General question about Sound Cards

[davidlzimmer]

Hey folks. I have a simple question about sound cards in general.

Specifically, with gain. Are they, for the most part, a unity gain component? In other words, if I drive it (line in) with a CD player that puts out 1 volt and have all the volume controls at max, should I get 1 volt out? Theoretically, of course. Or do they amplify the signal?

Would appreciate any response from those of you that know.

Thanks much!

 

[Sonusthree]

Hi,
Line (& sometimes Mic) level in -> Line level out.

Of course, line level is open to a lot if interpretation and manufacturers don't seem to publish these specs.

The signal output can usually be amplified to be greater than the input.
Limiting factors are noise and headroom (clipping). Don't expect to be able to use a lot of gain if your input is high.

I wouldn't call them unity gain devices but you can set them up for unity if you like.

What card did you have in mind?

Cheers,
Martin.

 

[davidlzimmer]

hey Martin,

Thanks for the reply. The card I'm using is a SB Live 5.1. It seems to me there is some gain but not much. Can't tell by Google searches.

I'm just in the planning (daydreaming) stage of building a preamp/source selector and I was just wondering what level the sound card puts out compared to a CD or phono pre.

I know, I can attenuate the higher level devices (to match up) but, was wanting to know just what level a sound card typically puts out.

Any advice or opinions appreciated.

Thanks,

 

[Sonusthree]

Do you mean you want to build a passive pre amp/selector?
In this case, all that matters is the impedances and the cards ability to drive them.

I don't understand why you need to know. Your soundcard will be able to output a high or low signal but there will be a 'sweetspot' where you have the right balance.

For example: High enough signal to mask the low level noise inherent with soundcards and not too high that it is clipping (itself) or the next stage (pre or power amp).

This should be around the same level as a CD player but line level is hardly set in stone and the pro and domestic versions of line level seem to differ.

Just take it as being regular line level just like a CD player except that you can adjust that level to suit your ears.

 

[davidlzimmer]

Sonusthree,

Thanks. I don't know why I need to know either

I just wanted to find out what I could. The system will not be PC based but there will be times when I use the PC to transfer LP to CD and other projects.

I guess the best for me to do is plan on having a good level of pre and then be able to attenuate to match levels when needed.

I will be wanting (just for fun) to compare LP to CD and even MP3 at times. It will be much easier to have the levels all matching. So, like if I play an LP and the CD sounds louder (maybe due to compression) I will know it is the media, not he equipment

I just remembered I have access to a SPL meter. So, I can use it to get all three sources fairly equal in volume. But that will be blind faith that the media is equal in volume.

Thanks all for helping me "think out loud".

Dangerous for me!