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Filtering


 
1/19/2004 3:44 AM
jeff
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Filtering
I'm working on a new amp and I had a question regarding B+ filtering. How many stages of pre-amp can be filtered by one 20uF filter stage. Usually, I see that two stages of pre are filtered by one capacitor, but is it possible to filter four stages of pre with one capacitor. Are there any downfalls to this and, if so, what are the results?  
 
Thanks  
Jeff
 
1/19/2004 5:03 AM
Chuck
Sure you can filter more than two preamp stages at a single filter node. But not a good idea if they are in series. BF Fender amps commonly filtered 5 stages from a single node but only 3 are in series for one input and 2 for the other.  
 
I think the reason for not doing three in series on high gain amps is noise and crosstalk. You should be able to get away with 3 if one is a cathode follower. But I'm no expert.  
 
Chuck
 
1/19/2004 6:01 AM
jeff
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Interesting. Thank you for your input. These will be in parallel so I wonder what kind of problem that will pose.  
 
Thanks  
Jeff
 
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