Valve Itch phono

[merlin el mago]

Salas how many mA have I to adjust the SSHV2 for the Itch?

 

[stajo]

If your circuit draws 1 mA on the input tubes and 6 mA on the output tubes that is 7 mA per channel. For two channel that is 14 mA. Add 20 for the SSHV and you get 34. Add some safety to 38 maybe? How much does your circuit/tubes draw in your config?

 

[merlin el mago]

I set to 40mA, how can measure how much the circuit draws?

 

[merlin el mago]

Mine version teorically draws 1.36mA input tube and 3.5mA output tube, total 9.72mA.

 

[stajo]

Put a 100R resistor between the Itch and the circuit temporarily and measure over that. Use ohms law, I=U/R

 

[merlin el mago]

Oh thanks, I forgot I did the same to know the current draws in my #26 preamp, the Itch draws 10mA

 

[stajo]

Cool. Set SSHV to 30 if that was for two channels.

 

[merlin el mago]

I set to 35mA to have 5mA of safety margin.

 

[stajo]

Yes. Current was a bit low so its good to take some head for other tubes in the future.

 

[merlin el mago]

Now is time to make the listening session but just now in 15 minutes starts the football match of Barça so the session must start after the match.

 

[merlin el mago]

I like more 168pF in place of 100pF.

 

[Salas]

 

[merlin el mago]

The sound of Partridge977 vs Jensen is big, I guessed same sound with more power but what surprise, a lot of less noise, more bandwith in lows and highs, very transparent cristal sound with extreme lows not inflated.

 

[Salas]

More refined this SUT class in general.

 

[merlin el mago]

Yes "refined" is the exact word to describe the SUT.

 

[merlin el mago]

If I remember correctly Erno Borbely used Jensen for his Microphone preamp

 

[Salas]

So by your build with your cable lengths and naked 103R as cart you recommend 6K8+168pF Zobel across the Jensen 44 secondary and 47K between input tube's grid and ground. Is that correct?

 

[merlin el mago]

Yes, sounds very very good.

 

[Salas]

OK. And one last thing for the resume, Jensen's black/white, white, black, shield cables go on input's ground side now? No hum, as no hum before?

 

[merlin el mago]

Yes Jensen wires connected as you describe, no hum before and no hum now.