Unity on Soundcraft Si Expression 3

P

Patrick Mattioli

Freshman
Mar 30, 2014
2
0
0
Hello everyone,

I recently got a Soundcraft Si Expression 3 for work at my church. One of the problems that I am having right now is the meters barely register any signal even though the sound is booming. Additionally, to get them to register something, I have to crank the gain up 3/4 way. I know on my old board (Mackie TT24) you could set the unity for the board, so that the meters represented a more accurate amount of signal. Is there a way to do something like that on the Expression? I looked at the documentation on how to set the unity and it was not very clear, and after following what it said, I saw no change in the signal meters.

Thank you in advance for the help,

Patrick Mattioli
 
Re: Unity on Soundcraft Si Expression 3

The system is not too loud with the channel gains in normal place. With them in a normal place the board's meters don't seem to register an accurate reading of the actual signal coming into the board. With a full band playing, the main 8 bar meter never lights up above the -54 bar. To get it to jump above that I have to crank up the gains to at least 40db. So are you suggesting turning down my amps, and then turning everything else on the board up?

I am new with this board so maybe its just the way its designed and can't be changed.
 
Re: Unity on Soundcraft Si Expression 3

Patrick Mattioli said:
The system is not too loud with the channel gains in normal place. With them in a normal place the board's meters don't seem to register an accurate reading of the actual signal coming into the board. With a full band playing, the main 8 bar meter never lights up above the -54 bar. To get it to jump above that I have to crank up the gains to at least 40db. So are you suggesting turning down my amps, and then turning everything else on the board up?

I am new with this board so maybe its just the way its designed and can't be changed.
Click to expand...

There is NO SUCH THING as 'unity' except as a ratio between 2 numbers. Mackie's marketing dept should be lined up and shot. I'm not joking. Repeat until you understand: There is no such thing as unity as you are thinking of it. Period, end of story.

Everything in modern digital consoles is referenced to Zero DB, Full Scale. That means "0 dB" is FULL TILT BOOGIE. Maximum output, no more 1's and zeros and the analog output is driving at it's maximum voltage.
 
Re: Unity on Soundcraft Si Expression 3

Patrick Mattioli said:
The system is not too loud with the channel gains in normal place. With them in a normal place the board's meters don't seem to register an accurate reading of the actual signal coming into the board. With a full band playing, the main 8 bar meter never lights up above the -54 bar. To get it to jump above that I have to crank up the gains to at least 40db. So are you suggesting turning down my amps, and then turning everything else on the board up?

I am new with this board so maybe its just the way its designed and can't be changed.
Click to expand...

You need to stop looking at the numbers and the position of the knob, and turn the knob until the channel registers an appreciable signal. Don't worry about what it looks like; the sound is what matters.
 
Re: Unity on Soundcraft Si Expression 3

Patrick,

To give you a comparison: let's say an analog mixer can output a maximum of +24dBu in signal level. If your meter's "0" or Unity point equates to +4dBu (professional Line Level signal, nominally), then when your signal reaches the "0"/Unity mark, you have about 20dB of headroom left before the output of your mixer will distort.

For the Expression Series, the manual states that the Mix Output is capable of a maximum output of 21.5dBu. If you wish to correlate this to your dBFS metering, then you would subtract the amount necessary to get you back to +4dBu, which leaves you with about 18dB of headroom, or "-18dBFS".

So, for this mixer, I would say that -18 would be a good "0" mark to shoot for. It's a compromise between enough headroom and Signal-to-Noise Ratio (but it's always been a compromise...the terms are just changing a bit).
 
Top Bottom