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Topic: Problem with contact microphones and Zoom H4n (Read 4527 times) previous topic - next topic
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Problem with contact microphones and Zoom H4n

Hello all
I am new here. I need some help solving a very annoying problem.
I have been recording on Zoom H4n using small piezo discs as contact mics.
I get unwanted buzz sounds that are very low level and occur in a very systematic pattern. It is like a longer buzz followed by three shorter ones.
That happens every 4 seconds or so.
This pattern is the same for all formats from 44.1/16 up to 96/24 but it sounds different when I record in mp3 format.

In my opinion it is the interference I get from H4n when it writes onto an SD Card. At least this is the only thing I can think of.
I tried new batteries, phantom power, staying away from any electrical or electronic devices.

Any ideas will be highly appreciated.

Problem with contact microphones and Zoom H4n

Reply #1 –
Quote
I tried new batteries, phantom power, staying away from any electrical or electronic devices.
What you're describing sounds like interference an I'd be surprised if it was coming from inside the recorder.  (Cell phones are known for making periodic interference patterns.)

Does it pick up the noise without the piezos plugged-in?

Have you tried an entirely different location? 

Are the cables to the piezos shielded?  Have you tried shorter cables?

Quote
I have been recording on Zoom H4n using small piezo discs as contact mics
Piezos are high impedance, so make sure the inputs are configured as high impedance "instrument inputs."  Low impedance mic inputs will reduce the signal (and it will affect the "tone") so that could contribute to a poor signal-to-noise ratio.  On the other hand, the low impedance input is less susceptible to noise than a high-impedance input...

 

Problem with contact microphones and Zoom H4n

Reply #2 –
Thanks for quick answer
I tried many different locations. Very seldom I don't get that noise.
It doesn't pick up this noise if mics are not plugged in.
It doesn't do that when I am using H4n external mics.
Yes. Cables are shielded but not balanced. One of my mics is made out of two piezo discs and it is on TRS jack. This one also picks up that sound.
I haven't tried shorter cables yet.


Quote from: DVDdoug on
Quote
I tried new batteries, phantom power, staying away from any electrical or electronic devices.
What you're describing sounds like interference an I'd be surprised if it was coming from inside the recorder.  (Cell phones are known for making periodic interference patterns.)

Does it pick up the noise without the piezos plugged-in?

Have you tried an entirely different location? 

Are the cables to the piezos shielded?  Have you tried shorter cables?

Quote
I have been recording on Zoom H4n using small piezo discs as contact mics
Piezos are high impedance, so make sure the inputs are configured as high impedance "instrument inputs."  Low impedance mic inputs will reduce the signal (and it will affect the "tone") so that could contribute to a poor signal-to-noise ratio.  On the other hand, the low impedance input is less susceptible to noise than a high-impedance input...

Problem with contact microphones and Zoom H4n

Reply #3 –
Try connecting them not to the XLR input on the bottom, but to the mic input in the back, that is a much higher impedance input (480kOhm instead of 1kOhm).

Sadly, there is no way to eliminate this completely with unbalanced microphones, but doing this will reduce the impact.
Music: sounds arranged such that they construct feelings.

Problem with contact microphones and Zoom H4n

Reply #4 –
I will try that today. Do you think  impedance transforming adapter like Hosa MIT-129 would solve that problem?
Is there a way I could attach an audio sample to this forum?
I wonder if there is a way to clean my recording off these beeps in after production. I tried a Paragraphic Equalizer but could not get rid of it.

Thank you all for great help.



Quote from: ktf on
Try connecting them not to the XLR input on the bottom, but to the mic input in the back, that is a much higher impedance input (480kOhm instead of 1kOhm).

Sadly, there is no way to eliminate this completely with unbalanced microphones, but doing this will reduce the impact.

Problem with contact microphones and Zoom H4n

Reply #5 –
I connected the same mic to the bottom of H4n and the same problem occurred.

But. When I changed SD card for different one the problem went away.
Are some SD cards better than others?



Quote from: klotzek on
I will try that today. Do you think  impedance transforming adapter like Hosa MIT-129 would solve that problem?
Is there a way I could attach an audio sample to this forum?
I wonder if there is a way to clean my recording off these beeps in after production. I tried a Paragraphic Equalizer but could not get rid of it.

Thank you all for great help.



Quote from: ktf on
Try connecting them not to the XLR input on the bottom, but to the mic input in the back, that is a much higher impedance input (480kOhm instead of 1kOhm).

Sadly, there is no way to eliminate this completely with unbalanced microphones, but doing this will reduce the impact.