dbbarron

I mentioned this in a separate thread, but thought it worthy of its own thread.

I have experimented for years with GoPro type video in my 997.2 for AX and HPDE. I have found the build in camera mics inadequate with issues of noise and dynamic range. Currently, I use a Zoom H5 recorder mounted to the rear seat passenger side shelf with a 'dead mouse' type cover over the mic capsules. I also use the H5 to mix in a Shure SM11 mounted at the rear plate (a great wind null). These locations seem good; however, the one problem I still face is forgetting to turn on the H5/hit record (is does not have a hard on-off switch) and battery/USB power issues. Too many other things to think about before a session.

The rear mic pics up exhaust and road/tire noise, the interior mic picks up cabin sounds and other ambient mechanicals.

In post processing, I would mix down the 2 mics, add some lo-cut, add some compression/limiting and then substitute the audio track. I really don't want to do any of this anymore.

This year I am upgrading to a VBOX HD2 which has a separate mic or line level input. I imagine these same issues apply to any video system with a mic/line in.

So, here's my potential approaches:

(1) Use the same Zoom H5 setup and run it's line out to the VBOX line in. Do not 'record' with it - essentially, use it as a mixer, limiter, lo-cut processor. Power it with USB from the car and rely on the AA batteries when the car and USB is off. Maybe put a small USB battery pack in line to guarantee it works. I will have to remember to turn it ON at the start of the day, but that should be it. Believe it or not, I might not remember to do this.

2)Find a small mixer that is 12V powered and hard wire it to the car. Perhaps the same 12 power the VBOX uses and mount it in the glovebox with the HD2. I found one candidate:

Rolls MX54s.
http://www.rolls.com/product.php?pid=MX54

This won't give me a limiter/compressor, but will perform everything else. I'll have to add a mic for interior cabin sounds. Probably on the rear seat deck area or up by the mirror with another 'dead cat'. More importantly, no power to worry about as it will be left on and hardwired to switched car power.

Shure SM11 is really small, tough and has high dynamic range:
http://www.shure.com/americas/produc...ier-microphone

Thoughts?

ProCoach

As a technical exercise, your approach sounds complete!

But I think you should try the conventional, included mic with the VBOX, in the cabin first to see what it sounds like.

For whatever reason, the VBOX mic, auto and fixed gain leveling and finished output is far better than the other hardware I've seen.

dbbarron

Definitely gonna try it the simple way first. Need to keep it thoughtless.

kgorman

New GoPro has better mics

Or use old gopro and use ear bud headphones as mics. They work great.

boxer-11

My experience with the VBOX is in the form of the dual/stereo mic cable with one of their supplied mics and the other side going to a TVC-15 that mixes in audio from radio or chatterbox and itself has an external mic input as well.

The VBOX mic does seem pretty good at picking up sound from inside the cabin. The main issue I've run into is placement of the mic itself to avoid an excess of wind noise. For DE's around me running "windows down" is required and in the GT4 cabin there seems almost no place I can put the mic that picks up good noise and avoids wind. I'm planning to try furry windscreen muff type apparatus this year to see if that helps.

MarcD147

I have put the mic literally in front of my mouth in my helmet so I can hear myself talk.

biggest benefit of this is that when I do this I talk more during driving which results in better driving

boxer-11

Agreed! The TVC-15 lets me plug my helmet (it's wired for radio) into it and thus I can make voice notes on the "tape" as I'm driving which I find useful later in review.

That mic does NOT do a good job of picking up engine and environmental sounds though...that's where the two other ext mic's come in for me.

ir_fuel

Good idea. If you want to try stuff and check on the data what the difference is you can add audio queues. I always have a hard time finding back that lap where I tried rolling the car more through the corner, or changing a line, when doing 45 minute stints on a 2:40 lap track. You can just say it at start finish what you want to try in the next lap.

dbbarron

I have experimented a bit in finding wind nulls. So far, the best spot is a mic with a dead mouse (furry type) windscreen cover on the 'back seat' (or where the back seat should be).

freeride

This is a great idea! I'll be screaming notes to myself next time out.

I use a Gamin Virb Ultra, which allows an external mic to record on L-channel of stereo and internal mic to record on R-channel. The internal mic hears my voice easily, and I'm experimenting on where to locate the external mic for most bestest engine/exhaust sound.

MarcD147

for engine sound I use a this mic:

in my gt4 I route the cable right out of my trunk over the exhaust and clip to the black grid next to the exhaust; no wind noise and great exhaust sounds

dbbarron

Here is a recording with a Zoom H5 on the back seat (removed) area mixed with a Shure SM11 mounted at the license plate. I tried for a more natural mix of in-cabin sound rather than an exhaust heavy mix (which sounds a little like a video game).

The wind noise is from a little bit of GoPro mic mix in there too. I'd remove it next time.


This is from the last session of the last event of the last season and my first time out in Blue solo.

db

dbbarron

Well, I went SCHD and have it installed. Yes, audio is terrible - mostly wind noise.

I'm going to continue this thread as I work through the options.

My requirements are a small mixer that can take up to 3 inputs (helmet mic, cabin mic and exhaust mic), be light/small, and output a mic level to the smartycam 'external mic' CAN cable which I have. I anticipate zip-tying the mixer to the cage.

Also, it has to be powered from the car and be completely thoughtless - nothing to turn on, charge, set, etc. Like the AIM system, get in and just drive.

I dismissed the Rolls referenced above mixer as it was too big/heavy.

I have ordered for testing a RDI ST-UMX-3 which seems perfect.

3 inputs, really light and small, hardwired and has a mic output.

One problem is the 24v input, but I already have a small 12-24v DC-DC converter off ebay ($15).

Once I receive the mixer I will start some testing and post results.

Question: How do I set levels into the SCHD? Is there any kind of VU meter for the audio?

ProCoach

Just five level settings, try them each.

dbbarron

The mixer has a VU type peak LED. I will adjust the mixers mic input levels to just hit the peak and then record some audio with the SCHD at each of the levels. I'll then inspect the resultant audio track of the .MOV files out of the SCHD to look at which just hits clipping and choose that level setting.