Anybody used a "Line to Mic Attenuator Cable" on the GH5?

[JDW]

Have any of you used a "Line to Mic Attenuator Cable" (passive, resistive padding) with your GH5? My SONY PCM-D100 audio recorder's Line Out is too hot for the GH5's Mic input even when I turn the GH5's audio input gain all the way down. The problem is, I don't know the spec on the GH5's Mic input and I can't find it in the GH5 documentation either. The SONY PCM-D100's Line Out specs are these:
• Output impedance: 220Ω
• Rated output level: 1.7 V
• Recommended load impedance: 22kΩ
• Output level: –21dBm to –15dBm

Here is a -50dB attenuator cable on B&H:

https://www.bhphotovideo.com/c/product/813404-REG/Sescom_LN2MIC_50DB_LN2MIC_50DB_Standard_50dB_Line.html

Perfect?  Or would a -25dB attenuator be better?  Do any of you have first-hand experience?  Thanks.

[Orangenz]

On 20/01/2018 at 3:21 PM, JDW said:

Have any of you used a "Line to Mic Attenuator Cable" (passive, resistive padding) with your GH5? My SONY PCM-D100 audio recorder's Line Out is too hot for the GH5's Mic input even when I turn the GH5's audio input gain all the way down. The problem is, I don't know the spec on the GH5's Mic input and I can't find it in the GH5 documentation either. The SONY PCM-D100's Line Out specs are these:
• Output impedance: 220Ω
• Rated output level: 1.7 V
• Recommended load impedance: 22kΩ
• Output level: –21dBm to –15dBm

Here is a -50dB attenuator cable on B&H:

Perfect?  Or would a -25dB attenuator be better?  Do any of you have first-hand experience?  Thanks.

1) A new thread has been started for you

2) you may have damaged the mic stage on the GH5 already. That's a mic input not a line level input.

3) to go from line to mic level you need a D.I. box not just an attenuator. 

4) at the end of the day your recorder is really not designed to do what you are trying to do with it. Record separately, at the same bit rate, sync in post. 

[Grimor]

With MKE600 and Lumix G80 i need to use a impedance transformer cable (Hosa MIT-156) designed to "match 600R output impedance to 2.5K  imput impedance".

Don't know if it will work for you, but it solved my mic-mic impedance mismatch problem.

[no_connection]

Most (from what I have seen) mic input have phantom power, that is why your headphones makes a noise when you plug them into your phone, so plugging a line output into that is not that great. I doubt the mic input have been damaged due to just that as it handles a DC voltage of about 2.3V (think I measured that on my computer) and you kind of run that over the pins while putting it in.

A few resistors and a couple of caps to remove DC would likely be just fine. if you want to make your own cable. There are plenty of L-pad calculators to get the desired dB of damping.

[JDW]

5 hours ago, no_connection said:

Most (from what I have seen) mic input have phantom power, that is why your headphones makes a noise when you plug them into your phone, so plugging a line output into that is not that great. I doubt the mic input have been damaged due to just that as it handles a DC voltage of about 2.3V (think I measured that on my computer) and you kind of run that over the pins while putting it in.

A few resistors and a couple of caps to remove DC would likely be just fine. if you want to make your own cable. There are plenty of L-pad calculators to get the desired dB of damping.

I am somewhat relieved to hear that my GH5's Microphone Input is likely not damaged, but I don't have a Mic with 1/8" cable with which to test it.

The GH5's documentation is seriously lacking details on the Mic Input, but Panasonic sells an optional DMW-XLR1 audio device for the GH5 that provides 48V Phantom power, so I do not believe the built-in Mic Input of the GH5 offers such phantom power output.  (And if you're wondering, I am not interested in buying the $400 DMW-XLR1 because it is bulky and mainly targeting people who want to use XLR Mics, which I do not.)

I don't see how I can effectively use an L-Pad Calculator because, again, I don't know the LOAD IMPEDANCE (which in this case is the GH5's Mic Input).  Remember, I know the spec only of my D100's Line Output:

• Output impedance: 220Ω
• Rated output level: 1.7 V
• Recommended load impedance: 22kΩ
• Output level: –21dBm to –15dBm

The GH5's manual does not give any specifications of the GH5's built-in Microphone Input.  It's probably something low like 680Ω, but that is just a wild guess.  (If it was high like 22kΩ then my D100's Line Output shouldn't clip when fed into that Mic Input.)  So what do you suggest in light of this?

Furthermore, you mention capacitors to remove DC, but from what I see a lot of L-Pad "Line Level to Mic Level" attenuation cables simply have the dual voltage divider resistors.  I don't see that they have the caps inside.  A previous poster suggest I use a D.I. box, but those are just as big and bulky as the $400 Panasonic DMW-XLR1 box.  If I can solve the problem with a short cable (with needed circuitry built-in) that would be the best overall solution.

Further thoughts in light of this would be greatly appreciated.

Thank you.

 

[webrunner5]

Capacitors basically store voltage, they do not reduce it. Resistors do that. Diodes are basically a one way valve, and Transistors are basically a Switch.

[scotchtape]

I've used one from Zoom H6 to GH5.  Works fine. 

One of these, not sure which one. I think -35db

https://www.amazon.com/gp/product/B01GW69IQ2/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

[JDW]

2 minutes ago, scotchtape said:

I've used one from Zoom H6 to GH5...

But do the electrical specifications of your Zoom H6's "Line Out" match that of my Sony D100?  

• Output impedance: 220Ω
• Rated output level: 1.7 V
• Recommended load impedance: 22kΩ
• Output level: –21dBm to –15dBm

[scotchtape]

Honestly in all my years of rigging up ridiculous adapters the only time I've ever heard of that stuff needing serious attention is connecting speakers to an amplifier.  The worst case scenario using that cable with your recorder is that it won't be the absolute best sound quality which you would never notice anyways considering the preamps in the gh5.

I'm not saying it doesn't matter but with consumer level electronics there's no much that can go wrong

I don't know the specs for zoom h6

[IronFilm]

Good news: the new Panasonic GH5S will be the first stills camera ever to accept Line in.

[no_connection]

9 hours ago, webrunner5 said:

Capacitors basically store voltage, they do not reduce it. Resistors do that. Diodes are basically a one way valve, and Transistors are basically a Switch.

A capacitor will indeed store a charge, and by doing that make a voltage potential over itself, thereby making a opposite voltage to that the camera would put out thus canceling it out or "reduce it". It does not need a current through it to keep it there so it's great for removing DC voltage.'

A resistor needs a current through it to make any voltage potential.

 

With L-pad you need output and input impedance to calculate an accurate damping value, however you can guess it and see if it affects it much at all. 100k series with 10k parallel would likely do just fine, at worst you get a little more attenuation than you wanted. Depending on the recorder it could handle any DC just fine, especially when attenuated since current will be very low.
22k with 2k resistor might be less noisy and also load the recorder with what it wants. If you want less attenuation you just use higher parallel resistor.
*edit* you could ignore caps for now as it should be fine.

[no_connection]

12 hours ago, JDW said:

The GH5's documentation is seriously lacking details on the Mic Input, but Panasonic sells an optional DMW-XLR1 audio device for the GH5 that provides 48V Phantom power, so I do not believe the built-in Mic Input of the GH5 offers such phantom power output...

 

To clarify, the phantom power is only 2.3V typically and is there to power condenser microphones that ether have built in FET buffer or just need bias voltage to operate. The purpose of it is the same but on a lot smaller scale.