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GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?

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Joe Bell
GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Feb 19, 2013 at 4:16:41 pm

Hi, I'm about to invest in a Panasonic GH3 video camera. It has a stereo 3.5mm audio input, and I want to know the best way to connect two XLR mics using only passive devices.

My mics are both battery powered (Rode NT2 and Audio-Technica AT899).


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Sam Mallery
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Feb 19, 2013 at 4:35:45 pm

Here's a couple options:

Beachtek DXA-2T

Studio 1 Productions XLR-BP (doesn't mount to camera)

http://www.sam-mallery.com


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Bob Kessler
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Feb 19, 2013 at 5:00:03 pm

As much as folks hate hearing it, you should get a separate audio recorder like the Tascam HD-P2, Marantz PMD-661, Fostex FR-2 or Tascam DR-100. Your sound will be much better.

Yes, it's a little more work syncing the audio in post, but that's been done ever since "The Jazz Singer." And it's a lot easier with a guide track (camera sound) and you can partially automate the process using something like PluralEyes.

If you still want to go direct-to-camera don't forget to look at juicedLink Riggy products as well as the BeachTek stuff.

Peace,

Bob
____________________________________________________________________
Filmmaking is the art of the invisible;
If anyone notices your work you haven't done your job right.


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Vico Prima
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Feb 25, 2013 at 9:38:58 am

Thanks for the information, actually I have same question.


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Ty Ford
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Feb 20, 2013 at 12:36:04 am

Hello Joe and welcome to the Cow Audio Forum.

I wouldn't do it without a mixer in between for many reasons, but if that's what you want to do.....

Try this: all in one, all done. http://tinyurl.com/aswtcrh

Regards,

Ty Ford
Cow Audio Forum Leader

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


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Richard Crowley
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Feb 20, 2013 at 3:52:09 pm

The Rode NT2 is NOT battery powered. Did you mean NTG2?

It is not clear whether your GH3 camera provides plug-in power. If it does, then you need an adapter that blocks this DC voltage from going back into your microphones.


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Eric Toline
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Feb 20, 2013 at 10:17:19 pm

As an FYI, Yesterday I made the OP an adapter (2xXLR-F to 3.5mm TRS, wired unbalanced)cable that allows two mics to connect to the camera.

Eric

"I push the RECORD button and hope for the best"


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Ty Ford
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Feb 21, 2013 at 12:08:33 am

Great Eric,

Did he need one with blocking capacitors?

Regards,

Ty Ford
Cow Audio Forum Leader

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


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Eric Toline
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Feb 21, 2013 at 6:20:06 pm

I didn't a didn't add any BC's since I couldn't find any info about a powered mic connection on the camera. Based on my knowledge of other DSLR's like the Canon's I believe the mic input is unpowered. OTOH if I'm wrong about the powering issue it's never been a factor. OTOOH I only plug wireless hop's into DSLR's as a scratch feed to be used as a sync track with Plural Eyes & the like.

Eric

"I push the RECORD button and hope for the best"


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Bill Davis
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Feb 21, 2013 at 9:18:15 pm

Did anyone ask the OP if that camera has AGC?

If it does, he's kinda scroodged no matter what else he does.

Do the Beachtek outboard solutions still provide pilot tone to try to defeat the AGC?

Just a thought.

Know someone who teaches video editing in elementary school, high school or college? Tell them to check out http://www.StartEditingNow.com - video editing curriculum complete with licensed practice content.


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Craig Alan
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Feb 23, 2013 at 1:52:21 pm

I know you said passive devices but I'm going to suggest this anyway:

http://www.bhphotovideo.com/c/product/764543-REG/Sound_Devices_MIXPRE_D_Mix...

http://www.bhphotovideo.com/c/product/293005-REG/Sound_Devices_XL_3_XL3_Min...

http://www.bhphotovideo.com/c/product/765186-REG/Sound_Devices_XL_CAM_XL_CA...

phantom power, mic input, or line level. great metering. great headphone amp. great preamps. filters, limiters. the only quality mixer that can be mounted under your camera with or without a tripod.
it will significantly improve your audio by being able to turn the cam's preamp way down. calibrates with cam with standard tone. Sound Devices customer service is great. The build quality is great. Very small form factor.

MacPro4,1 2.66GHz 8 core 12gigs of ram. GPU: Nvidia Geoforce GT120 with Vram 512. OS X 10.6.x; Camcorders: Panasonic AG-HPX170, Sony Z7U, Canon HV30/40, Sony vx2000/PD170; FCP 6 certified; write professionally for a variety of media; teach video production in L.A.


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Guy McLoughlin
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Feb 27, 2013 at 5:20:48 pm

The GH3 audio level setting is really an AGC-Boost control, where the AGC boost is +3 dB when the camera is set to 1, and goes up to +20 dB at level 19.

The native noise floor for the GH3 is -66 dB RMS, which is quite good for a DSLR, but you have to set the camera's audio level to 1 and feed the camera a strong -15 dB signal to realize the full 66 dB range. This means you need to use a good external mic pre-amp or mixer to achieve a low-noise recording with the GH3.

On the low-cost side of things, the JuicedLink Riggy RM222 mic pre-amp would be a good match for the GH3. It provides up to 30 dB of clean gain, along with phantom power for professional mics. ( RM222 costs about $330 )

Moving up in price, you might want to take a look at the Sound Devices MixPre-D mixer, which offers a huge range of professional features, but will set you back about $900.

Also, remember to set your GH3 to use the 50 Mbps MOV shooting mode which records audio in uncompressed LPCM format. This mode records a higher quality video image and the best audio this camera can produce.

...One last option is to use a low-cost portable recorder like the Tascam DR-40 which has reasonable mic pre-amps ( just don't go past level 65, or you will start to hear noise in your recordings ) and can supply phantom power to professional mics. The Tascam DR-40 sells for about $140 at B&H Photo in New York.


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Al Bergstein
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Mar 5, 2013 at 3:30:00 pm

What Guy Said. (G). Also, I have a 5Dmkiii and it runs fine with the Mixpre-d when I need two mics. I can turn off the AGC, and I assume that the newer GH3 allows the same, but Guy's thoughts are likely correct. The GH3 seems to be a fabulous camera for the price, a good friend got one.

Question for Ty: I have that splitter cable, but doesn't that cut the signal strength in half also, meaning more gain and likely more hiss? I read that somewhere after buying the cable. Of course, hiss removal is relatively simple these days.

Al


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Bill Bruner
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Mar 6, 2013 at 1:27:53 pm

I have this camera, and I plug powered XLR mics into it all the time. You have to match impedances though. The problem with a straight through adapter is that pro mics are at about 600ohms, while consumer cameras and camcorders are at about 2500ohms.

Joe - I hope you're not getting "hum" with Eric's DIY solution - but if you are, you may want to invest $17 in a Hosa XLR to 3.5mm impedance matching adapter.

Here is my GH3 with a battery powered Audio Technica AT835 and the Hosa adapter. Works like a champ:



Hope this is helpful,

Bill
Hybrid Camera Revolution


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Ty Ford
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Mar 6, 2013 at 1:59:24 pm

Excuse me Bill,

Back in Bell Labs day, that's the way things were. There may (or may not) be mechanical reasons why the connectors work better, but Impedance matching in this case is not an issue.

The thumb rule for impedances is, low to high is OK. High to low is a NO.

Visually, you can flow a low impedance circuit (think 6" pipe) into a high impedance (garden hose) and get a nice flow. If you go high (garden hose) into low (6" pipe) it just doesn't work.

Regards,

Ty Ford
Cow Audio Forum LEader.

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


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Kyle Brandson
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Apr 14, 2013 at 3:10:59 pm

One question,

So are you saying that if I just use a basic converter cable like this:
http://www.amazon.com/HOSA-XLR-Female-3-5mm-Sleeve/dp/B000068NZF/ref=sr_1_5...
I can use a rode ntg 2 with a GH3? I am also thinking about getting this camera and a mic, but I don't want to buy Rode Videomic or the Panasonic microphone as I want to use a good-for-all mic for recording separate audio for example with a boom pole, in quality video making. Just in case I don't have the space or the chance to use a separate recorder like a zoom h4n, I would mount the mic on the camera and record directly on it.

Thanks, Kyle


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Joseph Moore
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Jun 2, 2013 at 9:10:48 pm

My initial experience using powered mics with my GH3 and a Beachtek DXA-2T (an unpowered adapter) has been quite poor. I thought I could save a few bucks since all my mics are powered, but maybe not.

The the GH3's levels turned all the way to 0 and the DXA-2T trim controls wide open I got almost no sound level from a Rode NTG2 or a Shure SM58.

I had to turn the levels on the GH3 all the way up to end up with any signal. Obviously, the noise floor was horrible. Amazingly I was able to rescue it enough in post to be usable, but not a good experience at all.

I don't know what I'm doing wrong, or if some piece in the chain is defective. I've got to do some more testing, but my initial thought is that I need an adapter with power, like the Riggy222.


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Joseph Moore
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Jun 3, 2013 at 7:06:59 pm

So I did a bit more testing today with another powered mic, and it really does seem that the problem is that their just isn't enough juice coming from the mic through the Beachtek to yield much signal.

I left the GH3's levels at their lowest (1) as recommended and did some recordings. Virtually nothing showed on the GH3's on-screen meters, but once I got the audio into Audition there was a clean recording...it's just that the audio levels were very, very low. I was able to normalize them and get a usable recording (better than I got by cranking the gain on the camera) but this is definitely not how you would want to record...if for no other reason than it is virtually impossible to monitor anything while recording.

How does my experience compare with others using other non-amplified adapters?


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Luke Seerveld
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on May 7, 2013 at 6:51:31 pm

I'm not a real sound guy, but sometimes get called upon to record sound for interviews. I record directly to a Zoom H4N or through a Sound Devices 302 mixer to the Zoom. When I was using the GH2 I had a friend make up a cable that went from the tape out on the 302 to a male mini 2.5mm, but with a pad to bring the line level of the mixer to the mic level of the camera. This worked well. Recently, I had a vendor custom make a similar cable for the GH3 from 302 to male mini 3.5mm, but I can't tell if the pad is there.

When I set the camera mic level to 1 or 6 or higher and hit the tone switch on the 302, the same volume appears on the tiny camera audio meters. Why is this? Then it seems like if I go anywhere above 0 on the mixer I get distortion on the camera's recorded audio... there's no headroom.

I'm figuring the pad was maybe not put in after all, but either way, I seem to be missing something. Any thoughts?

Needless to say, I'll continue to record double system to be safe.


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Richard Jett
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Mar 1, 2014 at 1:38:47 am

Guy,
I am trying a audio setup with the Zoom H4n and the GH3. Line out from the zoom to camera mic in but I need a pad. Do you know of a cable that has one?
Thanks RJ


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Ty Ford
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Mar 1, 2014 at 1:47:01 am

Hello Richard and welcome to the Cow Audio Forum.

In the future, it would probably be a good idea to start your own thread in stead of glomming on to an old one.

What's a GH3?

You're trying to send audio from the Zoom to the GH3.

Are you trying to use the Hn4 as a mic to feed the GH3?

What are you trying to do?

Regards,

Ty Ford
Cow Audio Forum Leader

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


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Richard Jett
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Mar 1, 2014 at 11:48:03 pm

Hi Ty,

Thanks for the welcome and jumping here with the newbe.

I was reading a thread on using a Transcam field recorder as a mixer for a HDSLR. The post did not mention on how to get to the camera. My assumption was that the he must of taken a line out feed and inserted a pad between the connections.

I have a Panasonic HDSLR GH3. And I am using the Zoom h4n. So I tried this and, yes, there must be pad put between the line out and the mic in on the camera. My question in my post was where do you find a male mini to male min line with a 30 (20?) db pad.

Thanks Ty, Richard Jett


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Ty Ford
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Mar 2, 2014 at 1:29:47 am

Hello Richard,

You want to use the mics of the H4N as a mixer, with its mics or others?

Regards,

Ty Ford
Cow Audio Forum Leader

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


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Richard Jett
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Mar 2, 2014 at 1:52:35 am

I will be connecting to lav,s to the H4n.


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Ty Ford
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Mar 2, 2014 at 2:08:34 am

Richard,

Lay it all out for me.

Are you using the H4 to record?

What are you up to?

Regards,

Ty Ford
Cow Audio Forum Leader

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


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Richard Jett
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Mar 2, 2014 at 3:13:15 am

I am using the h4 to record the two lav,s and to also send a good quality stereo signal to the camera.


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Ty Ford
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Mar 2, 2014 at 3:37:53 am

Richard,

Something like this?

http://www.markertek.com/Cables/Audio-Cables/DSLR-Audio-Cables/Sescom/LN2MI...

Regards,

Ty Ford
Cow Audio Forum Leader

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


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Richard Jett
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Mar 2, 2014 at 4:30:05 am

Hey Ty, I think that might do it. Thanks so much. Richard Jett


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Rob Dunford
Re: GH3 Audio Input & External Mics - Wiring, Impedance... Incompetence?
on Jul 26, 2016 at 4:17:51 pm

Hi Guy, this is an old thread but it seems you have addressed an issue that came up recently. I have a Panasonic GH3 and a SoundDevices 552. I wanted to connect the mixer out to the GH3, to record audio direct as well as internally.
So using the XLR's on Line Out, with the GH3 audio level set at about 14, awful noise floor and feedback on one of the mics (through the h/p's) Couldn't work it out at first, since 'I assumed' that the audio input would accept line in. Then 'just for fun' I switched the XLR's to mic output level and set the GH3 level at 1. Bloody Bingo! No more noise floor and no more feedback.
So looked at the 552 output settings, seems Mic Out is -20dB@0.078vrms and I'm wondering whether that more or less corresponds to your suggestion of -10dB.
There is the -10 setting, but that corresponds to +6dB@1.5vrms...



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