4000G Insert Sends

[perfectsnd]

Today I was calibrating some levels on some of my outboard gear especially my 1176s and testing some different outboard gear and some plugins.  My 1176 seemed to be needing to see a lot more input gain the plugins.  Just to test some things out I ran a signal generator in one channel, Channel 10, at unity 0 db, and then I took the insert send an put it into a line input of another channel, Channel 9, to check the level of the send. The input level of the send from channel 10 going into the line input of Channel 9 was showing right -3 db not the O VU that I expected to see.  I checked this around the desk and this is seems to be the way the desk is. Is this the way the SSL G are designed. Is the send -3db from the actual channel input?  My manual states that the insert send is 0db relative to the nominal operating level of +4dB so I was expecting to see the send hitting my desk back at 0db if I sent a signal that was coming at 0 db. Am I missing something simple?

[Matt Salazar]

Per the calibration instructions posted on this forum, after calibration is complete, the signal at the insert send is 4db lower than the signal received at the line input. No clue why, often wondered though.

[perfectsnd]

I'm not sure why either, but if I take a send from one channel and bring it into the return of another channel and then pan that hard left or right I get 0 VU at the master buss.

So that must mean the return is making up for that 4 db of gain loss. The interesting part of that is that if you want to go "clean" into the desk while tracking from external pres a lot of people recommend coming back into the return of the channel. That would mean that channel is then getting an extra 4 db of gain.

Confused? I am a bit. I'm sure someone on the forum has the technical answer to this.

[wedge]

Many consoles operate at slightly lower levels internally.  It helps greatly with crosstalk specs.  That's probably why the inserts often are 3-5dB lower than the group and bus outputs.
The practice of bringing lines in to an unbalanced insert return (with its added boost) has never made a lot of sense to me - especially if you have G line amps available .  But, as they say, whatever works.

[amillar]

Many consoles operate at slightly lower levels internally.  It helps greatly with crosstalk specs.  That's probably why the inserts often are 3-5dB lower than the group and bus outputs.
The practice of bringing lines in to an unbalanced insert return (with its added boost) has never made a lot of sense to me - especially if you have G line amps available .  But, as they say, whatever works.

Yes, exactly. Because the insert send is unbalanced rather than balanced you've got 6dB less headroom. It's not that the insert points are low, it's that the balanced ins and outs are 4db high!

The reason it's only 4dB down (rather than 6dB) is a bodge. Since the group out might be going into a balanced or unbalanced input (depending what you're connecting it to) then either the group out or the insert point will run out of headroom first - rather than the group out always setting the headroom limit.

Cheers,

Andy