6sl7 cascode
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6sl7 cascode
I am designing an amp with a 6sl7 cascode input and plan on elevating the heaters by connecting the heater center tap at my cathode bias 6l6 bias resistor. Is there any reason this will not work, something about heater to cathode ratio or what not. I have done this before just not with a cascode. Thanks for the help
anything worth doing, is worth doing right
Re: 6sl7 cascode
You may not get a high enough heater elevation. Better way is to make a voltage divider from the HT/B+ rail (which can double as a bleeder for the filter caps). That way you can design it for the DC voltage you want. (You also need to 'decouple' the voltage divider knee with a decent cap to keep the DC voltage steady). I would aim for 60-80 volts elevation for a cascade
Example below:
[img:436:317]http://farm9.staticflickr.com/8325/8144 ... fd73_o.png[/img]
Example below:
[img:436:317]http://farm9.staticflickr.com/8325/8144 ... fd73_o.png[/img]
He who dies with the most tubes... wins
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- Joined: Mon Mar 13, 2006 4:17 am
- Location: akron, ohio
Re: 6sl7 cascode
Thanks, I have elevated the heaters that way as well. I was actually worried that I would be elevating them at too high a voltage for a cascode circuit at the bias resistor
anything worth doing, is worth doing right
Re: 6sl7 cascode
Just a suggestion, but you might like a 6SN7 better in cascode. Higher transconductance tubes work better in that configuration.
Steve
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- Joined: Mon Mar 13, 2006 4:17 am
- Location: akron, ohio
Re: 6sl7 cascode
This works well with a 6SN7. Use .68uf cathode bypass cap- it makes ia nice input stage.
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Steve
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Re: 6sl7 cascode
Grid bias upper triode. That is sorta what I was wanting to try. Was checking out some of the circuits in Merlin's book. Thanks I will give it a try
anything worth doing, is worth doing right
Re: 6sl7 cascode
I posted regarding this somewhere recently... I tried this same cascode with fixed and self bias. Grid leak sounded the best to me.
Steve
Re: 6sl7 cascode
6DJ8 (ECC88) is actually better suited for Cascode (150V on cathode) as it's designed for Cascode circuits..
Tony
Tony
" The psychics on my bench is the same as Dumble'"