V1 sound quality

[Piotr Wozniacki]

There have been a couple of threads on the low output level of the supplied shotgun mic (being low indeed - nobody questioned that), as well as the overall quality of the V1's audio section (disputable - some said it's extremely poor with the rolloff frequency being as high as some 1200 Hz, others strongly denying).

Well, I guess I can shed some more light on this, with a first-hand experience I've just had. Some of you may remember my posts on how well the live music performance in a church came out for me recently, using the Edirol CS-50 stereo mic:

http://www.dvinfo.net/conf/showpost....31&postcount=1

In fact, I was pleasantly surprised with the sound quality - until, that is, I received the sound track recorded independently by a radio station crew. Well, the two tracks' main differences are:

- the camera recording is much louder (which denies accusations on the whole audio section, not just the mic, being too low)

- the radio recording is by far reacher in lower frequencies (which confirms the claims of the V1 not being very good at producing flat freq response).

I was able to equalize the V1 audio track in Vegas to sound almost identical to the radio professional recording, so it's not that bad, after all. However, it can only work provided the audio is free from any handling noises, hums etc - otherwise, gaining up lower bands by more than 10 dB over quite a considerable bandwidth would inevitably bring the noises up, rendering the footage useless; the bottom line being that the V1 lacks in lower freq response for sure.

Just take a look at how much I had to equalize!

[Shawn McCalip]

Originally Posted by Piotr Wozniacki

- the radio recording is by far reacher in lower frequencies (which confirms the claims of the V1 not being very good at producing flat freq response).

Wouldn't this be more of an issue with the microphone? Granted, I don't know the technical intricacies of what goes on when the V1 writes audio data to tape, but I would think it would write what it "hears".

It would be a shame to have a camera like that where a high quality microphone could possibly be useless.

[Piotr Wozniacki]

Of course the microphone is an important link in the chain, but I have a lot of references on the internet that this model (Edirol CS-50) is renowned for being capable of 50Hz-20kHz +/-3dB, so it isn't likely to be the weakest link in this regard.

I'd like to stress though that the overall sound quality is good enough to get equalized very easily, and after bass boosting is no worse than the professional audio recording I'm comparing it to. I wonder, how do other camera of this class compare?

[Christopher Lefchik]

Piotr, thanks for sharing this information.

Wouldn't it stand to reason that boosting the low end would also amplify any background noise present in the audio chain? Background noise that would otherwise be at the normal level were the bass roll-off not present? If I'm reading the EQ graph correctly, you had to boost the low end audio by as much as 14 dB.

[Piotr Wozniacki]

Yeah, that's exactly what I stated in the original post. But then again, if there really is an unusually high bass roll-off that weakens the bass content of music being recorded, for instance - it'll also weaken the handling noise, won't it...Who knows, perhaps this is the purpose of the roll-off? Cause otherwise, I can't imagine why couldn't the V1 offer a flat freq response, when even the chaepest audio recording devices can?

[Christopher Lefchik]

Well, yes, a low-end rolloff filter would reduce handling noise. What I meant by background noise, however, was any noise inherent in the camera's audio circuitry and processing.

Really, though, I don't understand such a big rolloff. Like you said, why can't it have a flat response as is the case with even cheap audio recorders? Is such a rolloff natural with any current audio DSPs? Or is this something that would have to be added purposefully? If so, why wouldn't it be switchable by the user on such a pro broadcast camera?

The inclusion of pro audio features such as XLR inputs would tend to suggest that the V1U should handle audio decently. As such, the inclusion of an unswitchable high-pass filter doesn't make sense to me.

[Brian S. Nelson]

Were all of microphones placed next to each other? My first guess would be that the difference is explained by each microphone's placement within the room (e.g., relative to walls etc.) and not by the microphone's or V1's frequency response. Even a small change in position can cause a large change in low frequency response in many rooms.

[Christopher Lefchik]

Piotr, so that we could eliminate as many variables as possible, would it be possible for you to run a test? My suggestion would be to feed an audio test signal into the camera, first with the XLR inputs at line-level, then mic-level. I would suggest recording with the camera in DVCAM/DV mode so that the audio is recorded in uncompressed PCM format. Then you could capture the video and analyze the audio frequency response.

[Piotr Wozniacki]

Originally Posted by Brian S. Nelson

Were all of microphones placed next to each other? My first guess would be that the difference is explained by each microphone's placement within the room (e.g., relative to walls etc.) and not by the microphone's or V1's frequency response. Even a small change in position can cause a large change in low frequency response in many rooms.

Yes, the two radio mics were placed 2 meters away from where my tripod was located. But let me express my reservations for one more time: I've no idea if and how the radio recording was processed before I got it on a CD; it's quite possible it was also equalized in one way or another! One thing is certain: the frist time I heard it, I knew it was better in the bass department than my own. However, this is by no means any proof that the V1 has indeed a roll-off at 1200 Hz by -14dB!

[Christopher Lefchik]

Originally Posted by Piotr Wozniacki

However, this is by no means any proof that the V1 has indeed a roll-off at 1200 Hz by -14dB!

Whatever the specifics of what may be happening in the V1U's audio system, you did say in your first post that "the radio recording is by far reacher in lower frequencies (which confirms the claims of the V1 not being very good at producing flat freq response)."

Would you be willing to try the test I suggested to try to discover exactly what the V1U's audio frequency response is?

[Douglas Spotted Eagle]

it's already been done. More than once. Using both test tone generators and noise.
The FUD post that is here on DVInfo.net contains some of that discussion and result.

Christopher, if you're reading and accepting of that information, then the only test result that will likely satisfy you is one you take yourself.

The V1u, given a flat tone, at a standard level, will reproduce that tone. Given the variables of a microphone, room tone, and whatever other variables may be introduced isn't a test, it's a guess.
Putting in an oscillator sweep produces fairly accurate reproduction up to about 16k and down to approx 80Hz. This is typical of compressed formats.

[Christopher Lefchik]

Douglas, thanks for the response. Could you point me to the discussion you are referencing? I must have missed it somehow when I did a search.

[Chris Hurd]

Originally Posted by Douglas Spotted Eagle

The FUD post that is here on DVInfo.net contains some of that discussion and result.

Originally Posted by Christopher Lefchik

Could you point me to the discussion you are referencing?

Indeed, if there is a FUD post here on DV Info Net, then it needs to be withdrawn from public view. We're working hard to make this site a FUD-free zone, so if that sort of thing is happening here, it should be reported so it can be excised. Thanks in advance,

[Douglas Spotted Eagle]

My apologies to all, the FUD post had already been removed from public view (and forgotten).
The thread had been closed by one moderator and moved by another.
The edited version of the original thread may be found here

[Piotr Wozniacki]

Originally Posted by Christopher Lefchik

Whatever the specifics of what may be happening in the V1U's audio system, you did say in your first post that "the radio recording is by far reacher in lower frequencies (which confirms the claims of the V1 not being very good at producing flat freq response)."

Would you be willing to try the test I suggested to try to discover exactly what the V1U's audio frequency response is?

Christopher,

Sorry I didn't respond earlier. No, sorry - I have no testing facility or time for it; it's my eyes and ears I always trust. The picture from my V1E is gorgous, and the audio can be equalized to sound exactly like a pro recording. In fact, this has been the point of my posting: be aware that - should you expect to get some hi-fi music on tape - you're gonna have to play with it in post. The good thing is it can be done, and I'm happy with it. BTW, should I trust those many who say the V1 audio is also too low, I'd probably have turned the gain manually all the way up, not leaving enough room for equalization. I didn't (it was manual, but merely at 6-7) - and the recording is very loud, no distorsion, clipping etc. And possible to equalize, so what's the big deal?

With regards to your suggestion on any low-frequency inherent noise: no, there isn't any. Mind you, the music I recorded was quiet, chamber music (just violin and guitar), and yet - after boosting the basses up with as much as 14 dB - no hum or anything similar is audible. Yes, there was a very low frequency noise in my audio (the mic was on the working camera, and the DR60 drive was attached to it, too), only audible when using a high-end home theater system with LFE on and a subwoofer; you can see on my graph I cut it away as well (below some 40 Hz). If the V1 audio was that prohibitive on basses as claimed by the FUD posts mentioned above, nothing of this kind would ever get to tape!