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5E3 Deluxe has too much gain.


 :
3/2/2003 9:02 PM
David Harlson
5E3 Deluxe has too much gain.
Need help with headroom on 5E3 circuit.Almost no head room.Any suggestions?
 
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3/3/2003 12:32 AM
Troy

Are you using a 12AY7 preamp tube on the first gain stage? If not, try that it will definitely bring the gain down some compared to a 12AX7. Is this a homebrew or real 5E3? Depending on your tranny specs you could install 6L6's but you should up your cathode resistor to a 10 watter and whatever value gets you the bias you need.  
 
Troy
 
3/3/2003 12:47 AM
David Harlson

Thanks for your reply! I am using a 12AY7 reamp tube and a 12AT7 as the phase inverter. It is a DIY amp the power transformer is a Hoffman Tweed deluxe I am not sure it has the voltages for 6L6s or 5881s.I am also using a Hoffman 30watt output transformer.My set resistor is currently a 270 Ohm with a 25-25 bypass cap. I wonder if the resitor being 20 ohms greater than spec has any bearing on my problem.
 
3/4/2003 6:11 PM
Bruce /Mission Amps

I'm pretty sure the PT is OK with a pair of 6L6s.  
I don't know what the primary zed is of the 30 watt OT you are using with whatever speaker load you have as you didn't mention.  
If it's +4K at 8 ohms, you are OK.  
If not... then ???  
 
Use a 10 watt 270 ohm resistor for the cathode bias but make sure your cathode bypass cap is rated at 50v to 100v!  
Lower the first dropping resistor between the first two filter caps to half (or less) of the 5k in there now. Make it a two watter.  
Get rid of the four .1uF coupling caps and use .047uF to the power tubes and .022uF from the 12AY7 to the volume pots.  
 
Bruce
 

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