Among the accessories in the REL Acoustics catalog, the Bassline Blue occupies a very specific and often misunderstood niche. It is not a subwoofer, nor is it a general purpose interconnect. It is a purpose built high level line array connection cable, sold as a matched pair, engineered to link two REL subwoofers together into a stacked vertical array. For the experienced enthusiast who has already committed to REL's high level philosophy, understanding this cable is essential, because the way you connect subwoofers in an array is not a trivial detail. It fundamentally shapes how the array behaves as a coherent acoustic source. This deep dive breaks down what the Bassline Blue is, how it works, and why REL made the design choices it did.
What the Bassline Blue Is
What exactly is the REL Acoustics Bassline Blue?
The Bassline Blue is a high level line array connection cable sold as a matched pair, designed to link two REL subwoofers together in a stacked vertical line array configuration. In practical terms, once you have connected your primary REL subwoofer to your amplifier using REL's high level connection method, the Bassline Blue carries that same signal upward to a second stacked subwoofer, so both units receive an identical drive signal derived from the main amplifier. It belongs to REL's Bassline conductor family, which is the company's dedicated line of high performance connection cables for its subwoofers.
What is a high level line array in the REL context?
A high level line array in REL terminology is two or more subwoofers physically stacked in a vertical column and fed the same amplifier-derived signal so they act as a single, taller acoustic source. When you stack subwoofers vertically and drive them coherently, the combined radiating area behaves differently from two separate subwoofers scattered around a room. A vertical array narrows vertical dispersion and increases effective diaphragm surface area, which raises output capability and tightens the sense of pitch and attack in the low end. The Bassline Blue is the physical link that makes this possible while preserving the integrity of REL's signature high level connection.
The High Level Philosophy Behind the Design
Why does REL use a high level connection instead of a line level input?
REL uses a high level connection because it takes the signal directly from the same speaker terminals feeding your main loudspeakers, meaning the subwoofer hears exactly what the main amplifier produces, including its sonic character and phase behavior. This is the foundational idea behind REL's entire design language. When a subwoofer is fed from the power amplifier output rather than a preamp line level tap, it inherits the tonal signature, the damping behavior, and the transient shape of the amplifier that drives your main speakers. The result is a subwoofer that blends more seamlessly with the mains because it is quite literally sharing the same source signal. The Bassline Blue extends this principle into the second subwoofer of an array, ensuring the stacked unit is fed from the same derived high level signal rather than a separate, potentially mismatched path.
How does the Bassline Blue actually carry the signal between subwoofers?
The Bassline Blue carries the signal using REL's high level connection method, taking the drive signal that has already been established at the primary subwoofer and passing it up to the second stacked unit. Because it is derived from the main amplifier, the second subwoofer receives the same reference signal as the first. This matters because in an array the two subwoofers must remain phase coherent and time aligned relative to each other. If the second unit were fed by a different or degraded signal path, the array would lose the very coherence that justifies stacking in the first place. By keeping both units on a common high level derived feed, the Bassline Blue maintains the acoustic unity that makes a vertical array worthwhile.
Why is it sold as a matched pair rather than a single cable?
It is sold as a matched pair because a high level connection involves multiple conductors that must be consistent in their electrical behavior, and a stacked array benefits from cabling that is uniform on both channels. Matching means the two cables share the same conductor construction from the Bassline family, so there is no asymmetry introduced between the connection points. In a system where you are deliberately trying to build a single coherent bass source out of two physical enclosures, consistency in the connecting hardware supports consistency in the acoustic result. Buying them as a matched set removes the guesswork of trying to pair cables yourself.
Conductor Family and Build
What is the Bassline conductor family and why does it matter?
The Bassline conductor family is REL's dedicated line of subwoofer connection cables engineered specifically for the demands of high level signal transfer, and the Bassline Blue sits within it. REL developed the Bassline range because the high level connection places particular requirements on a cable that a generic interconnect does not address. The cable is carrying a full range, amplifier-derived signal, and the geometry and conductor construction are chosen to preserve the low frequency content and the transient information that gives bass its texture and timing. Because the Bassline Blue is a member of this family, it shares that design intent, applied to the specific task of linking two subwoofers in an array.
What materials and construction does the Bassline Blue use?
The Bassline Blue is built as a Bassline family conductor optimized for high level connection between REL subwoofers, prioritizing consistent conductor behavior and reliable termination for the array application. While the specific numerical parameters of the conductor are not something to invent, the design philosophy is clear: a cable in this role must present a stable, low compromise path for the high level signal so that nothing is added or subtracted between the two enclosures. The emphasis is on preserving the signal that has already been carefully derived from the main amplifier, which is why REL treats these cables as engineered components rather than afterthoughts.
System Integration and Compatibility
Which REL subwoofers work with the Bassline Blue?
The Bassline Blue is compatible with REL subwoofers equipped with a high level input, since the entire function of the cable depends on the high level connection method. If a subwoofer in your system offers the high level input that REL is known for, it is a candidate for the array approach that this cable enables. This is important to verify before planning a stacked configuration, because the high level input is the connection point the Bassline Blue relies on. The cable is not a universal accessory for any subwoofer; it is specifically a tool for building arrays out of REL units that support the high level topology.
How do you integrate the Bassline Blue into an existing REL setup?
You integrate the Bassline Blue by first establishing the high level connection from your main amplifier to the primary subwoofer, then using the Bassline Blue pair to link that primary subwoofer to the second stacked unit above it. The workflow follows REL's connection logic: the amplifier feeds the base of the array, and the array is built upward from there. Because the signal reaching the second subwoofer is derived from the main amplifier through the first unit, the entire stack remains on a common reference. This is why the physical stacking and the electrical connection go hand in hand. The vertical arrangement gives you the acoustic benefits of an array, and the Bassline Blue ensures the electrical connection supports that acoustic goal.
What audible benefit does stacking subwoofers into an array provide?
Stacking subwoofers into a vertical array increases effective radiating area and output capability while tightening the perceived control and pitch definition of the low end. A larger combined diaphragm surface can move more air with less individual excursion demand on each driver, which tends to reduce distortion at a given output level and preserve transient snap. The vertical geometry also alters how the array couples to the room, particularly in the vertical plane, which can be used to manage certain room interactions. The Bassline Blue is what allows two REL subwoofers to work together toward these outcomes rather than functioning as two independent sources fighting for coherence.
Positioning Within the REL Lineup
Where does the Bassline Blue sit in the REL Acoustics range?
The Bassline Blue sits within REL's accessory and cable offerings as a specialized member of the Bassline conductor family, dedicated to array building rather than to a single subwoofer connection. Where a standard REL high level cable serves to connect one subwoofer to your amplifier, the Bassline Blue is the cable you reach for when you have decided to go beyond a single subwoofer and construct a stacked vertical line array from compatible REL units. It represents the natural progression for an enthusiast who has embraced the high level philosophy and now wants to scale the low end through arraying rather than simply adding a disconnected second box.
Who is the Bassline Blue actually for?
The Bassline Blue is for the experienced REL owner who intends to run two subwoofers as a stacked vertical line array and wants the connection between them to honor REL's high level design principles. It is a niche but meaningful component. If you own compatible REL subwoofers with high level inputs and you are pursuing the coherence and output advantages of a true array, this matched pair is the purpose designed link that makes that configuration behave the way REL intends. For the enthusiast who values doing things the way the engineering demands, the Bassline Blue is the correct tool for the job.
Conclusion
The REL Acoustics Bassline Blue is a small component with an outsized role. As a matched pair of high level line array connection cables from the Bassline conductor family, it exists to link two REL subwoofers into a coherent stacked array while preserving the amplifier-derived high level signal that defines the REL sound. Every design choice, from the high level connection method to the matched pair format to its membership in the Bassline family, serves the single goal of turning two enclosures into one unified bass source. For the enthusiast building a serious REL array with compatible high level equipped subwoofers, it is not an optional flourish. It is the connection that makes the array an array.