How to Add a REL Subwoofer to a Two-Channel Audiophile System

A subwoofer in a serious two-channel system is not primarily about making bass louder. It is about extending the system below the useful range of the main loudspeakers and integrating that extension so the listener hears one coherent system.

REL has built much of its reputation around that idea, particularly through its high-level connection method, which takes a signal from the amplifier's speaker outputs while drawing negligible power from them.

The setup still requires care. Level, crossover, phase and placement determine whether the subwoofer disappears into the system or announces itself as a separate box.

Why Use High-Level Connection?

REL's own explanation is that the high-level input receives the same amplifier signal that is feeding the main loudspeakers. The company argues that this helps the subwoofer follow the tonal and dynamic character presented to the speakers.

The connection does not draw speaker-driving power from the amplifier; it is a high-impedance signal input.

REL supplies a Neutrik Speakon high-level cable with the T/9x, S/812 and Classic 98 according to current product specifications.

REL T/9x: 300 Watts, Active Driver Plus Passive Radiator

The T/9x uses a front-firing 10-inch active driver and a down-firing 10-inch passive radiator.

REL specifies:

Low-frequency extension: -6 dB at 27 Hz

Amplifier power: 300 W RMS

Amplifier type: Class A/B

Inputs: high-level Neutrik Speakon, low-level RCA and LFE RCA

Optional wireless: REL Arrow

The T/9x is a useful example of why subwoofer specifications should be read carefully. "300 watts" describes amplifier capability; it does not tell you how the unit will integrate in a particular room.

REL S/812: A Much Larger Performance Envelope

The S/812 moves to a 12-inch active driver, a 12-inch down-firing passive radiator and an 800-watt RMS NextGen 5 Class D amplifier.

REL specifies -6 dB extension at 19 Hz. It also provides high-level Speakon, stereo low-level RCA, LFE RCA and LFE XLR connectivity.

The S/812 supports REL's line-array approach, allowing multiple units to be stacked in larger installations.

For a substantial listening room or a system built around large, high-output main speakers, that additional low-frequency capability and amplifier headroom can be meaningful.

REL Classic 98: Different Architecture, Different Aesthetic

The Classic 98 is not simply a T/9x in a wooden cabinet.

REL specifies it as a closed-box design using a single down-firing 10-inch amended pulp-on-paper driver. There is no passive radiator.

Current specifications list:

Low-frequency extension: -6 dB at 27 Hz

Power: 300 W RMS

Amplifier type: Class D

Inputs: high-level Speakon, low-level RCA and LFE RCA

Finish: walnut veneer

Its visual language is deliberately traditional, making it particularly suitable for systems where a modern gloss-black subwoofer would clash with the room or the rest of the equipment.

Start With Placement Before Fine Tuning

Low frequencies interact strongly with room dimensions and boundaries.

A subwoofer position that produces excessive energy at one frequency can sound boomy even when the subwoofer itself is accurate. A position that coincides with a cancellation can make the subwoofer seem weak.

REL provides its own setup guidance, and following the manufacturer procedure is preferable to relying on a universal internet rule.

Once placement is established, adjust level, crossover and phase so the transition from the main speakers to the subwoofer is difficult to identify.

The Correct Level Is Usually Less Obvious Than Expected

For music, the subwoofer should not constantly call attention to itself.

A useful listening test is to set the system until it sounds balanced, then switch the subwoofer off. If the sound becomes smaller, loses weight and loses low-frequency ambience without the previous presentation having sounded obviously "subwoofer-heavy," integration is probably moving in the right direction.

That is a subjective setup method, but it reflects the goal: extension rather than special effects.

One Subwoofer or Two?

A stereo pair of subwoofers can provide additional placement flexibility and can help distribute low-frequency energy more evenly across a room. REL explicitly sells many models as single units, stereo pairs or, in the S series, line-array configurations.

Whether two are necessary depends on the room, system ambition and budget.

A single correctly installed subwoofer is preferable to two poorly integrated ones.

FAQs

What is the REL T/9x amplifier power?

REL specifies 300 watts RMS using a Class A/B amplifier.

How low does the REL S/812 go?

REL specifies -6 dB at 19 Hz.

Is the Classic 98 the same internally as the T/9x?

No. The Classic 98 is a closed-box, down-firing 10-inch design with a Class D amplifier. The T/9x uses a front-firing active driver plus a down-firing passive radiator and a Class A/B amplifier.

Can REL subwoofers be used in two-channel systems?

Yes. REL's high-level connection method is specifically promoted for integration with stereo loudspeaker systems.

Conclusion

A subwoofer should extend the main speakers, not compete with them.

The T/9x, S/812 and Classic 98 cover very different scales and aesthetics, but all support REL's high-level integration approach. The correct choice depends on the main loudspeakers, room volume, desired extension and visual requirements.

Careful setup remains as important as the model itself.

LINKS:

- Explore high-end speakers and subwoofers at Simco Audio
- Browse high-end audio components at Simco Audio
- Learn about Simco Audio listening appointments and system curation
- Contact Simco Audio for REL subwoofer system-matching advice