Marantz 1030 high gain and noise problem.

[guy75]

I have a problem on the preamp stage of a Marantz 1030.
I changed all 2sc458 with 2sc945 and the left channel have more gain and more hiss (at 9 o'clock i have the maximum power output) respect the right channel.

I checked R515 and C511 and seems to be ok. I changed also C503, C505, C509, C511 without success.

Thanks.

Guido.

 

[ryuuoh]

Were the transistors bought from a known quality source? How did the unit sound before the work?

 

[guy75]

I tried to change again the transistors but without success.
Before with the old devices the amp had the same gain problem plus the noise problem of the 2sc458.

 

[ryuuoh]

Maybe you have noisy resistors?

 

[glen65]

Are you sure the signal itself is actually higher?
Or maybe the "total" output is higher because of the added noise?