Drag Racing DVR multi-camera setup.

[Simon Bonney]

Thanks guys for the encouragement,
This is only the second time I have had the camera in the car and EVERY time it is a last minute rush....I need to spend more time playing around with it.
The Audio track on the original raw DV is not too bad but it does exactly what you say Dan, simply coming in too loud, Can you please give some more info on the amplifier you made?? Am I right in saying that the AV In microphone needs to be amplified?, and if so does it need a higher powered amp than a AA size battery provides? The 9 volt spycam mic works, a shotgun AA powered mic doesn't.
No doubt I will talk to you in real life one day Kenny! We go to all of the tracks around Oz!

Cheers, Simon.

[Kenny Shelswell]

Originally Posted by Simon Bonney

Thanks guys for the encouragement,
This is only the second time I have had the camera in the car and EVERY time it is a last minute rush....I need to spend more time playing around with it.
The Audio track on the original raw DV is not too bad but it does exactly what you say Dan, simply coming in too loud, Can you please give some more info on the amplifier you made?? Am I right in saying that the AV In microphone needs to be amplified?, and if so does it need a higher powered amp than a AA size battery provides? The 9 volt spycam mic works, a shotgun AA powered mic doesn't.
No doubt I will talk to you in real life one day Kenny! We go to all of the tracks around Oz!

Cheers, Simon.

Simon,

Be great to catch up, we are based at WSID so look out at the Sydney rounds.

On a Sony Mini DV camera when you use the A/V jack it will disable the inbuilt mic, but an external mic (with it's own power supply) should work fine .. is that what you're doing? Do a bit of research on unbalanced mics vs XLR mics.

Maybe have a good look through the camera's audio settings. there might be some sort of automatic filter, line level balancer or something that is causing you trouble. Unbalanced mics can give a really low sound level on your Mini DV tape too.

There is another forum on here specifically for audio, but Dan knows what he is talking about. The sound volume from your racecar is awesome and is probably way too loud for the mic you're using. I could not find a mic that can handle sound pressure level over 137 dB (AKG C1000s microphone, powered from a 9 volt battery, and you can change the polar pattern of the unit from Cardioid to hypercardioid).

I found that asking about mics used to record live bands and specifically for the drum kit can be promising. There might be better solutions but you'll soon find for what we are doing you're pretty much on your own; people either aren't interested in helping or they just don't know.

Simon, not sure if you follow the AVE Speed Week broadcasts, but I have lots of incar footage from Pro Stock, Top Alcohol and Top Fuel, as well as some from Pro Stock Motorcycle. I suspect it's the AVE guys and not the actual racers setting the cams up, do you know?

I've seen guys mounting the whole Mini DV cam to their rollcage but can't find any photos I have to pinpoint exactly who it was. Gary Phillips seems to have onboard cameras a lot as does Brett Stevens and Dave Rogan. On Phillips's dragster in particular the digital picture breaks up under hard acceleration.

All good!

[Bob Hart]

For mikes in areas where sound overpressure is going to be a problem, an alternative might be to use speakers instead, the cones, not in enclosures.

I suggested this in another forum for recording gunshots and subsequently another post confirmed this had been previously done with four inch speakers.

The speakers serve as low efficiency dynamic microphones.

You might have to soft mount them to the frame to screen out very harsh metallic sounds being conducted directly into the speaker frame and being resolved.

You might even get away with screwing the speaker face down onto a bit of conveyor belt then screwing this down to the nearest bit of flat bodywork. If the sound is defective due to polarity, swap the connections on the speaker.

I don't think it will be an issue but if you are mixing down live with audio from other sources, the audio from this one may chop into the audio from the others if it is putting out a negative signal.

If the dragster motor fails and reverts to its original components you also wont lose a good mike in the grenade attack if it is a cheap or salvage speaker in there.

For position of the engine bay source, my personal preference would be to have it somewhere very near to the rear, not front of the supercharger.

The parachute is going to be a difficult beast. If you want the "thupp" as it opens you likely will need a directional mike in back and there will be problems with slipstream wind as well as the wind driving off the big tyres.

I'm no audio engineer so pay little heed to my comments.

[Bob Hart]

For mikes in areas where sound overpressure is going to be a problem, an alternative might be to use speakers instead, the cones, not in enclosures.

I suggested this in another forum for recording gunshots and subsequently another post confirmed this had been previously done with four inch speakers.

The speakers serve as low efficiency dynamic microphones.

You might have to soft mount them to the frame to screen out very harsh metallic sounds being conducted directly into the speaker frame and being resolved.

You might even get away with screwing the speaker face down onto a bit of conveyor belt then screwing this down to the nearest bit of flat bodywork. If the sound is defective due to polarity, swap the connections on the speaker.

I don't think it will be an issue but if you are mixing down with other speakers, the audio from this one may chop the audio from the others if it is putting out a negative signal.

If the dragster motor fails and reverts to its original components you also wont lose a good mike in the grenade attack if it is a speaker in there.

For position of the engine bay mike, my personal preference would be to have it somewhere very near to the rear, not front of the supercharger.

I'm no audio engineer so pay little heed to my comments.

[Bob Hart]

Furthur to the above, I am having trouble getting this system here to accept edits :-

If you get bad vibration interference to the lipstick cams try mounting them inside a suitably long piece of thin stiff metal tube, stuff this inside black foam pipe insulation then strap this onto two cross elements of the rollcage structure.You might need a blob of silicone bathroom sealer on the lipstick mike to tube and tube to foam to stop it turning around inside.

Avoid having the camera overhanging the rollcage structural element you have it attached to as this will amplify not reduce vibration. Any overhang also introduces a penetrating injury risk to the driver.

The vibration will still be there but deflections of the camera lens off-axis should be reduced.

Also try to avoid runs of audio, video and power supply cable laced together. the video cable should be on its own. The power supply to the video camera, if it is shared with the audio system may directly affect the video signal if audio signal levels are very high. The power cable if it is run strapped to the video cable may inductively affect the video signal. so you may need separate power sources for audio and video cameras.

I'm no rigger/engineer so ignore my comments. They are however based in past problems experienced.

[Simon Bonney]

No worries, thanks for the great info.
Ken, not sure what they use in the doorslammers..never been that close to them. One meeting we went to at WSID a group of guys that were making a DVD of 4,6 & rotary cars installed a camera with the same equipment that I am using, but I never took much notice of the mic setup. So I think sometimes the organisers of the event employ people to produce a DVD or TV show, but I dont know who they are?!!

Good luck with it all,

Simon.

[Kenny Shelswell]

Originally Posted by Simon Bonney

No worries, thanks for the great info.
Ken, not sure what they use in the doorslammers..never been that close to them. One meeting we went to at WSID a group of guys that were making a DVD of 4,6 & rotary cars installed a camera with the same equipment that I am using, but I never took much notice of the mic setup. So I think sometimes the organisers of the event employ people to produce a DVD or TV show, but I dont know who they are?!!

Good luck with it all,

Simon.

Simon,

For the Speedweek program it is these guys http://www.ave.com.au/default.htm

They are not very helpful when asked questions ;-)

[Randall Allen]

Originally Posted by Bob Hart

The parachute is going to be a difficult beast. If you want the "thupp" as it opens you likely will need a directional mike in back and there will be problems with slipstream wind as well as the wind driving off the big tyres.

The KISS system would suggest that you take audio of the parachute deploying while the car is not running. Then edit this in during post. While there is a strong desire to get all the sounds and sights from the event as it happens, the bottom line is to make it "feel good" to the viewer while not killing the bottom line.

just my two cents.....

Randy

[Kenny Shelswell]

Originally Posted by Randall Allen

The KISS system would suggest that you take audio of the parachute deploying while the car is not running. Then edit this in during post. While there is a strong desire to get all the sounds and sights from the event as it happens, the bottom line is to make it "feel good" to the viewer while not killing the bottom line.

just my two cents.....

Randy

Randy,

I have no issue with using "non live" sound, however it's the crack of the parachute filling with air that makes the sound .. ie the racecar must be travelling very fast to pop the main chute open.

[Dan Euritt]

here is the lapel mic i'm using, unfortunately i don't think that they are selling it anymore: http://www.minidisc.org/images/radioshack_mic.jpg

along with this model of preamp, i believe: http://www.rainbowkits.com/kits/ebapsmd-2p.html

lapel mics are designed to only pick up the audio that's near the mic, which is why it apparently works well for this application.

i ran that rig on a ford V8 with nitrous, ~6.98@200 mph, the audio came out well... i lost the video signal halfway thru the pass, so it's back to the drawing board for the high-powered stuff :-)

[Randall Allen]

Originally Posted by Kenny Shelswell

Randy,

I have no issue with using "non live" sound, however it's the crack of the parachute filling with air that makes the sound .. ie the racecar must be travelling very fast to pop the main chute open.

I'm at a slight disadvantage here as I have never heard the sound of the parachute opening...have not been that close to a drag strip. A couple of ideas though...

I have viewed some skydiving videos on occasion. Would the sound of their parachute opening be close enough? Of course wiring up a sky diver would present similar problems to wiring the car. Airflow around the mic for example.

What about totally faking it? I keep having this mental image of a sound, but again I don't know how it would compare as I have never heard the original. Remember in high school when the bully would walk up behind the nerd, snort like he is pulling up a big luggie<sp?>, and the pretend to spit it into the nerd's hair. The effect is done by blowing air out of your mostly closed lips and then quickly flicking your tounge into the whole so it momentarily blocks the airflow.

There is also the high school past time of folding a piece of paper in such a way that it forms a collapsable pocket. From the collapsed state you would flick your arm and wrist, much like releasing a yo-yo, and the pocket would grab a bunch of air and pop open with a loud crack.


Anyway, I'm just tossing out ideas. Maybe someone will come up with the sound your looking for. Good luck.

Randy

[Kenny Shelswell]

Originally Posted by Randall Allen

I'm at a slight disadvantage here as I have never heard the sound of the parachute opening...have not been that close to a drag strip. A couple of ideas though...

I have viewed some skydiving videos on occasion. Would the sound of their parachute opening be close enough? Of course wiring up a sky diver would present similar problems to wiring the car. Airflow around the mic for example.

What about totally faking it? I keep having this mental image of a sound, but again I don't know how it would compare as I have never heard the original. Remember in high school when the bully would walk up behind the nerd, snort like he is pulling up a big luggie<sp?>, and the pretend to spit it into the nerd's hair. The effect is done by blowing air out of your mostly closed lips and then quickly flicking your tounge into the whole so it momentarily blocks the airflow.

There is also the high school past time of folding a piece of paper in such a way that it forms a collapsable pocket. From the collapsed state you would flick your arm and wrist, much like releasing a yo-yo, and the pocket would grab a bunch of air and pop open with a loud crack.


Anyway, I'm just tossing out ideas. Maybe someone will come up with the sound your looking for. Good luck.

Randy

Randy,

Oh you bad, bad man! I love this idea ... faking it is totally OK for my purposes. Now to work out the best fake!

[Bob Hart]

Faking it - try opening an umbrella for starters. One of those small ones would be pretty close. there is usually a bit of a lead-in noise with the real thing the skydivers use or maybe thats the sound they make ripping trough the air before they deploy their canopy.

(Got any base jumpers prepared to toss their drogue chute at the 65th floor so the canopy opens at the 60th floor where you are seen hanging out of the window with your mike- just kidding).

If you can live with guessing where the real thing on the dragway will open up and you are open to "faking" it with real location sound, then being alongside the track with a good directional mike and chasing the parachute position behind the car as it passes would be as good as any.

The engine noise should have just about spooled down by then anyway and all you should have is tyre and wind noise, all genuine location sound.

The same good directional mike with a shaggy cover on it should be good for in back of the car pointing rearwards for your chute deployment, only I'm thinking there is beginning to be a lot of dead weight building up in the car unless there is handicapping and some handicapping ballast can be exchanged for the weight of equipment.

Another try would be a couple of people flapping a double blanket out hard.

Another try would be dropping a big yellowpages flat onto a concrete path.