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Personaly, I always disable that ADC filter as I find that it adds unacceptable noise to the system. See my post on this issue here:
...

The most reliable approach would be to make one oscillator class that has multiple oscillators within the one class. That way, you can do any combination of hard sync, soft sync, or cross-mod that...

(double post)

When I ported the Audio Library to be floating point (for Teensy 3.6), I also added some classes to help with dynamic switching. Our library is under the name "Tympan" and is developed to work with...

Hey, this is super cool! It seems to work well for me on my Teensy 3.6. Thanks for making it happen and for "MTP (Experimental)" getting pulled into the mainline Teensyduino that we all download by...

I want a MIDI shield. MIDI In/Out/Through. Along with the MIDI hardware, the board should have assorted through-hole solder points for attaching analog sensors or whatever. Nothing fancy, just...

Or, instead of Tympan, you could consider buying the BC127 module that's available from Sparkfun and wiring it to your Teensy 4.0 + Audio shield. Or you could consider any other BT Audio capable BT...

I think that the Tympan Rev D will do this.

The Tympan is aimed at open source hearing aid algorithms, but in reality, it is a general purpose digital audio platform. Full Disclosure: I'm part...

No. But if you can point me to it, I'll learn something!

Chip

Lowpass filtering at Nyquist is not nearly as important for the sigma-delta ADCs used in audio codecs (such as the Teensy Audio board). Try it for yourself...run a frequency sweep into the board, one...

Note in my blog post how I show the spectrum of the self noise with and without the HP filter engaged. My two spectra reveal the chacteristics of the noise added by that HP filter: several very...

If you're curious, I did a self-noise analysis of the Teensy Audio board for a subset of the audible frequency range (not ultrasound)...
...

I love to see people getting quantitative. Fantastic.

As some friendly improvements:

* The term "signal to noise ratio" (SNR) is typically used instead of "contrast". You define what you...

The input impedance to most audio ICs is in the 10-40 kOhm range, which is too low for the output of guitar pickups. Guitar pickups really expect to be plugged into something with at least 500 kOhm...

With the Teensy 4, I've gotten stereo audio to flow on both the STGL5000 and on my AIC3206. With the Teensy 3.6, I've got 4-channel audio to flow on both the STGL5000 and with my AIC3206. Now, I'd...

Great!

Has anyone tried 4-channel audio with the Teensy 4.0, yet?

(I've done two channels by lashing up one Audio Adapter, but I haven't tried two. Too scared!)

Has anyone tried it?
...

In one of the Teensy 4 threads, there was a discussion of a revision to the Teensy Audio Adapter Board to be compatible with Teensy 4....not just adding the 100 ohm resistors, but actually making it...

Presumably, for this function: void setI2SFreq(int freq), the "freq" is the sample rate (in Hz) that I want?

So, if I want 44100 (ie, the default), I would call setI2SFreq(44100)? But, if I...

Hi All,

Previously, I made an extension of the audio library to enable float32 audio processing for the Teensy 3.5/3.6 (see Tympan library here). With Teensy 4, a bunch of stuff has changed,...

Including core_pins.h helped. It cured a bunch (not all) of my compilation problems.

Chip

Cool explanation! Thanks!

Hi KurtE,

Thanks for the suggestion. I'll give it a try.

As a point of education for myself...and stepping away from my own code to just focus on the stock Teensy code...how does AudioStream.h...

I've got a library that compiles fine under Teensy 3.6 but won't compile until Teensy 4.0. It's giving errors about not knowing F_CPU_ACTUAL. I suspect that this is a symptom of a larger problem,...

Our Tympan Rev D is also a Teensy 3.6 embedded as the brains in an audio processing system. Full schematics and design files are here: https://github.com/Tympan/Tympan_Rev_D_Hardware

Chip

It works! Yay!

Thanks so much,

Chip

Can anyone confirm that AudioInputI2S works with the Teensy 4.0?

It does not work for me. I can play sounds out via AudioOutputI2S but I can't bring audio in using AudioInputI2S.


My Setup:...

When I renamed the Greiman sdhc_isr() to another name (like was suggested above), nothing worked...presumably because the sdhc_isr was a special name that was being attached to an interrupt...

Walter and/or Frank,

I've recently updated my Arduino IDE / Teensyduino. Unfortunately, the SD writing via the greiman library doesn't work anymore.

As you know, your fast SD writing is...

Hey, if you do that Oakley Sound project, and if you post any pics or a writeup on the web, be sure to share the link here. Definitely interested.

Back to the audio issues that you're having, I...

Congrats on getting something to work! Sorry it's not satisfying sounding. Some thoughts after looking at your code:

Because you're using the Due's ADC, your audio signal has a big DC component...

Yes, it does look like Holger did what he said...extended the chorus to use an external signal source as the modulation. So to get ensemble working, you'd need several of these in parallel.
...

I just looked at the chorus effect code that's in the Teensy audio library...

h file: https://github.com/PaulStoffregen/Audio/blob/master/effect_chorus.h
cpp file:...

As you found, the delay object does not expect to be changed very often...it isn't designed that way. At best, it might be possible to change the delay time for every block of audio data, which is...

Thanks for replies and thanks for the good work! :)

I echo the chorus of experience that the performance of different SD cards is wildly different.

With the right card, I've done stereo recordings at 96 kHz at 16-bit for decently long (10s of...

I just found this thread while looking for how to write WAV rather than just RAW to an SD card. What a great project! (And thanks for using the Tympan BTW.)

And, Walter, thanks for packaging up...

The Texas Instruments AIC3206 has a programmable gain pre-amp. So, yes, you can connect a microphone directly to this chip without any additional amplification. For electret microphones, you do...

I see that my old GitHub link isn't correct anymore. Here are updated links:

"Rev C", which is the audio board as add-on to Teensy 3.6:...

If you're willing to use a teensy 3.5 or 3.6, you can use flowing point FFTs, which will make this much more feasible, given that we're just hobbyists.

I've done a formant shifter on the Hoxton...

There are a couple of folks who have gotten 32-bit transfers through the I2S and DMA subsystems. I did 32-bit transfer for the TI AIC3206 along as part of my Tympan project. See the I2S classes in...

When we were deciding how to integrate BT audio, I wanted to do digital...but it was never clear to me how to have multiple I2S devices working together with the K66 processor at the heart of the...

On the Tympan D with the BC127, you can talk to it digitally like a Bluetooth classic device, but for Bluetooth audio, we did not connect it to the I2S bus. Instead, we chose to connect the analog...

I add d the driver for the AIC3206 to the Teens audio library via Pull Request. I think that Paul accepted it. So, it should be now available beyond just the Tympan library.

Chip

Artur,

I looked at your papers, but have you shared your code (such as via GitHub)?

Chip
https://openaudio.blogspot.com

I think that I see that you're using the Teensy's ADC and DAC, as opposed to using an audio interface (like the Teensy Audio Board). Using the onboard ADC and DAC, you're going to have a limited...

WMXZ, thanks for the real-world feedback, and for the code. I've been looking at your audio recorder as I, too, am struggling with the less-then-speedy performance of the default SD libraray. As I...

Hi,

Why is the AudioRecordQueue limited to 53 blocks? I understand why one might want to limit the depth of the queue, but why 53?

If I wanted to, could I change the code to increase it to...

A little while back, I connected two Adafruit MEMS microphones to the Teensy Audio Board. It worked decently well, though I was always had to be careful with my wiring to keep the noise down.
...

I, too, tried to modify the I2S library to enable 24-bit or 32-bit transfer of audio data from the audio AIC. I, too, got stymied by DMA settings. Kudos to those who figured it out for 16-bit...

The Teensy Audio board can indeed be noisy. One of the main contributors to the noise is the highpass filter that is enabled by default on the AIC at the heart of the audio board. The highpass...