How closely does the panel layout have to be followed?

Not to the millimetre, but the relative positions matter, and a tidier-looking arrangement performs worse. Set out from the drawing rather than by eye. If something has to shift, shift the whole run rather than one panel. And do not substitute your own arrangement, however reasonable it looks. The layout is computed for your room, and the spacing between panels is doing the work, so the pattern has to survive the install.

The old guidance said the layout tolerated being approximate. It does not any more, and the reason is that the layout got better.

The layout is where the low-frequency reach comes from

This is the part worth understanding, because it explains why the layout is not decoration and not coverage.

One thing has to be clear before the comparison, because it is easy to hear as a claim we are not making: what follows compares reach against depth, and nothing else. Two different devices are doing two different jobs; the only quantity they can be lined up on is how low each one works for how much build-out it costs. We are not claiming to diffuse better: this is not a mathematical diffusor and does not try to be.

A conventional phase-based diffuser scatters by making sound take different path lengths down wells of different depths. Its reach and its depth sit on the same axis: to scatter an octave lower, the wells have to be twice as deep. Wells 50 mm deep reach down to around 1.7 kHz. To reach down around 143 Hz you would need wells about 600 mm deep, which is why devices that work low are deep enough to cost you the room.

This system reaches by spatial scale instead, and pays in surface area rather than in depth. The break-up happens between panels as much as at them, and the lowest frequency the array works to is set by the largest spatial scale in its pattern. That is the whole reason a shallow panel can do this job at all, and it is why the reach belongs to the layout rather than to the panel.

Which is exactly why the arrangement is what it is. A regular pattern's largest scale is one repeat of its period. An irregular one's largest scale is the extent of the whole patch, so it has something much longer to reach down with. Same panels, different arrangement, and the bottom of the working band moves by about an octave.

Three consequences follow, and they are the practical ones.

Leaving part of an array out is not a proportional loss. It shortens the largest scale in the pattern, so it raises the bottom of the band. Nothing about the panel has changed; the array no longer contains the scale it was reaching with.

A tighter cluster reaches less low than a spread one, for the same reason and with the same quantity of panels. Coverage and reach are not the same thing.

And it is why moving one panel is not a small change. You have not moved a panel: you have changed the pattern around it. Shifting a whole run moves the array while keeping its scales intact; moving one panel out of a group breaks the relationships that group was carrying.

Why the arrangement looks odd, and has to

A neat grid or a clean checkerboard concentrates its scattered energy at one scale, and that scale is the grid's own short repeat, which leaves it nothing to reach down with. The layout you are given is deliberately irregular so that it carries many scales at once, including the patch-wide ones that buy the low end. A tidier layout is a more regular one, and regularity is the thing the design is avoiding.

Three rules on site

1. Set out from the drawing, not by eye and not from the last panel you fixed.
2. If something has to shift, shift the run. Move the group together and the pattern survives; move one panel out of a group and it does not.
3. Do not substitute an arrangement. If the layout cannot be built as drawn, that is a coordination item to raise, not a judgement to make on the wall.

And one exception that runs the other way: the resonance panels go in the corners, and that is not negotiable at all. Corner loading is the entire mechanism: a resonance panel moved out of a corner is not a weaker resonance panel, it is close to not being one.

Why this is good news

The old story sold ease: install approximately, get the result. It was quietly arguing that the design was not worth paying for. The truth is better: the pattern is doing work no eye can reproduce, and following it is what buys the result. That is exactly why it is designed rather than estimated.

What to read next

The design service: one room, specified from your drawings, loudspeaker layout and seating. Or the Reflection Control Panel.