Forums - Mixing & FX
Subject: digital & analogue combi gain structure
Original Message Date: 10-Oct-05 @ 12:34 PM - digital & analogue combi gain structure
I like to sub group my drums through one of my focusrite compounders but am having problems deciding on whether to use the +4db inputs or -10db inputs. When I use the -10 db inputs - the signal peaks nicely at 0db on the compounder. When I flick the switch to +4db inputs then the compounder metre peaks at about -10db on the LED metre. The Mackie manual says that -10 db inputs are semi pro and +4db inputs are pro. Does that mean the Mackie desk is a semi pro desk and that I should be using the -10 db inputs on my compounder?
Finally I have the same input question with regards to my Focusrite Mixmaster. I have tried routing the final mix from my Mackie main mix output into both the -10db inputs and +4db inputs on the Mixmaster using both XLR's and Jacks and come out of the Mixmaster via an spdif lead back into one of the Delta 410 soundcard digital inputs and into a audio track with Logic. This is because I need to then throw Logic's AD limiter over the final WAV to have any chance of getting my final mixes to anything like the same volume/gain as commercial CD's. Do you think I am comprimising my final mixes by recording back into Logic from my Mixmaster? I mean when I play back my final mix WAV - it peaks at 0db on my Mackie faders whereas when I play back a commercial track ripped off a CD, it hits anything from +6db to +12db on my Mackie main metres - is this because they have been pro mastered? Would I be better off purchasing a standalone CDR recorder and going via spdif directly from my Mixmaster into the CDR recorder? Would I get a hotter signal that way?
I know there are a lot of questions above so thanks for taking the time to read this. Cheers.
Message 11/21 18-Oct-05 @ 05:29 AM - RE: digital & analogue combi gain structure
second of all how are you comparing your commercial CD's? are you ripping them, importing them into Logic, and playing them out the same output as your mix in Logic? Or are you using a CD player on a pair of channels or perhaps the tape ins of your Mackie? You need to compare apples to apples.
finally, how much gain reduction (and subsequent makeup gain) are you doing with the limiter in Logic? Chances are unless you're doing 6-15 dB of smack with it (which will sound like shit, btw), you won't compete in apparent level with commercial CD's. That kind of level is achieved through careful individual compression while mixing and multistage/multiband compression at the mastering step. But like milan says, peak meters should show 0 dBfs from a digital source consistently no matter the RMS (average, or apparent) levels, so you should be metering pro CD's on your mackie at the same peak as your mix from Logic, which leads me to think that you're getting the two sources into the Mackie via different methods of some sort.
Message 12/21 18-Oct-05 @ 07:23 AM - RE: digital & analogue combi gain structure
But that's just me.
Message 13/21 18-Oct-05 @ 09:52 AM - RE: digital & analogue combi gain structure
Message 14/21 18-Oct-05 @ 11:09 AM - RE: digital & analogue combi gain structure
Message 15/21 18-Oct-05 @ 11:46 AM - RE: digital & analogue combi gain structure
if you go into the line-in you must set the gain control, so where is 'unity gain' on the gain pot?... exactly, you cant set a level by the channel fader cos the gain will always be part of the signal path. You need to meter the return signal without any gain curcuit in the path adjusting the level prior to hitting the meter
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I had an idea for a script once. It's basically Jaws except when the guys in the boat are going after Jaws, they look around and there's an even bigger Jaws. The guys have to team up with Jaws to get Bigger Jaws.... I call it... Big Jaws!!!
Message 16/21 19-Oct-05 @ 09:52 AM - RE: digital & analogue combi gain structure
With delta control panel faders @ -10 levels=
Line Input = -1db
Tape Return @ +4 = -1db
Tape Return @ -10 = +12db
When delta control panel faders @ consumer (maximum)=
Line Input = +6 db
Tape Return @ +4 = +6 db
Tape Return @ -10 = +18db
When I plug an soundcard output into the tape returns my Mackie desk gain pot has no effect on the volume, eg it becomes redundant.
Message 17/21 19-Oct-05 @ 12:57 PM - RE: digital & analogue combi gain structure
Like I said, I'm not sure of what 'real world' level the Logic instrument is actually putting out. When you say 'hitting 0' though, I guess that's actually hitting 0dBFS, which is your absolute maximum.
It appears that your Delta card is still on 'consumer' rather than 'pro' level setting. Hence when your mackie is ser to receive -10dBv signals into the tape returns, a 0dBFS signal within logic is hitting your desk at a level of +18dB.
As mentioned earlier, a -18dBFS signal (a good conservative average) coming from Logic/Delta will subsequently produce a 0VU reading on your desk's meters, all being well.
This should also be the case if you set your soundcard and desk to 'pro' (+4dBu) reference level, as opposed to the current -10dBv (consumer) reference level, as the two will be optimised to work together. Don't mix & match the standards though, or you'll have gain structure headaches all over again.
Clarification point: When I refer to -10dBv, I don't mean set the output/control panel faders for the Delta to -10dB. -10dBv is the electronic operating reference level for consumer-type gear. +4dBu is th 'pro' standard, preferable where possible.
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When I plug an soundcard output into the tape returns my Mackie desk gain pot has no effect on the volume, eg it becomes redundant.
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This is correct. The gain pot only affects the signal coming into the main channel input. Think about this following example: Mackie desk like yours, connected to a 24 track tape or hard disk recorder.
Channel 1: Signal comes into channel 1 through mic input or line input - from a microphone, sampler, keyboard... whatever. Signal gets optimised with the channel gain trim, and EQ'ed to your heart's content. We're still within the 'main' channel path here.
Signal now leaves the main channel and exits the desk via the individual tape output for channel 1. Signal is recorded to track 1 on the 24-track machine. Contrary to your inclination, the main channel should not actually be assigned to the main L/R bus at this point. I know this suggests you won't hear anything, but bear with me...
So far so good...
Signal is now output from track 1 the 24-track, either by monitoring during record mode, or playback after the 'take'. Track 1's signal is fed back into the desk, via the tape return connection for channel 1.
You now control the level of this signal (channel 1) heard over your monitors or headphones by adjusting the 'tape return', 'channel monitor' or 'mix B' knob. Different desks call them different things, but they're basically the same thing.
Repeat for all 24 channels/tracks.
The above is a basic explanation of how a 'split' type console works. This is typical 'record mode', where the mic/line signal goes through the main channel controls, and the return from tape goes through the more basic 'mix B' controls, as you're only needing rough-and-ready monitoring of the recorded signal at this point.
On mixdown, you actually 'flip' all of this (using the 'flip' buttons on the console; no need to re-patch), so that the 24 tape tracks come through the 'main' channel controls, for more control during the mix. The mic/line inputs now feed the more basic 'mix B' controls, allowing mixing or monitoring of ancilliary or less important sources.
I've deliberately missed out where insert points & auxes figure in this lot - basically, they normally belong to the main channel, but can be assigned to the 'mix B' path if required (see assign switches on desk).
Complex? Yup. I never said it was easy... for all that most folks aren't particularly enamoured with it's sound, the 8-bus is a serious bit of kit, in terms of the facilities available.
I'd do some reading (as suggested) on in-line consoles, as the concept can take a little getting used to. Once understood though, it's a brilliant way of working. Mackie's FAQ page should make things a bit clearer.
Now... the question... where does your particular setup fit in to all of this?!
That's for you to decide. Personally, I'd connect the 8 analogue inputs and outputs of your soundcard to the first 8 channels of your desk, as if they were int ins/outs of a mulitrack tape recorder, as described in my example above.
This will give you 8 mic preamps with which to feed your soundcard at all times, and 8 returns into the same channels which can be monitored easily using the Mix B controls. When mixdown comes, you can 'flip' the channels and the soundcard outputs will feed the 'main' part of each channel, and the resulting mix of the 8 can be fed back into the computer for recording as a stereo mix.
Happy homework!! Hope this helps.
Mike
Am I stupid for thinking that this is confusing. I just wanna know where to plug my soundcard outputs into. I feel silly.
Message 18/21 21-Oct-05 @ 09:34 AM - RE: digital & analogue combi gain structure
Message 19/21 21-Oct-05 @ 11:52 AM - RE: digital & analogue combi gain structure
___________________________________
I had an idea for a script once. It's basically Jaws except when the guys in the boat are going after Jaws, they look around and there's an even bigger Jaws. The guys have to team up with Jaws to get Bigger Jaws.... I call it... Big Jaws!!!
Message 20/21 21-Oct-05 @ 12:17 PM - RE: digital & analogue combi gain structure
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