4-Way Stereo Active Crossover

Take command of a full 4-way rig

The XR204 is a 4-way stereo active crossover in a 1U, 19-inch rack case. It takes two balanced inputs and splits each one into sub, low, mid and high, giving eight balanced outputs, so every band of your sound system gets its own amplifier channel.

Built for sound systems, touring rigs, clubs, bars and stage PA, it divides the signal before amplification. That way subs, kick bins, mids and tops each get only the frequencies they are built for, which keeps drivers cooler, cleaner and safer, and stops amplifier power being wasted on sound a box cannot reproduce.

It is a straightforward analogue unit. Every crossover point and output level has its own knob on the front panel, so you can set up a stack by ear and see the settings at a glance, with no software or menus.

Key features

• Three sweepable crossover points per side. Separate frequency controls for sub/low (50–250Hz), low/mid (70Hz–1kHz) and mid/high (480Hz–7kHz).
• Dedicated sub section. Each channel has its own sub output with independent frequency and level controls.
• 30Hz low-cut. A switchable filter removes subsonic content that eats amplifier headroom and pushes sub drivers past their excursion limits.
• Phase invert switches. Flip polarity to line up bands and cabinets and fill in cancellation at the crossover points.
• Level control for every output. Balance sub, low, mid and high against each other to suit the room and your boxes.
• Steel 1U chassis. Black steel case with a standard 19-inch rack front.

Setting it up

Crossover points depend on your cabinets. As a starting point, 18" sub drivers such as the WM1850/8 and WM18X451 take the sub band, kick or low bins take over above that, mid bins cover the vocal range and horns or compression drivers handle the top. Our guide to crossover basics explains how to choose the points, phase and polarity covers lining the bands up, and limiter and high-pass settings for subs shows how to protect your drivers at the amplifier. Weighing it against a DSP? Read budget DSPs for sound systems.

Why run analogue?

An old-school analogue four-way crossover is a very cost-effective alternative to the more sterile experience of operating a menu-driven DSP. For a small reggae, techno or DnB rig with well-matched cabinets, it gives you direct control over sub weight, kick, midrange presence and the balance of the tops.

The British sound system way

It carries on an approach familiar to generations of British sound systems: equipment assembled, understood and tuned by the people playing it. Racks of amplifiers, purpose-built boxes and physical controls were the working tools of systems that developed their own recognisable character. Getting the balance right came through listening and knowing the equipment. Read more in our UK sound system history and selector, operator and MC guides.

Hands on, ears on the room

The hands-on advantage is straightforward. Each control has a permanent place, and its position is visible at a glance. You can listen to the room and adjust the system without breaking concentration to navigate a screen. With scoops underneath and kicks above, separate band levels let you shape the relationship between deep bass and attack while keeping vocals and percussion present.

A simple signal path

A genuinely analogue crossover also avoids an additional digital conversion and processing stage. That keeps the signal path simple. A clean unit whose filters suit the cabinets can deliver weight, definition and a coherent sound without elaborate processing.

Money left for the rest of the rig

The economics are strongest when the rig already works well. An affordable analogue four-way provides the frequency division and level control you need without paying for facilities you may never use. The XR204 makes good sense in that role: accessible controls, straightforward operation and money left for the rest of the system, such as 18" sub drivers for your scoops.

“Sterile” describes the experience of some DSP interfaces better than it describes digital sound itself. But there is a practical distinction: with analogue, the controls are under your hands and your attention stays on the music. For a soundman who knows the stack, that remains an effective, satisfying and economical way to run a system.

Signal flow

Each input feeds its own 4-way split. The three crossover points on each side set where sub hands over to low, low to mid and mid to high.

Technical specifications

Front panel

• Input gain
• Crossover frequency controls: sub, low/mid and mid/high
• Level control for each output band
• Phase invert switches
• 30Hz low-cut switch
• Power switch and indicator

Rear panel

• Inputs: 2 × balanced XLR female (Channel One, Channel Two), >50kΩ
• Outputs: 8 × balanced XLR male (sub, low, mid and high for each channel)
• Mains: IEC inlet with fuse

Inputs and outputs are electronically balanced and also work unbalanced. XLR wiring: pin 1 ground, pin 2 positive (hot), pin 3 negative (cold). Signal-to-noise figures are referenced to +4dBu with a 22kHz measurement bandwidth.