Rode NTG-2 onboard Phantom issues at DVinfo.net

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Old May 12th, 2008, 09:53 AM   #1
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Rode NTG-2 onboard Phantom issues

Allright so I bought a Rode NTG-2 and with cable and phantom power on the mixer turned on, the sound is great... But, as soon I turn on the build in Phantom power on the Rode, in order for being able to go wireless, the sound gets choppy. The smallest movements on the boom, create a doppler effect, and with the antishock mount it sounds as if a chopper is flying by.

Is this general only with NTG-2's, or with any self powered mics? I've been testing 3 different NTG-2's straight from the vendor with same results.

I guess expecting that a 1,5 Volt battery can make up for 48 Volt phantom power is silly, but then why do they make mics with that option?

I already checked if the bad sound is caused by the wireless unit, and it's not... Hard wired to the mixer, but turning off the Phantom in the mixer, creates the same problem. Can any one confirm whether the self powered unit on the NTG-2 simply is bad, or if anyone with other brands such as the Sennheiser ME66/K6 have experienced the same thing.

Thanks
Nik Skjoth is offline   Reply With Quote
Old May 12th, 2008, 12:40 PM   #2
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I haven't tried using but the battery yet, I'll have to see if I can duplicate your experience.

I was trying an experience where I was powering a SONY mixer using a battery, and I was trying to see how long that bettery could support it (BIG battery). I had the Rode hooked to one cahnnel and feeing phantom to it, and an AT815 to another, same setup. The limiting factor was apparently that the voltage for phantom fell, and while the AT still sounded good after 90 mins or so, the Rode started getting noise (which I attributed to inadequate pahntom power). I concluded that the Rode likes closer to 48v than the AT needs.
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Old May 13th, 2008, 12:06 AM   #3
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Quote:
Originally Posted by Nik Skjoth View Post
But, as soon I turn on the build in Phantom power on the Rode, in order for being able to go wireless, the sound gets choppy.
The smallest movements on the boom, create a doppler effect, and with the antishock mount it sounds as if a chopper is flying by.
The only thing I can think of is, there's no 48V power switch on the NTG-2. Are you turning OFF the low cut switch on the mic, resulting in low frequency noises and rumbles when you swing the boom. Always have the low cut switched ON. (it's also called the high pass filter)

Quote:
Originally Posted by Nik Skjoth View Post
I guess expecting that a 1,5 Volt battery can make up for 48 Volt phantom power is silly, but then why do they make mics with that option?
The NTG-2 and some other mics have a 1.5V battery option for cameras that don't have 48V available. When you plug the mics into a 48V source, they use a separate internal circuit to enable the 48V. You plug any phantom powered mic in first, then turn its power source on, or turn the camera on. Turn the phantom power or camera off first before unplugging it.

Hope this helps.

Cheers.
Allan Black is offline   Reply With Quote
Old May 13th, 2008, 01:36 AM   #4
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Thanks Chris and Allan

The Lo Cut switch does not have any impact what so ever in this issue.

Youre right there is no power switch in the mic, what Im doing is switching off the 48V power in the mixer, creating the chopping sound.

Im quite amazed that no one else has reported this earlier. It should be quite apparent that there is something wrong.
However Im not looking to find out whether my NTG-2 is broke or not. I know for a fact that all ( or at least 3 out of 3 testet NTG-2's) act the same way. But Id like to know if other brands also do it, since I need the mic for wireless transmission.

Here is how you provoke your mic to act wierd.
Put a battery inside it. Switch off the 48V phantom inside your mixer or camera. Prefferably put the mic on a antishock mount, or simply hold it lightly between two fingers. Aim the mic at something that makes a steady sound. either music or a testtone. If you have a antishock, try to shake your hand in small movements (as if you had parkinsons), then you will hear the shakes of your hand as if you were moving the volume up and down in the same rate. If you are holding the mic in your hand, try move it a few inches towards and away from the sound source in quick movements (just like throwing darts, but not quite as violently). Again, you should be able to hear that the volume increases quite drastically every time you move it closer, and decreases when you move it away (Yes I know that moving a mic closer to a sound makes the volume go up. But we are talking about inches here). Plus. After you stop moving the mic towards the sound, the volume goes down again. So in fact the volume only elevates uppon accelleration.
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Old May 13th, 2008, 10:23 PM   #5
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I am not in possession of my NTG-2 at the moment and so cannot duplicate what you report... but from my experiences I suspect the onboard battery is not up to the power requirement variances you are putting it through. Certainly no expert here, but as I ponder "WHY a battery powered mic sounds better on phantom power" I come to the power draw (remember electrical power is expressed as amps x volts) issues and the fairly quick peak demands of a highly modulated signal or a complex one with high high/low variance that the ramp up voltage divider network that turns 1.5 v into ???v (48?) cannot provide power wise. I'd be interested to know what the experienced hands think.
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