July 7, 2015 at 6:12AM

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Noise issue with GH4 and external recorder

Hi guys,

I recently bought a Tascam DR-70D to use with my GH4. It produces really high quality audio but my big problem is that when I attach the camera out on the Tascam to the mic input on the GH4, I am getting a lot of noise, or 'hiss'.

I emailed Tascam and they said that it shouldn't be an issue with the 70D and to try different cables - I've tried 3 different cables and still getting the hiss. They mentioned that it might be something wrong with the camera settings; I've played about with that and still nothing. Sound works perfectly when plugging a mic straight into the GH4.

Does anyone know of any solutions? It's kind of a pain not being able to use the Tascam as a pre-amp.

Thanks muchly!

Paul

11 Comments

It's a design defect with the Tascam DR-70. The Tascam DR-70 recorder that has a noise-floor problem when recording from the 3.5mm MIC level out, but this can be fixed with a 25 dB Sescom attenuation cable. Here's the cable that fixes the problem...

Sescom Line to Microphone Attenuation Cable for HDSLR Cameras
http://www.bhphotovideo.com/c/product/746645-REG/Sescom_LN2MIC_ZOOMH4N_L...

To use this cable you set your Tascam recorder to output a LINE level signal, and then use this Sescom cable to bring down the signal strength to something that your camera can record.

Using my Panasonic GH4 with my DR-70 recorder I am getting a noise-floor level of -70 dB RMS, which is the noise-floor limit of the GH4 camera audio. ( it's about the same noise-floor as a Zoom H4n recorder )

July 7, 2015 at 8:22AM

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Guy McLoughlin
Video Producer
32774

Fantastic, thanks. Do you reckon this is something that can be fixed in firmware? The reply from Tascam seems to me that they're unaware of this problem.

July 7, 2015 at 12:05PM

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>>>Fantastic, thanks. Do you reckon this is something that can be fixed in firmware?

In theory, yes. But I doubt Tascam will do anything until enough of us complain. I'm ok with having to use a special cable to connect my camera to the DR-70, but it would be nice if this could be fixed by Tascam.

BTW, the internal 48 kHz 24-bit recording by the DR-70 has a noise-floor that is 10 dB lower than the GH4. ( it's -80 dB RMS ) I consider any recording with a noise-floor of -60 dB RMS or better to be professional quality, but it's very handy to have the extra dynamic range when you record in case you need to boost the volume in post. ( i.e. You accidentally record your audio 15 dB too low, you can then fix this in post by boosting the volume by 15 dB, and the -80 dB noise-floor gets boosted to -65 dB which is still in the professional audio quality range. )

July 7, 2015 at 3:56PM, Edited July 7, 3:57PM

0
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Guy McLoughlin
Video Producer
32774

Yeah, it's not a big issue really. I've just ordered the Sescom cable so should be up and running when it arrives.

The internal recording of the DR-70 is fantastic. I basically got it for high quality sound when needed, as well as using professional mic's that use XLR cables. Although I see myself using the GH4 audio when I get the attenuation cable, as it'll save time in post and I presume it'll sound good for most purposes.

July 7, 2015 at 5:51PM

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For small quick turn around jobs I will use the internal GH4 audio. No problems at all.

Here's a quickie interview I shot back in 2012 with my hacked GH2 using audio from a Sennheiser G2 wireless handheld mic. The GH2 has no headphone out, so I could not monitor what I was recording, but I had shot many times with this rig, so I knew how to make it work.

Ronnie Burkett Interview
https://www.youtube.com/watch?v=wqVCP7MlCBY

The audio from the GH4 is a nice step up from GH2, so it's totally usable for professional work.

July 8, 2015 at 8:23AM

3
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Guy McLoughlin
Video Producer
32774

(duplicate)

July 8, 2015 at 8:23AM, Edited July 8, 8:23AM

8
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Guy McLoughlin
Video Producer
32774

I just got my Sescom cable in the post. Seems to make a massive difference. Although, I still seem to be getting a bit of hiss coming through. This is avoided when the GH4 audio is right down to -12dB, but then the mic level is too low. Would you be able to share some of your settings in both the GH4 and DR-70D? I'm testing using a Rode NTG-2.

Also, just wondering if you use an external USB battery to power the DR-70D? The battery life doesn't seem particularly good with AA's.

Thanks again for the help.

P.S. Interview sounds great!

July 15, 2015 at 6:22AM

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I'm on vacation right now so I can't check this, but I think the Tascam DR-70 allows you to adjust the LINE OUT signal level from the 3.5mm socket. I'm going from memory, but I think my best settings for this set up was...

GH4 audio level set to -12 dB

Tascam DR-70 audio level set to -10 dB LINE OUT

I haven't tried powering the DR-70 with USB power, but there are some really good portable USB batteries on the market that should be able to power it all day. ( I own two of these batteries, so I'll have to try testing how long I can run the DR-70 on USB power )

Here is the USB battery brand I've been using for the past year...

ROSMOSS SAILING Series
http://www.romoss.com/powerlist.php?SortID=10

What I like about this brand of USB batteries is that they put out 2.1 amps so they will charge a phone or a tablet really fast, and they use Samsung batteries which seem to be better made than the generic batteries.

July 15, 2015 at 1:25PM

0
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Guy McLoughlin
Video Producer
32774

Great. Thanks very much.

Sorry to bombard you with all these questions, I appreciate your help a whole lot. One more just... there is a setting for 'wide' on the Tascam, as a percentage; what should this be set at?

OK, maybe not just one more... I tend to need the gain set to 'high' in order to get a decent signal. Is that normal?

As you can see, I'm only beginning to learn more about audio!

Thanks again.

July 16, 2015 at 10:48AM, Edited July 16, 10:49AM

4
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>>>I tend to need the gain set to 'high' in order to get a decent signal. Is that normal?

More Gain = More Noise

You're using 'high' gain because the signal from your mic isn't very strong. I would recommend using a lower gain setting and then raising the volume of your recording with your audio editor.

July 16, 2015 at 11:15AM

1
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Guy McLoughlin
Video Producer
32774

I have the same setup. Hence same low output. Ntg2 Tascam 70d and it does seem to need some db push in post. Thanks for the discussion.

February 1, 2016 at 6:41AM

2
Reply
matthew
Youth Pastor
74

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