How to Build a Balanced Line Driver for audio testing.

How to Build a Balanced Stereo Line Driver for audio testing.

Testing an amplifier with a balanced input is easy if you have an audio source that has balanced outputs. If you don't, then testing is still possible if you simply short the 'cold' input to ground.
However, to fully test an amplifier with balanced inputs, you really need to test it with a balanced source, and this is sometimes a problem if you want to use a signal generator, or single-ended music source.

This simple project is meant to rectify that problem on my work-bench. It accepts an RCA input and produces a balanced signal through an XLR socket, with relatively little distortion or degrading of the signal.

Elliot Sound Products has an excellent write-up on this circuit, so have a look for yourself:
sound.whsites.net/project51.htm

See a series of 'Restoration Building Blocks' videos on detailed steps in the restoration process of tube radios and amps:
youtube.com/watch?v=7xvTGd4ysRE&list=PLy5M_…


See also playlists on some other completed restoration projects.

PHILIPS BX750A:
youtube.com/watch?v=i8U9Lteja5o&list=PLy5M_…

TELEFUNKEN OPUS 2114:
youtube.com/watch?v=_HO2bjY5vuw&list=PLy5M_…

SABA UW-175-Z 3D:
youtube.com/watch?v=cca4i60ZLw4&list=PLy5M_…

GRUNDIG 1070:
youtube.com/watch?v=i4J5l0fwhko&list=PLy5M_…

SCHAUB-LORENZ GOLDY 58 type 3020:
youtube.com/watch?v=RSbt7qVed78&list=PLy5M_…

BUSH VHF64:
youtube.com/watch?v=U--6JymkQ1M&list=PLy5M_…

GRUNDIG 3060A:
youtube.com/watch?v=7x2sK2GSYeE&list=PLy5M_…

TELEFUNKEN OPERETTE 8:
youtube.com/watch?v=5IsACM0mPzs&list=PLy5M_…

GRAETZ SUPER 171W:
youtube.com/watch?v=MhG-CH0gqm4&list=PLy5M_…

LOEWE-OPTA MAGNET 3737W:
youtube.com/watch?v=ZSZBJ5sKQm8&list=PLy5M_…

BRAUN ATELIER 3:
youtube.com/playlist?list=PLy5M_tA9ux7L3k5nPRvr…

LOEWE-OPTA TRUXA STEREO 4741W:
youtube.com/playlist?list=PLy5M_tA9ux7KhVk0KqPx…

GRAETZ COMEDIA 616:
youtube.com/watch?v=fwmW9k3TwNE&list=PLy5M_…

SABA FREIBURG W2:
youtube.com/playlist?list=PLy5M_tA9ux7IqvS-LshU…

GRAETZ MUSICA 4R417:
youtube.com/playlist?list=PLy5M_tA9ux7Ios98E59d…


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CAPACITOR LEAKAGE TESTER:
youtube.com/watch?v=0pySErvzUIY&list=PLy5M_…