Do you remember the last time you skinned a knee? Or an elbow? Second to last time for me was when I was like 10 years old or something… But the last time was last friday, push starting a shifter kart. Moral of the story: nothing beats reality for rapidly evolving your technique, which is why it is VERY important to recognise the day you are no longer a student, studying technique… because reality doesn’t have time for theory – it’s too busy being real!
The thing with shifter karts is that are they low to the ground & when they are cold they take a bit of starting… so here am I, with the onboard mics rigged & the onboard recorder doing its thing, and my external mic on a little stand with my 722 recording me push starting the kart…. Push push… push… the engine fires & the little object I was totally leaning on just shot out from under me & is 200m down the straight by the time my knee impacts the road, and my elbow joins in, sending a form of pain I haven’t experienced in years directly to my brain… But all I could think of was getting back to the 722 and getting the cans on, ready to record the first passby…. Three more laps & I am starting to feel it….
But that wasn’t all that reality had to teach me that day – lesson two was that you can’t always trust your headphones. Heres the backstory: I knew rigging onboard mics wasn’t going to be easy and I spent maybe half an hour putting an AKG D112 and another AKG dynamic mic in close proximity to the exhaust, gaffer taped to the seat support struts. After half a dozen laps I wave the driver in and rewind the onboard recorder & hit play…. hmmmm… first problem = no signal on channel 2, I have a moment of deja vu from when I physically lost a mic off Burt Munros V Twin Indian while recording onboard FX for Worlds Fastest Indian, but no – both mics are still firmly attached. Trace the cable from the recorder & ahar! Its a ‘technical air gap’ – the cable had worked itself loose from the mic & has been dragging on the ground for the last bunch of laps… I marvel at its new shiny appearance, plug it back in, tap the mic – affirmative, and then gaffer tape the cable to the mic, which I should have done in the first place…. Now problem 2 – the recording is distorted as all hell. I can see it in the meters without even plugging in my headphones, its like the worst brickwall limiter you ever saw. So I switch on the -20dB pad, turn up the gain a little and set the recorder going again.
Push start number 2 goes much better – my grazed knee taught me to not be still pushing the kart when he drops the clutch (once bitten, twice shy) – get it up to speed, give a big final push & recover balance…. Off he roars… Ten more laps & I flag him in again… Rewind the onboard recorder a bit, press play – hmmm there’s better movement in the meters but it still sounds overloaded to me through my headphones… I decide to shift one of the mics away from the exhaust incase its the maximum SPL that’s the issue, so I gaffer tape one of the mics to the front of the radiator….
Push start number 3 I don’t even have to think about & for the next half hour we record every move possible, with me running around the course so I get multiple coverage of every corner, especially 120kmph passbys on the straight, the big sweeping corner which he is sideways for most of, and the tight chicane where I recorded the best tyre shrieks. I stop him a couple more times to check the onboard recorder & swap batteries but I know there isn’t a lot more I can do – through headphones the onboard mics still sound overloaded…
By the time we finish the poor guy is exhausted – he explains he has done 86 laps, whereas on a normal race day there would be three heats of 10 laps… As a final effort to ease my paranoia about the onboard recording we put the kart on its stand, start it up & step it through its gears, although its not on a dyno and under load I am just interested to see how my Sanken CSS5 mic & 722 compare to the onboard mics…. and in the process I realise just how loud that 250cc motor is – it screams, relentlessly!
We pack up & I head back to the hotel & transfer all the recordings to my laptop & listen through my Sony headphones & think hmmmm those onboard mics still sound overloaded, but the overloading sounds really low frequency…. Now the D112 is made for low frequencys so I start to wonder if the issue isn’t with the mic or the recorder but with my headphones… So first I add a HPF plugin: ahar! the mids & highs don’t sound distorted… Now I also brought my Sennheiser open air HD545 headphones with me, so I plug them in and experience an even bigger AHAR! Those lows don’t sound so distorted – they just sound heavy as all hell!!! There is hope!
This morning I make the 5 hour drive back to work and the first thing I do is plug my drive into my ProTools system & hit play – Ahhhhh there is a ton of low end & its making my subwoofer work overtime but a gentle filter reigns it in… In hindsight this makes sense – I’ve talked to a few people who race shifter karts and they all comment about the huge G Forces and the vibrations; shifter karts have no suspension and the power to weight ratio is HUGE! So of course a LOT of low end energy is transmitted to the driver (which is why he was so tired) but that low frequency energy also goes into my mics… Under these circumstance no headphones will tell you the truth!
One of the best aspects of going out recording is learning about the physics and techniques of the objects you are recording, and I showed Seth, the shifter kart driver, some of the footage from the scenes in the film and we talked through what gears he would be in etc… I quizzed him about engine braking and he put me right – there isn’t time to engine brake, at the end of the straight he will be flat out in 5th or 6th gear and then he will drop it down to 3rd in the process of braking, ready to power through the corner – it tends to be full on or full off! These aren’t things you learn in a book, but they are crucial to realistically cutting these sounds… He also commented about point of view: gear changes sound very different from inside your helmet. And I’ve thought about that ever since…. Depending how the cutting goes I have started planning one last shifter kart record mission, and this time I want to record multi-track onboard. I definitely want to put mics inside his helmet, so we can capture what the driver is hearing…. but THAT really illustrates interesting issues of remotely setting gain, as those mics will be relatively quiet, especially compared to the mics that are pointed at that screaming exhaust… Ah such fun challenges!
