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Subject: digital & analogue combi gain structure


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Original Message 1/21                 Date: 10-Oct-05  @  12:34 PM   -   digital & analogue combi gain structure

Dominic

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I'm having major issues with deciding on -10 db and +4db inputs and outputs in my studio. I run 24 channels of delta 410 soundcard outputs down 24 channels on my Mackie 32:8:8 analogue board. I have made sure that my control panel card outputs are at -10db consumer and that 0db on my instrument channel in Logic 5.5 on the PC exactly matches 0db on the repective Mackie desk channel. I try to have my mixes peaking at +3db on the Mackie - is that about right?

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.



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Message 2/21                 Date: 13-Oct-05  @  12:49 PM   -   RE: digital & analogue combi gain structure

k

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dude, if you send out a test tone signal from the delta and the level is set to 0 on the delta applet meters and you feed that into the mixer TAPE L/R... whats the meter on the desk reading?

___________________________________

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!!!



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Message 3/21                 Date: 17-Oct-05  @  02:14 PM   -   RE: digital & analogue combi gain structure

Dominic

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Cheers K. If you can cope with my silly rantings then check link.



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Message 4/21                 Date: 17-Oct-05  @  04:11 PM   -   RE: digital & analogue combi gain structure

milan

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Message 5/21                 Date: 17-Oct-05  @  04:11 PM   -   RE: digital & analogue combi gain structure

Dominic

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K - link doesn't work. I asked the same question on SOS forum and Mike asked me about tape inputs aswell.......are you saying that I should plug my soundcard outputs into my Mackie tape returns because they have a -10db / +4db selectable switch?



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Message 6/21                 Date: 17-Oct-05  @  04:13 PM     Edit: 17-Oct-05  |  04:15 PM   -   RE: digital & analogue combi gain structure

milan

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whats your thread called? or your nick?

edit: nevermind, found it



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Message 7/21                 Date: 17-Oct-05  @  04:53 PM   -   RE: digital & analogue combi gain structure

Dominic

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Milan, Cheers dood. We must be posting at roughly the same time cos I keep missing your replys till I reply to my reply. Cheers alot for checkin' bruv.



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Message 8/21                 Date: 17-Oct-05  @  06:07 PM   -   RE: digital & analogue combi gain structure

milan

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hmm... not to get too deep into this... but do generate a sine test tone at like -0.5 dbFS in something like wavelab, reset all the gain pots and faders to their nominal position (0bb usually), and route it thru all your gear as you would during a mixing/mastering session, and back to your computer. fiddle with i/o gain settings until you get the same strenght signal back to the pc. that should be your "ideal" gain setting in your system.

what i dont get is this:

quote
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


it looks to me you are mixing well bellow the maximum level, but do you normalise your mixes at the end of the process? you said you put a normalizer across the mix at the end. that should ensure your mix peaks at 0dbFS, which means when you play it back it should peak at the same level as your commercial cd's. yes? no? does it?

i'm not sure if you're getting this: the max level (0dbFS) coming from your pc should approach maximum level on your mixer, NOT 0db on the meters. dBFS (full scale) and 0dB on the mixer are NOT the same value. all of those are RELATIVE values which have nothing to do with each other!

if you dont know this yet, then read this SOS article first, esp. the "DAT'S THE WAY TO DO IT"
chapter, because its crucial to your question.

bah... yer making me type even tho i dont want to :P

look... the process should in praxis work like this (this is the gain structure in a digital/analog studio):

you want to mix outside of the pc, right? set all your logic output channels/busses to zero to ensure you get a good, strong signal out of the box (approcahing max level on the meters without overloading). then set the gain on the mixer input channels until you get a good, strong signal INTO the mixer (again, approaching max level w/out overloading). then when you mix, set the main out faders as high up as it will go without overloading. THEN set the input gain on your mix compressor untill it peaks at zero, or whatever its nominal setting is called. then to send it back to the pc, set its output gain until the input meters in your pc are reading almost 0dbFS (max value without overloading).

basicaly, you always want to send as strong a signal as possible from one unit to the next one, without overloading anything. you HAVE to fiddle with the knobs from song to song, or even during a mix.

anyway, read that article, learn about different dB levels and voltage, and come back to us (i know you will 



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Message 9/21                 Date: 17-Oct-05  @  06:11 PM   -   RE: digital & analogue combi gain structure

milan

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actually, read this first: Decibels Explained

somewhere on the web, there is an article explainin EVERYTHNG about different kinds of dB's and all the rest, just cant find it right now... grrrr



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Message 10/21                 Date: 17-Oct-05  @  06:18 PM   -   RE: digital & analogue combi gain structure

milan

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oh fcuk it, just go here and read : http://en.wikipedia.org/wiki/Decibel

read about dBu, dBv, and dBfs



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Message 11/21                 Date: 18-Oct-05  @  05:29 AM   -   RE: digital & analogue combi gain structure

psylichon

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First of all regarding the compounder, what kind of cables are you using on your subgroup outputs from the mackie to the compounder? Mackie should support a +4 signal output but you need to use a TRS cable (tip, ring sleeve) not a TS (tip, sleeve). I could be wrong on this, but I don't think you'll get +4 with an unbalanced cable.

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.



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Message 12/21                 Date: 18-Oct-05  @  07:23 AM   -   RE: digital & analogue combi gain structure

psylichon

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finally, i must add that Mackie's are not renowned for great mix headroom or vibe. They're great for the price, but the potential of the mix bus in Logic far exceeds that of the Mackie, imho. I won't get into the whole digital vs. analog summing debate so popular on gear forums these days, as most of them are comparing DAW summing engines to very expensive consoles or dedicated summing boxes. The Mackie isn't in the same league as any of these. I'd sell it and get a kickass computer to run more plugins.

But that's just me.



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Message 13/21                 Date: 18-Oct-05  @  09:52 AM   -   RE: digital & analogue combi gain structure

Dominic

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Wow - fantastic info/help - thanks alot guys. Gonna do that reading and come back to you both (like Milan said - hehehe). Just can't resist to clear a few things up. Yes I am comparing my tracks to ripped commercial tracks played directly from an audio track in Logic. Plus if I have all my card outputs up to maximum (on the delta control panel) then I end up with all my Mackie faders down around -20db once I've mixed every channel in (which in my mind can't be a good signal to noise ratio). But I find the point interesting that 0 on a Logic instrument is not 0db on my Mackie. Plus I did the sine wave thing and tweaked the gain pots on all Mackie channels so all channels hit 0db which has had a positive effect on my mixes. Gonna come back with questions though. Thanks again.



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Message 14/21                 Date: 18-Oct-05  @  11:09 AM   -   RE: digital & analogue combi gain structure

Dominic

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A dude on the SOS forums says that I should be plugging my soundcard outputs into the Mackie tape returns rather than the line inputs?



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Message 15/21                 Date: 18-Oct-05  @  11:46 AM   -   RE: digital & analogue combi gain structure

k

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well that's why i asked you to route from the soundcard to the mixer TAPE input cos it is fixed & also to set the level not in Logic meters but in the Delta applet.

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

___________________________________

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!!!



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Message 16/21                 Date: 19-Oct-05  @  09:52 AM   -   RE: digital & analogue combi gain structure

Dominic

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Right I got's dem numbers for you:- (oh yeah these numbers are with Mackie channel fader and master fader both @ unity gain and gain pot all the way counter clockwise). Triology generating a 1 K sine wave hiting 0.0 on the Logic instrument channel but with the Logic instrument channel fader also left untouched @ 0.0.

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.



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Message 17/21                 Date: 19-Oct-05  @  12:57 PM   -   RE: digital & analogue combi gain structure

Dominic

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THis is Mike on SOS forum reply:-



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.


Quote:
--------------------------------------------------------------------------------

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.


--------------------------------------------------------------------------------



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.



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Message 18/21                 Date: 21-Oct-05  @  09:34 AM   -   RE: digital & analogue combi gain structure

Dominic

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Stopped sobbing now and sorted it out. Milan - that article you linked up from SOS really helped me understand everything. O vu on my Mackie is not 0db. I decided on having the delta control panel volumes at maximum and now have my mixes peaking at around 8-9 VU on my Mackie. Everything is connected at the +4db inserts on my focusrites and now the output of my Focusrite exactly matches the Logic audio track that I'm digitally recording too. Basically (I hate that word) when my Mackie peaks at 8-9 VU then that equals 0.0 on the Logic audio track that is recording the final mix from the Focusrite. Cheers everyone for putting up with me. Again.



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Message 19/21                 Date: 21-Oct-05  @  11:52 AM   -   RE: digital & analogue combi gain structure

k

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yeah those mackies do have an odd 0db level as far as i remember cos this came up before a year or so back. I'm wondering what the deal will be with you ramming the delta inputs up to max tho in terms of the noise from delta preamps when you use the analog i/o's

___________________________________

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!!!



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Message 20/21                 Date: 21-Oct-05  @  12:17 PM   -   RE: digital & analogue combi gain structure

Dominic

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Afternoon K - problem is if I have delta soundcard panels at -10 then the signal going through the Mackie and coming back out of Mixmaster into Logic is too weak - eg 0 vu on the Mackie only hits -22 on the recording audio track in Logic. The Mackie metres have to hit 12vu just to reach -5 on the audio track.



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Message 21/21                 Date: 28-Oct-05  @  09:24 PM   -   RE: digital & analogue combi gain structure

k

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are you sure?... -22 on a logic PC channel meter isnt really visible in normal view. The very bottom single segment of the channel meter = -24

grab the meter right bottom corner with the mouse and drag the thing out big and check the meter

___________________________________

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!!!



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