Just for fun, I built the circuit in the TPA6120A2 datasheet: a PCM1792 DAC, a quad opamp, and the TPA. As a source for the PCM i used an USB-I2S IC, the Silabs CP2114.
It's a nightmare!
For some reason, I get clicking noises all the time. Sometimes that clicking is once every 2-3 seconds. Sometimes it's 3-4 times per second. And it's LOUD!!
What can be the problem here?
Here's a capture of the clicking:
As you can see, after the clicking there is a HUGE spike (enough to make your ears ring).
This only happens when sound is playing. When I stop the music, I2S data stops, and noise too. If I mute the DAC (via software, enable attenuator at -120dB), I can still hear the clicking.
The problem happens in 3 different machines (Core2duo laptop, Core i5 desktop and an old athlon64).
I've tried setting a higher USB audio buffer. I also tried using an ASIO driver.
Changing USB ports doesn't help either (Neither my USB2 or USB3 ports make a difference).
Is the CP2114 just a bad USB-I2S bridge? Is it a windows problem?
It's a nightmare!
For some reason, I get clicking noises all the time. Sometimes that clicking is once every 2-3 seconds. Sometimes it's 3-4 times per second. And it's LOUD!!
What can be the problem here?
Here's a capture of the clicking:
As you can see, after the clicking there is a HUGE spike (enough to make your ears ring).
This only happens when sound is playing. When I stop the music, I2S data stops, and noise too. If I mute the DAC (via software, enable attenuator at -120dB), I can still hear the clicking.
The problem happens in 3 different machines (Core2duo laptop, Core i5 desktop and an old athlon64).
I've tried setting a higher USB audio buffer. I also tried using an ASIO driver.
Changing USB ports doesn't help either (Neither my USB2 or USB3 ports make a difference).
Is the CP2114 just a bad USB-I2S bridge? Is it a windows problem?
Well, it's not that I'm very proud of my laoyut, but here it goes.
Board on the left is the USB-I2S chip, on the right there's the DAC board, I/V stage, and audio amplifier.
Pay no attention to the 46MHz oscillator. This has been replaced with a 48MHz one. This board runs off two oscillators: an external one at 48MHz for USB, and the CP2114's internal oscillator running at 49.152MHz (Fs=48KHz * 256).
I doubt this is a layout issue since the popping is regular, not random.
Board on the left is the USB-I2S chip, on the right there's the DAC board, I/V stage, and audio amplifier.
Pay no attention to the 46MHz oscillator. This has been replaced with a 48MHz one. This board runs off two oscillators: an external one at 48MHz for USB, and the CP2114's internal oscillator running at 49.152MHz (Fs=48KHz * 256).
I doubt this is a layout issue since the popping is regular, not random.
For these sort of designs you need at least a 2 layer board with one layer being an contiguous ground plane, same for the wiring between the boards, each signal needs a ground return in intimate proximity and the next pin on the PCB.
The clicking is related to some data being fed to the board, and I suspect some sort of EMC problem, where a clock or a data line is coupling to some other input/output and causing the problem.
The way that clock is connected is possibly the worse thing you could do for a clock or oscillator, the clock signal should be as short as possible, same with the power leads and add some decoupling. Same with the IC's there is no effective decoupling on any of the devices, again this wont help. The caps need to be next to the pins not on some skinny traces a few mm away.
The clicking is related to some data being fed to the board, and I suspect some sort of EMC problem, where a clock or a data line is coupling to some other input/output and causing the problem.
The way that clock is connected is possibly the worse thing you could do for a clock or oscillator, the clock signal should be as short as possible, same with the power leads and add some decoupling. Same with the IC's there is no effective decoupling on any of the devices, again this wont help. The caps need to be next to the pins not on some skinny traces a few mm away.
Last edited:
- Status
- Not open for further replies.