Fan causing noise in audio circuit

[The Master]

Hi, I've made an audio circuit that gets quite warm so I want to add a fan to it. I've tried a 12V DC brushless fan but it causes audiable interference. Is there a way to stop it?

I have tried:-
Wrapping the fan wires around a toroid with no effect.
Placing a diode backwards accross the wires. This stops the fan from working.
Running the fan through a separate regulator. No effect
Adding capacitors. No effect or stops the fan depending on the configuration.

Unfortunately I don't have the option to run the fan from a completely separate supply. Is there anything else I can try or maybe a different type of fan?

[mister_e]

What kind of audio circuit is that to be that sensisitve and heat at the same time? a brushless shouldn't make ANY noise.

High likely some kind of Faraday cage 'round the high gain audio stage would help.

[The Master]

It's a simple 14W TDA2030 setup as per the test circuit in the datasheet

[sayzer]

Have a bobbin serially connected to GND of the circuit.

Try different bobbins if you see no change.

[Ioannis]

Totally agree with Steve. Brushless should make NO noise. Also TDA2030 is a little insensitive to noises since it is an automotive chip.

But on the other hand you may have a ground loop that is causing noise. Connect all grounds to a signle point preferably at power supply 0.

Ioannis

[mister_e]

Ground routing could be a problematic, a poor layout as well. Disconnect your audio source, Short the input to ground and see if you still have noise.

[The Master]

Sorry, I'm not sure what you mean by "bobbin" (not in an electronics sense anyway).
All grounds are connected to the same power supply. The audio source is a SOMO-14D which is also powered from the same power source. I tried disconnecting the input and grounding it anyway but I still get the noise.
This circuit is currently on a breadboard so the layout could be a problem but it shouldn't affect it that much.