Valve Itch phono

[stajo]

But what about R12? Its in the system and it will squeeze voltage allowance across sections as the mA go up. Need to progressively go lower to allow the same voltage as before.

Yes your right, needs a recalc also with larger bias adjust

 

[Salas]

Salas I will wait for your news about resistors.

R9 & R11 180 Ohm 1/4W

R12 5.6 kOhm 2W

 

[merlin el mago]

Tomorrow I will change, thanks Salas.

 

[stajo]

Is the grid leak passing so much current?

 

[merlin el mago]

R9 & R11 180 Ohm 1/4W

R12 5.6 kOhm 2W

R12 can be 6kOhm?

 

[Salas]

R12 can be 6kOhm?

Yes but make the other two 150R to surely pass your 9mA bias mark

 

[Salas]

Is the grid leak passing so much current?

Which one, the 820k one?

 

[stajo]

Which one, the 820k one?

Upper tube V4 is biased with cathode resistor R11 and grid (leak) resistor R12 right? Normal auto bias uses R11 to lift the cathode over grid reference in that most or all current passes thru the cathode and not the grid (hopefully).

So what I want to try and understand is why you set R12 to 5K6 2w. Is it carrying a current?

 

[Salas]

Sorry for the misunderstanding its my mistake. I referred to changing R10 also (originally 12k) as R12. I mixed up the value with the designation. Should correctly have typed R10=5.6k or 6k

 

[stajo]

Ok thanks, then my coin dropped. Hopefully Merlins to.

 

[merlin el mago]

Salas have I to change SSHV22 CCS now set to 40mA, I guess not, right?

 

[merlin el mago]

Ok thanks, then my coin dropped. Hopefully Merlins to.

I understood always Salas was speaking of R10 5K6

 

[merlin el mago]

Right channel 53.32V across 5K6 = 9.5mA
Left channel 55.60V across 5K6 = 9.9mA

 

[Salas]

Salas have I to change SSHV22 CCS now set to 40mA, I guess not, right?

It still covers but 45mA would be nicer now, not "must"

 

[Salas]

Right channel 53.32V across 5K6 = 9.5mA
Left channel 55.60V across 5K6 = 9.9mA

Matter of tubes tolerances, close enough though. Check channels gain closeness again which really matters in the end.

 

[merlin el mago]

Now I'm listening.

 

[merlin el mago]

7N7 works better with 9mA, told me the seller.

 

[Salas]

Were there any differences that you could hear from 6mA before to 9-10mA now though?

 

[merlin el mago]

Subjectively speaking more: live, transparent, bass, punch, dynamic, detail.

 

[Salas]

OK, leave the 7N7s at such bias then. They now dissipate 1.2W per triode only keep in mind.