Using JuicedLink with BMCC tech Question

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Taylor Camarot

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Using JuicedLink with BMCC tech Question

PostThu Sep 05, 2013 5:41 pm

Hey, I (like so many others) just recently found out how poor the BMCC audio recording is, even with my external mic. Knowing BMD's track record Im not hoping for a fix any time soon, so I decided Im going to get the Juicedlink BMC336. I have a few questions though about exactly how it works.

1. When it is plugged in to my camera, will the levels it actually records in camera be of sufficient volume? If so, how does it do this without increasing the noise threshold?

2. When it is plugged in to my camera, will it record audio when I press 'record' on the camera? As in I wont have to hit record twice and stop twice, right?

Thanks for your help, any advice would be greatly appreciated.
Taylor Camarot Cinematography
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ChrisBarcellos

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Re: Using JuicedLink with BMCC tech Question

PostThu Sep 05, 2013 6:32 pm

1. I am using an older Juiced Link, the CX231. I have found that for narrative film making, that I can get a pretty decent track by setting the external mic settings at around 18 to 24 %, and setting the Juiced Link output as high as I can go. This seems to leave me with low background noise, and a track I can raise in gain in post if needed, without adding the hiss. It also seems to not have as much loss of the low range. This is with version firmware 1.4.1. Its seems to work different with each of the firmwares, and I think BM is making adjustments without documenting them to users.

2. A Juiced Link is only a preamp, it has no recorder on board, though you could use it with an independent recorder rather than a camera. The camera has a preamp, but the idea of the Juiced Link is to provide a better external preamp with XLR inputs and mic power. By increasing the signal to the camera, you rely less on the camera preamp and more on the presumably better preamp in the Juiced Link. Point you seem to miss is that the Juiced Link aids in inproving in camera recording.
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Taylor Camarot

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Re: Using JuicedLink with BMCC tech Question

PostThu Sep 05, 2013 8:21 pm

ChrisBarcellos wrote:1. I am using an older Juiced Link, the CX231. I have found that for narrative film making, that I can get a pretty decent track by setting the external mic settings at around 18 to 24 %, and setting the Juiced Link output as high as I can go. This seems to leave me with low background noise, and a track I can raise in gain in post if needed, without adding the hiss. It also seems to not have as much loss of the low range. This is with version firmware 1.4.1. Its seems to work different with each of the firmwares, and I think BM is making adjustments without documenting them to users.

2. A Juiced Link is only a preamp, it has no recorder on board, though you could use it with an independent recorder rather than a camera. The camera has a preamp, but the idea of the Juiced Link is to provide a better external preamp with XLR inputs and mic power. By increasing the signal to the camera, you rely less on the camera preamp and more on the presumably better preamp in the Juiced Link. Point you seem to miss is that the Juiced Link aids in inproving in camera recording.



Gotcha. My question is a little different however, as I'm asking how does it deliver acceptable audio levels to the BMCC where normally it's levels are around -30/-40 Db? Does it just take the audio signal and make it WAY louder to compensate for the BMCC's low recording levels? How does it do that without increasing noise levels? Or is there something I am missing?

Thanks again
Taylor Camarot Cinematography
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ChrisBarcellos

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Re: Using JuicedLink with BMCC tech Question

PostThu Sep 05, 2013 10:56 pm

Taylor Camarot wrote:
Gotcha. My question is a little different however, as I'm asking how does it deliver acceptable audio levels to the BMCC where normally it's levels are around -30/-40 Db? Does it just take the audio signal and make it WAY louder to compensate for the BMCC's low recording levels? How does it do that without increasing noise levels? Or is there something I am missing?

Thanks again


I am not techy, but yes its an amplifier, just like what is in the camera. Difference is it is supposed to be better and have a lower noise floor. Thus the idea is you send a stronger clean amplified signal to the camera, so you don't have to push up an inferior preamp in the camera. That's always been the idea behind Juiced Link. It is the same as running everything through and external mixer. You get a pumped up signal sent to the camera, that has lower noise floor.

I ve seen a lot of people say run firmware 1.4 input levels at 80%. I disagree, and say run it as low as you can, and then pump it up through your mixer or Juiced Link if you have that capability.

I hope the camera actually can be fixed through firmware to allow more control and cleaner preamps, but BMD just is not saying they will correct it.
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Dennis Nomer

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Re: Using JuicedLink with BMCC tech Question

PostFri Sep 06, 2013 8:27 am

Audio noise can come from a few sources. The microphone will contribute some noise. That is why it is smart to use a good one, because it is the most difficult part to manufacture with really low noise. Remember that the microphone is starting with the lowest signal level, and making a physical conversion, so it has the toughest job in the signal chain. In addition, for location sound, you usually need a shotgun mic so you can mic from some feet away and keep the mic out of the shot. This is VERY difficult, and requires a really good mic, because the sound level reaching the capsule reduces with the square of the distance from it. Good shotguns (with phantom power, which should be 48 VDC) put out a nice strong signal, unlike cheaper ones. So do not ever think that the mic does not matter. There are very large differences in microphones, as a little testing will show you. All good shotguns require phantom power. Since the BMCC does not provide phantom power, that is one of the jobs of a preamp that you need.

Next up is the preamp. A really good one (like JuicedLink models) does not contribute much noise of its own, even when amplifying the signal, but it will OF COURSE amplify the noise from the mic. Normally a good preamp will outperform the preamps in the BMCC, so you want to boost the level in the preamp (with version 1.2 of BMCC firmware) so that you can set the BMCC level to only 25% to get your sound at the proper level (see Robert's lecture on the subject for details). When using digital gain (as in the BMCC), all noise is multiplied, so you much prefer to amplify in the JuicedLink, not in the BMCC.

I personally am still on firmware V 1.2, for better audio quality.
Dennis Nomer
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ChrisBarcellos

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Re: Using JuicedLink with BMCC tech Question

PostFri Sep 06, 2013 5:14 pm

DNomer wrote:I personally am still on firmware V 1.2, for better audio quality.


Thanks for a more technical explanation. This mirrors my general feeling about what is going on with the BMCC.

Problem with sticking with 1.2 is that at some point we hope BMD will correct some issues, and if you stay with older firmware versions, you won't be able to avail yourself of the changes. For instance, in the next update, Grant indicates a firmware change to improve ProRes performance will be on board. This is why I have attempted to work with current updates.
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Jules Bushell

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Re: Using JuicedLink with BMCC tech Question

PostFri Sep 06, 2013 5:40 pm

ChrisBarcellos wrote:
DNomer wrote:Problem with sticking with 1.2 is that at some point we hope BMD will correct some issues, and if you stay with older firmware versions, you won't be able to avail yourself of the changes. For instance, in the next update, Grant indicates a firmware change to improve ProRes performance will be on board. This is why I have attempted to work with current updates.

A good ploy is not to based anything on what might be coming out. There is also when or if something will be coming out too.

Jules
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