How do I choose 2 channels or 4 channels when I decide I need an amplifier for speakers?
When you’ve committed to upgrading your sound system this question might have been very sharp and clear in your mind.
Let’s dive into a real world example. This could happen if you talked with a sales person and they go to the effort of trying to understand your motives. Often there is a hidden complication or twist that comes from a difference of understanding what can be done.
Tip for Better Communication: Ask open-ended questions when you’re in discovery mode.
This is pulled from an online discussion. Jim is the inquisitive shopper.
Jim: is there a way to wire the left door speakers together such that they run as a stereo channel off one input, or is this only for subwoofers?
Barry: Two doors, two speakers wired together means you have one input which cannot be stereo. It doesn’t matter what type of speaker it is, that is going to result in one channel of sound.
In this example the same input signal will be played back from the front left door and the rear left door. Is that what you want?
What do you want?
“the same input signal will be played back from the front left door and the rear left door.”
Jim: Isn’t this how it already is since all the speakers are mono?
It was mostly just hypothetical because I wanted to know if I should buy a 2 channel or 4 channel amp, but I understand now. Appreciate the help!
Barry: No. I think the confusion is because we’re using a prefix, “Mono”, to mean one, yet we’re talking about different parts of the signal chain.
The input starts with the source, or the program material. We assume you’re playing music that’s made to have Left and Right channel separation(Stereo sound).
The next step is a division of this signal that takes place at the radio. I don’t know what radio and vehicle sound system you have so I’m making an assumption that it’s the standard radio with 4 speaker outputs, Front Left, Front Right, Rear Left and Rear Right.
For the pleasure and comfort of the passengers we have all 4 speakers on 4 separate outputs. By adjusting the Balance and Fade controls in the radio you can find that you will be able to play a mix of as few as 1 speaker up to all 4, redirecting the emphasis or loudness throughout 4 quadrants of the interior.
Let’s go back to the music, which we assume has Left and Right separated, in Stereo sound. The radio sends the Left channel sound to both the Front Left and the Rear Left speakers, and so on for the right side. For your decision, we’re not done.
Choose 2 Channels or 4 Channels?
Why do we buy a separate high power amplifier for speakers?
More power to better drive less efficient aftermarket speakers
and a bit more loudness and fullness to the sound.
Ask yourself two questions
Do I want all 4 speakers, front and rear, to get these improvements?
Is it possible I mainly want to improve the sound where I sit?
Choosing a 4 channel amplifier is usually a safe decision. Some car amplifier manufacturers don’t even offer 2 channel amplifiers, as the market has dictated they aren’t in high demand.
Normally we can still use a 4 channel amplifier as a 2 channel amplifier.
If you begin using the 4 channel amplifier as a 2 channel amplifier that offers an upgrade path.
Sometimes it makes sense to use the 4 channel amplifier as a 3 channel amplifier.
Is it a horrible idea to have more options with one purchase? Talk with your sound system designer.
Keep It Simple is a lesson I have broken many times. Depending on the perspective, that could be a blessing or a curse. If you don’t know it, I’ll give a quick retelling of my story.
I got started with car audio by entering the family business at age 14, and everything about it was new. This was 1995 and car audio was pretty simple. I remember watching my uncle David joining wires together to install a new radio. Even that routine task was a lot to take in.
Once I moved away from home for good I also started backing off from car audio. I was still listening to music obsessively, but it was a time of transition in my 20s(sound familiar?) and cars took on a different meaning. When I got back into car audio on a professional level, nearly a decade later, I went to the Internet to catch up. Things had progressed massively in terms of the volume of information to find for free, and I also quickly realized car audio had gone through a couple of paradigm shifts (huge SPL subwoofers? What the heck? Time alignment??).
Car audio had gone through a couple of paradigm shifts.
Unchecked growth can get you in trouble. Don’t fall victim to the appeal of starting with a huge sound system in mind, or taking a small system and growing it with every neat or trendy concept you see.
Keep It Simple
Over several years of testing and experimenting with different sound system configurations I have some highlights to indicate how far from simple this became. Not all of the parts listed here were in the system at the same time.
Touch screen head unit with smartphone connectivity
8 channel digital signal processor with 8 channel amplifier inside
Two 6-channel amplifiers
A separate bass amplifier
Three passive crossovers
Two pairs of tweeters in the front
Two pairs of 2″ mid-tweeter wide range pods on the dash
Two woofers in the front doors
Two 2-way coaxial speakers in the rear deck
Two speakers added to the front doors, for a total of 3 speakers per door.
Up to two subwoofers at one time
The biggest number of speakers at one time was 11, using 8 DSP channels, in a 5.1 multichannel configuration. I write this not to brag, but because I have to tell this so you can understand
I’ve Been There – It Is Awesome If It’s Done Right, But It Can Burn You
Potential Causes of Pain
Planning a complicated system can get overwhelming.
Time management. If you’re doing something in a way you’ve never done before this can be hard to predict in all arenas of life. What do you do when it’s 1 a.m., the vehicle is still torn apart, and you MUST drive it to work in the morning? When is your next opportunity to work on this project?
More parts = more chances to damage something. One more pair of speakers could mean one more set of panels to remove, which is another set of panel clips that might get broken or bent, which is…Maybe you get the point. It can really compound in ways that are costly.
Have you reached out for guidance or counsel in some other part of your life? Did that experience save you some money and pain?
If you’re in need of help with your car audio system I invite you to book your call with me right now. Let’s keep it simple.
Have you ever sat down to for an event, like you’re out with your special someone to the movies and you got there early. Sweet parking spot, perfect weather. You got the popcorn when it was super fresh and hot. The lights dim way down and someone behind you lets out a cheer because it’s OPENING NIGHT and they waited 3 YEARS for this.
And then you get a few minutes into the movie. Huh? Why is it so hard to understand what they’re saying? Why is the music and the crashes and explosions so OVERPOWERING? Gosh, didn’t they listen to the soundtrack before they put this out? Think this doesn’t happen?
A customer who complained to a London Picturehouse cinema said: “We were told they had received complaints about not being able to hear the dialogue after virtually every showing.
If Something Sounds Wrong It Is Wrong
Maybe you’ve never been to a movie and maybe you have, but the dialog wasn’t a problem. If you have, you knew something was wrong and it wasn’t just you.
You know something is wrong with the sound.
You were in a group, the audience, and you had immediate feedback from the murmurs or complaints from those sitting near you.
What if you’re alone and listening to a new song and you start to wonder.
Is something wrong with my system? Do I need to clean my ears? Man this sounds a little too crispy, or the bass is too strong, or the singer kind of makes me cringe. She’s a Grammy award-winning artist, surely she warmed up before recording this.
It could be a bad performance, or a badly done recording, or yes something might be weak about your sound system.
The point is, if it’s bothering you then trust your gut. Trust your ears and trust your intuition.
If Something Sounds Wrong It Is Wrong
What should you do if your vehicle sounds bad? This question has led a lot of people down the rabbit hole of following blue link after blue link, or hopping Facebook Groups. Read, read, read.
You worked up the courage to post a question. Man these people are talking a new language. I hope I don’t sound dumb.
Do I need to buy something?
I read that I first need to do X…is this true?
Can someone meet me and listen to this?
Should I go to “The Car Audio Shop”? I’m afraid they just want to take my money.
Drop a comment below if this makes you say, “That’s me!”.
Have you got a bad opinion of bass and treble tone controls? Sometimes these are on the front of a receiver or amplifier as knobs. Today these are absent on aftermarket car receivers (aka head units, decks) but why? As a person who is deeply interested in good sound you should know that tone controls are your friend.
Our hearing is very sensitive to small broad spectrum tilts, up or down. What is a broad spectrum tilt?
I want you thinking in terms of a tilt, like how a see-saw kid’s toy will pivot on a fulcrum. One side goes up as you push up with your legs and then the other side goes down.
What you see in the see-saw image could represent a broad spectrum tilt to take the bass down and bring the treble up. This isn’t a deep concept and I’ll get to the point shortly.
A bass tone control setting for your sound system could be one of your most frequently used tools. Music sometimes gets produced with too much or too little bass. You can read the blog post Myth Busting: Music is Pristine for an example of this. If you have a bass tone control setting at hand what would you do? You’d give that knob a turn while playing the offensive music and stop when it sounds right!
We Want Both a Powerful Equalizer AND Tone Controls
When we work to make the system perform with smooth frequency response, for better sound quality, the equalizer is one of our powerful tools. The upper midrange peak illustrated below could be addressed with an equalizer.
If we were correcting the response of a bass-limited speaker, and careful use of the equalizer brought the frequency response down to the black curve what would we get? In the car it’s possible you would think the treble is too bright. People with normal hearing are likely to want a downward tilt to the treble, starting at roughly the middle of the spectrum(visually speaking). The bass is also a problem, but a subwoofer is needed to fix that issue.
What To Do
If you will follow me through to the conclusion of this series of articles, and get into the forthcoming training, you will understand the following:
How a skilled listener of music thinks and responds to changing music quality.
What is an equalizer and how to best use it.
Music currently CANNOT be produced consistently and
We should have simple and broadly acting bass and treble controls ready at hand.
If you have a radio with tone controls it’s OK if you feel like you need to change these as you change music. You’re compensating to what you’ve got so you enjoy it more.
We might not know exactly why good sound is important to us, as a species or to you as an individual. Neuroscience research, as of a few years ago, had no distinct answer to “Why music makes us feel good”. 
To get some quick feedback on the question “Why do you enjoy music?” I asked online. Do you feel these comments are out of ordinary?
Have you ever been in love? Maybe you’ve been asked, “Why do you love me?”
How did that go? We struggle to form sentences to logically explain what we like, and this brings up a topic that’s not simple. I fumble through this as I’m not a psychologist or research scientist. What you might enjoy reading is “The Complex Psychology of Why People Like Things – How do you account for taste?”
Two worlds collide – Art and Science
Reproducing sound well brings science together with art. Without the desire to hear a performance again and again, the art that is the music, we wouldn’t need good sound systems. There are lots of ways to say why we value music. Relating with the artist. Expression. Relief.
Whatever it all means, there’s a sense of duty to do it exceptionally well. Respect the art. Respect yourself as the listener to get sound right. Getting sound right doesn’t come from guessing or luck.
Science in the service of art is our business.
Good sound is our product.
Follow along as there will be instructional content coming in the near future. One topic in the queue is Acoustic Measurements, along with tips on what to do with acoustic measurement data.
Are you struggling to understand what people say to you? Has it become less enjoyable to listen to music, watch TV, or go out in crowded places? Perhaps for you this happens because the music you often hear is not by your selection, because it’s so hard to find something good on TV, or because you’re an introvert. For a huge number of people it’s not about choice or personality, it’s because their hearing is damaged.
“Hearing loss is the third most common chronic physical health condition in the U.S.,” said Col. Phillip Goff, the associate chief for Bioenvironmental Engineering in the Air Force Medical Support Agency. “However, many people do not know what level of noise presents a risk to their hearing.” 
In the workplace you might be guided by a government agency’s guidelines for addressing the question of “How much noise is too much?” and “What must we do to protect the hearing of our people?”. That agency is OSHA.
A shocking fact I learned is that despite all the knowledge, planning, the awareness of risks to our hearing, the training and education I have seen as an employee, the Personal Protection Equipment to prevent damage…
Despite the good intentions, and despite wearing the recommended hearing protection, if you do everything as required while working in a sufficiently loud environment the OSHA 1910.95 standard for Occupational Noise Exposure is not set up so hearing damage will not occur!
It’s Ok If You Didn’t Know The Risks. It’s Not Ok to Ignore the Risks.
If your hearing gets damaged it’s never going to be the same, even as hearing aids get more advanced. That loud music you enjoy? It’s still fun while wearing hearing protection. You’re only going to use the saw for a few minutes on that home improvement project? It’s not worth the risk, get ear plugs and USE THEM.
It’s time for some myth busting! Let us not put our music collections on a pedestal. Let us also not discard a song or album because it doesn’t sound “good enough”. There’s a belief held by some audio enthusiasts that the music must pass from media to the ears with as few alterations as possible.
We know music quality isn’t consistent. In later articles this concept will be explored in depth.
I don’t want you to pass up a good time just because some music needs some help to sound better.
Joshua shared in the Facebook group ‘Car Audio DSPs and Tablet Tuners’ the following question.
So can anyone help me narrow down frequencies that are too strong in songs? Right now, its so powerful my ears actually hurt. only certain songs ( i love tbh )
A fun new album recommendation was shared with the community of FB group ‘Strictly Sound Quality’, a discerning audience, even though the mix isn’t great.
The mix could have been better for sound quality. Does it mean the music is the problem? A comment from the discussion:
Off the cuff, here are some tips about putting together DIY component speaker sets:
1) What fits? Maybe you’re in the tiny minority that is willing to cut and rebuild the door, for example, to fit just about any speakers. Most people want to keep new mid-woofers and such hidden or relatively modest in exposure to onlookers.
Consider available mounting depth. We want the windows to roll all the way down.
Consider space needed in front of the speaker up to the door panel. It’s not good for anyone if the speaker rubs against the plastics and gets ruined.
If you use a speaker fit guide the clearance in front of and behind the speaker will be taken into consideration for you. It might be assumed that the installation will be completed using an adapter bracket.
Consider tweeter placement and fitment. Does it need to fit in a new spot? Is there an existing tweeter location which you want to re-use?
A lot of aftermarket tweeters do not have any mounting solution except to flush mount, meaning it drops into a hole. When you get into “DIY” component speakers the tweeter mounting can leave people stumped. What if you don’t have a hole, or the hole is too small or too big? These are important questions.
Consider the intended application, sound-wise. Woofers(midbass, midrange) normally are not well-behaved on the top end even if they can play relatively high frequencies. This is why as you get into more complicated passive crossovers there are large parts dedicated to rolling off the top end of the woofers. (Low Pass Filter)
It can make for better sound.
Consider the crossovers. I often see people sharing links to generic passive crossovers, asking “Is this good for X mids and Y tweeters?” The short answer is the one people hate, HATE, to get but it’s true:
IT DEPENDS on what you want from your sound system.
This deserves its own discussion as it’s really misunderstood. How much power do I need to play good and loud? How much power is too much? What do I do when these tweeters I have saved in my shopping cart say they are rated for only 10W each? What the heck?
Matching tweeters to woofers:
It’s not this simple, but one shortcut to better sound is to try to have the sensitivity ratings close. If the tweeter is rated at 93 dB 1W1M sensitivity and the woofer is rated at 88 dB 1W1M sensitivity something needs to happen to make it sound good. For those still reading, my question for further discussion is:
What might need to be done to make this woofer and tweeter pair sound good together?
Do you do things as part of your job or hobby a certain way, a way that just seems right and comfortable? Have you ever studied your craft and found something that seemed wrong, darn wrong in fact, yet the evidence suggests otherwise? Evaluation of a music performance might be far from what you were thinking, and I want to tie this new concept into your development of a person who has a deep understanding of great sound.
Definition of evaluation:
the act or result of evaluating – a situation that requires careful evaluation : determination of the value, nature, character, or quality of something or someone What’s your evaluation of her writing ability? a patient undergoing psychiatric evaluation 
We make our own evaluations every day, quickly, at the speed of electricity. As a person who has a very high value of music in your life, you evaluate whether a new song deserves to make your playlist. When you have decided it’s time to do something about your sound system you have evaluated the current state of things and decided “Enough is enough, it’s time to fix this!”.
What Makes a Great Sounding Car Audio System?
“So what is Sound Quality? SQ … encompasses all of the performance factors which give the system the ability to reproduce an accurate and life-like rendition of the original recording as perfectly as possible. It includes factors such as tonality, ambiance, subtle nuance, system gain structure, dynamics, transient response, and the list goes on and on…
When a system is said to have perfect SQ, it generates the most accurate sound possible, with a sense of musical realism that gives the listener the impression that they “hear” a live performance right in front of them, as if the listener was in the audience watching the actual performers on an actual stage.” (emphasis added – BS)
As you think about “SQ” as described by the staff writer for Team Audio Nutz, focus on “a live performance right in front of them“.
You Must See Music Performances Up Close and Personal
How can you imagine a recreation of a live performance, in front of you in a car, if you haven’t seen any live performances? You’ll miss out on a DOMINATING factor to judging a great music performance! It’s not the sound!
When you get in front of music performers, unless your vision is impaired, you’re going to get bombarded with interesting eye-catching things. Costumes. The light show. The audience around you. The venue. The stage.
What Can Be More Important Than Sound? SIGHT
This was very surprising to learn while reading a paper about a series of experiments conducted to “examine the impact of visual information on expert judgment and its predictive validity for performance outcomes.”  To summarize, even if you expect the sound to be the most important factor in judging music performances, the visual part of the brain does a much better job in predicting excellence.
I want to know what you think. I want to know what questions this might have raised for you.
You need to get out there and see live musicians! It’s not hard to find them.
Whatever happens, enjoy the experience and take in the sights.
In the car audio realm, yes it does matter if the speakers and other equipment are visible. We can’t help but judge the experience with our eyes as much or even more than our hearing.
Since my perspective on bass is coming from sound quality, both my own experiences and what research has shown, I want to add an important note:
Bass is said to make 30% of the total product of what anyone will consider to be good sound quality for music reproduction. Thirty percent. This is not a small factor.
In a car one of the biggest enemies to sound quality, once we get the basics of good quality audio parts and the installation handled, the biggest enemy is going to be vibrations, rattles and resonances.
We’re adding energy and pressure to a closet-sized space built of sheet metal and thin molded plastics layered on top of each other. It wants to “talk” back. If you learn to appreciate great sounding bass, which anyone with normal hearing can do(and maybe even the hearing impaired) you will need to discover where the offensive noise sources are in your own vehicle. Some of this only happens by testing. Sometimes you can learn from the experiences of others who own the same vehicle.
Positioning the subwoofer, if you have the freedom of several choices, must also take into consideration how the vehicle will talk back as the music is played loudly.
I found that placing the subwoofer enclosure to face the rear of my sedan would cause no end to the rattles. I documented much of my acoustic treatment experiments in the series of articles starting with this one: