[Portable mic modification help]

audioguru

Can you suggest a better quality AC adaptor and a place to purchase online

Thanx

[Portable mic modification help]

I have a small personal sound amplifier - essentially a mic with a headphone jack - that is powered by a single AAA bat.  I use this quite a bit and wanted to mod it so that I could plug it into the AC outlet.

I soldered wire to each bat terminal and then connected the wires to a variable AC adaptor. 

When set at 1.5V I get amplification similar to while on bat power but there is a terrible whistle.  If I bump the voltage to 3v I get less whistle but less amplification as well.

Suggestions?