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Veho 360 speaker with the S2? — Parallax Forums

Veho 360 speaker with the S2?

Duane DegnDuane Degn Posts: 10,588
edited 2012-11-17 08:08 in Robotics
I ordered a couple of Veho 360 speakers after Ken showed his off.

I'm pretty sure the Veho 360 is supposed to be plugged into a headphone jack. Will connecting it the the S2's speaker socket (with a suitable adapter) cause a problem for the S2 or the Veho 360?

Edit: Here's the S2's speaker amp schematic.

attachment.php?attachmentid=87827&d=1324497146
S2SpeakerAmp111221a.PNG
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Comments

  • Duane DegnDuane Degn Posts: 10,588
    edited 2011-12-21 19:18
    The schematic identifies the speaker amplifier chip as "10708-SSOP". I'm pretty sure "SSOP" is just the package size of the chip. I couldn't find an amplifier using the numbers "10708" in a search. Looking at the chip itself, I saw "T990". Seaching for "T990", I found a datasheet for a TS4990 1.2W Audio Power Amplifier. I've attached the datasheet to this post.

    In the datasheet I found the "Load Resistor" should be at least 4 ohm. I know 8 ohm is a common resistance for small speakers (such as the S2's) and I'm pretty sure headphones usually have a higher resistance (I think around 16 ohms). So I decided the Veho 360 shouldn't hurt the Scribbler 2 and as long as I keep the volume low, hopefully the Scribbler 2 wouldn't hurt the Veho 360.

    For my first test, I loaded a song from the GUI into my S2. I had the Veho 360 (power off) connected to the S2. I moved the Veho 360's volume switch to the lowest setting. It was loud. Very loud. I don't think it was so loud as to damage the Veho 360 but I quickly turned the Veho 360 off.

    I then changed the "SPKR_VOL" constant from 35 to 10. With the "SPKR_VOL" set to 10, and the Veho 360 at its lowest volume, the speaker had, what I thought, was a good "robot" volume. Even with "SPKR_VOL" set to 1, the Veho 360 was still very easy to hear.

    One observation I made while performing these tests was the volume slider in the GUI is apparently just for the PC's volume. It doesn't seem to affect the Scribbler 2's speaker volume.

    In my experience, the Veho 360 may be used with the Scribbler 2 if the Scribbler 2's volume is lowered in software and if the Veho 360 is used at its lowest volume setting.

    The adaptor I made to connect the Veho 360 to the Scribbler 2 connects the tip of the 1/8" jack to the left pin of the speaker connection. I connected the right pin of the speaker connection to the sleeve of the 1/8" jack.
    pdf
    pdf
    speakerAmp.pdf
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  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2011-12-21 19:38
    The Veho 360 is designed to operate from line level audio, since it has it's own built-in amplifier, so I'm not surprised you got good output at the lowest volume setting. I just got mine a couple days ago and have tested it only with the Prop Demo Board. With Chip's "singing" vocal tract demo, I got quite a bit of fuzzy distortion. But I shouldn't be surprised, since the Demo Board output is amplified. I have yet to try it with line-level audio.

    -Phil
  • StempileStempile Posts: 82
    edited 2012-11-17 08:08
    I have been using the Veho360 with the PropBOE and running some WAV files through using the OBEX#324. Its very loud even switched to the lowest setting. Had to change to a different speaker that has more control over the volume.

    Any suggestions for reducing the Veho360 volume with the PropBOE?
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