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Hello,

Recently I purchased a used Grace 101 mic preamp and it is acting strange.

Basically, when I power it on (nothing plugged into it line or mic) the LED

slowly changes from green to red. When I plugged it into my mixer the

signal was red lined on the mixer! Is it possible that I was supplied the

wrong wall wort with it? Or what? I am seriously frustrated. Please

advise :(

Comments

anonymous Wed, 07/04/2007 - 20:48

Note: The wall wort specs read 6VDC 1000mA

The Grace 101 reads 6VDC 800mA

Could this be the cause? Also, I tries plugging the 101 into

different power outlets and got the same result: a steady rise in signal

until redline...which is strange because nothing is plugged in to the pre.

I know it is actual screaming noise because at one point I plugged the pre

into a mixer (balanced out into balanced in) and heard the menacing

screech through some headphones laying a few feet away. F#$k!!

anonymous Wed, 07/04/2007 - 23:26

Yes, I am a noob...but I think with only the supplied ac adapter plugged in to the pre, that the Grace's LED should not be slammed in the red. I thought perhaps that it was the wrong ac adapter for the pre???

Well...lesson learned the hard way...no more ebay gear. The buyer had 100% positive on 70+ items over 5 years so I thought I was safe.

Boswell Thu, 07/05/2007 - 02:05

lawless wrote: Note: The wall wort specs read 6VDC 1000mA. The Grace 101 reads 6VDC 800mA. Could this be the cause? Also, I tries plugging the 101 into different power outlets and got the same result: a steady rise in signal until redline...which is strange because nothing is plugged in to the pre. I know it is actual screaming noise because at one point I plugged the pre into a mixer (balanced out into balanced in) and heard the menacing screech through some headphones laying a few feet away. F#$k!!

The power supply rating is fine, as long as it's a regulated unit. It may be too late, but make sure the connector is wired correctly such that the + and - outputs of the power supply go to the + and - power input pins of the 101.

The problem sounds like high frequency oscillation inside the pre-amp. This may possibly be due to poor output filtering in the power supply, but, as AudioGaff says, it's more likely to be a fault in the pre-amp, which will require a service.

I've had lots of good bargains from Ebay, but you get what you pay for, wall warts and all.

anonymous Thu, 07/05/2007 - 11:28

Space wrote: You have the gain knob all the way to the left, the trim knob all the way to the right and 48V(phantom power) OFF...right?

Yes, That is how I first turned the unit on. I then connected a cond. mic and turned phantom power on and about that time I noticed the red light.
Since then, I tested to see if the pre would red line w/out anything plugged into it...and to my dismay it did.

On the plus side, I contacted the seller and he is willing to take the pre back and expressed regret that the unit arrived broken.

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