No hum with headphones?

[WestyBassBob]

I own a rather noisy Ibanez Mikro. When the pickups are turned up it whines like crazy until I touch the strings. I always assumed this was because it’s a cheap instrument with crappy shielding. But tonight while practicing with headphones I had the pickups turned up all the way and the amp up high and noticed almost no hum whatsoever. What gives? Does this mean it’s my crappy amp instead? Anybody else experience this?

 

[megafiddle]

It sounds like acoustic feedback. The strings are being excited by the sound from the amp's speaker.

That excitation is absent when using headphones.

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[WestyBassBob]

It sounds like acoustic feedback. The strings are being excited by the sound from the amp's speaker.

That excitation is absent when using headphones.

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That’s possible I guess. I’ll play around with it. Thanks.

 

[megafiddle]

I based that on your description of the sound as a "whine". In other words, maybe some frequency other than 60 cycle hum.

When you release the strings, does the whine build up in volume gradually?

Does this only occur at higher volumes?

If so, that would indicate acoustic feedback.

Or does it start and stop abrubtly as you touch and release the strings?

Does it stop when you touch the strings anywhere, even at the tuners?

If so, that would indicate a shielding or ground problem.

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[WestyBassBob]

I based that on your description of the sound as a "whine". In other words, maybe some frequency other than 60 cycle hum.

When you release the strings, does the whine build up in volume gradually?

Does this only occur at higher volumes?

If so, that would indicate acoustic feedback.

Or does it start and stop abrubtly as you touch and release the strings?

Does it stop when you touch the strings anywhere, even at the tuners?

If so, that would indicate a shielding or ground problem.

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Thanks! I’ll check that out.