Scott Dorsey
September 11th 03, 11:12 PM
Josh Snider > wrote:
>Ok here's my query. I've got an Eela Audio console S191 from about 1985.
>When I plug my Radial DI into it, I've got no issues at all. Everything
>sounds just the way it should, however, upon plugging a cheaper condenser
>into it (MXL 990) there was a horrible 60hz hum, which got louder upon
>gaining up, and was also audible through the headphones as well as the main
>monitoring desk. I disassembled the mic, and noted that pin 1 was tied to
>the chassis, disconnected that and the problem got worse, reconnected and
>noted that while I was touching the chassis the hum was notably louder.
What does an SM-57 in the same input do? What happens when you turn the
phantom power on and off with an SM-57? What do you hear with no input?
Is your cable good?
Does it happen on all channels or just one?
>Now this is a European desk, however it was operating in a Canadian
>broadcast station for years before I got it, and I believe had been phase
>flipped (at least the mic inputs, the line inputs had not as I came to
>find), and it IS a cheap condenser but can anyone tell me what the possible
>source of this hum is and how to eliminate it. I donšt have another mic to
>swap out with it at the moment, but the Radial (Passive) DI has no issue
>with it so I assume it could be a phantom power issue (although I do measure
>+48V across the to legs of the power supply), but it may also be a grounding
>issue between the mic and the input, or possibly the signal ground is tied
>or leaking to the chassis? Any help would be much appreciated. I'd hate to
>have this sitting here useless.
It could be any of these. Get a dynamic mike and see what happens with
the dynamic mike with and without phantom.
>Also I was wondering if anyone could tell me what the wiring convention was
>for this desk, I'd like to know which colour wire went to which pin on the
>XLR input so I can double check to see if this desk HAS been phase flipped
>or not.
Why does it matter? As long as it preserves phase, it doesn't matter which
pin is hot as long as the input and output are the same way.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
>Ok here's my query. I've got an Eela Audio console S191 from about 1985.
>When I plug my Radial DI into it, I've got no issues at all. Everything
>sounds just the way it should, however, upon plugging a cheaper condenser
>into it (MXL 990) there was a horrible 60hz hum, which got louder upon
>gaining up, and was also audible through the headphones as well as the main
>monitoring desk. I disassembled the mic, and noted that pin 1 was tied to
>the chassis, disconnected that and the problem got worse, reconnected and
>noted that while I was touching the chassis the hum was notably louder.
What does an SM-57 in the same input do? What happens when you turn the
phantom power on and off with an SM-57? What do you hear with no input?
Is your cable good?
Does it happen on all channels or just one?
>Now this is a European desk, however it was operating in a Canadian
>broadcast station for years before I got it, and I believe had been phase
>flipped (at least the mic inputs, the line inputs had not as I came to
>find), and it IS a cheap condenser but can anyone tell me what the possible
>source of this hum is and how to eliminate it. I donšt have another mic to
>swap out with it at the moment, but the Radial (Passive) DI has no issue
>with it so I assume it could be a phantom power issue (although I do measure
>+48V across the to legs of the power supply), but it may also be a grounding
>issue between the mic and the input, or possibly the signal ground is tied
>or leaking to the chassis? Any help would be much appreciated. I'd hate to
>have this sitting here useless.
It could be any of these. Get a dynamic mike and see what happens with
the dynamic mike with and without phantom.
>Also I was wondering if anyone could tell me what the wiring convention was
>for this desk, I'd like to know which colour wire went to which pin on the
>XLR input so I can double check to see if this desk HAS been phase flipped
>or not.
Why does it matter? As long as it preserves phase, it doesn't matter which
pin is hot as long as the input and output are the same way.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."