The AC Infinity Inline Duct Fan Silencer 4″ (100 mm) is a galvanised-steel muffler that drops into a 100 mm duct run and takes up to 50% of the fan noise out of it. Inside is neoprene foam in an egg-crate profile: the peaks and valleys break up sound waves travelling down the duct while leaving the bore clear, so airflow passes through and the noise does not. Reversible stainless flanges slide over the fan collar at either end, which means it works the same on intake or exhaust.
Where the noise actually goes
A running inline fan makes noise three ways: the motor and blade themselves, vibration carried through the duct into the structure around it, and turbulence where air hits a bend or a rough joint. A silencer targets the first of those — the airborne sound travelling along the inside of the duct. The egg-crate foam gives that sound a soft, uneven surface to hit instead of a hard steel wall, so it loses energy rather than bouncing along the run and out the far end.
The galvanised steel shell does two jobs at once: it contains the foam and resists corrosion in a room that runs warm and humid for months. The stainless flanges are reversible, so you can face them in or out depending on whether you are sliding the silencer over a fan collar or into a length of ducting.
Fitting it into the run
The silencer takes 100 mm duct at both ends and sits anywhere in the chain. The usual position is directly on the fan outlet, because that is where the sound is loudest and where you get the most out of it. A second common position is at the point where the duct leaves the room, which stops noise escaping to the outside or to a neighbouring space.
What it works with
Anything running 100 mm duct: CLOUDLINE T4, S4, A4 and other 100 mm inline fans, and the same size carbon filters, dampers and ducting. Beyond the grow room it is equally at home on bathroom extraction, AV and server-cupboard cooling, or any HVAC run where the fan is audible from a room you would rather keep quiet.
Full specifications
| Manufacturer | AC Infinity Inc. |
| Product / model | Duct Fan Silencer 4″ / AC-DSA4 |
| UPC | 819137021051 |
| Duct opening size | 4″ (100 mm), both ends |
| Total dimensions | 14.96 × 6.97 in. (38.0 × 17.7 cm) |
| Flange length | 3.8 cm (1.50 in.) |
| Flange material | Stainless steel, reversible |
| Shell material | Galvanised steel |
| Foam material | Neoprene, egg-crate profile |
| Noise reduction | Up to 50% |
| Weight | 1.04 kg (2.30 lb) |
FAQ
Will it reduce my airflow?
The bore stays the full duct diameter through the silencer, so the restriction is small — far smaller than the bends and the filter already in the run. In practice most growers notice the drop in noise and not the drop in flow. If your setup is already at the limit of the fan, run the speed up a step to compensate.
Which end goes on the fan?
Either. The flanges are reversible and identical, so orientation is up to whatever makes the run tidier. It works the same on intake and exhaust.
Can I fit it in the middle of the ducting rather than on the fan?
Yes. Cut the run, slide a length of flexible ducting onto each flange and clamp both ends. Mounting on the fan outlet usually gives the biggest improvement, but mid-run works well when space around the fan is tight.
Do I need anything else to install it?
Two clamps per joint. Stainless duct clamps do the job, and the AC Infinity ducting packs include a pair. A wrap of foil ducting tape over each joint seals the last of the leaks.
How much quieter will it actually be?
AC Infinity rate it at up to 50% noise reduction. How much you hear depends on the rest of the setup — a fan mounted hard against a tent pole with sharp duct bends has other noise paths the silencer cannot touch. Pair it with a rubber noise reduction clamp and smooth duct runs and the result is a setup you can sit next to.
Is this genuine AC Infinity stock with Australian warranty?
Yes. Quick Bloom Lights is the official Australian importer and distributor for AC Infinity. Stock is held in Sydney, orders ship domestically, and warranty is handled here rather than through an overseas seller.