Tuning Your No.36 or No.35

How to tune your Reference Sub-Bass System for seamless integration, precision, and extraordinary musical performance 

The finest bass is not simply heard. It is felt, understood, and experienced as a natural extension of the music or film unfolding in front of you. With the REL No.35 and No.36, achieving that experience is a matter of careful placement, thoughtful adjustment, and learning to trust what you hear. 

The No.35 and No.36 are exceptionally capable Reference Sub-Bass Systems, designed to deliver deep extension, dynamic authority, and the kind of speed and delicacy that allow bass to become part of the overall musical experience. But even the most accomplished subwoofer must be properly integrated with the room and the main loudspeakers to perform at its full potential. 

Fortunately, tuning a Reference system does not require specialized measurement equipment or an engineering degree. It requires a methodical approach, a familiar listening track, and a willingness to make small adjustments until everything comes together. 

Here is how to tune your REL No.35 or No.36 for the best possible performance. 

Content: 

• Why Proper Tuning Matters
• Step 1: Establish the Right Starting Point
• Step 2: Fine-Tune Your Position
• Step 3: Set Phase for Maximum Integration
• Step 4: Find the Right Crossover and Level
• Step 5: Tune a Stereo Pair
• Step 6: Tuning a Reference Line Array
• Step 7: Integrate Your Reference System with Home Theater
• When to Consider Parametric EQ
• The Final Test: Trust Your Ears

Why Proper Tuning Matters

One of the most common misconceptions about subwoofers is that more output automatically means better performance. With a Reference system, the objective is not simply to fill a room with bass. It is to create a coherent, full-range presentation in which the subwoofer and main loudspeakers behave as a single, integrated system. 

Too much output in the wrong frequency range can make music sound thick, slow, or disconnected. Too little output can leave the presentation thin and lacking in scale. An incorrectly set phase can reduce bass energy rather than reinforce it, while an unsuitable position can create unevenness across the listening space. 

The No.35 and No.36 offer substantial output capability, but their greatest strength lies in how naturally that power can be integrated into a system. 

The No.35 employs a 12-inch long-throw carbon-fiber driver and a 900-watt amplifier. The No.36 steps up to a 15-inch long-throw carbon-fiber driver and a 1,000-watt amplifier. Both are designed to reproduce the deepest notes while preserving the articulation, texture, and timing that distinguish exceptional bass from bass that merely dominates.

Reference No.36 & No.35 with Remote

The secret is balance. 

Step 1: Establish The Right Starting Point

Before adjusting any controls, make sure your main loudspeakers are properly positioned and performing at their best. A REL Reference system supplements your loudspeakers; it does not replace the need to establish a strong foundation with them. 

Next, choose a familiar piece of music with a repetitive, low-frequency percussion line. Our preferred reference is “Cosmo…Old Friend,” Track 4 from the Sneakers soundtrack (Columbia CK 53146). Its repeated concert bass drum strikes provide consistent reference points for evaluating placement, phase, and crossover settings. 

You will want a passage that gives you enough time to listen carefully and make adjustments without constantly stopping playback. 

Understand your remote 

Reference Remote 

The Reference remote provides the primary controls needed for tuning: 

• CROSSOVER: Adjusts the crossover frequency for high-level and low-level inputs, over a 20–90 Hz range.

• HI/LOW LEVEL: Controls output level for the high-level or low-level connection. 

• .1/LFE LEVEL: Controls output level for the dedicated home theater LFE input. 

• PHASE: Selects between 0 and 180 degrees. 

• PARAMETRIC: Selects the first or second parametric EQ for adjustment. 

• LOCK: Locks the remote settings when not in use. 

The front-panel LED display identifies the parameter being adjusted and its current value. For example, CO indicates crossover, HL indicates high/low level, .1 indicates LFE level, and PH indicates phase. 

One important distinction: the high-level and low-level inputs use both the crossover and HI/LOW LEVEL controls. The dedicated .1/LFE input bypasses the normal REL crossover and is controlled independently by the .1/LFE LEVEL setting. 

For initial setup, begin with the crossover and level settings at conservative values. The Reference manual identifies Level 25 and Crossover 36 as starting points for positioning a single unit. For the subsequent crossover-tuning procedure, a setting around 30 Hz is a useful starting point. These are reference settings, not universal final values; your room, loudspeakers, and listening preferences will determine the best result. 

RELTip: Make one adjustment at a time. Once you discover a setting that works, record it so you can return to it if necessary. 

Step 2: Fine Tune Your Position

Positioning is one of the most consequential parts of subwoofer setup. Even small changes can affect the amount of bass you hear, how evenly it fills the room, and how naturally it connects with your main loudspeakers. 

For a single No.35 or No.36, begin in a front corner behind the main loudspeakers. Corner placement can increase acoustic loading and provide greater low-frequency output, helping the subwoofer energize the room more effectively. 

However, do not assume that pushing the cabinet as tightly into the corner as possible will produce the best result. 

Find the room's natural response 

With your reference track playing, begin moving the subwoofer diagonally away from the corner in small increments. Listen for changes in depth, weight, and definition. 

At certain positions, the bass may become noticeably deeper or more powerful. At others, it may lose definition or sound less consistent. Pay attention to the moments when the bass becomes both more substantial and more articulate. 

When you find a position that delivers satisfying extension without sacrificing speed or clarity, pause and listen again.

Reference No.35

Fine-tune the orientation 

Once you have established the distance from the corner, experiment with the cabinet's toe-in. Rotate the subwoofer gradually, listening for the position that offers the best combination of richness, focus, and evenness. 

If the room sounds overly full, a slight adjustment outward may help reduce excessive richness. The goal is not to maximize bass at every opportunity; it is to achieve the most natural and balanced presentation. 

RELTip: Positioning and tuning work together. Resist the temptation to correct every acoustic issue with a control adjustment when a small change in placement may provide a better solution.  

Step 3: Set Phase for Maximum Integration

Phase determines how the subwoofer's output interacts with the output of your main loudspeakers. When the relationship is favorable, their contributions reinforce one another. When it is unfavorable, some bass energy can cancel, leaving the presentation weaker than expected. 

The Reference remote offers two phase settings: 0 and 180 degrees. 

Begin with the crossover set to its lowest setting so that you can concentrate on the deepest bass. Adjust the HI/LOW LEVEL control until the subwoofer and main loudspeakers are producing a useful, balanced amount of sound for comparison. 

While playing your reference track, switch between 0 and 180 degrees. Listen for the setting that produces the fullest, most convincing bass response. 

In accordance with the Reference setup procedure, the correct setting is generally the one that sounds louder or fuller through the listening position, indicating better reinforcement rather than cancellation. 

Avoid overthinking this step. You are listening for a clear difference in the weight and presence of the repeated bass drum strikes. 

Once you have selected the better setting, leave phase unchanged while you begin refining crossover and level. 

RELTip: Phase affects the high-level, low-level, and .1/LFE inputs. If you change the subwoofer's position substantially or alter the system configuration, revisit phase as needed.

Step 4: Find The Right Crossover and Level

This is where the Reference system begins to disappear into the performance. 

The crossover determines how high in frequency the subwoofer contributes to the sound. The level determines how strongly it contributes. These controls must work together: raising the crossover often increases the subwoofer's contribution through more of the upper-bass region, so a small level adjustment may be needed to preserve balance. 

The most common mistake is setting the crossover too high and then turning the level down to compensate. This can emphasize upper bass while leaving the overall presentation thick or disconnected.

Begin with a low crossover 

Start with the crossover around 30 Hz, following the Reference manual's tuning procedure. Turn the HI/LOW LEVEL control down, then gradually bring it up until you can just begin to hear the No.35 or No.36 contributing alongside the main loudspeakers. 

You are not trying to make the subwoofer announce its presence. You are establishing the foundation upon which the loudspeakers can build. 

Raise the crossover gradually 

Increase the crossover in small increments, listening for the point at which the subwoofer and loudspeakers begin to sound like a unified system. 

As you adjust, pay attention to three things: 

• Depth: Are the lowest notes reaching further into the room without becoming exaggerated? 

• Texture: Can you hear the definition of the bass drum rather than a vague wash of low-frequency energy? 

• Integration: Does the bass seem connected to the music, or does it sound like a separate source? 

Continue until the crossover is slightly too high. At that point, you may hear the bass become thick, prominent, or less natural. Reduce the crossover until the presentation regains its balance. 

Now make small adjustments to the HI/LOW LEVEL control. The final result should retain a subtle richness and scale without drawing attention to the subwoofer itself. 

Listen for the signs of a good blend 

When the crossover is too low, the system may sound slightly thin, cool, or lacking in weight. When it is too high, the bass can become overly warm, plummy, or slow. 

The right setting creates a natural transition between the main loudspeakers and the subwoofer. Bass notes have weight and extension, but their timing and texture remain connected to the musical event. 

Remember that the ideal settings will vary. A published loudspeaker frequency specification cannot tell you exactly where your REL should be crossed over in your listening room. Room dimensions, boundaries, furnishings, speaker placement, and listening position all affect the result. 

Trust what you hear rather than trying to calculate a perfect setting from specifications alone. 

RELTip: After making a crossover adjustment, revisit level. When the crossover is lowered, you may need a little more level; when it is raised, you may need less. Small changes are usually more revealing than large ones.

Step 5: Tune a Stereo Pair

Reference No.36 Stereo Pair

A stereo pair of No.35 or No.36 subwoofers is about more than additional output. Properly integrated, two subwoofers can provide greater control over the left and right sides of the room, helping deliver more consistent bass, clearer definition, and a stronger connection with the main loudspeakers. 

Begin by placing the two units in the front corners, or experiment with positioning them slightly behind and outside the main loudspeakers if your room responds better to that arrangement. 

The tuning process is the same as for a single subwoofer, but each unit must be adjusted independently. 

Tune one channel at a time 

1. Disconnect the signal input to one subwoofer so that only the other is playing. 

2. Tune the active unit's position, phase, crossover, and HI/LOW LEVEL setting using the preceding steps. 

3. Reconnect the first unit and disconnect the other. 

4. Repeat the process for the second subwoofer, focusing on its integration with its corresponding main loudspeaker. 

5. Reconnect both units and listen to the system as a whole. 

Once both subwoofers are operating together, the combined output will typically be higher than that of either unit alone. This is normal. Reduce the HI/LOW LEVEL setting on each unit as needed to restore a balanced presentation. 

Listen from your normal seating position, and pay attention to whether bass remains evenly balanced between the left and right sides. 

The final adjustments should prioritize integration and control rather than sheer output. When the two units are working together correctly, the system should sound more effortless, with greater authority and definition across the listening space. 

RELTip: Do not assume that two individually tuned subwoofers will automatically have the right combined level. Always evaluate the stereo pair together and make the necessary final adjustments. 

Step 6: Tuning a Reference Line Array

Reference No.36 Line Array

A Reference Line Array takes the performance of the No.35 or No.36 further by combining multiple units in vertical stacks. The resulting system can deliver extraordinary scale, depth, and dynamic ease, but the additional subwoofers must be integrated carefully. 

The process begins with the main loudspeakers, not the subwoofer towers. 

First, establish the best possible performance from the main loudspeakers. Next, position and tune the bottom left and right subwoofers as a stereo pair, following the procedure above. 

Once the bottom units are properly integrated, add the remaining subwoofers to the stacks.

Tune each unit independently 

Each subwoofer in a Line Array retains its own level, crossover, and other adjustable settings. Daisy-chaining the signal does not automatically tune the units as a group. 

Keep the phase setting of the middle and upper units consistent with the corresponding bottom units. Then tune each additional subwoofer individually, with only that unit playing at a time. 

The listening priorities change as you move up the stack: 

Bottom units: Foundation and extension 

The bottom pair establishes the fundamental relationship with the main loudspeakers and provides the foundation of the system's low-frequency performance. 

Middle units: Attack and definition 

Focus on the leading edge of the bass drum and the precision of the mid-bass. Listen for the mallet striking the drum skin: it should sound crisp, clearly defined, and controlled. 

Upper units: Air and openness 

The upper subwoofers contribute to the sense of openness, delicacy, and transition between deep bass and the low-frequency output of the main loudspeakers. Their crossover and level settings may need to be slightly higher than those of the units below them. 

These are listening priorities rather than rigid rules. The final settings must be established in your room, with your system. 

Rebalance the complete array 

After tuning every unit individually, connect the required daisy-chain cables and listen to the complete system. The combined output will generally be higher, so you will need to reduce the levels across the array to restore the correct balance. 

Make final crossover and level adjustments as necessary, listening for coherence from the lowest frequencies through the mid-bass. 

A properly tuned Reference Line Array should not simply sound bigger. It should sound more effortless, with greater dynamic headroom, a convincing sense of scale, and bass that remains connected to the performance. 

Important: No.35 and No.36 Line Arrays are heavy. Ensure that the floor is level and stable, use the supplied couplers correctly, and secure stacked units to a structural part of the wall with an appropriate furniture restraint. Follow the owner's manual for safe assembly and installation. 

Step 7: Integrate Your Reference System with Home Theater

The No.36 and No.35 are designed to support both high-fidelity music and demanding home theater systems. 

One of the Reference system's advantages is the ability to use the high-level connection for integration with the main loudspeakers while simultaneously using the dedicated .1/LFE input for movie soundtracks. 

The high-level or low-level connection provides the musical foundation, with crossover and level adjusted for proper integration. The .1/LFE input handles the dedicated low-frequency effects channel from the home theater processor. 

Set up the .1/LFE channel 

Once the subwoofer has been positioned and tuned for music, connect the processor's subwoofer output to the REL's .1/LFE input using a suitable RCA or fully balanced XLR connection. 

Play a dynamic scene with substantial low-frequency effects. The Reference manual suggests Chapter 14 of Iron Man as a useful example. 

Use the remote's .1/LFE LEVEL control to increase the effects-channel output gradually. The objective is powerful, dynamic bass that supports the action on screen without audible strain or distortion. 

Remember that the .1/LFE LEVEL control is independent of the HI/LOW LEVEL control used for music. This allows you to adjust the cinematic impact without disturbing the established musical balance. 

For stereo pairs and Line Arrays, adjust the .1/LFE level of each unit as necessary to achieve the desired overall output. 

Check your processor settings 

Home theater processor menus vary, so consult the instructions for your particular equipment. The Reference manual recommends full-range or “Large” settings for the main speaker channels where the processor supports them, allowing the high-level connection to deliver its intended benefits. If your processor cannot provide full-range output during multichannel playback, set the main speaker crossover to its lowest available value. Also verify that the subwoofer output is enabled so that the LFE signal reaches your REL. 

The goal is to preserve the natural integration achieved during music tuning while adding the appropriate level of cinematic impact. 

When to Consider Parametric EQ

The No.36 and No.35 include two optional parametric equalizers designed to address certain room-acoustic challenges. Each filter can adjust a selected frequency between 23 and 90 Hz, with up to 4 dB of boost or cut in 1/3 dB increments. The two filter frequencies must remain at least 10 Hz apart. 

These controls can be useful, but they should not be the first step in tuning a Reference system. 

Begin with placement, phase, crossover, and level. These adjustments often resolve many of the problems listeners initially attribute to room response. 

Only consider EQ once the fundamental setup is working well and you have identified a specific issue that remains. 

Use gentle corrections 

Rooms commonly exhibit uneven bass response, including elevated output in portions of the upper-bass region and reduced output at lower frequencies. The Reference EQ provides an opportunity to make modest corrections when these characteristics interfere with the desired balance. 

During development, REL found that a gentle boost of 2 dB at 25 Hz and a reduction of 2 dB at 43 Hz, with the crossover at 34 Hz, produced a more even result in its studio. This is an illustrative example, not a universal prescription for every room. 

Avoid attempting to force a perfectly flat response or applying large boosts and cuts over narrow frequency ranges. Such adjustments can be counterproductive and may compromise the system's performance. 

The parametric filters are optional, and REL does not recommend that inexperienced users experiment with them casually. Incorrect application can produce detrimental results and, in extreme cases, pose a risk to the subwoofer. If you are uncertain, seek assistance from an authorized REL dealer or qualified setup specialist.

The Final Test: Trust Your Ears

Reference No.36

Tuning a REL Reference system is a process of discovery. The controls provide precision, but the purpose of that precision is to help you achieve a result that sounds natural in your own room. 

After making your adjustments, return to familiar music and listen for the qualities that matter most: depth without heaviness, impact without strain, and detail that remains clear even when the music becomes demanding. 

The bass should not feel detached from the loudspeakers. It should become part of the performance, adding weight and scale while preserving the character of the instruments and the space around them. 

For a home theater system, the same principle applies. Effects should be powerful and immersive, but never at the expense of control or clarity. 

Do not be afraid to make small adjustments, revisit a previous setting, or take time to listen. The best result may not correspond to a number you found online or a specification printed in a brochure. It will be the setting that allows your system to communicate the full intent of the music and film. 

With a No.36 or No.35, the potential is already there. Proper tuning allows you to experience it. 

Enjoy the journey. The finest bass is not simply more bass. It is bass that belongs.