Single-driver loudspeakers in the room: walls, toe-in, height and distance

A single-driver loudspeaker plays the whole range from one cone, with no crossover dividing it between drivers. That changes how it should be placed: the axis of one driver carries all of the treble, the type of cabinet decides how much space it needs behind it, and its modest bass depends on the walls more than a large multi-way design does. This guide covers distance from the walls, toe-in, height and listening distance for full-range loudspeakers, with the facts about our single-driver model, Perseus MkII. Why one driver is used at all, and how it compares with a multi-way design, is explained in our guide to single-driver and multi-way loudspeakers.

What changes with one driver

• The treble narrows on one axis. A cone spreads sound widely while the wavelength is large compared with its diameter. As the frequency rises and the wavelength becomes comparable to the cone, the sound concentrates in front of it, a behaviour called beaming. A multi-way loudspeaker hands the treble to a small tweeter; a full-range driver plays it from the large cone, so the top octave depends more on where you sit relative to its axis.
• The sound comes from one point. With no crossover, there is no distance at which separate drivers have to blend, so a single-driver loudspeaker can be heard from closer than many multi-way designs.
• The bass is modest. One cone is a compromise between treble and bass, and the walls and the cabinet type decide much of what reaches the seat in the lowest octaves.

The cabinet decides the distance from the wall behind

Our full-range models are built with the cabinet type chosen for your room before the build. The type sets how close to the wall behind the loudspeaker can stand:

Whatever the cabinet, the wall behind and the side walls add bass as the loudspeaker moves closer, and the bass becomes less even. Avoid equal distances to the wall behind and to the side wall, because their effects then add up at the same frequencies. Our article on getting the most from your loudspeakers gives the general method: move in steps of a few centimetres and listen to a familiar recording with a steady bass line.

Toe-in and the listening axis

Because the treble of a full-range driver concentrates on its axis, toe-in has a larger effect than with a tweeter:

• Start with each loudspeaker pointing straight at the listening seat, so that you sit on both axes.
• If the treble seems too strong, turn the loudspeakers outwards a few degrees at a time, so that the axes cross behind you; if it seems too weak, point them straight at you or let the axes cross just in front of you.
• Match both sides precisely. A laser or a straight edge on the cabinet top makes small changes repeatable.

Height and tilt

With one driver, the listening axis is the axis of that driver. Note the height of the driver’s centre on your cabinet and compare it with your ear height when seated, which is usually around 1 m. If the driver sits well above or below your ears, a small tilt of the cabinet, backwards or forwards, brings its axis towards you. Floorstanders must stand level and firm, on spikes or feet suited to the floor; a rocking cabinet loses the alignment you have set.

Listening distance and level

A single driver can be heard at a shorter distance, and the shorter the distance, the louder it plays: leaving out the room’s reflections, the direct sound falls by about 6 dB each time the distance doubles. High sensitivity is what lets a full-range loudspeaker work with a low-power amplifier at a normal listening distance. Our guide to loudspeakers for single-ended amplifiers works out the level at the seat from sensitivity, power and distance, with a table for 2 to 30 W.

Perseus MkII: facts for placement

• Perseus MkII: Supravox 215-EXC field-coil full-range drivers, 93–102 dB (1 W / 1 m), 6 Ω / 8 Ω. The cabinet measures 500 × 400 × 1300 mm and weighs from 50 kg per loudspeaker. The enclosure can be aperiodic, open baffle, sealed, transmission line or bass reflex. The field coils are energised through a separate mains supply, built for 100, 120 or 230 V.
• Perseus MkII can be built as a three-way system as well; this guide is about its single-driver form.

For the lowest octave, the Zeus subwoofer, passive or active (with a Class A or Class D amplifier to order), has a 15-inch field-coil woofer covering 10–300 Hz, accepts RCA or speaker-level inputs and is built for 100, 120 or 230 V mains.

A setup sequence

1. Set the triangle. Loudspeakers and seat at roughly the corners of an equilateral triangle, with the seat away from the wall behind you.
2. Set the distance from the wall behind for your cabinet type, then adjust in steps of a few centimetres for even bass.
3. Aim the axes at the seat, then adjust the toe-in a few degrees at a time.
4. Check the height of the driver against your ears, and tilt if needed.
5. Fix the position. Level the cabinets, mark the floor, and change one thing at a time.

Questions

Can a single-driver loudspeaker stand close to the wall?

It depends on the cabinet. A sealed or aperiodic cabinet tolerates a wall closer behind it than an open baffle, which needs the most space. Tell us the distance you have when you order, and the cabinet type can be chosen for it.

Do single-driver loudspeakers need a subwoofer?

Not necessarily. Whether the bass is enough depends on the room, the placement and the music. A subwoofer is an option if you want the lowest octave at higher levels.

How much toe-in is right?

There is no fixed angle. Start with the axes pointing at the seat and adjust a few degrees at a time; with a full-range driver small changes are easy to hear in the treble.

Write to us by e-mail or WhatsApp with the size of your room, a sketch of where the loudspeakers and the seat can go, and your amplifier, and we will suggest the cabinet type and the placement.