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Thread: Multiple Phase Shifted Mono-Outputs (8+) Possible?

  1. #1
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    Multiple Phase Shifted Mono-Outputs (8+) Possible?

    Hi all,

    I'm planning to construct an array of 8 speakers, all broadcasting the same signal with a phase shift/time delay between adjacent elements. I stumbled across the teensy and the audio library, and if I only needed to output to a single speaker or set of headphones - my problems would be solved. But since I need to output to 8 speakers and the teensy 3.6 has only 2 DAC output pins, I'm not sure if I'll be able to leverage the audio library for my project.

    Might there be a simple solution I'm missing? Any advice is greatly appreciated, thanks so much!

  2. #2
    Senior Member Frank B's Avatar
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    Use two Teensy and four audioshields ? Or 4 teensy ?

  3. #3
    Senior Member PaulStoffregen's Avatar
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    Yup, you'd need at least 2 Teensy boards. If you use both the built in 12 bit DACs and two 16 bit audio shields, you can get at most 6 outputs. You could get a 7th low quality output with PWM. But currently there's no way to get 8 simultaneous audio outputs from a single Teensy. You'll need at least 2. With 4 audio boards (two on each Teensy), all channels could be high quality 16 bits.

  4. #4
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    Quote Originally Posted by PaulStoffregen View Post
    Yup, you'd need at least 2 Teensy boards. If you use both the built in 12 bit DACs and two 16 bit audio shields, you can get at most 6 outputs. You could get a 7th low quality output with PWM. But currently there's no way to get 8 simultaneous audio outputs from a single Teensy. You'll need at least 2. With 4 audio boards (two on each Teensy), all channels could be high quality 16 bits.
    So the audio shields have an additional built in DAC? Very cool! I was unaware you could slap two of those onto a single teensy.

    If I chose to use multiple teensy boards, would I have trouble getting them to function together cohesively given that timing is pretty important to my project?

    Thanks to both of you for your help and responses!

  5. #5
    Senior Member Frank B's Avatar
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    Quote Originally Posted by apt2b View Post
    So the audio shields have an additional built in DAC? Very cool! I was unaware you could slap two of those onto a single teensy.

    If I chose to use multiple teensy boards, would I have trouble getting them to function together cohesively given that timing is pretty important to my project?

    Thanks to both of you for your help and responses!
    No, if you do it right, you can sync them very exactly.

  6. #6
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    Weighing my options and considering settling for few channels by using a single teensy with two audio boards. I understand a teensy 3.5/6 grants you two analog outputs from the DAC pins, and two audio boards give you two more channels each for a total of six. And if I understand your responses, the only way to achieve eight high quality channels would be to double the amount hardware - is that correct?

    Regardless, the audio adapter board's store page states that two adapters on a single 3.5/6 has not yet been tested, so I worry that I may not be able to use the benefit of the DACs afforded by the new teensy boards.

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