6al5

[skal1]

what  do you  apply dc to a 6al5 to set the voltage for the in coming ac  signal.


skal1

edit

I think i am asking  the ? incorrectly

so what i meant to ask was what sets the threshold in the 436c at 20v when the when the the threshold pot is ccw , if the dc voltage was less than 20v , say 1v dose this mean that the compression would be almost instant with a small ac signal at the cathodes.

skal1

 

[pyjaman]

Hi, Skal,
As I see it (as I'm still trying to understand that, too, so let's see if my take on this make the knowlegeable people jump on their chair to correct me...) The 6al5 will only let pass negative voltages ( I look at it as if the two 6al5 diodes and SC RC network were comparable to the rectifier/filter section of a negative PSU).
So, until AC feeding the cathodes doesn't exceed 20 volts peak negatively, the potential at them will stay positive and they won't pass anything. So no change at the head amp and no compression.

So to answer your question, if this voltage were 1v instead of 20, The diodes will pass everything below 1V, making the sidechain reacting, thus changing the headamp bias .

Just what I think I understood, so let's see if it provoques better explainations if I'm wrong.

Laurent.

 

[simonsez]

How to make dc booster after 6AL5, so i can get deeper compression without cranking input? like scamp booster for solid state SC poorman? Thanks..

 

[zebra50]

Most users turn up the input and pad the output. Is that approach a problem for your application?

 

[simonsez]

I did that too, crank the input, lower the output, turn up threshold (specially when input signal is low like OH track), but if there is some kind of scamp booster for 6al5 it will be nice.