Soldering the 5V bias jumpers

Hello from Seattle, we’re trying to power an electret microphone (hydrophone, actually) with the Pisound HAT and wonder:

Where exactly are the “two solder jumpers near the input port”? Would it be possible to add a diagram or annotated photo to the guidance we’ve read (and puzzled over) here – , or provide one to the community forum??

Scott & Val Veirs

The solder jumpers are above the ‘VOLUME’ text. The one that is closer to VOLUME is for the left channel, the other is for the right channel.

We plan to add high quality photos to the documentation.

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Thanks @Giedrius . To be completely clear, we’re talking about jumpers that make a connection that is parallel to the word “VOLUME” (as opposed to diagonally), right?

Can you confirm I should solder jumpers where the red lines are in this new version of your image?


Hi Scott, yes, the direction you marked is correct.

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Thanks @Giedrius! Here’s a few pix showing our work. Happy to report the 1/4" input jack is now powering our hydrophone very nicely!



For jumpers we used Cat5 Ethernet cable wire (solid core, stripped of insulation)…

It worked well to pre-coat the wire tip with solder and pre-bend it to match the jumper spacing.

Then use smallest available snips (or manicure clippers) to trim the excess wire, leaving just the jumper behind…

Glad to hear it worked out for you! Keep us posted about your project developments! :slight_smile:

is there any way to make these jumpers semi-permanent? you see pin headers in eurorack modular for semi-permanent configurations a lot.

is there a suitable SMT pin header for the pisound jumper footprint? I guess it would also need to be a right-angle header too…

I don’t think there’s a suitable header for that.

You can build a solder bridge or remove it using just your soldering iron and solder however, as many times you like.

ok cool, thanks giedrius.

Hi all!

I’d like to write my experience when we soldered these jumpers.

After we soldered the jumpers a new weird noise was introduced even when microphone wasn’t plugged in.
Tried changing from RPi’s original AC adapter to power-bank and it’s the same.
When I connected electret microphone I’ve got a lot of noise, and I would really give some gain to hear it loud, but then noise would became a lot louder.

Did anyone used PiSound with electret microphones, and have you guys noticed the same?
Which microphones you used?
For my purpose, none of noise reduction filters shouldn’t be used so software solution isn’t a way to go, sadly…

Any thoughts how “fix” this?

Mics I’ve tried:

  • RODE VideoMicro
  • Sony ECM battery powered condenser
  • BM700 from China, cheap mic, has least noise, but still noticeable
  • some lapel microphone, no name
  • dynamic karaoke microphone

All of these mics sound great when plugged in for example Zoom H4n, no noise…

Oh and, I’ve noticed now that somehow (I think) electricity that should go to microphone some of it goes to the headphones, with low impedance headphones it’s more noticeable, with high impedance ones there’s less noise but still noticeable!

Thanks! :slight_smile:

Sorry, @vedranius, we’re using an underwater microphone (hydrophone), so I can’t offer any experience with electret microphones. Maybe @Geidrius has some thoughts about your results?

This time we tried a solder bridge instead of the wires. It was pretty easy, though it seemed important to minimize the time during which the soldering iron tip was in contact with the board. Here are the results: