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BMCC audio: Tap, tap, tap … is this thing working?

May 17, 2013

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UPDATE 12/22/13: “WhiteRabbit” has posted a helpful summary of the current state of BMCC audio performance as of firmware v.1.3.

IMHO, “looking” at the Blackmagic Cinema Camera’s current audio performance in isolation, Blackmagic Design has fallen short of reasonable expectations.

According to its specs, the BMCC hardware appears to be capable of recording “48 kHz and 24 bit” audio, has balanced audio inputs, and is switchable between mic & line level audio signals. If true, this means the camera is capable of recording audio that should sound fairly good, especially from line-level sources.

In actual practice, although this is somewhat true when using a BMCC with line-level audio sources, it’s definitely not true when working with mic-level sources.

I use Sennheiser ME66 & ME64 microphones with a variety of video cameras. Though not the best-sounding mics available, they’re quite popular, and when used properly can deliver results easily good enough for many professional applications. Of the two mics, I think the ME64 has better sound quality. These mics can be self-powered (using a AA battery) or they can use external phantom power (such as from a camera or preamp), and they have much higher than average output levels — they are relatively “loud” mics (which is a good thing).

However, when directly connected to a BMCC (without an external preamp), the resulting sound isn’t very good compared to using them with most other cameras, including cameras that cost a fraction of the BMCC.

The following video is an example of what my ME64 sounds like when directly connected to my several-year-old Panasonic GH2 “DSLR”, which cost me about 1/3 of the BMCC’s $2K price:

Not perfect, but quite usable.

I don’t own a BMCC yet and I don’t have a sample video online that demonstrates what the ME64 & ME66 mics sound like when directly connected to a BMCC. However, I tested these mics with a BMCC I had on loan for a few days, and believe me, it didn’t sound anywhere near as good as a GH2 or any other pro or prosumer video camera I’ve ever used these mics with. In my informal tests with the BMCC running firmware 1.2, the ME66 & ME64 (and also my Sennheiser wireless mics) sounded so bad (noisy! awful! terrible!) when directly connected to the BMCC (without aid of a preamp) I decided I couldn’t use them that way, at all.

Instead, I used my ME64 mic with my old SoundDevices MixPre preamp together with the line-level settings on the BMCC, and got the following result (see my notes on the Vimeo page for more info):

I think the results are quite good — not perfect, but completely usable for many professional applications. Based on what I’ve heard others achieve using various preamps (@ mic or line level), similar or better results are possible even when using preamps that cost far less than the MixPre (or current model MixPre-D), such as those from JuicedLink.

Going forward I hope BMD updates the audio portion of the camera firmware ASAP to “get out of the way” of what the BMCC hardware appears to be capable of.

Among other things, I think the low-frequency roll-off (hi-pass) filtering BMD added to the current version 1.3 BMCC firmware was a mistake, because BMD applied it to all BMCC audio, including audio from external audio inputs. The previous v1.2 firmware had other issues, but at least it didn’t feature an always-on hi-pass filter. BMD might have added the hi-pass filter to make audio from the camera’s built-in internal mic more usable (to reduce handling & fan noise), but it’s completely inappropriate for this hi-pass filtering to be always applied when using an externally-connected audio source.

Chris Hocking and others describe BMCC audio issues when using firmware 1.2 & 1.3 in a detailed thread on BMD’s forum.

Although I’d love it if  BMD would please, please add audio level/VU meters displayed full-time on the BMCC LCD, I’d settle for a possibly simpler-to-implement “audio peaking” display, perhaps as simple as a small icon or dot that alternates between green & red to show when audio is either OK or clipping. That, combined with monitoring with good headphones, should be enough to get good, distortion-free audio recordings.

I don’t expect the BMCC’s mic-level performance to be as good as most standalone pro audio gear, but I do expect it to be at least as good as an old GH2. I don’t know for sure, but I suspect BMD can adjust the BMCC firmware so that using it with a good self-powered mic (or other self-powered mic-level audio source) without a preamp can result in good-quality audio recordings. But I could be wrong; maybe the current BMCC hardware can’t do it.

Having said all that, let me go back to what I said at the beginning: “Looking at the BMCC’s current audio performance in isolation” …

What if we take a step back, and look at the bigger picture?

Given the BMCC’s considerable (awesome!) video capabilities, and the amazing software BMD includes with it, I actually don’t have a problem paying an additional few hundred dollars or so to add an external audio preamp to a BMCC kit if that’s what it takes to also record high-quality audio.

The way I look at it, the BMCC is an incredible value “as-is”, and for the user to have to add a few hundred dollars to its kit cost (buying a preamp to get really good audio) doesn’t really reduce its overall value all that much.

Yes, I definitely think BMD should fix the remaining firmware audio issues ASAP, but changing the actual camera hardware design — such as adding built-in high-quality mic transformers — is probably never going to happen to the currently-shipping or currently-announced BMD cameras. Hopefully BMD will do that in some future, unannounced camera, but at this point the hardware specs for the current BMD cameras (BMCC-EF, BMCC-MTF, BMPCC, and BMPC-4K) are pretty much set in stone.

I don’t think it’s unreasonable for BMD to expect users to add an external preamp for high-quality in-camera sound recording. But I also think it’s reasonable for users to expect that the BMCC should be capable of recording at least good-quality mic-level audio without an external preamp, too.

My list of related links, short films, and resources for Blackmagic Design cameras.

For my words & videos only: ©2013 Peter J. DeCrescenzo. All rights reserved.

Note: I don’t receive income or remuneration for this blog, or for products seen or mentioned here. Advertisements on the page have nothing to do with me. The ads support WordPress, the publisher.


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