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HQ-IV tube output balance DAC

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Hi Blitz!

Thank you for showing me,

Yes, I was confused schematic, very sorry for you!

And this is my circuit diagram!

Quanhao, I am studying the schematic and the pcb, you have two different schematic, can you please post again which one is the correct one? I am a bit confuse. The one you said was yours, it does not have C3, R11 (left), but the pcb has it?? Please clarify
 
Quanghau - For ECC99 tubes R5, R14, R20, R29 = 470R? Same as 6DJ8?

Is it possible to use other tubes for V2/V4 ex: 12AX7, 12BH7 if we calculate R8, R9, R23, R24 and R1, R2, R16, R17?

Or change R8, R9, R23, R24 and adjust VR's?

yes, 6DJ8 can change by Ecc99.

12AX7, 12BH7 , i not test this tube, but 12BH7 you can usre
R5, R14, R20, R29 = 470 - 1K, set curent = 10-15mA at 260V +b

and all shema for two options output. An HV supply
thanks
 

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Quanghau - I would like to use Shinkoh resistor for R6,R12 & R21,R27 low pass filter but no 2k2. Can I use 2K4 with 470pf for filter?

Can we reduce value of 2k2 and increase 470pf for same frequency filter?

Is this correct?
Cut off Frequency: 2K2 & 470pf = 153999.67968067 Hz.

We can also use 1k3 & 800pf for same frequency cut off?

Low Pass Filter Calculator


yes, you can get the value you like!
thanks
 
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