Pultec SRPP - gain adjust ??

[matthias]

Hi,

is it possible to adjust the gain of the G-Pultec SRPP gain stage???

as I see from the schematic there is no feedback path...
maybe there's another possibilty ???

thanks,
mat

 

[gyraf]

Basically - No.

The SRPP runs more or less at the voltage gain of the tube.

If you need to alter gain, put an attenuator in front of it.

On TubeCad.com there's a series of good articles on SRPP.

Jakob E.

 

[matthias]

ok... thanks...

so the gain in your srpp circuit is adjusted to the level loss of the passive filter network...

mat

 

[gyraf]

Yup - the ECC88 matches that pretty close with that output transformer..

 

[Steffen]

just replace the 10k resistor in front of the srpp (the one that conects from the 220n coupling cap to ground) with a pot. thats the way I did it.

steff

 

[dukasound]

[quote author="Steffen"]just replace the 10k resistor in front of the srpp (the one that conects from the 220n coupling cap to ground) with a pot. thats the way I did it.

steff[/quote]
Hi
10K :?: I havent 10K on main board. I asked before long time about 10K what exist in schematic but missed on board.
http://www.groupdiy.com/index.php?topic=751&postdays=0&postorder=asc&start=30
Duka

 

[matthias]

it's the 10k on the board containing the tubes that is connected between filter pcb in and ground...


@ steff:

when I swap the 10k to a pot.. then I can only decrease the input volume, but I don't get more gain.. is this correct ??


thanks,
mat

 

[gyraf]

yes.

 

[dukasound]

Hi
Its 10K connected on unbalanced input or on secondary of optinonal transformer.
What with 10K what I am talking about.
Thanks
Duka.
Last time I have my discussion about voltage on my Gyraf Pultec. I saw only 230V, if I use two transformers 220V/12V. Is is enought?