Discover the exclusive 'constant directivity' technology only available in Electro Voice speakers

Electro-Voice's Constant Directivity (CD) technology is one of the breakthroughs that has contributed to the solid reputation of the professional loudspeaker brand from the US. Launched in 1974, this technology helps the loudspeaker maintain a stable sound coverage angle, ensuring that listeners in any position in the space can feel the sound clearly, evenly, without "dropping" sound or distortion.

More than just a theory, the CD Horn has become the core foundation in the design of a wide range of EV loudspeakers, from entry-level models like the ZLX, ELX200, to professional performance models like the EKX, ETX and Evolve 50M.

Through a flat-walled speaker structure, a combination of Waveguide directional, DSP phase processing, and premium driver materials, Electro‑Voice delivers a sound system with good feedback resistance, outstanding vocals, and deep, solid bass while still saving installation costs.

The article below will provide you with the most comprehensive and complete view of the exclusive "constant directivity" technology only available in Electro-Voice speakers - the factor that makes sound engineers always prioritize this brand for all stages, halls and high-end karaoke systems.

What is Electro‑Voice's “Constant Directivity” technology?

Electro-Voice is one of the few audio brands to pioneer Constant Directivity (CD) technology – also known as Constant Directivity – to ensure sound is evenly and clearly dispersed throughout the listening space. This technology was born in 1974 and to this day remains the core foundation of most of EV's professional loudspeaker lines.

The Concept of Constant Directivity in Loudspeakers

Constant Directivity (CD) is a term that describes the ability of a speaker to disperse sound with an even and consistent coverage angle across the frequency range – especially in the mid and treble. This prevents sound from “dropping out” at off-axis or distant locations. In other words, CD speakers help audiences in all positions hear the same sound, creating a smooth and consistent sound experience.

Why EV developed this technology since 1974

In 1974, EV realized that standard loudspeaker systems at the time had a major problem with angular distortion – the sound would be concentrated in the middle, while the sides would be diluted. To solve this, they invented the CD Horn design to maintain stable horizontal and vertical coverage throughout the frequency range from 1kHz to 16kHz. This was a huge step forward at the time, and is still the reason why EV is always the choice of engineers for professional stages and karaoke.

How constant orientation technology works

To achieve even and distortion-free coverage, EV has simultaneously optimized the speaker throat design, signal processor and driver construction materials.

Flat-Front Horn Design Structure

Electro‑Voice uses the Flat-Front CD Horn, which has a flatter face, a wider mouth and precise sound-conducting geometry. This allows the high frequencies to be dispersed evenly rather than concentrated at one point. The horn dimensions are typically 90° x 60° or 100° x 100°, ensuring coverage angles both horizontally and vertically.

Combination of Waveguide + DSP + Horn geometry

The three elements that make up a stable orientation include:

• Waveguide – helps direct high frequencies along a predetermined pattern.
• DSP handles phase and amplitude – balancing the emitted energy between frequency bands.
• Horn geometry optimizes geometry – eliminating sound wave overlap.

When combining all three of the above elements, EV creates a sound system with absolute stability, good anti-feedback and always clear vocals.

Outstanding advantages of constant orientation technology in practice

EV's CD technology is more than just a theoretical concept. In practical implementation, it creates a series of clear benefits for sound engineers and listeners.

Disperse sound evenly on horizontal and vertical axes

CD-based speakers maintain consistent coverage – for example 90° x 60° – across the entire frequency range. This allows people sitting off to the side or further away to hear as clearly as those sitting in the middle. When measured with an RTA, the response curve off-axis drops by only <3dB, which is extremely impressive.

Reduce distortion and enhance vocal intelligibility

Because the sound energy is not concentrated at one point, the listener does not feel “screaming” when sitting close to the speaker. The vocal becomes separate, clean, easy to mix and less mixed with the background music. This is a big advantage in karaoke singing or live vocal performance.

Reduce feedback when using microphone

CD Horn helps avoid sound reflection in the wrong direction, thereby reducing the risk of the microphone picking up the sound back - which is the cause of howling. Combined with DSP frequency cut 2k-6kHz, EV helps the system operate more stably and easier to control than speakers without this technology.

EV speaker lines apply constant directivity technology

Electro‑Voice has widely applied Constant Directivity Horn technology to most of the stage and karaoke speaker lines, from popular to high-end. Although the design is different, they all follow the principle of stable and even sound direction.

• ETX, EKX, ELX, ZLX: Integrated CD horn technology
• ZLX and ELX200: Popular line, integrated horn with fixed coverage angle 90° x 60° or 100° x 100°, suitable for karaoke and small events.
• EKX: Mid-range speaker, compression horn designed with polyimide material combined with waveguide to expand dispersion.
• ETX: Top of the line with solid titanium CD horn, optimized for vocals and large stages.

FIR-Drive DSP supports maximum CD effects. In particular, all of these lines allow DSP configuration for each space, helping to fully utilize the CD Horn.

Evolve 30M, 50M: Column speakers but still using vertical waveguide

Although they are line array speakers, Evolve 30M and 50M still cleverly apply the CD Horn principle thanks to the vertical waveguide design + DSP module. With a coverage angle of 120° horizontally and 40° vertically, these two lines still maintain even sound throughout the height - suitable for restaurants, garden cafes, and mobile events.

The impact of this technology on space design and installation

Using EV speakers with CD Horn not only brings quality sound, but also changes the way to design and construct smarter sound systems.

How to place speakers optimally to take advantage of CD technology

To maximize dispersion efficiency, you should: Place the speaker >30cm from the wall, facing the speaker directly at the main listener's position.

• Speaker height should be from 1,5–1,8m, or higher if the space is large.
• Avoid tilting the speaker too much, as dispersion is built in.

For example, ZLX15P has a dispersion of 90° x 60°, so only 1 pair is needed for a karaoke room of ~40–50m².

Reduce costs by requiring fewer speakers for even coverage

With even dispersion, engineers only need 2 medium-power speakers for a space of 50-70m², instead of having to add satellite speakers like when using other brands. This reduces investment costs by 20-30%, while minimizing phase errors, delays and feedback due to multiple sources.

Application of CD technology in performances, karaoke and halls

Electro‑Voice’s Constant Directivity (CD) technology is not only a step forward in acoustic design, but also demonstrates its real-world value in applications such as home karaoke, stage performances and large halls. Thanks to its consistent coverage angle control and linear response, it optimizes the listening experience in a wide range of usage scenarios.

Increase vocal efficiency, reduce howling - family karaoke

Electro‑Voice uses CD technology → to create a loudspeaker with a fixed direction of sound and a precise opening angle (SPO) → to control the sound area, reducing unwanted feedback from walls, ceilings and glass (O).

In a home karaoke environment, where users move around a lot and hold the microphone in an unstable position, CD technology ensures that vocals are always clear in every position. The 90° x 60° coverage angle helps distribute sound precisely, avoiding echoes that cause howling - an inherent disadvantage when using speakers that do not control sound direction well.

In addition, when combined with DSP with notch filter, EV also helps to accurately cut feedback-prone frequencies such as 2.5kHz or 4kHz. This is a big plus for karaoke systems under 30m², where just 1 pair of ZLX12P or ELX200-12P is enough to create a clear listening and singing experience, without fatigue and without howling.

Even sound coverage – large halls & stages

In large spaces such as 200–500m² halls, churches or performance stages, the sound must be uniform both horizontally and vertically so that audiences sitting in all positions can hear equally well.

Constant Directivity Technology maintains a consistent sound pressure level (SPL) from the center of the axis to the far corners, without distortion or loss of high-end range, which is where non-CD speakers often experience a “drop” in treble when moving away from the main axis.

EV deploys this technology on many performance speaker models such as EKX-15P or ETX-15P, with large CD horn + elliptical waveguide design.

This helps to expand the coverage angle to 90° horizontally and 60° vertically, suitable for placing speakers >2.5m high, covering the audience. Thanks to that, instead of needing 6-8 speakers spread evenly, the engineer only needs 2-4 full speakers + subwoofer for the entire stage. Construction efficiency increases, costs are reduced but the sound quality is still up to standard.

Frequently asked questions about Electro‑Voice Constant Directivity (CD) technology

Which EV speakers have this technology built in?

Lines like ZLX, ELX200, EKX, ETX all have CD horns. Column speakers like Evolve 50M also features a vertical waveguide design that simulates the horizontal dispersion of a CD horn. All are DSP-tuned by EV to take full advantage of this technology.

Does CD technology help reduce distortion?

Yes. CD horns disperse sound energy more evenly, so there are no “hotspots” or “drop-offs” at the listening angle. As a result, listeners in off-axis positions still receive clear sound, without distortion or loss of high frequencies.

Do I need to match a separate subwoofer with the CD horn speaker?

Depends on the purpose. CD horns primarily control mid-high frequencies. If you want deeper bass (below 80Hz) for stage or dance music, adding subwoofer as ELX200-18SP or ETX-18SP is extremely necessary.

Can CD horn technology be used for large-scale outdoor sound systems?

Yes. CD horn helps to precisely control the sound direction, avoiding unnecessary energy dispersion outside the audience area, thereby reducing howling and saving the number of speakers when deploying line array or cluster for outdoor stages.