Antminer soundproofing (again) - gypsum+MLV

[Oschoir]

I know this is a well covered topic, so I'll keep my question precise.

I have three Z9 Minis and want to quieten them down as much as possible (I understand the effect will be limited).
I will build a single plywood box lined with a double layer of soundproof plasterboard.
I will make cut large rectangle vents in the ends of the box and form angled ducting using the same construction method (ply box section with double gypsum lining). The angle is an attempt to deaden the noise from the vent holes.

Q) How much improvement can I expect to achieve with an additional internal layer of mass loaded vinyl in the box and rigid ducting?

Thanks for any qualitative (or even quantitative) responses.

[ShyvHX]

Z9 minis don't use too much power.
You should be fine with two 120mm high quality case fans and put one on each side of the antminer.
You also need a device that makes the antminer think it has its delta fan connected, otherwise it won't start hashing.
I don't recall the name of the device but I remember seeing it advertised in some immersion cooling reddit.

[ricecooker]

Alot of the noise will come from the fans intake / exhaust points. Insulated ducting or those silencing ducting on both ends will significantly reduce noise level.