Building A Sound Proof Server Cabinet - Mechanical Construction

During the Christmas of 2018, I finally acquired a rack server to go in the lab. The purpose of this was to facilitate software projects and to acts as a general purpose PC for the lab (before I was just using my laptop). Despite the server doing everything I wanted to and more, it had one major drawback...

Enterprise grade hardware is always located in separate server rooms so they are designed without having to worry about noise level. To say the server fans are noisy is a grave understatement.

Without diving into the details, I tried a few different methods to quiet them down from software fan control to physically replacing the fans, but nothing I did worked. Instead I decided to design and build a custom server cabinet. The cabinet would not only be covered with soundproofing material, but it would also store the server properly (for the past year it just sat on the work surface) and provide rack space for more server hardware down the line.

I started by drawing up a design, looking at what wood I had, the size of the server and the size of the space I wanted the cabinet to go. I also did a fair bit of research and worked out the most practical way to sound proof the cabinet was to layer it with mass loaded vinyl. The design process was tricky, the cabinet had to keep all the sound inside while still letting plenty of cool air in and hot air out to stop the equipment from overheating. My design achieves this by taking in air through filters at the bottom back of the cabinet (tucked in the corner to reduce noise), pull it through an air corridor at the bottom, have it sucked up through the front of the servers where it will finally exit them and vent out the top back (also tucked in the corner to reduce noise).

I started construction during the summer of 2019, after I purchased my new belt sander. The first task was cutting and prepping the supporting wooden beams.

The main component that will make it a server cabinet and not simply a wooden box with a server in it was the front and back server server strip rails. You will find these rails in all server cabinets as they provide a common mounting point for all server cabinet hardware. Once those were screwed to the wood and spaced correctly, theoretically any server rack hardware should be compatible to mount in my cabinet.

I then started assembling the frame of the cabinet.

I then mounted a network switch to the strip rails, and used this to ensure the whole structure was spaced correctly before screwing it all together.

Time for the side panels. Unfortunately, none of my second hand recycled wood would do. I instead bought a huge new piece of MDF, which I still have a lot left over for other projects.

To make the cabinet mobile, castors were added to the bottom. This will allow the cabinet to be rolled out for hardware maintenance and upgrade with relative ease.

The next task was to make it sound proof. I cut a the big roll of mass loaded vinyl into sheets and screwed + glued them onto the inside of each side panel, floor and roof of the cabinet.

You can see in the last image that the sides of the bottom are raised up with wooden beams. When a flat piece of hardboard is placed across the top, it forms an air corridor with the inlet to the cabinet being at the bottom back causing the air to be delivered to the bottom front where the server intake fans are. This can be seen in the following images; the air exhaust holes can also be viewed at the back top of the cabinet. 

Filters were made using plastic tubs with screw on lids. Holes were cut in the lids and nylon fabric stretched over them to create a dust filters that can be replaced by unscrewing them.

Blank spacers were made to fill in the remaining rack slots such that the hot air from the back of the servers didn't mix with the cool air entering the front. These blanks will be removed as more hardware is added to the cabinet.

The back door was made using a simple wooden frame and an MDF panel. The front door utilized two layers of Perspex sheets such that the inside of the cabinet could be viewed but sound insulation was still maintained. Originally the doors stayed in place via a friction fit using protruding bolts. But this wasn't enough to create a good seal, so I instead embedded nuts into the cabinet frame, and essentially turned the bolts into large thumb screws that allowed the door to be screwed shut by hand.

After testing the server in the cabinet with the doors shut, I was confident that the noise was substantially reduced. The only problem was that heat built up faster than expected, which in turn caused the server to increase its fan speed leading to more noise. It was clear that I needed to increase air flow, so I repurposed the air outlets (white plactic tubs) as cable pass throughs, and cut out 3 new outlets holes behind them where I attached 3 PSU fans. Since these fans are quiet anyway, they enable heat to be vented faster without adding much noise.

It was at this point that construction stopped for 2019 (for various reasons). It would be the summer of 2020 before I resumed work on this. The next post will detail the cabling and networking side of the project.