jamesmking Posted January 5, 2023 Report Share Posted January 5, 2023 (edited) 22 hours ago, micon21 said: Sorry, but how does the signal get to pin8. I see that the cathode feeds transistor Q8, no signal comes to Base Q8 through R11. Simplified explanation: There are multiple methods for changing how a transistor or valve conducts. You can vary the voltage on valve grid or current on the transistor base. Another way is to vary the current supply to the transistor emitter, collector or valve anode or cathode, another way is to vary the voltage at the valve cathode. .. Just because the valve grid or transistor base does not have audio directly applied does not mean that there is no audio passing through the device.... Q1 is constant current. Since its emitter has a constant load and voltage applied and so has a constant current available and the base also has a fixed resistor and fixed voltage. Rv1 can adjust slightly the overall emitter resistance and therefore available current to each half of Q1 so some current balancing can be done to compensate for mismatches in the halves of V1 and V2 etc. The Q1 current is shared between the second 6922 (V2) (the one which does not have its grids connected to the audio input) and Q4/Q5. If second 6922 (V2) pulls more current then less current must be available to Q4 and Q5 since the total current available is constant and visa versa is true if the 6922 pulls less current. So the current through Q4/Q5 is effected by the current pull from second 6922 (V2) whos current draw is effected by the audio on the grid 1 of the input 6922 (V1) . Since the second 6922 (V2) supplies the anode current to the input 6922 (V1). if Q4/Q5 are effected by input 6922, Q11 and Q12 must also be since they get their current directly from Q4/Q5 and the base of Q11 and Q12 is held constant by the resistor string .. R36, R49,50,60 If Q11/Q12 have current draw effected by the audio input 6922 then the voltage drop across R11 and R12 and current through R11/12 must also be based on the audio input... since the current through R11 and R12 is directly controlled by the current through Q11 and Q12 The current through R11 and R12 control the current at the base of Q8 and Q9 and therefore control the current through Q8 and Q9. Q8 and Q9 control the voltage at the EL34 cathode and that's how the audio gets into the EL34s and that's the AC audio voltage than can be measured with an multimeter at the cathode of the EL34s. Edited January 6, 2023 by jamesmking 1 Quote Link to comment Share on other sites More sharing options...
boinger Posted February 22, 2023 Report Share Posted February 22, 2023 Anyone have the links to the bom and schematic for the group by? The first post seems to have the links unavailable. Quote Link to comment Share on other sites More sharing options...
Pars Posted February 22, 2023 Report Share Posted February 22, 2023 Links in the first post work for me... Quote Link to comment Share on other sites More sharing options...
boinger Posted February 27, 2023 Report Share Posted February 27, 2023 I got it to work. Had to open in new tab for some reason. Quote Link to comment Share on other sites More sharing options...
audiostar Posted June 14, 2023 Report Share Posted June 14, 2023 (edited) On 3/11/2019 at 2:36 PM, JoaMat said: Well, I rather not make recommendations but I would go for +400V/-460V and add one 20K/3W resistor on each board between +220V and +400V pads. I think I want something like this… ...for power supply. Now, going to order some transformers 🙂 Is there anything speaking against using the following secondaries with this PSU? 320Vac @ 0.18A -> 400Vdc 365Vac @ 0.18A -> -460Vdc For the +220Vdc I'll use a separate GRHV, like the kgsshvpssicfetsinglenewright but without the Bias portion on it. Edited June 14, 2023 by audiostar Quote Link to comment Share on other sites More sharing options...
jamesmking Posted June 14, 2023 Report Share Posted June 14, 2023 4 minutes ago, audiostar said: Going to order transformers. Is there anything speaking against using the following secondaries with this PSU? 320Vac @ 0.18A -> 400Vdc 365Vac @ 0.18A -> -460Vdc thats close to what I used and should work fine. I used 190Vac 0.18A for the 220VDC rail 1 Quote Link to comment Share on other sites More sharing options...
JoaMat Posted September 21, 2023 Report Share Posted September 21, 2023 mini T2 one channel lsk389 replacing 6DJ8/6922. Still on drawing table. 4 Quote Link to comment Share on other sites More sharing options...
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