Valve Itch phono

[Salas]

I think it still stayed within good operational limits

 

[merlin el mago]

Sounds more organic, it's a high improvement of SQ vs the 1n4148 x 2

 

[merlin el mago]

Impressive, amazing, stunning.

 

[Salas]

Told you, hack the remotes

 

[merlin el mago]

I don't expected this amount of huge improvement in SQ

 

[Salas]

You saw in rev 1.2 but nobody can know from paper only

 

[merlin el mago]

I'm just listening all my new vinyl collection, now playing opera.

 

[merlin el mago]

Salas could I do the IR LED mod to the ECC81 mu-follower (attached schematic)?

 

[merlin el mago]

Itch now playing.

 

[merlin el mago]

Salas do you know what's the input impedance of Itch?

 

[stajo]

Salas do you know what's the input impedance of Itch?

R1

 

[merlin el mago]

?

 

[massimo]

The value of R1, most probably 47kOhm, dear Merlin

 

[merlin el mago]

What capacitance have R1 caro Massimo & dear stajo?

 

[massimo]

That's a different story... should be measured, not predicted (and it's not related with R1 value)

 

[merlin el mago]

Measuring the capacitance with a tester at the RCA inputs?

 

[massimo]

 

[stajo]

Feed it from the signal generator through a large resistor. With the scope on the output, determine the -3dB frequency (i.e., where the output drops to about 70% of midband gain). If you run out of signal generator, make the resistor larger. Now you can calculate the input C of the input stage (dominated by Miller) by C = 1/(2pi*f3*R).

 

[Salas]

Salas could I do the IR LED mod to the ECC81 mu-follower (attached schematic)?

You should measure the voltage drop across the resistor you want to substitute with IR Led. If it is compatible with the amount of Vf one or more IRs can give you, you change. Be aware that while it is not out of concept in the Itch, when for higher bias and voltage swings in different stages a resistor may still be preferable. As it follows the bias and aging of tubes better. So don't think it will necessarily perform better. Maybe worse. It depends.

 

[merlin el mago]

ECC81 now is using 2V red LED