I propose a mu folower driver using ECC83 and E180F tubes that can provide a gain of 100 on a load resistance formed by the power tube grid resistor of 82kohm. For an output voltage of 50v THD it is 0.3% and for 90v THD it is 1.56%. The driver can easily drive power tubes requiring a large attack like 2A3, GU50, 300b, PL504, PL509 practically all common tubes and has the advantage that there is only one stage preamplifier
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Is this a simulation?
When looking at the pretty close curves of a e83cc there should be something close to Ugk 1V at Ua 170V and 1,7mA as your circuit suggests.
Shouldn't that 100ohm cathode resistor and 171mV Ugk be much higher, like 560 ohm or so, just to stay out of gridcurrent and charging up the coupling cap?
I cannot imagine there would be so much of a difference between a ecc83 and a e83cc, but i have no good curves of the ecc83 at my disposal rigth now.
When looking at the pretty close curves of a e83cc there should be something close to Ugk 1V at Ua 170V and 1,7mA as your circuit suggests.
Shouldn't that 100ohm cathode resistor and 171mV Ugk be much higher, like 560 ohm or so, just to stay out of gridcurrent and charging up the coupling cap?
I cannot imagine there would be so much of a difference between a ecc83 and a e83cc, but i have no good curves of the ecc83 at my disposal rigth now.
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Hi guys,, this driver has been designed and tested basically, I am not familiar with the simulation procedure but maybe someone can check this driver through simulation. In addition to this driver we tested an extensive SE with PL36 containing two local negative reactions that greatly decrease input sensitivity but the driver easily drives the end tube
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The gain is too high.
Input sensitivity is too small 500mV
most of the digital sources has 2Vrms output it is about 5,6Vp-p
more than 10X from 500mV...
And without pramplifier in the chain.
...
Solution is to put some other tube to replace ECC83
with smaller amplification factor
And -Ug equal or more than -3V to
accept standard putput max voltages sources without overloading the inputr tube...
in that configuration the max signal for staying in negative region for power tube is 2x abs(-53V)=106Vp-p
If the gain of the mju follower is 100 than input sensitivity is 106Vp-p / 100 = 106mVp-p
for full power of output tube - too small value
Again sources has 5.66Vp-p output.
.
And this is the most commom mislead in tube devices...
Very small input sensitivity.
In the PL 36 end tube example, there are two local negative reactions through the two resistors, the 1K/16w resistor in the cathode and the 1M resistor (SCHADE), which decrease the total gain so that the input voltage is approx. 1Vrms, compatible with digital or analog signal sources. These local reactions greatly reduce distortion and provide a good harmonic response, basically the driver molded to the requirements of the end tube
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I hate to be the one to point this out, but sand does a better job than E180F in mu-follower duty. No heater requirements too. The most significant contributor to the low THD is likely to be the schade feedback, as gorgon53 notes as well. Of course if you throttle the gain then your THD ain't gonna be a problem right? 
Vh-K = 60V according to Mullard specs, so gorgon53 probably has a point. Of course, if your E180F lives for a decent time before dying then that might be acceptable. Last time I checked these weren't hard to source for a nice price.
I had a nice bunch of these some time ago (NOS gold pin, Teslas) but finally decided that I needed to reduce, and that other pentodes I had were better candidates.
Nice to see you working on a use for them. They are certainly interesting little pentodes.
Vh-K = 60V according to Mullard specs, so gorgon53 probably has a point. Of course, if your E180F lives for a decent time before dying then that might be acceptable. Last time I checked these weren't hard to source for a nice price.
I had a nice bunch of these some time ago (NOS gold pin, Teslas) but finally decided that I needed to reduce, and that other pentodes I had were better candidates.
Nice to see you working on a use for them. They are certainly interesting little pentodes.
We specified that the supply of the e180f filament is made separately from that of the ecc83 tube, i.e. it is a floating voltage relative to the ground, so there is no danger to Uf-k. The e180f tube was not chosen randomly, one can read in Alan Kimmel's article the requirements for designing a mu folower driver but I agree that this tube can be replaced with a corresponding CCS
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@gorgon 53, the maximum amplified voltage in the cathode of the E180F tube is 94V rms or 188Vp-p and is reported relative to GND and the alternating voltage of 6.3v applied to the filament is completely isolated from GND so Uf-k=60v is recommended only if one end of the filament would be connected to ground
@20to20, a universal driver must provide the end tubes capable of being driven in the situations required by it with a minimum of intermediate stages, for tubes working in A2 it is imperative that a driver capable of delivering a positive grid current that can be a mosfet or a Michimori floor, in the context this driver does exactly that
[QUOTE="popa marius, post: 7688211, member: 243344"
@gorgon 53, the maximum amplified voltage in the cathode of the E180F tube is 94V rms or 188Vp-p and is reported relative to GND and the alternating voltage of 6.3v applied to the filament is completely isolated from GND so Uf-k=60v is recommended only if one end of the filament would be connected to ground
[/QUOTE]
To bad that you still do not understand. The heater circuit (wich includes the transformers heater winding stray capacitance) cannot possible follow the cathode voltage +-94V excursion without exceeding the +-60Vmax limit. It will always be exceeded unless you take measures to make the heatercircuit follow the cathode excursion with less than +-60V deviation.
Otherwise, even if your heatercircuit would float at the ideal midpoint the voltage would be half of your 188Vpp and far exceeding the 120Vpp limit the tube data sheet givs.
If the cathode/heatercircuit voltage division is left to whatever it "floats" at, i.e., to the combination of cathode/heater leakage and capacitance division between Ckf and the transformers heater winding stray capacitance to ground all bets are off and you are guaranteed there will be uncontrolled cathode/heater voltage far exceeding the +-60V limit.
Furthermore, think what happens, should your heater not "float" to signal 188Vpp excursion midpoint, but instead settles 10V higher or lower than cathode midpoint. You still have 68Vpp overvoltage but you now have in one direction 24V and in the other 44V over limit. Should your midpoint be off by 26V you have in one direction still 8V more than the 60V limit, but in the other direction you are 60V over the limit.100% heater cathode OVER VOLTAGE
@gorgon 53, the maximum amplified voltage in the cathode of the E180F tube is 94V rms or 188Vp-p and is reported relative to GND and the alternating voltage of 6.3v applied to the filament is completely isolated from GND so Uf-k=60v is recommended only if one end of the filament would be connected to ground
[/QUOTE]
To bad that you still do not understand. The heater circuit (wich includes the transformers heater winding stray capacitance) cannot possible follow the cathode voltage +-94V excursion without exceeding the +-60Vmax limit. It will always be exceeded unless you take measures to make the heatercircuit follow the cathode excursion with less than +-60V deviation.
Otherwise, even if your heatercircuit would float at the ideal midpoint the voltage would be half of your 188Vpp and far exceeding the 120Vpp limit the tube data sheet givs.
If the cathode/heatercircuit voltage division is left to whatever it "floats" at, i.e., to the combination of cathode/heater leakage and capacitance division between Ckf and the transformers heater winding stray capacitance to ground all bets are off and you are guaranteed there will be uncontrolled cathode/heater voltage far exceeding the +-60V limit.
Furthermore, think what happens, should your heater not "float" to signal 188Vpp excursion midpoint, but instead settles 10V higher or lower than cathode midpoint. You still have 68Vpp overvoltage but you now have in one direction 24V and in the other 44V over limit. Should your midpoint be off by 26V you have in one direction still 8V more than the 60V limit, but in the other direction you are 60V over the limit.100% heater cathode OVER VOLTAGE
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