I recently ticked one off my field recording bucket list and recorded an explosive-fuelled demolition. Four enormous cooling towers that have dominated the skyline of Rugeley, UK since the 1950s were demolished in just ten seconds. I stood at a healthy distance and captured the event with a small array of microphones.
In this post I’m going to talk about organising this kind of session, what I learnt, and most importantly, share the recordings! (Click here to jump straight to the recordings)
Idea
I’ve wanted to record a demolition since listening to the Tonebenders Podcast Implosion episode. Rene recommended setting keyword Google alerts for news articles containing words like “demolish” to find the events.
I actually never managed this, but instead discovered the Rugeley demolition by chance. I was travelling through the midlands when the four towers suddenly imposed on my train window view. Having watched HBO’s Chernobyl recently, (learn about the incredible sound design here) I googled it out of curiosity. I learnt that the decommissioned coal plant was set to be demolished in June. Discovering this felt like fate, and I knew I needed to plan a field recording trip.
Preparation
Good planning for a recording session is vital, especially when the sound you want to record is a non-recurring event.
The most important decision (before microphone choice) is location for me. How much unwanted noise are you likely to encounter? Is the location near a major road or rail lines? Is there housing or industrial activity? Are you under a flight path? How close are you to the source? Is the location safe / legal? Is there a giant music festival planned that weekend? These are all serious questions that need answering if you don’t want to be disappointed on the day.
For this trip, the signs were looking good. Because of the scale of the demolition, the nearby A-road was closed off. I predicted that the rail traffic would also be halted, and possibly even flights diverted. It was also planned for 11.15am on a Sunday morning, so less traffic and construction works.
On one side of the power station is the town, the other is fields and woodland, with a public footpath running parallel to the towers. I booked a bed and breakfast at a nearby farm, giving me time to scout a location the day before the demolition.
Equipment
For the microphones, I wanted to make a selection that would be varied but also incorporate some redundancy. I opted for the following mics:
| Make and Model | Polar Pattern | Reason for choice |
|---|---|---|
| Sennheiser MKH 8060 | Shotgun | For recording the detail and punch in mono with off-axis rejection |
| DPA 4060 | Stereo Pair in spaced A/B | Chosen for their exceptional bass response and to capture the atmospheric tail and reflections of the explosion |
| Rode NT4 | Cardioid XY Stereo | A catch-all mic; capturing detail and some ambience, but offering some rear rejection too. |
| Sony D100 | Cardioid XY Stereo | The Handheld backup recorder. Contains reliable, high quality onboard mics, similar to the NT4 |
| Lom Geofön | Geophone | Made for capturing seismic activity and adapted for field recording. |
I recorded the microphones using my Sound Devices Mixpre 6 Mark 1 and also a Mark 2 that I borrowed from IFATREEFALLS. The Mk2 is capable of 32bit float recording. In practice, this means almost infinite headroom for the mics. I could set the levels anywhere with confidence and know that there would be no digital distortion. This feature couldn’t be more suited to ultra-dynamic events like an explosion!
I recorded at a sample rate of 192kHz. Whilst this may be overkill, it allows for processing and time stretching the recordings as far as they will go without aliasing or introducing artefacts.
Scouting
Arriving the day before the demolition gave me time to walk the fields that I thought would be my best recording spot. The location turned out to be as good as hoped. Open, accessible countryside that banked down to an uninterrupted view of the power station, with no roads or houses in the vicinity.
My biggest concern was access to the footpath. Police had issued a warning that they would be evacuating some houses, blocking roads and actively discouraging viewing due to COVID-19 gathering concerns.
I decided to leave the D100 handheld recording at the farm as a backup, despite the surrounding farmyard and residential noises. I wanted a fail-safe recording for if I was turned away from the site.
The final step was to perform a full kit-check; confirming that all batteries are powered and memory cards inserted the night before the recording.
Setup
On the morning of the demolition, I set off in a cloud of unforecasted rain. I took a long route round, which I hoped would avoid any police roadblocks or questions. After a damp 90-minute trek through the fields, I arrived on the track.
As I reached my scouted spot, I heard voices and a dog barked at my approach. Concerned about meeting security, I diverted down a concealed path.
The rain was an issue, because I couldn’t set up in the field as planned without some shelter from the rain. I settled for a small plantation of trees further back, where I could hang a makeshift tarp. Under this, I set about connecting microphones and performing level checks.
From 10am the area grew busier. By 10.30 there were families arriving in the vicinity, photographers with long lenses trudged past and even the odd dirt bike rocked up. It became clear that I had overestimated the police warnings!
Thankfully nobody chose the same spot as me. I had set up somewhere with no clear view – a tip I learnt from The Tonebenders podcast. As the minutes counted down, the rain finally began to let up. This was great news, as damage from wet electronics aside, raindrops hitting the microphones and environment would affect the recording.
Detonation
With 15 minutes to go, I brought my microphones into the open and directed them towards the power station. I had my NT4 and MKH 8060 on tripods, and my spaced DPAs attached to a coat hanger, which I hung from the 8060’s blimp. (read about the technique here). I attached the geophone to a metal spike and planted it in the ground.
5 minutes to go and some air raid-style warning sirens sounded. A hushed expectation silenced the distant chatter of onlookers. This was pierced by the whine of 3 drones being launched into the air behind me. For a moment they hovered directly above my microphones, before mercifully flying off towards the towers.
11.15am came and went. I held my breath, transfixed on the towers. Suddenly the geophone channel on my recorder rocketed up. Sound travels faster through denser mediums.
I watched the first tower begin keeling and slipping towards the ground. There was just enough time to register this before the explosion ripped through the air, ringing out as the sound of crunching cement filtered through. The four towers collapsed downwards, sending smoke rings of dust skywards like steam train chimneys.
As the dust settled I shut off the recorders, packed up my gear and trudged off to collect my backup recorder before the train back to London.
Comparing The Recordings
Below are the unprocessed microphone recordings as MP3s. These recordings are bass-heavy and uncompressed. (Not recommended for listening through phone / laptop speakers.)
The best recording actually came from the backup handheld Sony D100! It was the only mic to capture the cracks from the explosives detonating. This was surprising, as the distance was similar to that of the other mics. However it was captured from the other side of the towers. Predictably the tail of the recording is disturbed by car alarms and dogs barking, as this side was residential. The background crackle is rain falling on power lines.
The DPAs delivered once again with an incredible representation of bass. The low-frequency response is full bodied and rich. The reverberation tail of the explosion sounds incredible to my ears as it rumbles across the fields. The only downside is that the recording sounds very indirect. All boom but very little detail of the falling towers to pick out.
The result of the 8060 recording is a little disappointing to me. Although better than the DPAs, I was hoping for even more detail and punch, similar to the D100. Shotguns don’t “zoom” on sounds and it should have been placed closer to the source. As a RF circuit mic, the 8060 is also the only mic that I would have trusted in the rain.
The NT4 again sounds too far away for the detail and not a wide enough pick to really capture the atmosphere of the explosion. The bass response lacks badly when compared to the DPAs and 8060, however it does capture more of the falling debris than the DPAs.
The Geophone’s subsonic capture, whilst impressive in nature, is not particularly exciting to listen to. A quick look at the spectrum shows just how much energy is present sub-bass levels. The next step is to try processing this by pitching it up!
Mixed Recording
Processing and time-aligning these recordings is a whole other subject to blog about another day. For now, I have mixed my two favourite recordings together. I de-noised and used volume automation and very gentle compression to keep the recordings raw and dynamic for this post.
Insights
Ultimately the session was successful. All mics captured the source. Thanks to good estimates and 32-bit float, nothing distorted. However there’s always room for improvement. I took away some lessons from this trip:
My biggest regret is not getting myself closer to the explosion. This was hampered by the rain and the risk of being turfed away by the police. Therefore my advice is this:
Prepare for the elements
As a Brit, this one should come naturally to me. Whilst I had a waterproof coat and rucksack, I had no real plan for setting up microphones in the rain. In the future I’ll be considering what lightweight solutions there are to this issue.
Don’t Underestimate your backup
Whilst I thought my backup D100 would be used as a last resort, it ended up capturing the best recording. This leads me on to my next point…
Record from multiple locations
Its still not clear to me why the D100 sounds so much closer than the other mics, but the fact is it does. With so many unknown variables, the logic in capturing from several locations has been made very clear to me.
Take a recording buddy
All of the above would have been easier if I had been with another sound recordist on the site. It would have allowed for one of us to risk venturing closer in the rain with the shotgun and geophone. Whilst none of my colleagues were available for this trip, I should have reached out to the field recording community, rather than go it alone.
Download the Recordings
You can download the raw 32-bit 192kHz recordings here for your own use. If you process them in a cool way, let me know so I can share them! If you’re feeling generous, you can buy me a coffee here. Thanks for reading!
Comments
Very interesting piece. Thanks for sharing. This kind of knowledge can only come from experience. The D100 mixed with the DPA4060 s sounds excellent !