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previous: Ray Ivers Natko,What are your... -- 5/12/2000 2:03 PM View Thread

Re: Help: Losing singnal when adding a filter cap

5/15/2000 10:55 AM
Natko
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Re: Help: Losing singnal when adding a filter cap
OK, I tried it.  
 
First of all, (thanks to Bruce on the open forum) the pre-amp became a different beast alltogether after I put the coupling caps in their proper place. The hum level became tolerable (although there is still much to improve on) and the gain increased and the sound became fatter and clearer. I can drive my Crate VC-508's 5Watt El84 power stage into clipping and attached to a 12" Speaker cabinet it sounds awesome.  
 
Going with 400V HT, your TubeCAD program predicted the numbers perfectly. I measured the exact values you wrote. The sound was very much worse (almost brittle) though and the hum became intolerable.  
 
I also dropped the 220K part of the divider and then went only through the 100k resistor which worked just fine. I will start experimenting with lower values now to explore the envelope.  
 
Thanks a lot everybody, now I have a working prototype which I can experiment with and expand.  
 
natko.