6SN7 driving EL34PSE

[neskor]

Recently I got Tektron EL34PSE intergrated amp with 6SN7 as input/driver tube.
My version is older version with 6SN7 connected as two gain stages (picture 1).
New updated version is using 6SN7 in SRPP configuartion (picture 2).
Is there any benefit to convert old version to new one?
Also is there enough gain in 6SN7 in SRPP configuration to drive two EL34 in PSE?

 

[artosalo]

Also is there enough gain in 6SN7 in SRPP configuration to drive two EL34 in PSE?

To answer that question is diffucult since you have not told what your signal source is / its output voltage.

 

[neskor]

It is standard intregrated tube amplifier with 3 line inputs and 100K volume pot before 6SN7.
Source can be CD, tuner... so let's assume it is around 2V.
It wil be used without any preamp.

 

[waltube]

Recently I got Tektron EL34PSE

I know personally Attilio, the owner of Tektron.
Ask him.
In case it seems that the total gain of both circuit is similar.

Walter

 

[mbrennwa]

The 6SN7 has a voltage gain of 20x, and the gain of the SRPP circuit will be in this ballpark. With a 2VAC input, that's more than enough to drive the EL34 to full swing -- except maybe if there's global negative feedback in the circuit, but your diagrams do not show anything like that.

 

[neskor]

No NFB in this amp.
So, if you need to choose, which version will be better to implement, first or second one?

 

[andyjevans]

Is a single 6SN7 gain stage an option, resistor loaded?

 

[neskor]

I would like to keep as original as I can, so unfortunately single 6SN7 gain stage is no option.

 

[soulmerchant]

Is the gain enough right now? Can you live with half the gain you will get with the SRPP?

 

[soulmerchant]

Is a single 6SN7 gain stage an option, resistor loaded?

He could parallel the triodes of the 6SN7. Or change to using two 6J5's instead. ST shaped 6J5G's look pretty.

 

[neskor]

let's forget about the gain for a second, which version (2 gain stages vs SRPP) will be better, sound wise?

 

[soulmerchant]

You can build them both and tell us subjectively which one you prefer. But electrically speaking, they are quite different, so the comparison is like saying which one is better, the pear or the peach.

Each option has
1. Different levels of amplification
2. Different sources of distortion
3. Different levels of distortion
4. Different output impedance
Ah, and
5. different input sensitivity...

But 6SN7 is a fairly low distortion tube to start with, so SRPP tends to sound pretty good in this topology. Output impedance will be lower than the series differential amplifier for sure as well. SRPP brings in it's own distortion as a toplology, but usually it is not terribly bad.

So - is the gain enough? If so you can probably stick with SRPP.