RollE2k,
CCS anode loading of SE common cathode gain stages is FINE. However, differential gain blocks are a very different "animal". CMRR is highest, when symmetry between the 2 sides is maximized. That means a CCS in the tail. If you want very high impedance anode loads, when differential topology is employed, use gyrators to "synthesize" inductances in the hundreds, if not thousands, of H.
CCS anode loading of SE common cathode gain stages is FINE. However, differential gain blocks are a very different "animal". CMRR is highest, when symmetry between the 2 sides is maximized. That means a CCS in the tail. If you want very high impedance anode loads, when differential topology is employed, use gyrators to "synthesize" inductances in the hundreds, if not thousands, of H.
So, i cascoded DN2540 in the tail - dropping at least 50v. Then a gyrator for each of the anodes?
To bad i have never built any gyrators - do you have any link where to read more about this, or care to explain how curcuits work. All i know is that it is there pretty much to simulate a large choke - or high AC inductance, low DC resistance.
To bad i have never built any gyrators - do you have any link where to read more about this, or care to explain how curcuits work. All i know is that it is there pretty much to simulate a large choke - or high AC inductance, low DC resistance.
Eli: I have been looking around for this now for a while, but at least what i have found it seems mostly that there is usually problem running Tail CCS plus plate gyrators, since they seem to build on a current source at the plate also. So the tail/plate sources seem to fight eachother?
Do you know of any circuit that would work? I've started thinking about maybe going for lundahl common mode choke (~around 2x800H per choke) instead, and using 6072A or 7062A/5965A/E180CC tubes.
But gyrators (if working good with tail CCS) would probably be better - and cheaper, since i won't need the extra swing the chokes would give.
Do you know of any circuit that would work? I've started thinking about maybe going for lundahl common mode choke (~around 2x800H per choke) instead, and using 6072A or 7062A/5965A/E180CC tubes.
But gyrators (if working good with tail CCS) would probably be better - and cheaper, since i won't need the extra swing the chokes would give.
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