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I am very new in Electronics. I have Condenser mic with this following Spec in Short: model HT-D38 (brand HTDZ) Power Supply: Phantom Power 48V/DC3V

It is working on Mixer by 48v Phantom Power very well. but When I am connecting it to Sound card which produces 24V phantom Power it is coming electrical background noise.

I understand it is blame of unsufficient Power supply, I have tried to add several kind of Resistors on out from Mic and Capacitors but anyway the the noise is coming anyway.

Please if somebody can suggest how I can resolve this problem, it is not problem adding something in Circuit it is acceptable for me. Thank you very much in advance for support.

Dato Pilpilashvili
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2 Answers2

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Do note that the microphone seems to be connected to a 'professional' audio plug - which normally means that the plug has 2 signal lines and the shield. The audio is then transported symmetrically over the 2 lines.

At the other end (sound card) you need a balanced-to-unbalanced transformer, else interference will couple into the line.

I've found very little technical information on the HTDZ - none about if the microphone is balanced or not. I just assumed that all 'professional' microphones should be balanced. Also, the XLR connector is for balanced lines. I'd be interested to know how you found if the HTDZ is unbalanced.

Here's good article about balanced lines, and how to correctly 'unbalance' them at the other end. Mostly, this is done by a balanced electronic input (which most soundcards do not have). This article and this, even more complete article have several such circuits.

Note that some articles, including an example in the first article suggest that you can couple a balanced source to an unbalanced input. I would not recommend that, unless you are sure there is no strong interference.

jcoppens
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  • thank you very much for your answer, but there is balanced input on Sound card As well. Can you suggest me any kind of such transformer from unbalance to balance. Please consider that the microphone is unbalanced (with Led light) – Dato Pilpilashvili Jul 10 '15 at 09:01
  • I added more info to the reply above. It was too long to put in the comment. – jcoppens Jul 10 '15 at 14:49
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It does sound like your soundcard is not supplying sufficient voltage (or current?) for the microphone. Putting in any extra components between the card and mic won´t help, most probably the opposite. Neither will any kind of balancing transformer - the mic needs powering.

You could build your own phantom power supply, use the mixer you mention as a preamp, or use something like this:

phantom psu

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