[sdiy] Combined output / headphone jack?

[Mike Bryant]

Mixers often use 4 5532 opamps in parallel with larger resistors to give same drive current.   A short will have no bad effect then.

On 15 Oct 2024 13:23, Mattias Rickardsson <mr at analogue.org> wrote:
On Mon, 14 Oct 2024 at 22:09, Neil Harper via Synth-diy <synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org>> wrote:
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?

On Tue, 15 Oct 2024 at 00:48, grant musictechnologiesgroup.com<http://musictechnologiesgroup.com> <grant at musictechnologiesgroup.com<mailto:grant at musictechnologiesgroup.com>> wrote:
The Pro-One has a mono-for-stereo-headphones/audio output jack, again
with the NE5532:
Stereo headphones can be plugged directly into the AUDIO OUT jack. The
headphones should have a minimum impedance of 600 Ohms,"

As you have pointed out, the signal on the ring will need to handle being permanently shorted to ground if a TS plug is connected.

Many typical headphones will be around 100-200-300 ohms. Feels a bit underspecified to use an op-amp with 500-1000 ohm load capabilities here, perhaps worth making a proper headphone stage for these outputs?

/mr
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