Subwoofers
QSC KS118 Review: Cardioid Is the Reason to Buy It
Quick answer
Buy the KS118 if your church runs contemporary worship in a large room and the platform booms, because cardioid placement keeps low end out of open microphones. Skip it if you are buying one subwoofer for a corner, because a single box in a corner excites the room rather than fixing it.
The KS118 is the right subwoofer for a large contemporary sanctuary where low frequency energy on the platform is making the vocal microphones muddy and the drummer deaf. It is the wrong subwoofer for a small room, for a speech-led service, or for a church that plans to tuck one box into whatever corner has space, which is where most subwoofer money is wasted.
This review is drawn from published specifications, manufacturer figures and the consensus of verified owner reviews, not hands-on testing. The interesting specification on this cabinet is not its output, it is what cardioid arrangement does to a church platform.
On this page
Why cardioid matters more in a church than anywhere else
A conventional subwoofer radiates low frequencies in every direction, including backwards onto the platform. On a church platform that rear energy does three things, all bad: it makes the open preaching microphone sound boomy, it makes the drummer and the bass player hear a different room than the congregation does, and it excites the structure the platform is built on.
A cardioid arrangement cancels much of that rear output, so the congregation gets the low end and the platform does not. In a church running open vocal microphones near the subwoofers, that is worth more than the last few decibels of output. Work out whether you need one at all with the subwoofer sizing calculator, and see the field in the subwoofer roundup.
Published specifications
The low frequency figure is the one that separates this from smaller subwoofers. Reaching into the low thirties is a genuinely different experience from stopping at 41 Hz.
The KS118 pairs a 3,600 watt amplifier with an 18 inch driver reaching down to 32 Hz, with cardioid capability, at a catalog price near $2,199.
| Specification | Figure |
|---|---|
| Amplifier power, peak | 3,600 watts |
| Driver | 18 inch |
| Low frequency limit | 32 Hz |
| Cardioid capability | Yes |
| Onboard DSP | Yes |
| Catalog price | $2,199.99 |
Figures are QSC’s published specifications for the KS118. Nothing here was measured on this site.
The catch: one subwoofer in a corner is a room problem
The honest weakness is not the cabinet, it is how churches deploy it. A single subwoofer placed in whatever corner had floor space will excite the room modes of that corner, producing seats where the bass is overwhelming and seats fifteen feet away where it disappears. Congregations then report that the new subwoofer made things worse, and they are describing something real.
Cardioid operation also needs more than one cabinet to work as designed, so the cardioid feature that justifies the price is not available to a church that buys exactly one. Budget two boxes and a sensible placement plan, or buy a smaller subwoofer and spend the difference on the room. At $2,199.99 each, that is a significant planning decision rather than a detail.
What owners consistently report
Published owner reviews describe the KS118 as exceptionally deep and controlled, with the cardioid mode singled out repeatedly by owners working in rooms with open microphones. Build quality and the amplifier module draw consistent praise, and owners frequently note that it does not sound strained at high output.
The consistent criticisms are price, weight and size: this is a large cabinet that needs a permanent home and is not a one-person lift. A recurring theme in owner accounts is that placement mattered more than they expected, which matches the physics and is the single most useful thing to take from the consensus.
Alternatives worth considering instead
Budget pick, because most churches need less: the Electro-Voice ELX200-18SP at $1,099.00 has cardioid presets and fly points at roughly half the price, and is the usual first subwoofer purchase.
Smaller pick, because floor space is the real constraint: the KS112 at $1,299.99 fits under a platform or beside a riser, which is often the difference between a subwoofer existing and not.
Different priority, because the room may be the problem: corner bass traps address low frequency build-up that no subwoofer will fix, and cost a fraction of the price.
Who should buy it, and who should not
Buy it, in pairs, if you run full contemporary worship in a room of 500 seats or more, if the platform currently booms, and if you have floor space designated for it rather than left over. Buy it if low frequency energy is currently reaching your open microphones and making every vocal sound thick.
Do not buy it for a speech-led service, do not buy one on its own for a corner, and do not buy it before treating the room. Read subwoofer versus no subwoofer honestly first, then size it with the subwoofer sizing calculator.
Sources
- QSC KS series published specification sheet and user manual
- QSC cardioid subwoofer configuration documentation
- Consensus of verified owner reviews published on major retailer listings
Frequently asked questions
Does a church actually need a subwoofer?
A speech-led or traditional service does not, and adding one usually makes the room muddier. A contemporary service with kick drum, bass guitar and tracks does, because asking 12 inch mains to carry that content costs clarity everywhere else. The honest test is what your service sounds like, not what a specification sheet suggests.
How many subwoofers does a large church need?
For cardioid operation as designed, more than one, which is the specification most churches miss when budgeting. Two boxes placed together also give more even coverage than a single unit in a corner, because a lone subwoofer in a corner excites room modes and produces seats with too much bass and seats with none. Size it properly with the subwoofer sizing calculator.
What does cardioid mode actually do?
It cancels much of the low frequency energy radiated backwards toward the platform, so the congregation gets the bass and the stage does not. In a church that matters specifically because open vocal and preaching microphones pick up platform low end and turn it into mud. It is the single most church-relevant feature on this cabinet.
Where should a church subwoofer be placed?
On the floor near the platform, not in a corner, and not tucked behind furniture. Corners couple the subwoofer to the room and exaggerate its modes, producing wildly uneven coverage. Plan the position as part of the system rather than fitting the box into leftover space, and check the result by walking the room during a rehearsal.
KS118 or ELX200-18SP for a growing church?
The ELX200-18SP is the usual first subwoofer: cardioid presets and fly points at roughly half the price. The KS118 is the flagship, with far more amplifier power and deeper extension, and justifies itself in a large room with a loud band. Buy the Electro-Voice first unless your room is genuinely large and your service genuinely contemporary.
Researched, not professional advice. This page is compiled from published manufacturer specifications, operator manuals, FCC rules, published standards and owner-review consensus, not hands-on testing. Sound system design, rigging loudspeakers overhead, and any electrical work are jobs for a qualified professional: have flown loudspeakers and their attachment points signed off by a structural engineer or a certified rigger, and have all wiring done by a licensed electrician to your local code. Wireless microphone rules change, so confirm the current FCC position before buying. As an Amazon Associate we earn from qualifying purchases.