sound recording problem noctmig (1 Viewer)

[leonardo_simon]

Edit: by process of elimination I think I have found the source of the problem which is the external power supply to the microphone is adding the interference and causing the problem.

So......how do I externally power my microphone without this??? thanks

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I tried to do an all night recording last night but have encountered issues with the recording set up.

Any advice would be welcome especially whether this might be a known issue with the kit etc and how this may be rectified or any potential sources of the problem.

I have a tascam dr-05x recorder, connected to a Rode videomic microphone with the supplied shock mount. The kit was bolted to a table outside the house overnight. Power was supplied with a powerbank going to both the microphone (via usb-c) and the recorder. The recorder breaks the overnight recording into 2GB files, so i've got three files overnight, each one about 4hrs....

The issue is that I'm getting interference big tiime (which I haven't seen before when using for short periods hand held)

1) Bands of interference at 3, 6 and 9kHz
2) 'clicks' every second or so
3) then after about 5 1/2 hours the external sound recording stops and it's just getting the clicks every second



Any thoughts would be most appreciated (or what should I test?) , thanks ever so much

 

[Mono]

I know it is annoying but it actually interfering with your recording. If you are trying to get broadcast quality recordings I can see it would be an issue but if you are trying to id species and establish site presence then does it hinder you?

 

[iveljay]

Try isolating the problem, running recorder on internal batteries and microphone on power bank source, then reverse this and see what happens. Should eliminate something as a source of your problem.
The power bank runs at 5v which may give the microphone a problem as it expects 9v.
Clearly the test doesn't need to take much time, with the interference occurring so regularly.
If you get the interference in both configurations, run a test with both on internal batteries.
It will be interesting to see what happens.

 

[Joop99]

You don't give enough specs on the Rode mic, my guess is that it has USB and TRS as connection options. The TRS can use PIP, so then your power problems are gone. The clicks are a discharge of the membrane which is probably not up to the conditions. Also you might have a problem with the used cables which seems to be capacitive and with the input impedance you get a tuned filter which can pick up anything al the way up to radio transmitters. Had that once, very difficult to find. The video mic is intended for camera equipment and not for a recorder, the difference might be that the recorder does have diifferent input impedance which is not in sync with the mic. When the input impedance of the recorder is too high and your cables a little capacitive then you could have interference of radio transmitters, heating engines in houses, you name it. You can check if this is the case by just grabbing the cable and rub it a little, if you can hear that through headphones on the recorder you have a problem. Further you can't mix usb feeding with analog feeding, it goes wrong on the mass or minus pole. So you have a lot to test...

 

[leonardo_simon]

Thanks — having done some more investigation it seems like the noise/interference issue relates to the USB connection between the power bank and the recorder. I tried all configuration of internal/external batteries. The recorder is fine with the USB power, just that the microphone isn’t.

This is the exact microphone: VideoMic NTG On-Camera Shotgun Microphone | RØDE Microphones!
There’s nothing in the user manual suggesting that it take external power whilst recording so maybe I am expecting too much


@Joop99 please could you explain what the abbreviations TRS, PIP stand for ? That will help my investigations.

 

[iveljay]

Tip Ring and Sleeve = trs the connector has a tip which sends a signal, ring which can send a signal equal to the tip signal but with opposite polarity and a sleeve that acts as a shield. The oppositely polarised versions of the signal make noise cancellation by the receiver possible and this use is known as a balanced connection. TRS connectors may also be used for stereo microphones and receivers using two of the three channels for Right and Left signals. Generally the receiving equipment manual will clarify what it expects from the microphone. In this case the microphone claims to sort this out itself - interesting.

Simpler mic connections are simply TS with recorders that expect a stereo input writing the mono signal to the Left channel unless the menu gives you an option to change this.

PIP = plug in power, where a microphone expects the recorder to supply a 3.5v supply through the standard connecting cable, recorders with just a 3.5mm input usually are supplied with this feature enabled, there is frequently a menu setting to turn it on or off, in most cases, microphones that don't need it are unaffected by it being on.

Your microphone is far more modern than my experience with Rode video mics, so I apologise for my expecting it to use 9v.!

N.B. I see that your cable is in fact a TRRS with an extra ring to make it compatible with mobile phones etc., my experience with other audio devices using these has never led to clicks, being a problem.

 

[Joop99]

Thanks @iveljay for explaining TRS and PIP. The Rode mic does have a very low output impedance. You tried probably the input on the Tascam with PIP switched off. In that mode its switched to line level and does have an input impedance of 18kOhm, that's way too high for a sensitive mic like the Rode with 50mV/Pa. In that case your cable between mic and recorder has to be of very good quality or you get above mentioned trouble with unwanted noises like radio frequencies. And very good quality cables will cost you!
When you switch PIP on, the input impedance drops to 2kOhm, which is normally expected for a mic. With a microphone output impedance from 10Ohm its still high, but far better than 50kOhm. Forget USB on the mic unless you use an USB port on the computer.

 

[Dave Boyle]

If

Edit: by process of elimination I think I have found the source of the problem which is the external power supply to the microphone is adding the interference and causing the problem.

So......how do I externally power my microphone without this??? thanks

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Can you just power the recorder with the powerbank & use plug in power on the recorder to power the microphone?

 

[leonardo_simon]

If

Can you just power the recorder with the powerbank & use plug in power on the recorder to power the microphone?

I don't know -- I might ask Rode -- because maybe the TRRS is already supplying power to the microphone -- and if so then there is no problem. Powerbank for recorder works very well indeed.