Gain change on MC stage

[doctorcilantro]

I thinking about utilizing higher gain in my moving coil stage with a resistor change. The stock setting is 60db with 65 and 70 as options.

Dumb question, but if I bump up the gain, am I likely to see a higher noise floor out of the preamps tape out?

The manufacturer simply states the phono stage has better than -78db snr. Would this apply to the other gain settings or must it change as a result and raise the noise floor. I'm hoping it won't but almost inclined to say that will. that said I have run some tests with unmodulated grooves and the noise floor is mainly just low frequency stuff i.e. rumble and surface noise.

http://digitanalogue.blogspot.com/2008/08/hi-fi-news-analogue-test-unmodulated.html (if your interested)

dc

[LarryC]

Do you have a problem now, i.e., do you have audible background electronic hiss on phono? Or are you only wondering about noise from unmodulated grooves? If you have steady background electronic noise, higher gain should lower the noise relative to the signal from the cart. So, a higher phono gain would mean taking that noise down when the gain is reduced to compensate. It should have no relative effect on a signal such as unmodulated groove noise.

[doctorcilantro]

Probably should have been more clear and excluded mention of the unmod. grooves.

I think I see what you mean though. The two are seperate, the "noise" in the preamp circuit and the gain applied to signal. So if I bump up the gain 10db I won't neccessarily see the "background" (noise seen with no-inpu/playback) electronic circuit noise go up 10db.

Effectivly, I would get a better SNR?

thanks Larry.

DC

btw- it't not audible but about -65db on the Wavelab vu (PC wav editor); I would like to record a little hotter and listening volume could use a boost.

[LarryC]

I think I see what you mean though. The two are seperate, the "noise" in the preamp circuit and the gain applied to signal. So if I bump up the gain 10db I won't neccessarily see the "background" (noise seen with no-inpu/playback) electronic circuit noise go up 10db.

Effectivly, I would get a better SNR?

I think so. BTW, I wasn't that clear myself, and I'm not a real expert in any of this, just a long-time user and observer. Anyway, I've had less electronic noise from phono stages when their gain is high enough to bring the signal up out of their noise floor. When there wasn't enough gain, as in my earlier 46-db phonostage, turning up the volume didn't help because it only raised the noise level too. I don't know how to relate S/N ratios to that experience.

I can't predict SNR effects in your setup, but would expect the recording output to increase like you say. That could help it clear the recorder noise level and keep the the recording and output level controls in more reasonable and maybe beneficial positions. I don't think there's any harm in trying it.