Opamp at 5V into power amp at 18V?

[HankMcSpank]

5V Opamp connecting to a higher voltage power amp?

I've a small preamplifier, which has an opamp powered at +/- 5V supply.....the output of this opamp feed into an power amplifier powered at 18V

The input pin of the power amplifier is biased at 1/2 VCC ....9V.

The output of my opamp is biased at 0V ...so I need aDC blocking cap between.

What I'm worried about is at power up, the input to the power amplifier is going to slew up quickly to 9V DC bias - will this power up voltage will feed back through the blocking cap and zap my opamp output stage?

Is there a way of protecting against this power up voltage spike?

 

[alexan_e]

It seems strange to me that the power amp has a dc bias in the input, it should at least have a buffer stage.
I have never seen a power amp with a biased input, you should use symmetric power supply for audio.

Alex

 

[danf@radialeng.com]

Put a 100 to 470 ohm 1/4W resistor in series with the DC blocking capacitor to limit the inrush current and you will be fine. I do this for 48V DC differentials and it works fine.