[sdiy] Semi-OT: phantom-powered balanced line driver?

[Magnus Danielson]

From: Ingo Debus <debus at cityweb.de>
Subject: [sdiy] Semi-OT: phantom-powered balanced line driver?
Date: Tue, 10 Oct 2006 19:26:48 +0200
Message-ID: <3D0E45C7-7638-44A0-A759-9B2D386B80A3 at cityweb.de>

> Hi,

Hi Ingo,

> I've bought a nice little electret condenser microphone (for my  
> flute). The mic itself is connected to a belt pack with a one- 
> transistor preamplifier and a 9V block battery. The belt pack is in  
> an unshielded plastic case and a mono phone jack, and thus quite  
> sensible to noise and hum pickup. An ideal solution would be a  
> shielded case and a balanced XLR output. It would also be nice if the  
> thing could be phantom-powered to get rid of the battery.
> 
> Now, how do I get a balanced output? SSM2141? The datasheet of the  
> SSM2141 says passive circuitry in series with the outputs should be  
> avoided, but I need of course series caps to block the phantom power  
> voltage. Is the SSM2141 still a good choice or should I rather use a  
> good old transformer?

First off all, I assume you ment to say SSM2142 (which is the balanced driver,
rather than the balanced receiver SSM2141). Personally I think it is shooting
over the top and not very well fit.

I would use rather classic op-amps for the drive, such as the NE5534 or NE5532.
I would avoid using the capacitor solution if I can and use a propper
transformer and take out the voltage on the center-tap. Regardless if you drive
the transformer single-ended or diffrentially you want a series-cap to avoid
saturating it with DC.

But that's me.

Cheers,
Magnus