Help! Boss AC Adapters

[UMT]

I know this isn't a amp technical question but I figured someone here might know the answer: I'm playing around with an old Boss DR drum machine. It takes a 9 volt/90 mA AC adapter. I tried several of the 9 volt 100 - 200 mA adapters I have laying around here and the machine works but it has a noticeable hum. And, of course, if I try either of my Boss 9 Volt 100 - 200 mA adapters, I get no hum. If I measure the output with an ohm meter, they all read the same

Anybody know why the hum?

Thanks,
UMT

[UMT]

Ah, interesting development. The Boss DR machine makes a hum using a single cord from the output jacks to a mixer BUT, if I use a generic 9 volt adapter and plug into the mixer via the HEADPHONE out jack, no hum.

Anybody have any idea what's happening here?

[Ray Gianelli]

I know this isn't a amp technical question but I figured someone here might know the answer: I'm playing around with an old Boss DR drum machine. It takes a 9 volt/90 mA AC adapter. I tried several of the 9 volt 100 - 200 mA adapters I have laying around here and the machine works but it has a noticeable hum. And, of course, if I try either of my Boss 9 Volt 100 - 200 mA adapters, I get no hum. If I measure the output with an ohm meter, they all read the same

Anybody know why the hum?

Thanks,
UMT

Yes. The Boss adapters are voltage regulated, the others are not.