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External mic directly to the BMCC

PostPosted: Thu Feb 08, 2018 4:36 pm
by Cthe47
Hello

How can I connect my NTG-2 mic to the BMCC directly without using an adapter. Whould this cable work?

Roland RCC-3-TRXF (The forum does not allow me to post a link. You may google it)

It has a female 3 pin XLR connector at one end and a male 1/4” TRS (wired balanced?) at the other end.

Mant thanks

Re: External mic directly to the BMCC

PostPosted: Thu Feb 08, 2018 5:58 pm
by Denny Smith
The BMCC Preamp is too low an output for most mics. You need to use a good preamp between pro XLR mics to get enough preamp level and feed the camera with a line level from the preamp.

If you want to give a direct mic connection a go, you need a balanced TRS to XLR cable.
Cheers

Re: External mic directly to the BMCC

PostPosted: Thu Feb 08, 2018 7:05 pm
by Cthe47
Thanks Denny

So this one (Roland RCC-3-TRXF) should work, right?

What preamp would you recommend? The cheapest one suitable for getting enough pream level for BMCC please.

Many thanks

Re: External mic directly to the BMCC

PostPosted: Fri Feb 09, 2018 12:07 am
by Cthe47
I was wondering if anyone knows what cables/connectors I should use to connect NTG-2 mic to Tascam DR-60 MKII, and then the Tascam to the camera (BMCC)?


Edit:
Update - It seems I have to use a recorder, record on it, and do the sync in the post; instead of recording on the camera. This is because the signal coming from the recorder to the camera via a 3.5mm to 1/4" cable will probably be "unbalanced".

Re: External mic directly to the BMCC

PostPosted: Fri Feb 09, 2018 12:02 pm
by Robert Niessner
The problem is not that the signal is unbalanced - because the cable is very short - the problem is that the output of the Tascam DR-60D MKII is not loud enough to have a good signal to noise ratio in the BMCC.
And the BMCC has some odd low frequency filtering going on in its audio section.

I had this combination of BMCC and Tascam. Just record on both and autosync in post.

Re: External mic directly to the BMCC

PostPosted: Fri Feb 09, 2018 2:41 pm
by John Richard
JuicedLink makes a small pre-amp that works well with the BMCC. Has XLR mic inputs and 1/4 TRS outputs to the BMCC. Provides very low S/N ratio audio result recorded to the in-camera files.

Re: External mic directly to the BMCC

PostPosted: Fri Feb 09, 2018 5:00 pm
by Cthe47
Robert Niessner wrote:The problem is not that the signal is unbalanced - because the cable is very short - the problem is that the output of the Tascam DR-60D MKII is not loud enough to have a good signal to noise ratio in the BMCC.
And the BMCC has some odd low frequency filtering going on in its audio section.

I had this combination of BMCC and Tascam. Just record on both and autosync in post.


Thanks for the comment. Yes I will do that. To record on the BMCC as well, how did you connect your Tascam to the camera? What cables/connectors?

Re: External mic directly to the BMCC

PostPosted: Fri Feb 09, 2018 5:02 pm
by Cthe47
John Richard wrote:JuicedLink makes a small pre-amp that works well with the BMCC. Has XLR mic inputs and 1/4 TRS outputs to the BMCC. Provides very low S/N ratio audio result recorded to the in-camera files.


The 1/4 TRS output would be amazing! But I can’t find shops that sell JuicedLink preamp.

Re: External mic directly to the BMCC

PostPosted: Fri Feb 09, 2018 5:22 pm
by Denny Smith
JuiceLinkmis out of the preamp business. I use the Sound Devices MidPre, older used models are available (check ebay), and the new model has internal recording as well as great preamps, with enough gain.
Cheers

Re: External mic directly to the BMCC

PostPosted: Fri Feb 09, 2018 8:32 pm
by Brad Hurley
Denny Smith wrote: I use the Sound Devices MidPre, older used models are available (check ebay), and the new model has internal recording as well as great preamps, with enough gain.
Cheers


The MixPre line is very popular among videographers, and for good reason; some people are using them for professional recordings of classical music as well (standards are very high in that realm, so if it's good enough for them...). The MixPre-3 is the smallest and lightest; the 6 has a few additional features and of course more inputs.

Re: External mic directly to the BMCC

PostPosted: Fri Feb 09, 2018 9:07 pm
by Robert Niessner
Cthe47 wrote:
Robert Niessner wrote:The problem is not that the signal is unbalanced - because the cable is very short - the problem is that the output of the Tascam DR-60D MKII is not loud enough to have a good signal to noise ratio in the BMCC.
And the BMCC has some odd low frequency filtering going on in its audio section.

I had this combination of BMCC and Tascam. Just record on both and autosync in post.


Thanks for the comment. Yes I will do that. To record on the BMCC as well, how did you connect your Tascam to the camera? What cables/connectors?


I had a technician of a music shop make me a special cable. I have to dig up the order from 2013 to find the specs.

Re: External mic directly to the BMCC

PostPosted: Sat Feb 10, 2018 12:00 am
by Howard Roll
This is the cable.

3.5 mm TRS to dual 1/4" TS

http://hosatech.com/product/cmp-150/

Pretty common just make sure you don't inadvertently get a Y cable or phase cancellation will ensue.

Re: External mic directly to the BMCC

PostPosted: Sat Feb 10, 2018 12:32 am
by Cthe47
Howard Roll wrote:This is the cable.

3.5 mm TRS to dual 1/4" TS

http://hosatech.com/product/cmp-150/

Pretty common just make sure you don't inadvertently get a Y cable or phase cancellation will ensue.


Brilliant. Thanks a lot.
I just don't understand why using a Y cable will result in phase cancellation? Yes, the two signals will be identical, but they go to two separate 1/4" jacks, not one.

Re: External mic directly to the BMCC

PostPosted: Sat Feb 10, 2018 7:16 am
by Howard Roll
Phase cancellation can happen in a couple of different places, electrically or accoustically. If you have perfect separation between the LR channels and mic 1 is hard panned left (or right) you could be fine with a Y cable so long as you are not using a second mic panned right (or left). Similarly you can't use the insert cable I posted to record dual mono from a single mic because you'll get acoustic (in air) phase cancellation unless you reverse the phase of one channel prior to recording.

Re: External mic directly to the BMCC

PostPosted: Sat Feb 10, 2018 2:20 pm
by John Richard
Denny Smith wrote:JuiceLinkmis out of the preamp business. I use the Sound Devices MidPre, older used models are available (check ebay), and the new model has internal recording as well as great preamps, with enough gain.
Cheers


Did not know this. Very sad as it was a great solution and easy on-board mounting. From what I'm reading, Zaxcom is creating a lot of problems with lawsuits for what seems like overly broad patents. Blocking Tascam products as well. JuicedLink was just a very small company started by Robert Rozack who filled some audio needs.

Re: Audio recording on both the recorder and the camera

PostPosted: Mon Feb 12, 2018 11:16 pm
by Cthe47
Update:

For those who have this combination for audio recording and want to record on the camera as well as the recorder:
mic with XLR output (e.g. NTG2) + recorder with XLR input (e.g. Tascam DR-60D) + camera with 1/4" balanced TRS jack (e.g. BMCC)

I asked a studio shop today about what type of cables/connectors gives the best result for connecting the mic (NTG2), the recorder (Tascam), and the camera (BMCC or BMPC-4k) to be able to record sound on both the recorder and the camera with the highest possible quality. They suggest using an XLR splitter, and a balanced jack lead.

This is their recommendation:
The best way to get full-quality audio to both the Blackmagic camera and the Tascam recorder is to power the mic via batteries. This allows you to use a standard XLR splitter cable, which you can then adapt to balanced TRS jacks. Basically, it would go:

1.jpg
1.jpg (7.25 KiB) Viewed 1161 times

It’s important to note that the above will only work optimally if the TRS inputs are mic level – if they are only line-level, the sound will be super quiet.

For example:
2.jpg
2.jpg (25.44 KiB) Viewed 1161 times

I haven't tried it yet.

Re: External mic directly to the BMCC

PostPosted: Tue Feb 13, 2018 6:37 am
by Denny Smith
I disagree, the BMCC. If preamp does not have enough gain to support the NTG2 Mic, with an additional load placed on it by the Tascam recorder.

Re: External mic directly to the BMCC

PostPosted: Tue Feb 27, 2018 5:53 pm
by Cthe47
I was trying to connect the NTG-2 directly to my camera using an XLR to TRS lead. But the signal was surprisingly low, even lower than when recording by the camera’s internal mic. I contacted the audio shop about the issue and they thought there might be a short between pins 2 and 3 inside the lead. So I sent it back to them and they tested the cable and it was working correctly. So the conclusion was that the issue might be due to the camera’s preamp which is not very good and makes the camera useless in terms of recording audio on it.

Another surprising issue was that when I tried to connect the mic to both the camera and my Tascam recorder via an XLR splitter, there was no sound on the recorder at all. But unplugging the cable from the camera, the recorder received correct signal. Not sure what happens inside the camera!

My conclusion: Forget about recording audio on the BMCC.


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Re: External mic directly to the BMCC

PostPosted: Tue Feb 27, 2018 7:02 pm
by Denny Smith
Yes, the BNCC has the worst mic PreAmo of the lot. When using a pro xlr mic, you need to add a good mic preamp between the camera and mic, and set the camera to line (not mic) input. I use a Sound Devices MixPre with all my camera’s, works very well. This setup has been tested on the Cinema Camera, and you can get satisfactory audio for dialogue. I still would use a good external recorder on this camera for improved audio, like the new MixPre recorders.

This was BM’s first Camera, and it really was designed to be used with external audio recorders. The internal audio track is for a scratch track, and recording an audio LTC type sync track for help in re-syncing the separate audio tracks in post.
Cheers

Re: External mic directly to the BMCC

PostPosted: Wed Feb 28, 2018 5:12 pm
by Mike C Bonner
I can attest that if you are really concerned about quality audio, then don't rely on the BMCC audio. Sync the Tascam files.

However, if you are just doing corporate internet stuff, then the Tascam plugged into the BMCC might be good enough.

But, another suggestion for a pre-amp: Sennheiser wireless receiver. This ended up being my go to for convince on run and gun type shoots. I eventually left the JuiceLink in the case, and the wireless receiver had plenty of power to get proper levels on the BMCC.

Again, if you really want the best quality audio, don't rely on the cinema camera's recorder.

Re: External mic directly to the BMCC

PostPosted: Wed Feb 28, 2018 6:00 pm
by Howard Roll
Cthe47 wrote:Another surprising issue was that when I tried to connect the mic to both the camera and my Tascam recorder via an XLR splitter, there was no sound on the recorder at all. But unplugging the cable from the camera, the recorder received correct signal. Not sure what happens inside the camera!


Not that surprising. When you use a Y split you are changing the impedance of the signal. If you're using phantom power you can actually cook the input on one of the devices if they don't have proper protection. A Y cable is parallel so you are sending 48v out of one device into another. I don't know how the circuit protection works on the Tascam but if the BMCC is outputting phantom it could very easily just shut off the input on the Tascam. Most consoles have this protection, do either of these devices?

To use a y cable correctly one device needs to provide phantom and the second and device needs to have an isolation transformer inline to isolate it from the phantom power.

If you are going to ask a question on a forum it would behoove you to do less talking and more listening. I get it, everybody wants to be an expert. Your "audio" guy has obviously never used a BMCC, and you don't seem to have a clue. Maybe it's a better idea to try and learn something first before trying to teach the class.

Good Luck

Re: External mic directly to the BMCC

PostPosted: Wed Feb 28, 2018 10:28 pm
by Cthe47
Howard Roll wrote:
Cthe47 wrote:Another surprising issue was that when I tried to connect the mic to both the camera and my Tascam recorder via an XLR splitter, there was no sound on the recorder at all. But unplugging the cable from the camera, the recorder received correct signal. Not sure what happens inside the camera!


Not that surprising. When you use a Y split you are changing the impedance of the signal. If you're using phantom power you can actually cook the input on one of the devices if they don't have proper protection. A Y cable is parallel so you are sending 48v out of one device into another. I don't know how the circuit protection works on the Tascam but if the BMCC is outputting phantom it could very easily just shut off the input on the Tascam. Most consoles have this protection, do either of these devices?

To use a y cable correctly one device needs to provide phantom and the second and device needs to have an isolation transformer inline to isolate it from the phantom power.

If you are going to ask a question on a forum it would behoove you to do less talking and more listening. I get it, everybody wants to be an expert. Your "audio" guy has obviously never used a BMCC, and you don't seem to have a clue. Maybe it's a better idea to try and learn something first before trying to teach the class.

Good Luck


My previous post was not about phantom power. I was supposed to power the mic via batteries. However, I also turned the phantom power on for a very short period of time, and the camera input was not “cooked”! But still no sound on the recorder. The BMCC might have the required circuit protection. I don't know! This is not to teach people or encourage anyone to do that.

I do not want to be an “expert” in audio or cinematography. I am an amateur filmmaker and just need to know the basics (I make money in another business). And the audio shop that I mentioned above, they are experts in their business. Here, I’ve just shared my experience and there was no intention to teach people. I believe that, in this or any other forums, it would be nice to hear the experiences and findings of the people who open the topics at the end of them. [Mine: I have ended up with ordering a mini jack to 2x mono jacks splitter (stereo breakout, not the Y cable) to connect the recorder to the camera. I will test this when I receive the cable].

By the way, I know at least one thing that I can teach you: If you are using the internet, it would behove you to understand that people can share their own (true) experiences/ideas, and others can read all the related topics and make their own conclusions.

Re: External mic directly to the BMCC

PostPosted: Wed Feb 28, 2018 10:37 pm
by Denny Smith
Let’s keep it on the topic please. We are not doubting your audio shop, just they do not know the camera issues, and are going by general AV practices which work most of the time, but not always. But Howard and I have been in the video and audio recording business for more than 20 years, so we know from whence we speak. :roll:

I would avoid the use of any passive splitter or Y cable as that reduces the audio signal level. Does your Tascam have an audio output? If so, I would connect the Mic to the Tascam, then connect rhenausio out from the recorder to the camera, here you may need an adapter cable,your AV shop could provide. If the Tascammis unbalanced HiZ out, then get a DBox to cover the HiZ unbalanced to a Balanced out to connect to the camera. Then set the camera to line level with audio level around 50-75 Gain for best results.

Also, you can do a search here on BMCC Audio issues for more information from past posts, where this has been extensively discussed when the camera came out.
Cheers

Re: External mic directly to the BMCC

PostPosted: Wed Feb 28, 2018 10:49 pm
by Howard Roll
...and when you do fry the pre-amps on a camera because you sent Phantom power from your mixer down the line from a Y-split be sure to come back and share that experience as well.

Re: External mic directly to the BMCC

PostPosted: Wed Feb 28, 2018 10:50 pm
by Cthe47
Howard Roll wrote:...and when you do fry the pre-amps on a camera because you sent Phantom power from your mixer down the line from a Y-split be sure to come back and share that experience as well.


I will.


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