Recording Car Exhaust - Clipping and Gaps

[psyborg]

Hello All!

I am hoping for some advice for recording exhaust audio from a car; I'm hoping this is the correct form for this advice.

For this mobile recording I was hoping to use some digital device and a wired mic. I have two TRS microphones, a Rode VideoMicro and a generic clip on mic, both with nice foam windscreens. I purchased a USB-C to TRS adapter to hopefully use one of these mics to record. I know this is far from professional and really not ideal, but all I need is a clear recording of acceleration.

I had hoped that using a phone to record would be good enough; I found that my device can do 48Hz/192Kbps and tried using several apps that offer WAV recording, however I am running into a strange issue. Instead of just clipping the audio it seems that the recording will simply go to zero instead and record absolutely nothing.

I am trying to figure out if this is because the mic is underpowered, if the USB-C dongle is doing some kind of pre-processing or if the phone is doing something strange.

Aside from that issue I'm trying to figure out the *best* way to record this. Should I buy a small digital recorder and try using the mic? Is there one with an adjustable preamp or gain reduction? What would be the best way to record this 'on the go' as it is?

Any help greatly appreciated.

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Edit for clarity: The recording will continue when (I assume) clipping is not present. For example I will get the initial exhaust drone, but when it peaks the audio will go to 0db and remain until it drops beneath the clipping range again. So it seems that instead of clipping the audio it simply drops it to 0 until it no longer clips.

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Hardware:
Samsung Galaxy S21
Rode VideoMicro (https://rode.com/en/microphones/on-camera/videomicro#module_7)
BOYA K4 Female 3.5mm TRS Microphone Adapter Cable to USB Type-C Connector Dongle (https://www.amazon.ca/gp/product/B08CXJ16Q9/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1)

 

[Gtoboy]

Your best bet is to record from the outside as the car drives by as mics capable of getting a decent sound of only the exhaust while being out in the wind blast are going to be pricey IME.

 

[psyborg]

Your best bet is to record from the outside as the car drives by as mics capable of getting a decent sound of only the exhaust while being out in the wind blast are going to be pricey IME.

Thanks for that; I will probably setup for this. However I am still looking for a good recording device. What would be your preference for recording audio-only like this? I'd prefer to use my shotgun mic for the driveby, but the clipping issue is really blocking me here. I strongly suspect it's the phone.

 

[Ed Fones]

Zoom H6 on 32 bit?

If it were me trying to do that I would find a way of recording it stationary preferably inside where you can go through the gears. Outside you will get wind noise, road noise, and all sorts that you dont want.

 

[raybbj]

I can only comment on what I have done in the past. 2 x C414's in stereo 12inches from the exhaust pipe., offset so the exhaust blast doesn't create wind noise. It worked well for us, however we ere just trying to capture an idling car at 500 RPM. We were in the empty parking lot of the studio at night, so there was no other ambient noise.

 

[psyborg]

Thanks for all the great ideas! I'm thinking of maybe asking a local tuner if I could borrow the dyno for half an hour and have the mic behind the car far enough to record. That should let me record enough variations of acceleration I think.

 

[Slouching Raymond]

I recorded my mum's car idling, with a cassette recorder, when I was 13.
She thought I was nuts.