Subwoofers and PA Systems for Live Sound, Installation, and Studio Applications
A subwoofer extends low-frequency reproduction below the range of full-range speakers, adding output and definition to bass frequencies that standard tops cannot reproduce at sufficient volume or extension. The subwoofers and PA systems in this collection cover active and passive designs across multiple driver sizes and output levels, from portable gigging rigs to permanent installation systems. Understanding the difference between active and passive designs, and matching output level to venue size, are the two most important decisions before purchasing a subwoofer.
Active vs Passive Subwoofers — Which Integration Type Fits Your System
Active subwoofers have a built-in amplifier. You connect them directly to a mixer or audio interface output with no external amplifier required. Active designs are the correct choice for most gigging musicians, event producers, and installation applications where simplicity and fast deployment are priorities.
Passive subwoofers require a separate power amplifier to drive them. They are the correct choice for permanent installations where a specific amplifier is already part of the system, or where separate amplifier selection is a priority for the engineer specifying the rig. Every active subwoofer in this collection includes a crossover output for connecting full-range tops. HK Audio recommends crossover points between 80 Hz and 120 Hz for most applications — below 80 Hz leaves the tops reproducing bass frequencies they are not optimized for, and above 120 Hz makes the subwoofer's location audible to the audience.
HK Audio LINEAR Series — Active and Passive Subwoofers by Venue Scale
The HK Audio LINEAR series covers five models across 15-inch and 18-inch driver sizes, each designed for a different scale of application.
The LINEAR 5 MKII 115 Sub A delivers 600W RMS with a 1200W peak from a Class-D amplifier driving a 15-inch woofer. It handles small to mid-size venues, outdoor events up to a few hundred people, and touring rigs where portability matters alongside output. The LINEAR SUB 1500 A delivers 1200W peak Class-D power through a 15-inch woofer with low-frequency extension below 40 Hz, suited to medium-scale live sound requiring more low-end weight than a smaller sub provides.
The LINEAR 9 118 Sub A delivers 1100W RMS through an 18-inch woofer with extension to 35 Hz, covering large venues and high-SPL outdoor events. The LINEAR 5 MK II 118 Sub HPA delivers 3000W peak through an 18-inch woofer and is designed for professional touring rigs, large festivals, and permanent installations where maximum output and headroom are the priority. The LINEAR SUB 4000 is the passive option in the series — an 18-inch dual-vented bandpass cabinet designed for permanent installation where the amplifier is already specified.
HK Audio POLAR Series — Column PA for Speech Intelligibility and Controlled Dispersion
The HK Audio POLAR 8 and POLAR 12 are column PA systems rather than conventional subwoofer-plus-top configurations. Column PA uses a vertical array of small drivers to produce a controlled, narrow vertical dispersion pattern that reduces floor and ceiling reflections in acoustically difficult rooms. This makes column PA the correct choice for houses of worship, conference rooms, restaurants, and acoustic performances where speech intelligibility and even coverage are more important than raw SPL output.
The POLAR 8 suits small venues and acoustic performances. The POLAR 12 steps up to larger rooms requiring more bass output and higher SPL capability while maintaining controlled dispersion. Both POLAR systems integrate the subwoofer and column satellite into a single self-contained package, making them faster to deploy for mobile applications than a separate sub-and-top system.
HK Audio LINEAR 9 110 XA — Active Stage Monitor Application
The HK Audio LINEAR 9 110 XA is a 700W active stage monitor rather than a front-of-house subwoofer. It delivers 131 dB peak SPL from a 10-inch woofer in a wedge-format cabinet, covering applications where performers require a powerful floor monitor capable of handling vocals and instruments at high stage volumes without distortion. At 700W RMS into a 10-inch driver it has significantly more headroom than typical budget stage monitors.
Matching Subwoofer Output to Venue Size
Selecting the correct output level before purchasing prevents both underpowered systems and unnecessary cost. For small venues under 200 people, a single 15-inch active subwoofer at 600W to 1200W peak handles most applications. For medium venues between 200 and 500 people, an 18-inch active subwoofer at 1100W RMS provides the low-frequency extension and output required. For large venues, festivals, and permanent installations above 500 people, dual 18-inch subwoofers or a single high-output unit at 3000W peak delivers the headroom needed for consistent performance at volume.
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