Minimum what you have to use for C3 is good polypropylene capacitor, you can go for more expensive one here, but I can't say abut differences.My new preamp, coming soon
1, Red pcb (reference MM phono preamp)
2, Green pcb (reference line preamp GainWire)
3, small green, inteligent on/off module
Damir, Input selector with relay would be useful
What is the effect on the sound of selecting the capacitor at position C3 (Wima vs Jantzen Superior Z-Cap)
I used paper-polypropylene-aluminium-oil here, as I got it as a gift.
Input selector with relays is a good choice.
Hi Pavel,
Nice to see you here. Output stage is stable, I use it to years with no problem.
I had a stability problem during designing the layout, it's sensitive how the different ground lines were layout, oscillation started between input and output, you can see the ground wires on the back of the PCB, that I changed the input grounding cutting printed ground lines and changing with wires.
Output stage did not have stability problem when I tested in separation on small temporary board.
Best wishes, Damir
Nice to see you here. Output stage is stable, I use it to years with no problem.
I had a stability problem during designing the layout, it's sensitive how the different ground lines were layout, oscillation started between input and output, you can see the ground wires on the back of the PCB, that I changed the input grounding cutting printed ground lines and changing with wires.
Output stage did not have stability problem when I tested in separation on small temporary board.
Best wishes, Damir
Some audiophiles prefer the sound of single ended triode amplifier even with a THD up to 1%. Reason and explanation, THD second harmonic is much higher then the rest of the harmonics.
John Broskie shows here: https://www.tubecad.com/2024/01/blog0593.htm a Harmonic Restoration circuits (why he calls restoration something what was not there on the recording?).
My preamps and amps are all type of PP where second harmonic is canceled to lower lever and it does not dominate FFT.
Here I use a current conveyor where second harmonic cancelation depends on transistors and CM resistors matching. I use 0.1% tolerance resistors there, but I unbalance same of those resistors, let say R14 in last GW schematic(I use 47k paralleled to 1k R14 resistor) I got this, first plot without the resistor and second one with, so called "Harmonic Restoration" active. I use a switch to activate it.
John Broskie shows here: https://www.tubecad.com/2024/01/blog0593.htm a Harmonic Restoration circuits (why he calls restoration something what was not there on the recording?).
My preamps and amps are all type of PP where second harmonic is canceled to lower lever and it does not dominate FFT.
Here I use a current conveyor where second harmonic cancelation depends on transistors and CM resistors matching. I use 0.1% tolerance resistors there, but I unbalance same of those resistors, let say R14 in last GW schematic(I use 47k paralleled to 1k R14 resistor) I got this, first plot without the resistor and second one with, so called "Harmonic Restoration" active. I use a switch to activate it.
Attachments
He calls it “restoration” because you say this.
Regardless, I kind of agree with you. Distortion is distortion.
In my case, and with some kinds of music, I want no distortion. Other times, 2nd harmonic distortion is very pleasant.
In general, I do not like circuits that favor odd harmonics because that tends to be dissonant.