Valve Itch phono

[merlin el mago]

One Spanish vacuum tube seller told me a 6N8S criogenically treated sound better than an 1578 6H8C metal base hole plates!!!

 

[merlin el mago]

SQ ?

What is it ?

Sound Quality

 

[RCruz]

Thank you Merlin.... I should know better by now.

 

[merlin el mago]

You are always welcome Ricardo.

 

[RCruz]

 

[stajo]

So how you guys feel about an integrated version with the 6V6 pre? Selector and pot infront of R17 and an SSHV on 50-55 mA as source per channel. Just a starterschetch.

 

[Salas]

Integration is deleting the phono to pre interconnect so there is a benefit. It could be more challenging for doing everything properly not to catch any noises OTOH.

 

[stajo]

The idea came up merely because physical chassiework etc is a DIY factor that takes time and effort for most people when doing it properly and the powerline is a cost factor. When thinking of building 2 x 2 chassie+external psu, together with eventual microphonic sensitivity on the 6V6 that might take extra care in chassiework, it seemed like a decent idea.

What do you think of the powerline in this case, SSHV with following RCs?

 

[Salas]

It will work satisfactorily I guess since the μ follower shows good psrr so not to get easily affected by other stronger stages.

 

[stajo]

I was tinkering about the size of C6, 2,2 uF. It seems large for me related to sufficient bass response in this context. Is there any other particular reason for the choice of this?

 

[Salas]

You should choose a value just good enough for the input impedance of the 6V6 additional stage since its not a C6 value designated for coupling to general line preamps anymore.

 

[stajo]

If my calculation is right I can stay as low as 0,1 uF for optimal frequency responce down to 20Hz with 820k. But then comes the pot and its value of course. 1u5 for a 50k pot maybe?

 

[Salas]

That will do if with only R15 820K there. You mentioned introducing a vol pot also. If yes, things change to R15//pot.

 

[stajo]

Double post sorry

 

[Salas]

1u5 for a 50k pot maybe?

1uF will also do because C4 already restricts the infrasonic to a stronger roll-off.

 

[stajo]

That is great because it leaves me with a greater selection of hq caps to try, all from russkie teflons to the expensive silver/gold/oil pretto stuff. Its an imp cap here I beleave.

 

[stajo]

What ITs has been proven? Any evaluations?

 

[stajo]

C4 rolls of from 40 down to 4 -3dB if Im right so I can practise safe sex above that I guess. Is that for avoiding chassie reproductions? Ive never dealt with riaas as you hear

 

[Salas]

What ITs has been proven? Any evaluations?

Step up transformers you mean? The usual suspects have been good. I.e. Jensen, Lundahl, Partridge.

 

[Salas]

C4 rolls of from 40 down to 4 -3dB if Im right so I can practise safe sex above that I guess. Is that for avoiding chassie reproductions? Ive never dealt with riaas as you hear

Here is the roll-off for 1uF to 50K pot when C4 is kept at 0.047u.
1.5uF makes no appreciable difference for the same value pot due to C4's decisive effect on V2's grid impedance as designated in my original schematics. My 2C, don't change the infrasonic FR.