regular ticking noise (4.0+audio shield) when playing from sd

E

erikgroen

New member
Hello
Does anybody have experience with the basics of working with teensy 4.0 with audio shield?
My problem:
Playing wav's (from the sd-card on the audio shield) include a regular reoccuring noise in sinc with the pulses the internal led is flashing.

I followed the audio tutorial examples and came to the point that the blinking led does not work because the audioshield is using pin 13. I found no way around it so wont use the internal led in my code. The next example from the tutorial lets me play wav files from sd, nice. But this ticking noice is spoiling my fun to work further on my project.
Is there a sollution? Other than buying new hardware and try again...
 
How are you listening to the output from the Teensy Audio Adapter ?? Are you using the HEADPHONE output or the LINE OUT ?? Either connecting the HEADPHONE signals to a monophonic external device (speaker, etc.) and/or shorting the L & R signals from the HEADPHONE interface together (e.g. into an amplified speaker, which includes STEREO inputs, but has only a single speaker to generate the sound, so the L & R signals are somehow combined internally) can cause a "ticking" sound. The HEADPHONE interface of the SGTL5000 is only for headphones. For routing the output from the Teensy Audio Adapter to an external audio device, *only* the LINE OUT interface should be used.

Hope that helps . . .

Mark J Culross
KD5RXT
 
That would be great as solution, but... i am listening trough a headphone.
Is there anybody who also followed the tutorial with a 4.0 and audio shield and has the same experience and maybe solution?
 
Okay
do i buy a teensy 4.1? It also got the internal led on pin 13 so probably the same problem? Doesn't anybody use the audioshield anymore? Or should i buy an old teensy somewhere?
 
This sounds a bit similar to a sound variously reported as ticking or buzzing, when recording to an SD card on the audio shield. See this post and surrounding discussion for possible remedies, though they don't seem to work for everyone. Reading the SD card doesn't need as much current as writing, so it's a bit surprising you're hearing it, but it's entirely possible depending on your SD card and wiring.

Using the built-in SD socket on a Teensy 4.1 should fix the problem, and will also free up the built-in LED (whose pin is shared with the audio adaptor's SPI bus SCK signal, and thus becomes unusable when using either the SD card or SPI memory on the adaptor, as you've noted).

Many many people use the audio adaptor, which is a great starting point for exploring Teensy audio, but widely regarded[citation needed] as not really suited for high-quality applications.
 
Some codec with >=110dB SNR and < -90dB THD+N ? On a PCB with separate digital and analog regulators and suitable layout and PSU.
 
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