# I need to keep one of my input signal of my mixer intact

I'm currently working on an audio circuit.

I'm using a simple mixer to mix two audio signals together. It works well enough for now.

Here is the circuit :

simulate this circuit – Schematic created using CircuitLab

Yet, I would like to be able to have an unmodified version of my in1 signal.

• Maybe this is because I'm a newbie, but am I wrong to consider that this circuit makes it impossible to keep my in1 signal intact?
• Do I need to split it before mixing it or use a more complex mixer?
• Is there an easy way to do that?
• That's a pretty poor way of mixing. A summing amplifier would be better and if you use a quad opamp you could use two of those to buffer your input signals first, making the question moot. – Unimportant Feb 4 '19 at 11:20
• @Unimportant what op amp would you use for a simple buffer/unity gain circuit ? – Vincent Perez Feb 4 '19 at 16:16
• I'd use a ne5532. Because that used to be the go to audio opamp and I have a lot of them. There's probably some better ones out there by now tough. – Unimportant Feb 4 '19 at 16:32
• @Unimportant I'll try to get my hands on some to test it out. I might have TL072 lying around, would that be ok ? – Vincent Perez Feb 4 '19 at 17:26

Just take the signal from where you have put your in1 label. Audio signals are typically very low impedance, much lower than your 4.7 k divider. The divider will not affect in1 in any significant way, so the signal at the in1 point should remain as it were before modification.