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 rrog

I find it hard to believe you could hear the difference between a setting of 240 and 250. Actually with a slightly lower bias setting the vocals could sound a little smoother unless it was only one tube here and there that was low. In that case you could have one or more low biased tubes in a push pull pair that is low which would cause a rise in distortion which would explain hearing edgy or harsh close miked female vocals.