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Deluxe Reverb Voltages?


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7/19/2000 2:25 AM
Shocktone
Deluxe Reverb Voltages?
I checked the Plate Voltages in my Silverface DR.  
 
The power tubes were ok, but the voltage on the driver/preamp tubes was 280V instead of 170V.  
Whats does that mean?  
 
The amp doesnt sound bad. But I didnt compare it too antother DR yet.  
 
 
Thank you very much for your help.  
Greetings Jens.
 
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7/19/2000 3:10 AM
M/J

Are the voltages equal on both side of the preamp tubes? Could be some resistors out of spec. Check the resistors under the cover where your filter caps are too.  
 
M/J
 
7/19/2000 5:36 AM
Jim S.

Later silverface DRs use 2K2 as the first power supply dropping resistor instead of 10K. This is the resistor that sits between the screen and PI filter caps. (The other dropping resistor is always 10K.) The effect is to raise the plate voltage significantly on the PI and somewhat on the preamp stages. You might want to check which resistors you have and make sure they haven't drifted out of spec. The schematics that show 170 or 180 volts on the PI and preamp plates are for versions that have two 10K dropping resistors.  
 
BTW, changing that first 10K dropping resistor to 2K2 is a cool mod for earlier silverface DRs and blackface DRs. Same goes for Vibrolux Reverbs. The effect is to increase headroom slightly. The PI stays cleaner longer as you start cranking the volume. This can be useful when playing with bass and drums and you need some more dynamics out of those 20 watts. Of course, there's still plenty of overdrive when the volume is between 6 and 10.
 

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