Just got a shed load of new mics in to try out including some nice looking Heil drum mics. However we became quite moist when we opened the box of new ADK studio condensers. The Thor and the Odin: Crap names but infact very very good microphones

......CHECK THEM OUT.....

GA recently noticed that some PRE73´s can have a slight noise problem when using high gains, 60-80 dB and the problem was traced to noise induced in the ground. Normally you won't hear any noise at normal operating levels but if you use the pre really hard then the solution is to remove the small psu board at the back of the unit and follow the instructions below

1. There are two ground connections in the circuit which connect the main track to the 2 Pcb supporting lugs and on recent units the factory also added 2 wires from the pcb ground trace to these with screw terminals sitting between the pcb and these box support stands, to securely connect the pcb ground to the box.

 

The solution is to remove one of these pcb ground to box connections. Its a very straightforward mod and all you will need are a couple of screw drivers, First of all remove the lid and all the push in connectors to the small PSU board at the back of the unit and then unscrew the two screws connecting the board to the earth posts with the 2 white earth wires (If your unit has them ). Next up remove the small XLR fixing screws on the back of the unit and remove the plastic nut holding the unbalanced line out. Now you will be able to remove the board completely. Turn it over as in the picture above and the wire to remove is the one on the right as shown. (You could decouple the solder if you have a soldering iron but snipping it off close to the board is fine.

Now if you look closely you will see that there is a bridge from the main track to the earth post hole and you need to break that connection by scraping away the copper trace with a small sharp tool or screwdiver

 

 

 

 

 

 

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