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Thread: Speakers for Teensy 3.1 + Audio Board (v1)

  1. #1
    Senior Member+ MichaelMeissner's Avatar
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    Speakers for Teensy 3.1 + Audio Board (v1)

    I have the original Audio Board (bought in 2014) and Teensy 3.1's, and I would like to hook it up as a simple machine to play sounds for portable costume usage. At the moment, I have not soldered the Audio board to the Teensy.

    I have some simple speakers, and I was wondering exactly how to hook these up. Naively, I would assume I need an audio amplifier of some sort, and plug it into the headphone jack:



    Given what I have, what would I need to add between the audio board and the above speakers for either mono or stereo sounds?

    Or if those speakers won't do, what would that would be fairly small and work with 3.7 lipo batteries or 5v usb chargers (1-2amps).

    I saw there was a revision to the Audio board in January 2015 (I bought my board in January 2014) that increased the capacitors and added two pull-up resistors. For just acting as a wav player, would it be useful to upgrade to the new version of the board?

    Finally, if I wanted to go real small, to just play recorded mono sounds, would I be able to hook a speaker up to the LC with it's DAC port and no audio board and put the sounds into const memory (assuming I can cram them in)? I realize that the LC doesn't have the processing capability of the 3.1/3.2 so I wouldn't be able to do the more complex processing, but the level shifting of A3 would allow me to eliminate extra boards.
    Last edited by MichaelMeissner; 11-11-2015 at 01:49 PM.

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    I have been using one of the million and one little hook to your cell phone speakers that have a internal amp + battery + charger for under $10. Finding one with a volume control would be a plus. Or there are a number of boards like http://www.adafruit.com/products/2130, add a onehorse lipo charger and a battery and you are good to go.

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    Senior Member+ MichaelMeissner's Avatar
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    Quote Originally Posted by cartere View Post
    I have been using one of the million and one little hook to your cell phone speakers that have a internal amp + battery + charger for under $10. Finding one with a volume control would be a plus. Or there are a number of boards like http://www.adafruit.com/products/2130, add a onehorse lipo charger and a battery and you are good to go.
    Most of the Cell phone speakers that I've seen are too big.

    Exactly where would I connect the audio amp? Most of the Audio amps have L-/L+ and R-/R+, but the 3.5mm headphone jack only has 3 connectors. There are 2 L pins in the audio out, a G, and 2 R pins. Which is the + and which is the -?

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    Use line out instead of the headphone jack. Line out has a left and a right both referenced to ground.
    Last edited by cartere; 11-11-2015 at 03:43 PM.

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    Referencing the adafruit amp:
    A+ would go to either the L or R lineout pin
    A- would go to GND
    GND to teensy GND
    vin to teensy vin

    Speaker to the solder holes labeled + and -

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    Ok, thanks. I didn't know if one of the L/R pins was '-' and the other '+' (and if so, which one was which, since it isn't marked).

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    Click image for larger version. 

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    Along the top edge in the line out section L would be L+ and I believe the pin just above it is GRD which would be L- the pin labeled G is also ground and could be used as L-, the same applies for R.

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    Thanks again.

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    Senior Member+ MichaelMeissner's Avatar
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    Cool

    I was looking around, I came across so-called keychain speakers (also called bomb speakers). I had not known these existed, as I was mostly familiar with the larger speakers for computers and for phones to fill the room with sound.

    Beyond the keychain/bomb speakers, there are others that are called hamburger speakers (because the two speakers are on opposite sides, and look like hamburger buns with a smaller middle).

    I found a stereo speaker made by Vibe Sound that is a ball, roughly 1 3/4 inches in diameter with a keychain, usb cable (for power) and 3.5mm connector. I'm sure the sound quality will be somewhat lacking compared to bigger speakers, but for use on a costume where I just want a sound effect when something happens, it will probably be sufficient. The model I bought is white with purple stripes, but others now have a cartoon face of a bomb on it (the 3.5mm cable is the fuse).

    Some of the reviews indicated it stopped charging after a few weeks. Since I had bought it from an ebay seller for $5, I won't be too disappointed if it stops working. Since I plan to hide the speaker, I probably will leave it plugged into a USB battery charger permanently.

    Before finding the keychain speaker, I had ordered an Adafruit amplifier as well, but after I ordered it, I started wondering whether I could turn the volume down enough not to blow out the speaker (amp is 8ohm/2.8W, while one set of speakers are 8ohm/0.5W and the other is 8ohm/0.25W), and decided to see if there was a self contained unit made for 3.5mm input.
    Last edited by MichaelMeissner; 11-13-2015 at 04:15 AM.

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