# Why is there a popping sound (headphone output) when my audio circuit is turned on

**URL:** https://community.electricforum.com/t/why-is-there-a-popping-sound-headphone-output-when-my-audio-circuit-is-turned-on/13442
**Category:** Technical Discussions
**Created:** [March 16, 2018, 1:56pm UTC](https://community.electricforum.com/t/why-is-there-a-popping-sound-headphone-output-when-my-audio-circuit-is-turned-on/13442 "2018-03-16T13:56:06Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![Hamey](https://avatars.discourse-cdn.com/v4/letter/h/d26b3c/32.png) [@Hamey](https://community.electricforum.com/u/Hamey)
#### Post date: [March 16, 2018, 1:56pm UTC](https://community.electricforum.com/t/why-is-there-a-popping-sound-headphone-output-when-my-audio-circuit-is-turned-on/13442/1 "2018-03-16T13:56:06Z")

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I’m using a 3.3V DC-DC boost converter ([https://www.torexsemi.com/file/xcl101/XCL101.pdf](https://www.torexsemi.com/file/xcl101/XCL101.pdf)) as the power source for my audio circuit. There is a popping sound (headphone output) that happens when the circuit is turned on. There is no audible noise after power up. I viewed the boost converter’s output on my scope at power up, and there’s an AC-coupled voltage spike of about 2.5V that quickly decays back to zero:

 ![Nn2GL](https://canada1.discourse-cdn.com/flex030/uploads/electricforum/original/2X/a/af43dff4e39aa72a1f494299e3c66c993fd50856.jpg)

I’m using 10 uF capacitors at the input and output of the boost converter, as shown in the datasheet:  
 ![QTDme](https://canada1.discourse-cdn.com/flex030/uploads/electricforum/original/2X/c/c1dc09ffd6bb7038e350d075ceb4c15b90fbc5a1.jpg)

How can I eliminate this AC-coupled voltage transient that’s creating the popping sound?

I don’t have any popping noise issue when using a bench power supply. It’s only a problem using the boost converter. This is my audio circuit:.

 ![tU1TH](https://canada1.discourse-cdn.com/flex030/uploads/electricforum/original/2X/c/c4f3ac4ce9161cda5b9de971641253ba36b2bc0e.jpg)

I put the 1k resistor at the output in an attempt to eliminate the popping sound, as a discharge resistor. There is a large decoupling capacitance at the output because I needed a low cut off frequency. The op amps are power op amps that have the required current capability.

I tried using a different 3.3V booster circuit, and did not hear the pop sound. The booster IC is different, and the circuit includes a diode and 68 uF output cap:  
 ![PmmUR](https://canada1.discourse-cdn.com/flex030/uploads/electricforum/original/2X/b/b87b1814cc02a065011c57bc974b3aeb3ff64871.jpg)  
Datasheet of 3.3V booster:

> **[NCP1402SN19T1.pdf](https://www.kynix.com/uploadfiles/pdf65976/NCP1402SN19T1.pdf)**
>
> 172.54 KB