Here is one that you may be interested in - https://www.diyaudio.com/community/threads/omicron-headphone-protection.399585/
The Omicron project is a purely commercial one. Thus, I am not interested in "spectacular" achievements with unrealistic measurements.
This one works well, though I would not use it for balanced. For that, I would use Kevin Gilmore's protector board.
https://www.amb.org/audio/epsilon12/
https://www.amb.org/audio/epsilon12/
Omicron's DC protection circuits are not entirely commercialist, Alex has published schematics and I don't think there is any prohibition against making your own boards based on them.
There are many examples of protection circuits for power amplifiers, but most of them use the Vbe of the transistor as the threshold and are about ±0.6V or more, too high for headphones.
With a circuit using the LM336, you can freely set the threshold and time constant to suit your headphones.
A circuit using an inexpensive and easily available comparator would be a good reference.
There are many examples of protection circuits for power amplifiers, but most of them use the Vbe of the transistor as the threshold and are about ±0.6V or more, too high for headphones.
With a circuit using the LM336, you can freely set the threshold and time constant to suit your headphones.
A circuit using an inexpensive and easily available comparator would be a good reference.
Here is another one: SHPP by XEN.
@mason_f8 is right, with the full schematic published, anyone can build Omicron DC protection. You can do it on a perf board, design your own PCB, or sign up for the latest Omicron GB and get one I designed for you.
@mason_f8 is right, with the full schematic published, anyone can build Omicron DC protection. You can do it on a perf board, design your own PCB, or sign up for the latest Omicron GB and get one I designed for you.
Suposing your headphones are 32 ohm, a 470uF electo bypassed with, say, a 10uF unit will not degrade notoriously the sound while it prevents the DC at the output.
I use this, a DC protection designed by @miro1360 for the TDA1541A DAC (slightly modified) and a small Mute circuit of my own design with a 5s delay. Everything is powered by a separate +-12VDC power supply. With the 100k trimmers in NFB, I set the protection to turn on at 250mV DC.
Attachments
The blue led at the input are protection against excessive voltage (+-2V), I had that on hand. I don't recommend Schottky diodes, but you can put two 1N4001 or something. Blue LEDs work with very low currents, that's why I took them primarily. For example, two zener diodes 1V5 can be used, but they are connected in reverse and in series. The headphone amplifier has a +-15V power supply, so I thought that the OPA input should be protected.