GH4 GH4 + SD MixPre-D - what else for recording clean audio directly to cam?

TubEfingers

TubEfingers

Well-known member
Ive been an AF101 shooter for the last few years but need a lighter/compact option for the overseas jobs I do,

I had a GH4 to use on an overseas shoot this week and was impressed, so now Im thinking to buy a GH4 body to use on events jobs - with my Olympus 12-40 & 40-150 I've got the image side of things covered,

for audio I already have a MixPre-D and a few sets of Sony wireless radio mics - what's the best option in terms of set up and recording,
can I get audio into the camera via the radio mics and MixPre-D? Don't currently have the kit to hand to try out so anyone using a similar set up that can offer advice would be much appreciated,

can anyone recommend some sort of cage or bracket and shoulder rig that lets me hang the necessary audio kit onto the cam for run n gun type shooting with this kit attached?

I'll need to:
1.Record audio from the AV desk into the cam for presentations etc.
2.Record interviews on the fly around the event on a tripod or a shoulder mount.

I have a Zoom H4n but I'm more comfortable getting the feed from the AV guys directly into the camera using the available kit plus whatever else is required if possible.

Cheers
 
TubEfingers said:
For audio I already have a MixPre-D and a few sets of Sony wireless radio mics - what's the best option in terms of set up and recording...
Click to expand...

What most people do is tie the MixPre-D and camera together as a unit using the available camera mount for the MixPre-D. Take the MixPre-D's unbalanced mic-level output to the camera input (I had a custom short cable made for me by Redco Audio).

After that any external audio devices interface to the MixPre-D. If that's radio mics, the receivers talk to the MixPre-D's input XLR connectors. If it's condenser mics, through the XLR connectors (which also supply phantom power as needed). Etc.

But for taking a feed off a board at a conference, I'd much rather use a reasonable length of balanced XLR cable, at line-level. Cheap, clean, easy, better sound quality than a radio, and it's hard to get cell phone or pager interference using balanced cable, etc.

For trade show interview work, a reporters' "stick mic" like the EV RE50N/D-B and 5m of XLR cable through the MixPre-D is really hard to beat.

But just because that's how I like to work doesn't mean you'll like it. Clearly, YMMV.
 
Yeah I always use an XLR line in from the AV guys for presentation audio feeds,
radio mics were more for the interviews, I do have a Sony UTX-H2 wireless handheld as well or do you think a wired XLR mic would give better results?
I'll check out the camera mount - cheers
 
TubEfingers said:
I do have a Sony UTX-H2 wireless handheld as well or do you think a wired XLR mic would give better results?
Click to expand...

Yes, I do. Because radios are susceptible to RFI, where balanced XLR cables are designed to avoid it. Cables also don't do any compression or expansion to transmit, like most radio systems do. The best radios available haven't reached the sound quality of a cheap cable yet. Although Zaxcom and Lectrosonics are very close.

Wireless is a last resort -- only if I can't find a way to do it with a cable. I even do 90% or so of my lav. work with a cable. Talent doesn't mind it much and it makes them sound so much better.
 
If you disregard interferences; it shouldn't. I have never heard of such a statement. Maybe wireless can't transmit 96kHZ and is limited to 48? But even so, 48kHZ is more than enough. I'm not a sound guy though so I can't say anything for certain.
 
KINOKS said:
Why would a wired mike make the talent sound better??
Click to expand...

To be clear, I'm talking about sounding better using a cable vs. radio mic. Why would this be true? The radio mics have to compress the signal on the transmitter side, then push it through the radio, it's received on the receiver side, and decompress it. I've no doubt there's significant processing to make it work, otherwise radio mics would be much cheaper.

OTOH, the cable adds... nothing. The cable isn't active, so doesn't make any active changes to the signal at all.

No reason to believe me when I say that a cable sounds significantly better. It's easy enough to try it yourself.
 
TubEfingers said:
I should research this - does a wired mic give a fuller/richer sound due to less compression etc?
Click to expand...

Yes, it does. Not less compression. No compression. No compander artifacts. No radio artifacts.

No one needs to believe me on this -- it's way too easy to check for yourself. Mount a lav. on someone using your radio mic. Record them reading something. Then switch out the radio mic for an XLR cable using the same mic in the same mount. Recording them reading the same material. Bring both recordings into your NLE or DAW, normalize them to make them the same loudness level, and have a listen. Make your own decision based on what you hear.

For me, a $20 USD XLR cable sounds like a microphone upgrade compared to my Sennheiser G3 radio mics. It's not subtle. If you want a subtle difference, you have to have radio mics in the Lectrosonic / Zaxcom level. But the cable still wins. Try it and see for yourself.

BTW, I'm not saying that the my Sennheiser G3 radios sound bad. They don't, on the contrary, they should quite good. But not as good as a balanced XLR cable sounds.
 
KINOKS said:
If you disregard interferences; it shouldn't.
Click to expand...

On the contrary, it should. The radio mics have a lot of processing to do to the signal before and after transmission. Nothing is perfect -- if you compress the signal and then decompress it, you leave some artifacts in the signal. And there's a lot more processing going on that just compression.
 
Ok, that makes sense - on a sidenote, i much prefer the sony radio mics, i always found the G3's and supplied lav's gave a "raspy/harsh" quality to the interviewes voices in comparison
 
Wanted to double check - whilst my GH2 uses a micro 2.5 mm jack for inputs has the GH2 upgraded to a regular 3.5mm connection?
 
TubEfingers said:
Wanted to double check - whilst my GH2 uses a micro 2.5 mm jack for inputs has the GH2 upgraded to a regular 3.5mm connection?
Click to expand...

I take it you mean GH4? According to what I've read on the 'net, the GH4 uses a 3.5mm stereo jack for microphone, and a separate 3.5mm jack for headphones.
 
ok, I've picked up the GH4 body, a Sound Devices mounting bracket is on order and an XL-3 cable is due for delivery,
I tried running audio in from radio mics via the MixPre-D into the cam using a 3.5mm jack, getting clean audio with GH4 at -12db but I have to set the MixPre-D volume VERY low, is there any other settings to get me more room to play with the MixPre-D volume control - will the XL-3 cable do this?
 
TubEfingers said:
...getting clean audio with GH4 at -12db but I have to set the MixPre-D volume VERY low, is there any other settings to get me more room to play with the MixPre-D volume control...
Click to expand...

Use the 1kHz tone generator on the MixPre-D to set volume on the GH4 to -20 dBFS. Then don't touch the GH4 for audio at all, use only the MixPre-D.

The MixPre-D meters use the dBu scale, which is completely different than the dBFS scale used by the GH4. The dBu scale is a throwback to magnetic tape days (it's a replica of VU meters). So you're going to have to set volume on the MixPre-D like it's using mag tape. For dialog, you want your average peaks to be hitting around +8 dBu (that's not a typo, that's a "+"). That's where the red LEDs start on the MixPre-D meters. If it makes you more comfortable doing that at first, look back at the GH4 and you'll see that the +8 dBu on the MixPre-D gives you approx. -12 dBFS on the GH4, which is what you want.

Given that the MixPre-D will start clipping at around +20 dBu (or a little higher), it's considered "good practice" to set the limiters on the MixPre-D to +18 dBu (the factory default), but some people set them a little lower. The +18 dBu on the mixer translates to -2 dBFS on the camera, so you're still not clipping the camera.

I've set my own MixPre-D like this, and with the limiters at +18 dBu and the camera volume set using the 1 kHz tone out of the mixer, the system as a whole is practically unclippable. And the sound quality is first rate.
 
Bruce Watson said:
Use the 1kHz tone generator on the MixPre-D to set volume on the GH4 to -20 dBFS. Then don't touch the GH4 for audio at all, use only the MixPre-D.

The MixPre-D meters use the dBu scale, which is completely different than the dBFS scale used by the GH4. The dBu scale is a throwback to magnetic tape days (it's a replica of VU meters). So you're going to have to set volume on the MixPre-D like it's using mag tape. For dialog, you want your average peaks to be hitting around +8 dBu (that's not a typo, that's a "+"). That's where the red LEDs start on the MixPre-D meters. If it makes you more comfortable doing that at first, look back at the GH4 and you'll see that the +8 dBu on the MixPre-D gives you approx. -12 dBFS on the GH4, which is what you want.

Given that the MixPre-D will start clipping at around +20 dBu (or a little higher), it's considered "good practice" to set the limiters on the MixPre-D to +18 dBu (the factory default), but some people set them a little lower. The +18 dBu on the mixer translates to -2 dBFS on the camera, so you're still not clipping the camera.

I've set my own MixPre-D like this, and with the limiters at +18 dBu and the camera volume set using the 1 kHz tone out of the mixer, the system as a whole is practically unclippable. And the sound quality is first rate.
Click to expand...
What he said! I't's exactly what you should do. Have the same combo and it works great!
 
Took the new GH4 setup - Mixpre-d mounted on GH4 with SD bracket/connected using the XL-3 cable (bought from ebay, sooo much cheaper than the official Sound Devices one!) to an event in Stockholm this week,
apart from 3 feet of snow and temperatures of minus 2 the shoot went really well and audio quality with the new setup was flawless,
really happy with this setup and so much easier to transport than my AF100 kit on overseas jobs, thanks for all the info provided on this thread,
I also found the "Suggestions of Motion" website really useful in terms optimizing the GH4 for video, custom settings/fn buttons etc
 
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