying experience, but a requirement in all good car stereo systems.  No matter what you will have a crossover network as part of your stereo, the question will be what kind, and where will it be. Starting with what kind, there are two main types, active and passive.  Finishing with where they go, depends on what type. Active crossovers may be found in the circuit between the head unit and the amplifier, and is sometimes located in the amplifier itself.  Passive crossovers may be found in the circuit between the amplifier and the speakers.  Passive crossovers must be made from large heavy duty parts to accommodate the power that goes through them.  For this reason they can be expensive (if properly designed) and since they add resistance to the speaker at selected frequencies, heat is generated, and some power is lost. Active crossovers are the opposite in that respect, as they consist of a few circuit chips, and create no heat.        

If you intend to design you car stereo using only one two channel amplifier to run everything (sub woofer included), you will have to use passive crossovers.        

If you use a multi-channel amplifier with built in crossover(s), you will not need any passive crossovers.        

If you intend to run two or more amplifiers, you will have the option of running either active or passive crossovers or both.        

To keep life simple, I recommend when given the choice, use an active crossover, and buy the one with more adjustments/features.

FIG. 4

In Fig. 4 there are two sample crossovers.  They are active or sometimes called electronic crossovers.  The smaller one on the left is the basic minimally equipped model.  The two switches are for make coarse adjustments in crossover frequencies (points). The model on the right has some very important features which are:        

A) Variable level controls to adjust the volume (gain) going to each amplifier.  This is a major asset to properly balancing a system.  Even though each amplifier has an input level (gain) control on it, the additional controls on the crossovers allow for proper impedance matching.  Proper impedance matching has the audible effect of making the sound warm and rich, or lean and cold.  Personal taste, type of equipment, and acoustics of the car determine what impedance sounds the best.        

B) Infinitely adjustable crossover frequency.  Allows you to adjust the crossover points with exactness, and lets you create a gap between the high and low frequencies to counter act the cabin gain at peaks that fall in that area.        

C) Phase Switch for the low out.  Creates the same effect as switching the speaker wires plus for minus on the sub-woofer. This is not essential, but it can save several hours of your time.                

In the next chapter we are going to design a high quality sound system in incremental steps for people on a budget. Consider it a simple guideline for making your first car stereo purchases.  Be aware that there are dozens of ways to do the same basic things in car audio, therefor the following system is only an example of something that will work well.

CHAPTER 5

For several years I have worked sales floors specializing in car audio equipment.  About half of my customers during that time were starting from scratch, didn't have a ton of money, and wanted ten times more than they could afford. 

One of the first things I would do is point out that people who come in and buy a complete full blown stereo for their cars usually have poorer end results than those who build their systems in stages over time. A simple reason for this is that if you build your stereo slowly, and listen to each thing you add, you are in a position to know exactly what you need based on the sound you have.  The other person who buys it all at once can only guess.        

Lets assume that we have a sedan with a 4 speakers factory stereo cassette and everything works.  You would like to replace all this with state of the art gear.  The first thing to do is NOT to buy a new head unit and new speakers for the front and rear.  That's right, don't do it, not yet.  If you spend your first 500 bucks on that you will only improve the quality of what you have.  It won't get much louder, and the bottom line is that there still wont be any BASS.  The idea is to get as much audible difference as possible as soon as possible, which  means from the first purchase.  This first decision is the corner stone of your system design, and therefor the most important.        

In order to maximize your first purchase, we need to augment what you already have.  And everything we buy  must have a place in the finished system.  By that I mean never buy something because of price and plan on replacing it with something better down the road.  Since bass is what separates a high performance car stereo from an average one and the factory stereo has none, this is the place to focus.  We will be adding bass to the factory system as stage one - the first purchase.  To make this chapter hit home a little better let us bring in a couple new characters; Jane and Bill.  Jane will be my customer who owns the sedan with a 4 speaker factory stereo cassette.  Bill has an identical car, and Bill has just purchased an In-Dash High Power CD Player and 4 new speakers with his 500 bucks.  Lets assume Bill and Jane both work at the same place and bump into each other in the lunch room almost daily.        

See, Bill started it, that's why Jane came into the store. Jane really has her eye on that new CD player... like Bills.  Any sales person will tell you that I could have sold Jane that CD player and 4 new  speakers, had her 500 bucks and had her out the door in about 15 minutes, or less.  So why didn't I you ask? Because the sales business was pretty boring when you weren't waiting on someone, and since Jane and Bill are friends, somewhat competitive too I would guess, I knew that what I was about to do would, besides being the honest thing, create a domino effect of pure entertainment over the next several months as Bills superior male intellect goes up in flames trying to keep up with Jane.        

Back to Jane's car stereo.  You know she tried to buy the in-dash CD player and 4 new speakers.  I spent some time with Jane.  Jane decided to augment her existing system by adding a sub woofer in the trunk, and a couple of other things.  We decided that the place to start would be in selecting the amplifier to run the sub woofer.  Compromise in Quality is out of the question, yet the BEST sub woofer amplifier cost almost 500 bucks so obviously that was out of the question for now.  We selected a good high quality amplifier that gave a clean 100 (real) watts.  It would be ideal for running a sub woofer at a volume that would serve to augment the factory stereo and later on be used as a mid and high frequency amp.  That was 200 bucks. Then we built a no compromise sub woofer enclosure specially engineered for her car.  That was 150 bucks.  We selected an EFFICIENT 10" woofer with a lower power rating instead of an INEFFICIENT by comparison 10" woofer with a very large power rating.  This was 60 bucks.  Then we selected a pair of tweeters from the separates display.  They were 50 bucks.  The rest went for an amp install kit, and a line-level adapter to convert the rear speaker signal into an RCA type adapter that could feed the amplifier.        

We installed the 10" woofer into a band pass enclosure which we designed for Jane's needs.  Jane's 10" woofer would be joined by another 10" woofer at some future point making her box become isobaric.  This meant the enclosure had to be designed to work both ways and it does.  We then installed the amplifier and augmented the front dash speakers by adding some tweeters.  Later we will replace the dash speakers with a mid-range and eventually add the midbass drivers to the front doors. When we wired Jane's car, we installed passive crossover components on her front and rear factory speakers.  We used 99uf 200 volt capacitors on the dash speakers and 200uf caps on the rear speakers.  The lower value blocks more bass so we choose this value for the fronts since they are small 4" speakers.  The back speakers are 6.5" which will play lower, so we didn't need as large a capacitor.  By installing these passive crossover parts, we have effectively removed the low bass from her speakers, and as a result increased their power handling, and reduced their distortion.        

In an effort to give the most audible difference for the buck, we removed the rear speakers from Jane's factory stereo, and hooked them to the new amplifier.  We then bridged the sub woofer across both channels and used an additional passive crossover component called an inductor (coil) to remove the mid and high frequencies from the sub woofer.  Sub woofers should only play bass, you should never hear voices from your subs.  In doing this, we have effectively raised the SPL (sound pressure level) in Jane's car by a very noticeable 18 dB!        

By removing the rear speakers from the factory head unit, we decreased the amount of work it must do, and increased it's performance slightly.  By installing tweeters on the front dash speakers and adding crossovers, we increased the sound quality and performance by leaps and bounds.  By using a quality amplifier turned down slightly, we improved the performance of the rear factory speakers by at least 100%!  In fact, if you sat in Jane's car right now and listened to the radio, and than sat in Bill's car and did the same, you would be shocked to hear very little difference.  Except that Jane's car gets louder and has a more solid sound coming from the rear.  Last but not least, by installing the perfect sub woofer design in Jane's car the sound is now full, deep, rich, and powerful.  Jane is very pleased.        

A few days later in the lunch room, Bill and Jane get together and he asks if she got her CD player yet?  She informs him that she decided to wait on the CD player, and bought a sub woofer and some other little things instead for right now.  Bill jump in and says yea, he is going to get one of those next, soon as he saves up the money.  Bill and Jane go out into the parking lot and Jane invites Bill to take a listen.  Bill was in a bad mood for the entire remainder of the day.  A week or so pass, and by now every employee at work has asked Bill if he has heard Jane's system.        

Bill can't take this anymore, so long before originally planned, bill arrives at the stereo store.  "I want a sub woofer, and make it a damn big one!", Bill exclaims.  Bill and the salesperson haggle around for an hour or so, and Bill finds himself in somewhat of a compromised position.  What he wants and what he can afford are no where close.  Bill draws the line somewhere down the middle and buys a sub woofer and amplifier to run it.  Bill has a box with 2 12" subs off the floor and the same size amplifier as Jane.  Bill would have agreed to get a custom box built, but he didn't want to wait.  Another week of humiliation would be too much to stand.  Bill spent another 500 bucks.        

Bill's sub woofers are installed, and a passive crossover between the amplifier and the subs.  Since bill used the full power from the amplifier to drive his subs, and the 10 watts or so per channel from his CD player to drive everything else, guess what?  Bill's car is all bass.  Every time Bill turns it up the bass overwhelms the rest of the music, and you can't even tell what songs are playing.  But Bill has more bass than Jane, so he receives his vindication.        

About a month or so pass and the general consensus at work is that Jane's stereo still sounds better than Bill's.  Even Bill admits that it does.  Then Bill makes his next move... Bill adds a second amplifier to run the mids and highs, because his CD player doesn't have enough power.  Bill buys a small 4 channel amplifier of good quality, with a built in crossover, and has it installed on his 4 new speakers.  Now Bill his smiling big time! His stereo really sounds bitchen now.  The amp only set bill back another 179 bucks.  Lets see now, that makes 1179 bucks for old Bill.  While bill's system is a little louder than Jane's, and a little more sparkly, and a little more dynamic, you still can't sit in both cars and say one is better or worse than the other. Jane's system is a little smoother, a little better balanced, and the bass is tight and accurate, making Jane's system actually more musical, which is what Jane wants.  Several more months pass and the issue fades away until Jane makes her second purchase, the in-dash CD player she has been patiently saving for.  It was easy for her to wait, because her car stereo already sounds good. Jane buys a CD player.  She even choose a better model than the one she originally looked at because of the sale!  Yes, a slightly nicer one than Bills, unfortunately.          

We install Jane's CD player, and her system simply came  alive.  Everything it did well before it does better.  Because we have taken car to keep Jane's system balanced, and put separate  tweeters in a different location on her dash, Jane is now hearing the music presented in a large dimensional stage with precise  imaging and depth.   Bill, with his new dash speakers cannot achieve this performance because of the location.  The most amazing thing that happened in Jane's car was the BASS improved dramatically.  Jane's bass is now as loud as Bill's was and sounds much better.  Funny thing is, she is only using one 10" woofer!  Since the new CD player we sold Jane is a high power model similar to Bill's, we gained a large increase in performance from the factory dash speakers due to the increased power and lower distortion of her CD player. Since the front speakers got louder, we turned up the volume on the rear amplifier a little to maintain balance.  This also increased the bass proportionately.        

Yea, Jane and Bill, by now all the salespeople are aware of the situation between Jane and Bill, and anxiously huddle around to hear the latest each time one of them leave.  Jane's stereo is audibly superior to Bill's, and so far has cost less money. Jane's stereo has been audible superior to Bill's since day one.        

I don't need to tell you that Bill is in a bad way trying to figure out what he can do to improve his stereo without spending more money.  What can Bill do?  Gee, Bill bought 4 new speakers, and amplifier to run them, a sub woofer, an amplifier to run that, and a in-dash CD player.  Bill is done.  There is nothing fundamental that bill can do to improve his stereo without getting rid of something he already has.  Unless bill want's to spend big bucks on digital processing accessories to act like a Band-Aid to smooth over some of the rough spots, Bill is done.        

Well, Bill's not done.  Bill is now highly motivated.  And you thought Fred had it rough.  Bill rearranges his priorities and sells some non stereo related things that he owned.  Bill buys a bigger sub woofer amplifier.  Bill sells his original sub amplifier at a huge loss.  Bill now has more bass.  Bill cannot use all of the power his new amplifier has because his box starts to make the woofers flop around.  The box is a generic design, and does not maximize the acoustics of the car like Jane's box. Also, the mids and highs start to get lost again when Bill turns the bass up too loud.  Never the less Bill has something new again, and lives with it for awhile. Bill buys a BASS ZONE CD to really push his system, and blows a woofer.  That's OK, Bill didn't like those woofers anyway, the flop around when you turn it up.  Bill buys 2 new woofers that are a stiffer compliance. Bill didn't realize that the new woofers have a different quality factor than his original woofers that came in his box.  The new woofers require a different size box, and need a different size port to go with it.  The new woofers which are in the wrong box, play higher bass notes much louder than the old ones, and play lower notes much quieter than the old ones.  Bill's new bass is loud and high, with no deep bass extension.  This made bills bass CD sound differently than it used to.  Some songs sounded better, and some sounded worse.  One track in particular was Bill's favorite, it had a pounding thump that made your hair vibrate.        

After work one day, Bill and Jane ran into each other in the parking lot and started to chat.  Eventually Bill decided he would like to hear his Bass Disk in Jane's car.  They hopped inside, and Jane started the car.  She popped the CD in the player and turned it to Bill's favorite track.  The loud pounding thump Bill was used to hearing was now a tight clean kick drum, which until now Bill always thought it to be... well... not sure. Then Bill's eyes lit up, and looked at Jane.  The console and the rear view mirror were starting to shake.  Not buzz, but shake! There was a super low synthesizer playing behind the kick drum, generating some 28 cycles tones.  The bass actually squeezed you a little.  Bill was flabbergasted.  Bill got back in his car and did the worst thing he could ever have done in regard to his stereo.  He played the CD.  There was no synthesizer at all. Bill's head sinks down to the steering wheel and suddenly the total that he'd spent to date popped into his head, 1800 bucks, and he lost it.        

To wrap up a long story, Jane having had so much positive attention as the result of her stereo's performance, decided to Finnish the system.  We sold her the high quality  midrange speakers for her dash, and some 5.25 inch midbass drivers and installed them in her door panels.  We then replaced the rear speakers with a pair of 5.25 inch midbass drivers, and installed a pair of tweeters on the rear deck next to the midbass speakers. Now Jane has eliminated all of her factory speakers.  Next we took the amplifier that was running her sub and moved it to the front and rear speakers.  We then replaced the sub amplifier with a larger one, and added a good active crossover.  The sub woofer cabinet was re-fitted and re-tuned to accommodate the second 10" woofer making Jane's Box isobaric.  Jane's bass now goes down to 20 Hz.  Before it was hitting just below 30 Hz.  Jane's stereo is now of competition quality in both sound, and appearance.  Bill is screwed, because he buried himself in his system and can't sell it until it's paid for.        

This has been one of the most common scenarios I've seen as a sales person.  It is in fact the motivating factor behind writing this book.  Remember it's not how much money you spend, but how you spend your money.  And, if left alone to purchase your first system without the knowledge of experience, you will fail and find yourself in Bill's shoes.  Jane's stereo has been a constant source of pleasure since day one.  Bill's stereo has been a source of pleasure and an even bigger source of stress, ending up solely as the later.        

In the next chapter we will be looking at various system layouts which yield a balanced high quality output.  You may use this as a guide for your future reference.

The Rest of the book:

Chapter 6 - System Layouts

Chapter 7 - Re-installing Fred's Stereo

Chapter 8 - Designing a subwoofer

Chapter 9 - What can I do now?

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