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What Do You Hear When Your Amp Needs Biasing?

Hi, Everybody,

I was listening to my rig the other day and noticed that some (but not all) closely miked recordings of female singers (Diana Krall on some of the cuts on "When I Look in Your Eyes" comes to mind) sounded a bit edgy or harsh. I checked the bias on my Manley Mahi amplifiers and found that some of the values on the multimeter, which should have been at 250, were as low as 240. I made the bias adjustments and, lo and behold, the vocal tracks sounded better. So I'm wondering what, in general, is a tipoff that a to be of a fire needs to be biased?

Thanks!
rebbi

Showing 1 response by doc77

doc77
47 posts
 
More often than not I'll think I hear something off, check the bias and it's still dead on. There was one time however that a certain piano concerto I'm very familiar with sounded a bit zingy, so checked the bias and one of the power tubes was way off.

Most of the time though I think it's pretty hard to hear the small wanderings that are common.
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