Have you ever wondered how condenser microphones are made? At the end of September I was fortunate enough to be invited to visit the Soyuz Microphones factory which is situated just outside the city of Tula about 2 hours drive south of the Russian capital Moscow. What you are going to see in the next two videos is the process of turning stock Brass, Steel and Aluminium into a finished Soyuz SU-017 microphone.
Part 1 - Heavy Lifting
In this first of two videos we are going to see how the raw material is turned into the constituent parts of a microphone.
First the stock material is cut to size. We see a solid brass rod being cut to size on a mechanical band saw. Both the speed of the blade and the cut pressure are controlled by an engineer to make sure the brass is cut evenly as brass does not like to be worked too fast.
Next the pieces are shaped and turned to form the parts of the microphone body and capsule.
In the video we see an engineer turning the brass on a lathe to form the hemispheres that make up the two ends of the body of the mic. This is not as easy as it look as I found out when they let me have a go. I’m told the trick is to keep an even pressure and speed on the cutting head, but I think I need a lot more practice.
We then see one of the engineers turning a slightly smaller piece of stock into the rough blanks for the capsule rings. He first cuts deep grooves into the brass even distances apart, then changes the chuck and bit to drill out, or ream the centre of the brass to form the rings.
Next we see the capsule backplates being drilled. Each of the capsules in the Soyuz range of mics has a different hole configuration specific to it’s design. The raw backplate is first clamped into a case-hardened steel template and the holes are slowly and carefully drilled. The drill bit is lubricated with fat. In this case the fat is actually Parmesan cheese. Not left over from someone’s lunch I am assured.
It is not only the mics themselves that are built on site but also the custom designed shock-mounts. Here we see one of the engineers using a milling machine to cut a groove into an already worked piece of Brass which will form the mounting section of the shock-mount.
Up until now the tolerances for the work have been very tight but it reaches an entirely new level at the next station. The lathe that is being used to turn the, now drilled backplates down to the correct thickness originally came from the Kalashnikov factory and at some point would have been used to make weapons. This military specification lathe, in the hands of a skilled craftsman can achieve a finish of around 1 or 2 microns. Perfect for making sure the all important capsule backplates are as smooth as possible.
Next, the parts of the mic that are required to have a finish put on them make there way to the spray booth. In this area a powder coat is applied with a spray gun. And once again I got the chance to get my hands dirty. The coated parts are then placed into an oven and cooked to cure the powder to the metal.
In the next video you will see how these component parts are finished and brought together to form the finished, tested and checked Soyuz SU-017 microphone.