*noob* running mic's through stereo pre amps, -10 or +4DB

[mesaboogie5050]

I have researched the internet and it seems I cannot find a straight answer for this. All I find is, "Prosumer gear uses +4 and consumer gear uses -10.) BUT, I've also read that the reason prosumer gear uses +4DB is because it's always balanced. I am always using balanced as well.

I am not sure where my VU meters at 0 are supposed to be on my DAW in Logic. I have read -18. Although I've read other things.

I am using a Saffire pro 40 interface. Do I go -10 or +4? And why?

Also, what should the logic meter read when my VU is at 0?

Another question, when the VU goes into the red does that matter? Do I want to keep it at 0 or can it go over a little?

 

[ecc83]

I have researched the internet and it seems I cannot find a straight answer for this. All I find is, "Prosumer gear uses +4 and consumer gear uses -10.) BUT, I've also read that the reason prosumer gear uses +4DB is because it's always balanced. I am always using balanced as well.

I am not sure where my VU meters at 0 are supposed to be on my DAW in Logic. I have read -18. Although I've read other things.

I am using a Saffire pro 40 interface. Do I go -10 or +4? And why?

Also, what should the logic meter read when my VU is at 0?

Another question, when the VU goes into the red does that matter? Do I want to keep it at 0 or can it go over a little?

FIRST! Of all, welcome!

Secondly, the line level only matters (in a projjy studio context*) when it is being sent/exchanged with another piece of gear,e.g active monitors.

Thirdly, let us get the terms correct, not because of any "tekky pedantry" (which I have anyway!) but just so that we all know precisely what we is talking about!

It is +4dBu and that is a voltage referred to 0dBu = 0.775volts (rms) and is NOT referenced to any impedance or resistance.
Thus +4dBu is a tad over1 volt.

-10dBV is a totally different measurement scale and is referenced to One volt (rms again) also not linked to any load and thus -10dBV = 0.316V. Thus it is prudent to connect equipment that uses the same signal level exchange level otherwise you can be short of level and turning up the gain (if you can!) could result in excess noise. Or the following gear can suffer overload at its input (NB, overloading an input will not cause damage in these voltage ranges, just sound crap).

The level in the DAW software is a completely different matter. If say you are running a mic in you should ensure that any "clip" LEDs on the AI NEVER light. Next look at the DAW level and adjust the AI for an average of -18 even -20dBFS on the internal meters. Peaks may go to -12dBFS but rarely if ever higher. Do not worry if the "waveform" looks small or the level low, you can bring that level up later digitally and there is no noise penalty (naturally it cannot be better than the mic, AI pre amp and the room!) . This all assumes you will be recording at 24bits (44.1kHz).

Forget all about "VU" meters unless you want to join the Mad Ones at Analogue Only!

There is more (like, why 775mV?) but I shall cease my jabber for now.

*The higher signal level is used in studios because it gets it above any ambient electrical noise. Balanced operation, as you have already mentioned, helps enormously here as well.

Dave.

 

[rob aylestone]

-10 or +4 relates to voltage at the input stage, so meter readings are not 'glued' to these. The difference is simply just that, consumers used phono connectors at three quarters of a volt , while the pro kit used balanced audio at a higher level but when correctly connected, to an appropriate input full scale is still full scale, and the reality is simply that to get to the maximum at 0dB on the meter, the two systems have different voltage levels. As most interfaces have gain knobs rather than just attenuators, you can turn down a +4 and turn up a -10 to match levels. Balanced or unbalanced at line level rarely makes much difference apart from in troublesome installations with poor design when you have far more grief fixing unbalanced circuits.

 

[mesaboogie5050]

So, having a safer pro 40, running into the most powerful Mac out right now, do I set my pre amp at -10 or +4? I tried both. At -10 the 0UV seems to be around -18DBFS, meaning I have to use an extra compressor inside logic to create the make up gain to make it as loud as it was before I compressed it. Because if I compress it at -10 setting and turn the make up gain up to 0VU, just before going into clipping on the pre amp, it's only at -18DBFS.

But at +4, I get no headroom when I turn the makeup gain up. It goes in the yellow on the DAW strip.

Which should I go with?

 

[mesaboogie5050]

FIRST! Of all, welcome!

Secondly, the line level only matters (in a projjy studio context*) when it is being sent/exchanged with another piece of gear,e.g active monitors.

Thirdly, let us get the terms correct, not because of any "tekky pedantry" (which I have anyway!) but just so that we all know precisely what we is talking about!

It is +4dBu and that is a voltage referred to 0dBu = 0.775volts (rms) and is NOT referenced to any impedance or resistance.
Thus +4dBu is a tad over1 volt.

-10dBV is a totally different measurement scale and is referenced to One volt (rms again) also not linked to any load and thus -10dBV = 0.316V. Thus it is prudent to connect equipment that uses the same signal level exchange level otherwise you can be short of level and turning up the gain (if you can!) could result in excess noise. Or the following gear can suffer overload at its input (NB, overloading an input will not cause damage in these voltage ranges, just sound crap).

The level in the DAW software is a completely different matter. If say you are running a mic in you should ensure that any "clip" LEDs on the AI NEVER light. Next look at the DAW level and adjust the AI for an average of -18 even -20dBFS on the internal meters. Peaks may go to -12dBFS but rarely if ever higher. Do not worry if the "waveform" looks small or the level low, you can bring that level up later digitally and there is no noise penalty (naturally it cannot be better than the mic, AI pre amp and the room!) . This all assumes you will be recording at 24bits (44.1kHz).

Forget all about "VU" meters unless you want to join the Mad Ones at Analogue Only!

There is more (like, why 775mV?) but I shall cease my jabber for now.

*The higher signal level is used in studios because it gets it above any ambient electrical noise. Balanced operation, as you have already mentioned, helps enormously here as well.

Dave.

Thanks for the help. But it didn't really answer my question. Is the safari pro 40 able to handle +4 and should I be using that instead of -10? With -10 I can compress something and then when I use the gain to bring it back to normal volume, I sometimes can get it as loud as before it was compressed, (due to it going to -18.) -4db goes to -12 at 0UV so I am able to get it even louder than the original signal.

Do I need to do -10, keep it at -18 and just compress the whole track to get it louder? Or use another compressor on the track for make up gain? Or just do it all with the +4.

Same deal on the pre amp I have. 0UV equals -12, (not much head room.) and 0UV equals -18 on the -10 setting. I have the VU meters set to those numbers. I calibrated it myself.

 

[mixsit]

I'm just going to through a bunch in here.
What do you mean 'go in at +4'? Are you talking about recording from another line level device? Here's a spec page I found- it'll take +28dBu. (add.. Does it have a '-10' switch for 'CD players or such?
Specifications | Focusrite
'Nominal / average operating -like-similar to VU- is +4 for a line level device (and your Safirre) like EEC83 explained.
And like he indicated record level is a separate issue and target is around -18 or 20 or so dBFS.
Now, is to ask yourself, - why are you mixing the tasks of 'line level standards, with target record levels, with compression thresholds, and makeup gains.
You get your tracks recorded within decent target range.
Then you set thresholds for the amount of reduction you like on your compressors. Then the track faders do track mix levels.
(Often you don't even need makeup gain on a comp unless you are doing a lot reduction.

I just saw this..

Same deal on the pre amp I have. 0UV equals -12, (not much head room.) and 0UV equals -18 on the -10 setting. I have the VU meters set to those numbers. I calibrated it myself.

You have a pre with selectable out level(?
I think I know where you might be going. Here's the deal.

Some gear operate at slightly different comfort ranges (in/around, sometimes well above nominal line level -i,e. they have tons of head room above 'nominal.

Different converters can have various volts in to equal different record level results. I.e. this means how much or little gain they have ahead of going into their converter chips, not much more.
The bottom line with some combinations of 'hot signals or gear combinations - you may at times (depending on how the converter is set up) simply have to either adjust the pre's output level -or sometimes even add a pad- (the '-10' setting is essentially throwing a pad onto the pre's out..) to get to your target record level, which is the whole point of all of this.

 

[mesaboogie5050]

Oh, I thought you had to use -10 or +4. The reason I brought up compressors is because my compressor does the same thing. The back has a -10 switch and a +4Dbu switch. I read everywhere that consumer gear doesn't use the +4 but the -10. Yet I seem to be using the +4 fine. Of course I don't know if a saffire pro 40 is consumer gear or not.

But basically I am not getting much head room at +4

 

[mixsit]

Oh, I thought you had to use -10 or +4. The reason I brought up compressors is because my compressor does the same thing. The back has a -10 switch and a +4Dbu switch. I read everywhere that consumer gear doesn't use the +4 but the -10. Yet I seem to be using the +4 fine. Of course I don't know if a saffire pro 40 is consumer gear or not.

But basically I am not getting much head room at +4

Ok, let's run this by again, but first -you are talking about whether to use the +4 vs -10 setting on your pre right?
Here's a page I meant to post earlier- it's one that's been handy to use to brush up on this stuff
http://hux.com.au/Soapbox Items/World Audio level Reference.pdf
Notice how the 1.2 volt / +4dBu row aligns with 0VU. And to the right is a few different digital conversion setups in dBFS.
Input with the same voltage, different converters can come in at different record levels.
RME for example only give you about 9 dB of headroom above nominal line level at their '+4' setting. Then they have a 'Low gain option setting that pads their converter input down 6dB, giving about 15dB head room -(actually closer probably to norm for line level into an A/D.
The point is the gear is flexible, and so are these operating ranges. The levels are not hard fast- their just norms to work in and around. I typically use that '+4' setting on my RME's, but still shoot for around -20 - 24dBFS record levels (that's of course for the average', body' of the signals).
That just means to keep in that record range the choice is to run the pres feeding it a little lower than they could run.
So.. we have your Saffire and the RME with similar alignments around '+4dB'.
I can shift to 'low gain at the converter, and you can run your pre at the lower output. Or either of us can just trim the pre's level or output a bit if we want to keep a bit more headroom at the converter.
The current party line is better to err' a bit low (stay 'cleaner) in record level than push the analog sections above norm.