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Grounding elevated ccs series filament supply

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velvetsunrise

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Joined 2005
#1
Hi,

I am planning a mu follower hi gain phono stage, similar to the one in Morgan Jones Third edition.

Valve line up will be 6C45P mu stage / 75us eq/ 6DJ8 mu stage/ 318,3180us eq/ 6n6p mu stage.

In an effort to reduce filament current, i am planning on running the left and right channel filaments of each stage in series, each left right pair fed with its own simple LMXXX CCS. and each pair of valves referenced to a suitable voltage for that particular stage

Can anyone tell me the best way to connect each seperate filament supply to the HT elevated reference points? Is the center of the left/right channel series filaments ok as i have shown in the diagram?
 

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#2
Your schematic isn't very clear, so it is difficult to read it.
Concerning your question, a schematic with elevated current regulated heaters supply is attached.
When few different tubes heaters are in series, it is mandatory to verify that all tubes have the same rated heater current.
 

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#3
Hi Thanks for your reply,

With regard to the lower filament supply on your diagram, with the 2 filaments in serise.

Can i ask what is the purpose of the 3 x 1K resistors on your diagram?

Is it ok to omit these 1k resistors and take the center of the series filaments straight to the ht reference point

Thanks.
 
#4
The purpose for the 3 x 1K resistors is to connect the ~+35 Volt to the heaters in a balanced way. I'm not sure if connecting the portion of the HT directly to the connection between the heaters is as good. If there is only 1 heaters supply you can try it, but if there are few heaters supplies, it's better to separate them from one another.
 
#5
Hi Joshua, i have 4 seperate heater supplys, each one comprising left and right channel series connected filaments, and each of the 4 filament supplys referenced to a different elevated voltage.

So, i think it best to include the balancing resistors as in your diagram🙂

Thanks, its much clearer now.
 
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