Hissing problems Sovtek mig 50

[Satamax]

Pio, where are you located?

[pyo]

I live in France, Marseille!!
I just saw that you live in the french alps, near the italian border!!
Where exactly??

[Satamax]

Hi Pyo.

Well, i live near Briançon. If ever you need some help.

Bye.

Max.

[pyo]

Well yeah, if you could help me out!!
Do you think the hissing problem could come from the transformer. Either the power transfo or the output transfo. Which could be the most noisy??
I was planning on padding them with some absorbing material, and then try again if the hiss is lower.

Let you know

pyo

[gribnick]

Resistor type?

What kind of resistors are in this amp? Carbon comp resistors are known suppliers of hiss especially the grid stop of the first stage. Many people get the quietest metal film resistor they can to put on that first stage. The larger (ohmage) the resistor, the more hiss it can generate. The larger (physically) the resistor, the less hiss it will generate. Go for a larger wattage, smaller value grid resistor on the first stage. Standard size is 68K but often 33K or even 10K will do a sufficient amount of radio reception rejection and reduce hiss..

[pdf64]

See
http://www.geofex.com/ampdbug/hiss.htm
it mostly the 100k plate resistor which goes noisey, but replacing the 68k grid stoppers and mounting them at the tube socket is a great idea also. Peter.

[strata]

Do you think the hissing problem could come from the transformer. Either the power transfo or the output transfo. Which could be the most noisy??

It's almost certain that that's not the problem.