[sdiy] Combined output / headphone jack?

[brianw]

It's possible that a slight amount of distortion will be added when the TS plug is inserted, but it depends upon the circuit. At least these are things that recording studios worry about when considering the best way to wire up gear.

For output that are designed to be balanced TRS, but which also support unbalanced TS connections, I have seen some manufacturers warn that the unbalanced mode loads the output more due to the shunt, and that can cause minor distortion issues. But a circuit for automatic detection of headphones versus unbalanced single-channel (Right only) might not have quite the same loading issues.

Maybe the NE5532 circuit could be modeled in SPICE with the 220 Ω load?

Brian


On Oct 14, 2024, at 1:03 PM, Neil Harper wrote:
> On 2024-10-14 15:42, Andy Lambert wrote:
>> The Prophet VS does this. The Left jack is Left/Phones and the Right
>> jack is Right/Mono. I haven't looked into the implementation but the
>> schematics are widely available.
> 
> thanks andy, here are the schematics:
> http://www.retrosynth.com/docs/pvs/pvs_service.pdf
> 
> output section on page 11.
> 
> looks like the stereo output and headphones are being driven by the same
> circuit, NE5532's with 220 ohm series resistors. and if I understand the
> normalizing properly, the "shorting" situation I was worried about only
> happens if the LEFT/PHONES output is used with a TS cable without a
> cable in the RIGHT/MONO jack. even then there's still the 220 ohm series
> resistor in place so it's not even a short.. wonder if the 5532 would care?
> --
> /// Neil Harper
> /// Every Wave is New Until it Breaks