Hardly DIY : SE to Balanced converter

This is one of those niggly projects that I have been meaning to get around to forever but could never motivate myself to put in the effort.

I have built similar modules into amps in the past as it made sense to integrate them into the build but I have occasionally found the need for a balanced signal without having a balanced source handy.

I went scrounging through the parts bin and found a few DRV134's and slapped this little box together put of scraps.





The power supply is a salvaged DC-DC converter which actually has a very low noise floor. The rest is pretty much as the tech sheet for the DRV134 suggests - buffered input and the chip does the rest.

works as good as it looks.

..dB

 

Why not use audio transformers? Are there advantages?

 

this was extremely cheap - aside from my time which was minimal too. It is more for testing than permanent installation

..dB

 

At different price points the 'best' is not always the same. Cheap transformers have far more distortion then active circuits. It's not until you get to pricey amorphous cores that transformers 'disappear' from the audio chain.

 

Would you consider the op-amp solution better than a Jensen JT-11p-1?

 

I have personally never used the Jensen but I have tested this circuit SE vs real Balanced input and it is very difficult to tell them apart. This is only with headphone gear.

..dB

 

Hi. I’m trying to do a rca to balanced cable, and have found multiple explanations about letting the 3 pin floating or not.
Can someone give a solid advice?

 

It mostly depends on what you are trying to do.

You never want to drive a high current signal to ground ie headphone amplifier balanced out. So if you decided to use a liquid carbon output as a preamp, then leave the negative signal floating or tie it to ground with an appropriate 100k resistor. This applies to making a 4 pin xlr to trs adapter for headphone outputs too. ie do not tie these negative signals directly to ground.

Most people making an RCA to XLR cable are using it between a balanced source (CD player/DAC) where the current output is minimal. In this case it is generally recommended to tie the negative signal to ground. You could use a resistor too but it is not necessary.

The alternative is naturally an SE to balanced converter.

.. dB