Forum Rule: Always post complete source code & details to reproduce any issue!
Results 1 to 18 of 18

Thread: hydrophone with pre-amp connected to Audio board

  1. #1

    hydrophone with pre-amp connected to Audio board

    Good day,

    I would like to connect a hydrophone with pre-amp (PIP) to the audio Shield (Audio Shield 4 Rev D). Can I simpy solder the wires to the MIC terminals? Where can I find the commands to set the SGT5000 Mic bias? I assume I will need to scale down gain on amplifiers of the SGT5000 as well?

    Thanks
    Jaco

  2. #2
    Senior Member
    Join Date
    Jul 2014
    Posts
    2,723
    Quote Originally Posted by Jaco Versfeld View Post
    Good day,

    I would like to connect a hydrophone with pre-amp (PIP) to the audio Shield (Audio Shield 4 Rev D). Can I simpy solder the wires to the MIC terminals? Where can I find the commands to set the SGT5000 Mic bias? I assume I will need to scale down gain on amplifiers of the SGT5000 as well?

    Thanks
    Jaco
    I assume you are referring to PIP Series by virgo.
    You simply connect to Line-in (not sure about AC coupling)

  3. #3
    Senior Member
    Join Date
    Jul 2020
    Posts
    331
    The AudioControlSGTL5000 documentation explains setting source and volumes on the rev D audio shield.

    Make sure your preamp can't burn the Audio shield - the line inputs go via dc-blocking capacitors straight into the SGTL5000 chip on
    the schematic so the datasheet for the SGTL5000 is the place to check what's safe.

  4. #4
    Sorry, I should have stated that PIP -> Plug in Power. (I use the hydrophones from Aquarian Audio ...)

    I see the Rev D board has a MIC BIAS line, which provides the plug-in power to drive the pre-amp of the microphone.

    I see you can set the gain of the amplifiers sgtl5000 object in the code.

    How do I adjust the mic bias? According to the SGT5000 datasheet this can be done?

    Thanks,
    Jaco

  5. #5
    Senior Member
    Join Date
    Jul 2020
    Posts
    331
    The Audio shield MIC input is only for an electet mic.

    Perhaps provide a link to the hardware you are talking about so we know for sure?

  6. #6
    Senior Member
    Join Date
    Jul 2014
    Posts
    2,723
    Quote Originally Posted by Jaco Versfeld View Post
    Sorry, I should have stated that PIP -> Plug in Power. (I use the hydrophones from Aquarian Audio ...)

    I see the Rev D board has a MIC BIAS line, which provides the plug-in power to drive the pre-amp of the microphone.

    I see you can set the gain of the amplifiers sgtl5000 object in the code.

    How do I adjust the mic bias? According to the SGT5000 datasheet this can be done?

    Thanks,
    Jaco
    OK,
    which model are you using, which pre-amp?

  7. #7
    Senior Member
    Join Date
    Jul 2014
    Posts
    2,723
    Quote Originally Posted by MarkT View Post
    The Audio shield MIC input is only for an electet mic.

    Perhaps provide a link to the hardware you are talking about so we know for sure?
    OK for more reference, but there are hydrophone pre-amps that 'simulate' a electret mic. In fact they only have a FET and some protection diodes (ignoring source and bias resistor)

  8. #8
    Thank you for the replies.

    Thank you for the reference to the AudioControlSGTL5000 documentation.

    I have both the H1c and H2c hydrophones (https://www.aquarianaudio.com/h1a-hydrophone.html and https://www.aquarianaudio.com/h2a-hydrophone.html )

    I prefer to use the H2c, with the built-in amplifier. If I am correct, I can solder it to the Mic solder pads, and the MICBIAS will drive the pre-amplifier of the Hydrophone.

    See attached sketch of the REV D where I indicated the MICBIAS line.

    Click image for larger version. 

Name:	Screenshot 2020-07-14 20:07:45 (copy).png 
Views:	6 
Size:	42.4 KB 
ID:	20960

    I assume the LINEOUTL and LINEOUTR are Audio lines, and due to capacitors cannot provide "bias / PIP" for the pre-amps.

  9. #9
    Senior Member
    Join Date
    Jul 2014
    Posts
    2,723
    To me it seems OK.
    The H2a (not seen H2c) simulates a electret microphone (it has also only 2 lines). So I would simply connect as it were a microphone.
    to set the mic go to audio library where you find control_sgtl5000. have a look into audio examples to see how to setup audioboard.
    If you ever put this underwater, please provide a noise spectrogram.

    Edit: found H2c (is thread mounted version of H2a)

  10. #10
    Senior Member
    Join Date
    Jul 2020
    Posts
    331
    The H2A is the only one that is low-impedance output so you need that one I think.
    Don't expect miracles from the MIC input of the audio shield, its low quality (I've been playing with
    FFT visualization and it clearly shows breakthrough from the headphone output, including obvious harmonics,
    and has at least one spurious tone around 17kHz.) The SGTL5000 isn't HiFi quality, alas.

  11. #11
    Senior Member
    Join Date
    Jul 2014
    Posts
    2,723
    Quote Originally Posted by MarkT View Post
    Don't expect miracles from the MIC input of the audio shield, its low quality
    That is why I'm interested in seeing field data.
    OK, I know at least one company that uses SGTL5000 and Teensy for a hydrophone recorder.

  12. #12
    Senior Member
    Join Date
    Oct 2015
    Location
    Vermont, USA
    Posts
    256
    While the Teensy Audio Shield is amazing for its price, there are alternatives if you want better performance...

    * Blackaddr has his "Teensy Guitar Audio Shield". IMO, it sounds much better than the Teensy Audio Shield (primarily, lower noise). Unlike the Teensy Audio Shield, this device also has high impedance inputs, which can be helpful for certain types of sensors. But, I don't believe that it can provide any sort of mic bias, which may or may not be a problem for you. It is quite reasonably priced, which is great. http://blackaddr.com/products/

    * Then, there's the "Tympan", which is one of my projects. It also has lower self-noise than the Teensy Audio shield. Its primary appeal is that it is more self-contained by including (A) a bluetooth link for remote control or audio streaming, (B) a LiPo battery with on-board charging, and (C) an SD card slot for recording audio. Taking all three of these features together, you can imagine sealing up your device for safer testing around water. Perhaps this appeals to you with your hydrophone testing? The biggest downside is that it is more expensive. https://shop.tympan.org/collections/all


    Chip

  13. #13
    Quote Originally Posted by WMXZ View Post
    That is why I'm interested in seeing field data.
    OK, I know at least one company that uses SGTL5000 and Teensy for a hydrophone recorder.
    Which company uses the SGTL5000 for a hydrophone?

    As soon as I get the system working, I will upload Spectrograms. I do have spectrograms from the H2a and a ZOOM H1n containing signature whistles from bottlenose dolphins ...

  14. #14
    Senior Member
    Join Date
    Jul 2014
    Posts
    2,723
    Quote Originally Posted by Jaco Versfeld View Post
    Which company uses the SGTL5000 for a hydrophone?
    https://www.loggerhead.com/snap-unde...ustic-recorder

    He integrated Teensy3.2 with custom SGTL5000.

  15. #15
    Thanks for all the help so far.

    Is there an easy way to add wav write capability to the Teensy 4.1 and Audio board? Alternatively If I write raw data to the SD card, can I use Matlab/Octave to convert the raw data to wav files?

    Does the microSoundRecorder run on theTeensy 4.1? (I assume the Teensy 3.6 is maybe more suited because of power consumption if a long-term deployment is envisaged ...)

    Also, what is the file output of microSoundRecorder - is it wav or raw?

    Also, can I run the Tympan AIC shield straight from a Teensy?

  16. #16
    Senior Member
    Join Date
    Oct 2015
    Location
    Vermont, USA
    Posts
    256
    Regarding the Tympan, it already has the Teensy 3.6 built into it. We buy the Teensy 3.6 bootloader from Paul (the maker of Teensy) and use the same processor and all that. Therefore, it *is* a Teensy 3.6 with the other stuff added to it.

    Chip

  17. #17
    Senior Member
    Join Date
    Oct 2015
    Location
    Vermont, USA
    Posts
    256
    Regarding SD recording, you can use the Tympan software library with anyone's hardware, as long as it is a Teensy 3.5 or Teensy 3.6. The library is a floating point extension of the Teensy Audio library. One of the extensions is built-in WAV writing to SD card. There are examples that you can use without additional modification. Just use a good SD card!

    https://github.com/Tympan/Tympan_Lib...ree/master/src

    Also, to make it more obvious that you can use any teensy 3.5/3.6 hardware, we've been moving a lot of the good stuff over to the OpenAudio library. So, you could look at that version if that makes you more comfortable.

    https://github.com/chipaudette/OpenAudio_ArduinoLibrary

    OpenAudio is also in the process of being updated for Teensy 4.x, but I'm not sure that the SD is working satisfactorily for audio-rate writing yet.

    Chip

  18. #18
    Senior Member
    Join Date
    Jul 2014
    Posts
    2,723
    microsoundrecorder is written for T3.6 but could be ported to T4.1, if really needed.
    For T4.1 I would consider to start from https://github.com/WMXZ-EU/MTP_t4/tr...les/mtp-logger
    it has more or less everything, but ADC.
    It should be easy to add code for your preferred ADC (SGTL5000, TI-320AIC, Cirrus ADCs, TI-320ADC, etc). Lot of source code has been discussed on the forum over the years.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •