Switch-mode Power Supplies - Are they more quiet?

[i_g55]

I've been using a home-made regulated 9V power supply to feed my pedal board. However, whenever I powered my Boss TU2 tuner from the power supply, it used to make a noticeable buzz when I stomped it on. Also I was lacking power lately, as my pedal board got more crowded.

A couple of days ago I went to a local electronic shop to buy a more powerful transformer for my power supply. They guy at the shop recommended me a 25W switch mode power supply which switches at 100kHz and can provide over 2A at 9V. I tried it with all the pedals I have at home, plus a Boss BE-5B processor all together. The good thing is it was able to power them all, and what's better is the buzz from the TU2 had disappeared.

My question:
Are switch-mode power supplies quieter than linear power supplies? Are they kind of immune to electrically noisy places (with neon lights etc)? Could they be a cure for tube pedals getting noisy because of the electrical noise from the mains?

Thank you...

[niftydog]

They are certainly less noisy in the low frequency range where you find mains hum and interference from fluoro lights etc. But they can be more noisy at the other end of the spectrum, sometimes creating whining or hissing noise.

[bongomania]

Also, I have found they may be very quiet on their own, yet introduce noise into power supplies connected to the same outlet. E.g. I recently had an annoying hissing and clicking noise while testing one pedal, and the noise went away when I removed a particular switchmode wallwart from the outlet strip. The respective pedals were not connected to each other via patch cables, only through their wall warts.