Creating ‘Polarity’ – a fascinating SFX library with sounds of science, technology & electricity:

The trailer for Polarity

Hi Mattia, please introduce yourself:

Hello, my name is Mattia Cellotto, I am a sound designer/recordist based in the UK. My passion for recording sounds started with music, while my passion with games probably first sparked when I watched the movie “The Wizard” as a kid.

Coming from a very small town in Italy back in 2000, to think playing games or recording/designing sounds would lead to stable career seemed madness to most parents, but thanks to a good sound design course, perseverance and a bit of luck, now I get to do both things I always loved.
 

How did you come up with the idea for Polarity? You’ve also captured some unique machines and devices for this library – can you highlight some of those?

I normally try and find myself something to do during holidays to flex the recordist muscles and get the dust off my Zaxcom recorder. Last year, back in November, I got in touch with an electricity museum in Italy, we arranged for me to visit it near the Christmas holidays, when it would have been closed to the public. We sorted out all concerns prior my visit, from AC to equipment list, so everything went down quite smoothly, but I couldn’t get as close as I wanted to the big machines like Jacob’s ladders and such.

After Christmas I decided to expand on the recorded material, I bought an insurance for my equipment and collected contacts to help me gather the best electrical sounds at the closest distance.

I must have heard the phrase “you can get closer, but it’s your equipment” about ten times within a week from different people

I must have heard the phrase “you can get closer, but it’s your equipment” about ten times within a week from different people, but when you focus on recording ultrasonic content proximity is too important, placing a Sanken CO-100K too far from the source means only using half of the mic. The collection of contacts turned into a month full of travelling during which I met some awesome professionals. I first drove to the Victorian Science Museum in North Yorkshire, a long trip but definitely worth it: the owner, Tony, is a truly inspiring person. Then I visited the UK’s largest high voltage test lab, a great electrician/youtuber’s lab and a science laboratory where my girlfriend works.
 

What was your recording setup?

For this library I used a Zaxcom Maxx and a Sony D100 as recorders. While I always used the same set of 4 microphones with the Maxx (2 x MKH8040, the CO-100K and a KMR81i), I alternated the use of the D100’s built-in mics with an Elektrosluch electromagnetic “pickup” from LOM. While the Maxx would allow me to record endless top end, the Elektrosluch would pick up lower frequencies which were not audible with the other mics.

You’ve got some pretty wild spark sounds in there – how did you capture those?

The wildest sounding material is a good blend of all of the mics mentioned above, where the truly unique ingredient is often added by the Elektrosluch. All these microphones are great but picked alone they do have weaknesses, here are some examples.
Here is the recording of what I describe as an “electric wand” where we only hear what the CO-100K captured:

You can hear how the CO-100K is a bit high frequency biased, it doesn’t have great sounding mids and the very deep low end is pretty quite weak.
Here is the same recording picked up by the pair of MKH8040, responsible for the stereo image of the file:

The 8040s behave in a similar manner, they add something to the low-mids but in a way that does not support the central image of the Sanken, so now our sound is still lacking some low mids richness and has lost its center focus.
To bring back the focus we add the MKR 81i’s perspective:

You can hear it right away, the KMR is nowhere near as harsh as the other mics and that’s why I bought it to record this library. In some form this mic seems to ignore the harshness the overwhelms both 8040s and the CO-1OOK to bring a sound that feels balanced and rich, but not quite powerful enough.
In reality this mic brings us the least reliable representation of the sound, which was truly as harsh as the CO-100K makes it.
One thing that we notice about all these recordings is the lack of proper proximity effect: because we are recording an electric arc we can only get so close before the equipment gets fried or suffers from too much interference.
Luckily the Elektrosluch 3+ is picking up exactly what we were missing:

Now we can really crank the harshness of the first two mics knowing that our signal will remain balanced as we have total control over mids and lows separately.
So the final asset is a mixture of all of these recordings where I made use of the best parts of the spectrum for each mic. Because all mics brought something different to the table, the result is a round yet aggressive sound:

Any surprises during the recording process? And what are some of your favorite sounds in the library?

I think the biggest surprise was when I first played back my recordings at 1/4 speed. Here is the same “electric wand” sound we just listened to played back at ¼ speed:

Most of the recordings, especially the Jacob’s ladders, preserved quality very well, but became something completely different.
You’d notice that up until ½ or 1/3 speed the classic 50Hz tonal element would simply shift lower and lower, but at ¼ speed it becomes subsonic, what is left is a very organic, transient-ful sound.

My favourite sounds in the library are the 1928s tram which has some nice, wellrounded pulley feel, and the “electric wand”, mostly because I got to control it myself while recording, amazing experience.

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