How REL Acoustics' Subwoofer Series Differ: Reference, Serie S, and Planar

Updated

REL Acoustics organizes its subwoofers into distinct series, and the differences come down to three things: performance tier, physical form, and how the subwoofer is meant to sit in a room. Reference Series sits at the top as the brand's highest standard in power, finesse, and appearance. Serie S is positioned as a mid-level range that still outperforms anything REL has previously offered at that tier, aimed at higher-end systems in medium to large rooms. Planar is a different category altogether: an ultra-thin subwoofer designed to be wall-mounted, placed behind furniture, or integrated into living spaces where a traditional subwoofer would be impractical. If you are choosing between them, the deciding factors are your room size, your existing system's level, and whether physical footprint or interior integration matters more than raw output.

Reference Series: the top of the range

REL describes Reference Series as "the pinnacle in subwoofer design and engineering" and "the absolute maximum in power, finesse and beauty on offer." The current lineup named on the site includes the No.36 at $12,000 and the No.35 at $10,000, with the No.32 and No.31 also presented as representing the pinnacle of the series.

Choose Reference if:

  • You are building or upgrading a system where the subwoofer is expected to be the reference point for the rest of the chain.
  • Budget is not the primary constraint — these are the highest-priced models shown.
  • You want the series REL itself frames as its highest standard rather than a step toward it.

The trade-off is cost and physical presence. These are full-size subwoofers, not design-integrated ones, so they assume you have the space and the system to justify them.

Serie S: mid-level performance for larger rooms

Serie S is described as combining "a higher performance level than we have ever set out to deliver within our mid-level range," with the explicit purpose of elevating higher-end systems in medium to large rooms.

Choose Serie S if:

  • Your room is medium to large and you need output that fills it.
  • Your existing system is already at a higher-end level and you want a subwoofer that keeps pace without moving to the Reference tier.
  • You want more performance than an entry-level subwoofer but do not need the flagship series.

The key phrase is "medium to large rooms." Serie S is positioned around room volume and system level, so it is the middle path: more capable than the entry point, less extreme than Reference.

Planar: a different category, not just a lower tier

Planar is not simply a cheaper subwoofer — it is a different design premise. REL and John Hunter (in a PALE BLUE Magazine interview) describe Planar as "a groundbreaking new category of subwoofer that blends high-performance audio with modern interior design." Its ultra-thin profile allows it to be wall-mounted, placed behind furniture, or integrated into living spaces where traditional subwoofers would be impractical.

Choose Planar if:

  • Floor space is limited or a conventional subwoofer box would disrupt the room.
  • You want bass that integrates into the room's design rather than sitting in it as a separate object.
  • You are willing to accept the constraints of a thin-profile form factor in exchange for placement flexibility.

REL's own framing supports this: the brand's stated philosophy is that "when bass is done right, it disappears. Everything else comes alive." Planar is the series that takes that idea literally in physical terms.

Side-by-side comparison

Series Positioning Best for Key constraint
Reference Series Pinnacle of design and engineering; maximum power, finesse, beauty Reference-grade systems; buyers who want REL's highest standard Highest cost; full-size footprint
Serie S Higher performance within REL's mid-level range Higher-end systems in medium to large rooms Needs room volume and system level to justify
Planar New category blending performance with interior design Spaces where a traditional subwoofer is impractical Thin-profile form factor rather than maximum output

How to decide

Work through these in order:

  1. Can a conventional subwoofer physically work in your room? If not — if it would block a walkway, sit awkwardly, or fail aesthetically — Planar is the series built for that problem.
  2. How large is the room? Serie S is explicitly aimed at medium to large rooms. If your room is smaller, the larger series may be more than the space can use well.
  3. How high is the rest of your system? Serie S is positioned to elevate higher-end systems. Reference is positioned above that, as the maximum REL offers.
  4. What is your budget ceiling? Reference models shown on the site run $10,000–$12,000. If that is out of range, Serie S is the next tier down, and Planar is a separate design choice rather than a budget step.

The honest summary: Reference is the flagship, Serie S is the mid-level workhorse for bigger rooms and better systems, and Planar is the answer when the room itself — not the budget — is the constraint.