Audio Noise on Breadboard

[eev_carl]

Hi,

I'm troubleshooting a pedal circuit that is producing a lot of noise.  I broke the circuit down (removed the actual function) to just the input jack connected to the output jack and am still getting the noise.  As a reference, I run a 15 ft cable b/t a bass and a small amp.  I hear some noise. but much less, at high volume.

On my breadboard, I have T -> T and S -> S wired between the input and output jacks.  My bass goes into one jack using a 15ft cable (same as my reference).  Coming off the breadboard, I have a 6ft cable.  The wires between the jacks are about 5mm.

Is this expected from a breadboard set up?

Thanks,
Carl

[eev_carl]

I think it's the large breadboard.  I used a very small breadboard with the same input and output jack breakout wiring and the noise went away.

Here's a link to what I'm using. https://www.sparkfun.com/products/12046

For anyone replying...Is this stray capacitances?  Is there anything I can do to reduce this on my larger breadboard.

[madires]

Most likely the noise is simply picked up from the environment by the large breadboard. The tiny one has less area, i.e. it picks up less mains hum and what have you. You could try to put the large breadboard into a metal can (maybe connected to signal ground). The breadboard's capacitance starts to matter when you play with RF or fast digital signals.

[Ian.M]

You need screening.   A tin plated steel biscuit tin would be reasonably good for a large multi-panel breadboard, if you sanded any paint or varnish off the top 1/2" of the sides and the insides of the edges of the lid for good metal to metal contact.   Use chassis mounted connectors with a metal shell mounted to the tin for signals in & out to screened cables, and solder-in bulkhead feedthrough caps for all power connections.

[FotatoPotato]

For any sensitive projects, built on a breadboard, you will always encounter noise. It's just how it is. The best way to get rid of it is to use a soldering perf board. That should get rid of most noise.

Good luck!