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Working with Hard Drive Hum/Noise

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Jordan Wolf
Working with Hard Drive Hum/Noise
on Nov 24, 2008 at 6:44:31 am

Hi All,

This is my first post here, but I've browsed around and seen some good stuff. I myself am not an audio professional, but I figured some of you might have encountered a similar problem.

For the film I am working on, we had to record the audio to the camera. The camera is hard drive based, but on every recording there is a high-pitched, almost multi-band whine. The whine is not a mic problem since it occurs with both the shotgun mic as well as the wireless and even when there is no audio signal present.

I have tried a number of methods to lessen the whine and have not been pleased with the results as it takes away too much from the voice.

Two questions:
1. What has caused this whine/noise?

I'm sure one of the last things the video camera manufacturer thought about was audio, so I wouldn't be at all surprised if the answer comes back as "it's a video camera, not an audio recorder".

We're working on getting a standalone portable audio recorder (Sound Designs), but if the whine occurs with our camera's HDD-based system, why would it not be the same with the HDD system in the audio recorder?

Just some thoughts...onto the next question.

2. What have you found (other than ADR, etc.) is the best method to remove this whine/noise?

Brief Equipment List -

Camera Used: JVC GY-HD250U
Recording Medium: ProHD 100GB HDD
Microphones: Sennheiser MKH60 & Sennheiser ew100ENG G2
Mixer/Preamp: Shure FP24

All connections are balanced and levels between the mixer and camera are calibrated to 0dBu @1kHz. The batteries were fresh and wireless frequencies had been carefully allocated for the area. Any other questions, feel free to ask.

Thanks in advance for any insight.

Wolf
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Ty Ford
Re: Working with Hard Drive Hum/Noise
on Nov 24, 2008 at 1:14:31 pm

Hello Jordan and welcome to the Cow Audio Forum.

[Jordan Wolf] "I have tried a number of methods to lessen the whine and have not been pleased with the results as it takes away too much from the voice.

Two questions:
1. What has caused this whine/noise?

>>I'm going to guess, the hard drive motor brushes.

I'm sure one of the last things the video camera manufacturer thought about was audio, so I wouldn't be at all surprised if the answer comes back as "it's a video camera, not an audio recorder".

We're working on getting a standalone portable audio recorder (Sound Designs), but if the whine occurs with our camera's HDD-based system, why would it not be the same with the HDD system in the audio recorder?

>>I think you may mean Sound Devices, not Sound Designs. It is very likely that the noise is both internal and external. Internal means any mic or mixer attached to the camera will be problematic. External means physical noise generated by the camera that you can hear while standing near the camera. This is not all that unusual and is seldom a problem. If you put the camera into record in a quiet room, can you hear it while standing next to it? Sony Digital betacam cameras are pretty noisy, but they have been used for years.

The Sound devices 744T and 788T are remarkably quiet with exceptionally good preamps. When I reviewed the 744T, I purposely under-recorded the audio with peaks at -30 dB. I transferred the audio to Pro Tools and normalized the file to have peaks at -.5 dB. While there was some noise, it was still usable. Very impressive.

Just some thoughts...onto the next question.

2. What have you found (other than ADR, etc.) is the best method to remove this whine/noise?

>>There are a number of noise reduction programs and the good news is that your noise is probably continuous, therefore, easier to reduce. Mac's Soundtrack Pro is good and comes with FCP. Izotope's Rx is good.

Brief Equipment List -

Camera Used: JVC GY-HD250U
Recording Medium: ProHD 100GB HDD
Microphones: Sennheiser MKH60 & Sennheiser ew100ENG G2
Mixer/Preamp: Shure FP24

All connections are balanced and levels between the mixer and camera are calibrated to 0dBu @1kHz. The batteries were fresh and wireless frequencies had been carefully allocated for the area. Any other questions, feel free to ask.

Thanks in advance for any insight."


>>What you're telling us leads me to believe you were operating the system correctly. I can't say for sure because I wasn't there. It would be interesting to know if anyone else has had noise problems with this external hard drive. There is the possibility that the individual hard drive is defective. If there is another way to record with the camera and the noise is not present, then you know it's the hard drive or, at the very least, the interface.

The drive you mention looks a lot like a Focus Enhancements Firestore. I don't know if they OEM'd it for JVC or if JVC made it themselves. I have a FS-4Pro for standard DV. The first year was not a pleasant experience. Not for noise problems. I hear others are quite happy with theirs. Maybe I just got a lemon. The replacement they sent last time seems to be working, but I've only used it 3 times because of the bad first experiences. Some minor noise, but OK for shooting even in the relative quiet of my recording studio with external mics and a Sound Devices 442 mixer.

Here's a clip:http://idisk.mac.com/tyreeford-Public/GuitarsOfPikesville/JoshGifts.mov

Give it a bit of time to load up. Sounds pretty good, right? I have very good mics and the Sound Devices 442 preamps are very good.

Having said all of this, Sound Devices 744T and 788T are stone quiet and sound a lot better.

Hope this helps.

Regards,

Ty Ford


Want better production audio?: Ty Ford's Audio Bootcamp Field Guide






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Jordan Wolf
Re: Working with Hard Drive Hum/Noise
on Nov 24, 2008 at 7:28:31 pm

Thanks for the advice.
I haven't yet had the chance to listen to the camera by itself in a quiet room, but I'll make sure I do sometime soon.

I recommended the Sound Devices 788T to our advisor, so hopefully that will be coming through soon. With all of the video upgrades going on, I don't want audio to be left behind.

I have been using the noise reduction tool in Soundtrack Pro and it has helped very much, but the whine is still slightly audible above the voices (maybe I'm being too picky, eh?). I have noticed most of the whine is from 5kHz to 12kHz. I also used a parametric EQ (+15dB @ 5kHz-12kHz, narrow bandwidth) to try and flesh out the frequencies but nothing popped out. Sony MDR 7506's were used for monitoring, so the full spectrum was audible.

I thought that it might be the computer's soundcard (sorry, no external interface here) but after soloing an imported music track, discovered that wasn't the case.

I am thinking of posting pre- and post- versions of the trailer to Vimeo so others can hopefully hear what I have noticed and offer soe more advice. I'll post the URL once the trailer is released.

Keep it coming!

Wolf
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