balanced to unbalanced

[gbono]

Not a description of one's mental state these days
What's the best way to provide a good solution for unbalanced (i.e. stereo headphone output) to balanced connection? What are MI amp designers doing to provide an iPad input into their products?

Interesting reading here: http://www.jensen-transformers.com/an/an003.pdf

I noticed that the Behringer 602 mixer has TRS inputs on two channels that say balance or unbalanced but can't find a schematic.

[eschertron]

best way to provide a good solution

I don't know if it's the "best" way - and you're certainly free to question my mental balance - but my "good" solution is to plug into a mixing board's hi-Z 1/4" jack with 1/4" mono (unbalalnced) plug. With a line-level signal, I don't worry about noise. If the board has a pair of RCA jacks (most tape returns are this type) but no 1/4" jacks, I'll use them. I doubt you'll find a mixer today that won't accept unbalanced inputs on any of its channels.

Actually, my cable consists of a 1/8" stereo-to-RCA plugs, with the option of using a set of RCA-to-1/4" adapters I always have handy.

[bob p]

A little confusing, as your thread says balanced to unbalanced, but your post says unbalanced to balanced.

Do you want to build a line driver circuit to convert unbalanced outputs to balanced outputs? ie: for driving long cable lengths or avoiding the 6dB loss that comes with driving a balanced input with an unbalanced singal?

Or do you want to convert a balanced signal back to unbalanced? ie: for accepting a long cable at the receiving end, and putting it into an unbalanced line device?

It used to be that you had to build balanced line drivers with transformers. That gave way to the use of opamps and high-precision (sub 1%) balancing resistors; the success of the match of the balancing resistors would play a large role in the line driver's performance. Today there are driver chips that are specifically designed for this purpose, with precision cut balancing resistors on the die. They're literally a single-chip solution. I've used the TI product to convert conventional HiFi preamps from unbalanced to balanced outputs to drive differential power amps.