NAD 3140 phono input mistake !!

[guizmo1967]

Hello,

I accidently connected my aux input (TV) to phono1 and now phono1 is louder (volume higher than phono2).

If I don't touch the volume knob and switch my turntable to phono2, the sound is very good on both but phono2 is just lower than phono1

Do you have any idea why ??

I look at the service manual and there is two 330K resistors connected to ground and to each phono inputs. Do you think that could be one of those resistors ?

[guizmo1967]

UPDATE !!!

I just read the Owner's manual and phono 1 and phono 2 has different output level, so nothing wrong with my amp !

[helius]

Hi-Fi amplifiers from decades ago often had selectors for different phono signal levels. That was because the output from a turntable depends on the cartridge design: moving magnet (MM) cartridges have much hotter outputs compared to moving coil (MC) designs. To provide a useful volume range, the preamplifier needs to use correspondingly different gain for these types.

Plugging a line-level output into a phono jack is a pretty bad idea, though. Line level can vary but in the worst case it can be over a volt, whereas a MC input expects a 250 microvolt signal. A MC input may also have a rather delicate transformer attached, and it could have been negatively affected.