Why a single-sided magnet array is superior for bass ribbons

A bass ribbon moves a lot of air. To keep it clean and linear at low frequencies, the magnetic field has to hold the ribbon evenly across its entire excursion — and the air around the ribbon has to be free to move with it. Some other panel and ribbon speaker manufacturers use a push-pull magnet arrangement for their bass sections, with magnet rows on both sides of the diaphragm. Clarisys places the magnets behind the bass ribbon only — the front of the ribbon is completely open. Here is why that matters.

What push-pull means

In a push-pull (or double-sided) magnet array, rows of magnets are placed on both the front and the back of the ribbon, with alternating polarity so the field grips the diaphragm from both sides. The intent is a more symmetric magnetic field through the gap, which in theory reduces even-order harmonic distortion at large excursions. It is a legitimate idea — for mid-range and treble. In the bass it creates serious problems.

1. It encloses the ribbon in a sealed cavity

With magnet rows on both sides, the ribbon sits inside a narrow slot bounded by magnets on the front and magnets on the back. The air around the diaphragm is trapped in that enclosed cavity — it cannot escape freely in either direction because magnet bars block both faces. The ribbon is, in effect, suspended in a closed box of its own making. (Yes, Clarisys also has magnets behind the ribbon, so the back wave there passes through a magnet array too — but the front of our ribbon is open, so there is no enclosed cavity and no trapped air on the listening side. The difference is not whether the back wave sees magnets; it is whether the ribbon is sealed inside a cavity.)

2. The trapped air becomes an air spring

At bass frequencies, where excursions are large and wavelengths are long, the air trapped in that enclosed cavity does not behave as open space — it behaves as a spring. The cavity forms an acoustic stiffness that resists the ribbon's motion. The harder the ribbon pushes, the harder the trapped air pushes back. This is the back pressure: a non-linear loading that rises with excursion and fights the diaphragm at exactly the moments it is working hardest. Because the cavity is closed on both sides in a push-pull array, that air spring acts on both faces of the ribbon.

3. That loading deforms the ribbon

Because the magnet rows and cavities are not uniform across the ribbon's height — the bar spacing, the cavity depth, and the local field strength all vary — the back pressure is not uniform either. The ribbon does not move as a single, even plane. Different regions of the diaphragm see different loading, so the ribbon deforms unevenly. That uneven deformation is distortion: the diaphragm is no longer the piston the magnetic field was designed to drive, and the waveform it launches into the room is no longer the waveform the amplifier sent. The error is literally on the panel — the ribbon is being bent out of shape by the air trapped around it.

Why magnets behind the ribbon are better for bass

On a Clarisys bass ribbon the magnets sit behind the panel only; the front of the ribbon faces the listener with nothing in front of it at all. The front wave — the wave the listener hears — radiates into completely open space. There is no front cavity, no trapped air on the listening side, no air spring fighting the diaphragm from the front. The back wave does pass through the rear magnet array, but because there is no second row of magnets in front to close off a cavity, the air is not sealed against the ribbon — it can move through and around the rear magnets rather than being trapped in a slot. The ribbon sees a uniform acoustic load and can move as a single plane across its whole excursion.

Super magnets, true dipole

The reason other manufacturers reach for push-pull in the bass is that a single-sided array needs a very strong magnet to hold the field linear through large excursions from one side only. Weaker magnets cannot do that, so the second row is added to compensate. Clarisys does not need the second row. We use the highest-grade N52 neodymium available — (BH)max ≈ 50–52 MGOe — to generate a gap field strong enough from the rear alone to keep the ribbon perfectly linear across its full excursion. With that magnetic problem solved by magnet grade rather than by a second magnet row, there is no reason to seal the ribbon inside a cavity. The bass ribbon stays as close to a pure dipole as possible: open to the front, magnets behind, free to breathe on both sides. That is the whole point of a ribbon bass — and push-pull compromises it.