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PA Subwoofer Buying Guide for DJs: Size, Matching and Setup
Add a sub when your tops are working too hard to make the low end, not just because the dance floor looks empty. The easiest win is a sub from the same family as the tops you already own, and below we walk through which ones we would point you to, what size makes sense, and what else you need to plug it all in.
Do you need a sub yet?
Maybe you run two powered tops and feel like something is missing. Usually it is the kick and the bass line. Tops can only push so much low end before they start to strain, and when you crank them to make up for it, the whole mix gets harsh.
A sub takes that job off the tops. The sub handles the deep stuff, and the tops get to play the vocals and the highs without fighting. Most people notice the mix sounds cleaner, not just louder.
If you mostly play small backyard parties, talks or background music, you may not need one yet. If you play cumbias, banda, reggaeton or house to a dance floor, a sub is usually the next thing we would add before a third or fourth top.
12, 15 or 18 inches: what the size gets you
As a general rule, a bigger woofer in a bigger box moves more air and reaches lower. A 12-inch sub is the easiest to carry and fits in a small car. A 15-inch sub is a middle ground. An 18-inch sub tends to give the most low end per box, but it is heavier and takes more room in the truck.
Size is not the only thing. The cabinet design, the amp and the DSP all change how a sub sounds, so a well-built 12 can surprise you. That is why we look at what the maker says about each model instead of just the number on the woofer.
Think about who is loading it. If you set up alone, out of a sedan, a compact sub you can lift yourself is worth more than a bigger one that stays home. If you have a helper and a van, an 18 opens up.
Match the sub to the tops you already own
The simplest path is a sub built to pair with your tops. If you run QSC K.2 tops like the QSC K12.2, the QSC KS112 is a small-footprint 12-inch sub that QSC says pairs with K.2 and CP tops. It weighs 62.6 lbs and has dual M20 pole fittings, so it can stand up or lie on its side.
If you own Mackie Thump v4 tops, look at the Thump15Sv4 or the Thump18Sv4. Both have four crossover modes, including Thump 12 and Thump 15 settings made for those tops, plus phase invert and an M20 pole socket. The Thump15Sv4 weighs 57.4 lbs. The Thump18Sv4 weighs 70.4 lbs and is the deeper, bigger box of the two.
Running JBL EON700 tops? The JBL EON718S is the 18-inch sub in that series, made to pair with the EON710, EON712 or EON715. Its DSP has a selectable 80, 100 or 120 Hz crossover, polarity inversion and speaker delay, and you can adjust it from the JBL Pro Connect app. Mixing brands can work fine too, it just takes a little more setup with crossovers and levels.
Room to grow: bigger floors and pro rigs
If you are booking weddings and quinceañeras every weekend and want more headroom, the QSC KS118 is a step up. It is an 18-inch sub that QSC built for serious dance-floor bass, with a selectable DEEP mode, casters and an M20 pole receiver. It weighs 104 lbs, so plan on two people and a ramp or a lift gate.
The QSC KS212C uses two 12-inch woofers in a cardioid design. QSC says it puts about 15 dB more output to the front than the rear, which keeps bass on the crowd and off the stage. That helps when you stand right next to your rig, or when a band and a DJ share the space. The KS118 also has a cardioid mode, but only when you run two or more units.
Honest tradeoff: these are heavier and take more to move. For a lot of mobile DJs, a matched pair of smaller subs is easier to live with than one big box.
One sub or two?
One sub is a solid start. Bass does not have a strong sense of direction, so a single sub placed near the center or under one top still fills in the low end for the whole floor.
Two subs give you more output, and you can put one under each top on a pole for a clean, even look. The catch is two of everything: two boxes to carry, two power cords and more cables. If budget is tight, we usually say get one good sub now and add a matching second one later, rather than two cheaper ones now.
If you do go to two, buy the same model so they sound and line up the same. With QSC, the KS118 also unlocks its cardioid mode once you have a pair.
Carrying, loading and setup
Check the weight before you fall in love with a sub. Lift it in the shop if you can. A sub you dread loading tends to stay home, and a strained back is no fun on a Saturday night.
For setup, the usual chain is controller or mixer into the sub, then the sub's high-pass or loop-thru outputs out to the tops. On the Thump subs, that is the stereo XLR high-pass output. Set the crossover to match your tops, then use phase or polarity to get the sub and tops working together at the listening spot. Joe can walk you through this the first time.
Most of the subs here have an M20 pole socket, so a pole can hold a top right above the sub. That saves you a tripod per side and puts the top at a good height over the crowd.
What else you need, and how pickup works
Plan on XLR cables from your mixer to the sub and from the sub to each top, plus a power cord and a grounded outlet or power strip for every powered box. Add an M20 pole per side if you want the tops on the subs, or speaker stands if your tops stand on their own. A cover or a dolly makes life easier too.
Checklist for when you talk to Joe: what tops you own (brand and model), what mixer or controller you use, the kind of events you play, what vehicle you load into, and whether you set up alone. That tells us fast which sub makes sense.
We sell gear only. We only sell gear: we do not play events, send DJs or lend equipment out. You buy and pick up at the shop in South Gate, and we can help get your sub and tops talking before you leave. Call (323) 944-7844 or text (213) 674-9042 to confirm the sub you want is on the floor before you drive over.
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Text us what you drive or what you are building
Car audio: send the year, make, and model, and Tony gets back to you with what fits and a price. DJ gear: tell Joe the room or the party, like "backyard party, 150 people" or "starter DJ setup," and he will put a setup together.
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Read itQuestions on PA Subwoofer Buying Guide for DJs: Size, Matching and Setup
Can I use a sub from one brand with tops from another?
Usually, yes. You send the sub's high-pass output to the tops, set a crossover point and check phase. A matched pair from the same family is just easier to dial in because the maker built presets for it.
Should I buy one 18-inch sub or two smaller ones?
It depends on how you load and set up. One 18 is often the most low end in a single box, but it is heavy. Two smaller subs split the weight and let you put one under each top. Tell Joe your vehicle and whether you set up alone.
What does cardioid mean on a sub?
A cardioid sub pushes more bass forward than backward. The QSC KS212C does this in one box. The QSC KS118 can do it when you run two or more of them. It helps keep the bass off the stage and on the crowd.
Do I need special cables for a sub?
Mostly XLR cables: one from your mixer into the sub and one from the sub to each top, plus a power cord for each powered box. Add an M20 pole if you want the top to sit on the sub.
Do you offer a payment plan?
Yes. Buy Now, Pay Later: 100 days same as cash, or up to one year with Synchrony. Approval and terms set by the provider.