Zoom H4n & Magic Lantern? at DVinfo.net

Sean Seah · June 22nd, 2009, 09:19 AM

I read with great interest of the Magic Lantern. I notice a lot of folks using the H4n and I was wondering if it can be used like the juicelink / beachtek as a pre amp? Its a lot more handy and comes with a lot more features. My idea setup would be to use the onboard mic for stereo recording via the 5D2. I am not sure if this can be done?

Jon Fairhurst · June 22nd, 2009, 10:09 AM

It would be possible to patch the Zoom into the 5D2. You would connect the headphone output to a pad (two resistors per channel to lower the voltage from headphone to mic level) and then to the 5D2. You would then need a headphone amp from the 5D2 to your headphones. It's a bit more complicated, because you need to ensure that you are recording on the Zoom, and that you have the headphone output level set properly.

There's one additional problem. The 5D2 provides power on its mic input for electret microphones. You might want to AC couple the devices with a capacitor. Not knowing the impedances and levels involved, it would take some fiddling to find the right values for the pad and cap.

Sean Seah · June 22nd, 2009, 10:19 AM

Yikes.. I'm quite a layman when it comes to audio. I do not have the expertise to have a go at it. I think I'll stick to the indepedant H4n solution first. Thks!

Tramm Hudson · June 22nd, 2009, 10:23 AM

Quote:

Originally Posted by Jon Fairhurst

It would be possible to patch the Zoom into the 5D2. You would connect the headphone output to a pad (two resistors per channel to lower the voltage from headphone to mic level) and then to the 5D2.

If the input analog gain is set to +0 dB, would that be low enough to handle the headphone output?

Quote:

There's one additional problem. The 5D2 provides power on its mic input for electret microphones. You might want to AC couple the devices with a capacitor. Not knowing the impedances and levels involved, it would take some fiddling to find the right values for the pad and cap.

The mic power can be turned off by writing a 0 to the PMMP bit in the SIGSEL1 register. According to spec sheet the input impedence is 30 kOhm and the output voltage is 0.8 x AVDD with a load resistance of 2 kOhm per channel.

Jon Fairhurst · June 22nd, 2009, 12:15 PM

Thanks Tramm,

Given that I'd use a 1.8k ohm series resistor and a 200 ohm load resistor. (The first resistor connects to the H4n output. Its other end connects to the 5D2 input and the load resistor. The other end of the load resistor connects to ground.

If the levels are too low, I'd go with a 1.5k ohm series resistor and a 500 ohm load resistor.

The pad should be close to the 5D2, rather than the H4n to help reduce any interference picked up by the wire. For the lowest thermal noise, choose wirewound resistors, rather than carbon. Make sure to shield it as the wirewound resistors make great antennas!

Jim Miller · June 23rd, 2009, 02:56 PM

Sean, forget about all those resisters, pads and such and just purchase a polyphase hyphadutenator. You can easily attach it between your 5D and the H4N with an ambihelical hex nut. Be care though - these things get looser the more you tighten them. Or - you could just fogetaboutit! :-) sorry, I couldn't resist. I think the devil made me do it.

June 22nd, 2009, 09:19 AM	#1
Sean Seah Trustee Join Date: Sep 2005 Location: Singapore Posts: 1,498	Zoom H4n & Magic Lantern? I read with great interest of the Magic Lantern. I notice a lot of folks using the H4n and I was wondering if it can be used like the juicelink / beachtek as a pre amp? Its a lot more handy and comes with a lot more features. My idea setup would be to use the onboard mic for stereo recording via the 5D2. I am not sure if this can be done?

June 22nd, 2009, 10:09 AM	#2
Jon Fairhurst Inner Circle Join Date: May 2006 Location: Camas, WA, USA Posts: 5,513	It would be possible to patch the Zoom into the 5D2. You would connect the headphone output to a pad (two resistors per channel to lower the voltage from headphone to mic level) and then to the 5D2. You would then need a headphone amp from the 5D2 to your headphones. It's a bit more complicated, because you need to ensure that you are recording on the Zoom, and that you have the headphone output level set properly. There's one additional problem. The 5D2 provides power on its mic input for electret microphones. You might want to AC couple the devices with a capacitor. Not knowing the impedances and levels involved, it would take some fiddling to find the right values for the pad and cap. __________________ Jon Fairhurst

June 22nd, 2009, 12:15 PM	#5
Jon Fairhurst Inner Circle Join Date: May 2006 Location: Camas, WA, USA Posts: 5,513	Thanks Tramm, Given that I'd use a 1.8k ohm series resistor and a 200 ohm load resistor. (The first resistor connects to the H4n output. Its other end connects to the 5D2 input and the load resistor. The other end of the load resistor connects to ground. If the levels are too low, I'd go with a 1.5k ohm series resistor and a 500 ohm load resistor. The pad should be close to the 5D2, rather than the H4n to help reduce any interference picked up by the wire. For the lowest thermal noise, choose wirewound resistors, rather than carbon. Make sure to shield it as the wirewound resistors make great antennas! __________________ Jon Fairhurst

June 22nd, 2009, 10:19 AM	#3
Sean Seah Trustee Join Date: Sep 2005 Location: Singapore Posts: 1,498	Yikes.. I'm quite a layman when it comes to audio. I do not have the expertise to have a go at it. I think I'll stick to the indepedant H4n solution first. Thks!

June 23rd, 2009, 02:56 PM	#6
Jim Miller Major Player Join Date: Jan 2007 Location: Tampa,Florida Posts: 236	Sean, forget about all those resisters, pads and such and just purchase a polyphase hyphadutenator. You can easily attach it between your 5D and the H4N with an ambihelical hex nut. Be care though - these things get looser the more you tighten them. Or - you could just fogetaboutit! :-) sorry, I couldn't resist. I think the devil made me do it.