Analog audio bypass

[jbernardino]

Dear all,
Hope to find you well!
I am developing a system to control audio and I would like to create a true bypass system but I don't want to do it with a physical switch. I am looking for something like a transistor based or relay. Any advice?
The functionality that I pretend is something like: if the battery of the system goes down, the system switch via the true bypass direct to the output, if I have battery goes via other bus.

Any ideia of components to do it ?
Thank you for your time.

[bebop]

Hi,

To my understanding, it can only be achieved with a physical switch be it thermal switch or actuator . Gears that have an electronic true bypass always require power to switch, so when the power is out, there is no signal going through, and when the power is on, the physical thermal/actuator can be fed in to operate .

Questions would rather be, imo, running true bypass is sometimes degrading the signal to the last buffer/preamp it has to come through and be reamped, because in a chain, the length can go up the cables' ability to support signal impedance . It sounds counter-intuitive, however keeping the signal hot all along is easier to make the final big sound .

Maybe someone else will have a better solution.
You're welcome

[BertKoor]

It must be a relay, semiconductors always need power. Like regular switches these do exist bipolar. Have two per channel. One switching the input side, the other switching at the output of your circuit. Then it truely bypasses (when correctly connected)

[jbernardino]

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Thank you for your opinion, I did a fast diagram of what I pretend to help you understand.
https://ibb.co/gVrvZv9 (https://ibb.co/gVrvZv9)

I have a signal amplified where I usually connect my headphones.
I pretend to create an AUX input to them. I have a digital audio signal from a Bluetooth Device that I convert to analog with a SGTL5000 codec. I am thinking to pull down the signal amplified, mix with the aux signal within the audio codec and send both already mixed to the output.
When I turn off my aux in, I just want have a bypass tu send the amplified signal direct to the output.

If I have a possibility to mix both amplified signals I just can keep the amplified signal direct to the output and just mix the aux in when I have signal from there. Is it possible?

Many thanks for your time

[BertKoor]

That diagram seems ok. Good luck with the project.