I had the opportunity to get my hands on this “old” german siren, ( I’m not sure how old it is exactly by the way, if someone knows please let me know in the comment section). Anyway, it looked cool and I knew I wanted to record it but I didn’t know if it was still in working condition.
I asked a friend to help me, we jumped into the car and drove to a quiet and isolated place so we could try to make it scream without attracting too much attention as we were convinced it would be super duper loud and that an old school german siren in 2019 Belgium would seem … at least strange or even alarming aha…
The instructions on the siren metal plate said ” 12V ” so … with earplugs in place, we grabbed a pair of car jumper cables and connected it on my car battery.
The result was … quite surprising, to say the least, it sounded like a small chainsaw mixed with a sporadic duck quack :
Martin Horn – 1st try :
After a good laugh, we decided to have a look under the hood and use our tremendous knowledge of old german siren to see if something looked odd or broken inside.
Without fully disassembling the thing, which wasn’t planned anyway, we saw what appears to be 2 magnets mounted symetrically on both sides of a coil. My genious friend noticed that one of them missed a spring and a metal part that seemed to apply pressure on this very magnet.
We tried again, but this time one of us manually pushed the magnet down to bring it closer to the coil…. and VOILA :
Martin Horn – success
It was already a bit louder ( even though not crazy loud as we thought ) but more importantly the tones and pattern felt right. You can hear that the beautiful chainsaw sound is still there but I guess it’s part of the charm of this oldie.
We then recorded it properly, 2 times ” broken ” and 2 times ” working ” , each time close and distant and … that was it, there was not much more we could do with it, and I was not really prepared to tape it onto the car and record dopplers ahah.
Back to the studio I edited/cleaned/metadata’ed it and decided to keep 2 versions of the siren sound (because you never know) : with and without ” the chainsaw “.
So I dropped it into iZotope RX and removed as much of the buzzing thing as I could without damaging the tones of the horns. I’m pretty happy with the result, what helped me is that the “unwanted” sound was more or less “noise” ( in RX lingo ) and what I wanted to keep untouched was “tonal” . So using a touch of spectral denoise and a pinch of spectral repair I managed to attenuate the chainsaw thing to a great extent.
Here are the before/after examples along with their spectrograms :
Martin Horn – original audio
Martin Horn – RXed audio (close)
Martin Horn – RXed audio (distant)