Good evening Forum,
maybe you noticed this thread:
https://www.vintage-radio.net/forum/...ad.php?t=16509
You can find fundamentals there how a dc coupled valve amp can be realized.
The fundamental component is a triode.
The triode makes it possible to replace all kind of coupling capacitors, coils, transformers, and resistors. I will call this triode "coupling triode".
As you know from the link, the input voltage at the plate is divided micro
times by the coupling triode if its grid is decoupled to ground.
Decoupling the grid of the triode to its cathode, the signal is divided by one
because the triode works in a "diode mode".
To get a "RIAA coupling" between the stages, the grid of the coupling triode
is coupled to ground or to cathode depending in the frequency.
The coupling triode makes a RIAA coupling now. I will call this triode "RIAA triode".
In the attachements you can see the fundamental schematic and the signal
flow schematic. Please note that there are only valves (triodes) in the signal
path, no caps, transformers, coils or resistors etc. This is unique, isn't it
.
I want to use the well known valves ECC83 and ECC82.
The power supply is solid state and makes 12V6 for the heaters,
+250V and -50V for the valve stages, -12V for the biasing.
the attached pics show the making of the power supply.
If it is of interest, I can explain it too.
Kind regards,
Darius