Figuring out how to choose a subwoofer can be a daunting task.  Like most of us out there you might be overwhelmed with all the terms, variables, and options available.  Single voice coil, dual voice coil, peak power, RMS power, series, parallel…what is all that?!  Well fear not, this is the first in a series of posts that will help make sense of it all and get your car bumpin’ in no time.

 

Where to Start?

When I’m putting an amp and sub package together I like to start by picking out the right sub for my taste.  Then I figure out the perfect amplifier to power it.

Why’s that, Scott?”

Great question!  The simple answer is that the subwoofer, and the enclosure you put it in, is going to play the largest role in determining the type of sound characteristics you get out of your system.

 

Size Matters

Perhaps the most important decision you’ll make to determine the type of sound you get from your amp and sub package is what size subwoofer you choose.  The four most common sub sizes are 8, 10, 12, and 15 inch.  Each has its own advantages and disadvantages.  Which one is right for you will depend on the type of music you like to listen to as well as how much space you have to work with in your car.  Let’s discuss each one and how they might be the right choice for different situations.

 

8 Inch Subwoofers

Eight inch subs are considered to be the smallest woofer that will still produce decent bass.  Its small size allows it to produce very accurate, “punchy” bass without taking up much precious real estate in your trunk.  This option works well for a person who listens primarily to jazz or classical music and is looking for a more well rounded audio system.

 

10 Inch Subwoofers

Ten inch subs offer great bass response and clarity and generally more sound pressure level (SPL) and low rumble than eight inch subs.  A ten inch sub in a sealed enclosure is well suited for someone who listens to a lot of rock and metal.  You will hear (and feel) every base kick.  Put it in a vented/ported enclosure and you’ve got a nice setup for those who listen to everything.

 

12 Inch Subwoofers

Twelve inch subs are hands down the most common size subs people choose.  They offer a great mix of “punch” and “boom”.  A twelve inch subwoofer in the right enclosure can really be tailored to suit just about anyone’s needs.  In general, I typically suggest a twelve inch sub to people who like to listen to rap, hip-hop, R&B, or basically anything with low “boomy” base.

 

15 Inch Subwoofers

If loud, rumbly bass is what you are after then a 15 inch sub might be the right choice for you.  The large surface area of the cone allows this monster to sustain long base tones but lacks in the precision you get with a smaller sub.  These are a popular choice for bass heads and those chasing high SPL.  If your taste in music consists primarily of rap, hip-hop, and techno and you want everyone you drive past to hear that bass drop then you might consider a 15 inch sub.  Just be sure you have plenty of space for it.

Now, before we move on please note that these generalizations hold true when you are trying to decide what size sub to get within the same line of products.  However, that is not to say that a high quality, well tuned eight inch sub could not perform as well or better than a cheap 15 inch sub in an improperly tuned enclosure.

 

Single or Dual Voice Coil

This is where things start to get interesting and a bit technical.  From my experience, this is the part that really confuses people the most and may even make them give up on the idea of purchasing an amp and sub package all together.

If you are one of these people, trust me, you are not alone.

Should I get a single voice coil or dual voice coil sub?”

“Is a dual voice coil sub better than a single voice coil sub?”

“Wait…what’s a voice coil?!”

All valid questions

Let’s start with the last one.  Well, the complicated answer is that it is a coil of wire wrapped around the former that is connected to the speaker’s cone.  The magnetic fields produced by the ever-changing currents running through the coil interact with the speaker’s stationary magnet to move the cone in and out, thus creating sound.

Huh…?”

Basically the voice coils are what you connect to the amplifier to get the subwoofer to play music.  The two or four wire terminals on the back of the subwoofer are the two ends of the coil of wire that makes up the voice coil.  A single voice coil (SVC) sub will have two terminals and a dual voice coil (DVC) sub will have four terminals.

Before we go any further with how to decide which one to get, let me dispel the myth that DVC subs can handle more power than SVC subs.  This is simply not true.  A DVC sub does, however, give you more options for wiring the sub to the amp.  Depending on the amp you choose, this could allow you to squeeze more power out of the amp.

Have I lost you yet?

Let me explain

Let’s say you’re looking at an amp that has an output of 1000 Watts RMS at 1 Ohm, 600 Watts RMS at 2 Ohms, or 300 Watts RMS at 4 Ohms.

An Ohm is the unit of impedance (or load) that the amplifier drives power into.

Ohms-law

Now let’s say there is a particular sub you are interested in that comes in two different flavors.  Option A is a single 2 Ohm voice coil sub rated for 1000 Watts RMS and Option B is a dual 2 Ohm voice coil sub rated for 1000 Watts RMS.

Which one should you choose?

Let’s find out.

 

Option A

With the single 2 Ohm voice coil, there is only one way that this sub can be wired to the amp (assuming you use just one sub).

Since the amp will “see” a 2 Ohm load with this sub, it will be able to deliver 600 Watts RMS to the sub.  This is well under the rated power of the sub.

1-SVC-Sub

Option B

With the dual 2 Ohm voice coil sub, the two voice coils can be wired together two different ways to get two different overall impedances; series or parallel.

Series:

In a series connection you are connecting the voice coils together end to end (or daisy-chained).  The positive output on the amp connects to the positive terminal of the first voice coil, the negative terminal of that voice coil connects to the positive terminal of the second voice coil, and the negative terminal of the second voice coil connects to the negative output on the amp.

It’s really not as confusing as it sounds.  Check out the diagram below to see how it’s done in practice.

In this configuration the impedance of each voice coil is added together and the amp will “see” the resulting impedance.  In this example the dual 2 Ohm voice coils will have an overall impedance of 4 Ohms.

Given the specs on our amp we will only get 300 Watts RMS to the sub wired this way…definitely moving in the wrong direction.  But before we rule out the DVC sub let’s look at the parallel configuration.

1-DVC-Sub-Series

Parallel:

In a parallel connection the positive lead on the amp is connected to the positive terminal of both voice coils and the negative lead on the amp is connected to the negative terminal of both voice coils.  See the diagram below for how these connections are made.

To figure out the overall impedance when connected in parallel you can apply a formula.  But for simplicity’s sake I’ll tell you that when two impedances of equal value are connected in parallel the overall impedance is equal to ½ of one of the impedances.  In this case two 2 Ohm impedances connected in parallel will have an overall impedance of 1 Ohm.

Given our amp specs, we will get 1000 Watts RMS to the sub in this configuration.  Bingo!  In this example the DVC sub is definitely the way to go.

Have I really lost you yet?  Don’t worry, this can be pretty tricky when you’re first getting to know it.  Be sure to check out my post that is dedicated to this very topic.  It covers all the different possibilities from just one SVC sub to how to deal with two or more DVC subs.

1-SVC-Sub-Parallel

Conclusion

Choosing the right sub is really a matter of personal taste.  As we’ve discussed in this post, the type of music you listen to, the kind of sound you are looking for, and the amount of trunk space you are willing to part with all factor in to answering the question, “What kind of subwoofer should I get?”.

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