Pro vs. Consumer Line Level

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oboedrew

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Hello, everyone. I'm learning how to use some new recording gear, and I've been reading some articles describing the difference between +4dBu "Pro" Line Level and -10 dBV "Consumer" Line Level. I understand that it's important to make sure my equipment is compatible, but I can't find any mention of line level in the specifications for some of my new gear. Here's what I've got:

Macbook with Logic 8
Apogee Duet
Denon AH-D2000 headphones
AT4040 mic

So, "Pro" or "Consumer" Line Levels? When I pull up the Apogee control panel in Logic, I see that I have a choice of setting the input line to "XLR Line +4dBu" or "XLR Line -10dBV." So I gather that the Duet can work with either Pro or Consumer mics. But which is my mic? Also, there's an option in the Apogee control panel to set the input to plain "XLR Mic," with no specification of +4dBu or -10dBV. What would this mean?

Many thanks for any explanation or clarification you can provide!

Cheers,
Drew
 
oboedrew,

First, welcome to the board! :)

Second, microphones do not operate at line level at all. This is why they need to be plugged into preamps; it's the preamp's job - along with your setting on the preamp's gain control - to bring the microphone voltage up to line level so that it can work "right" with the rest of your gear. Typically, a microphone can operate dozens of dBs below line level - depending upon the design of the mic itself and on which line level we're talking about, and it's the preamp(lifier) that boosts the signal to make up that difference.

The question is not which line level the microphone operates at, but rather which line level you need to boost the signal up to with your preamp gain control in order to match the line level expected by your next piece of gear in line.

In your case, that's a kind of a non-issue, because there is no next device - at least no next analog device - downstream. The Duet has the mic preamps and converters built into it and is sending digital direct into your PC. So there is no further "line level" to worry about. All you need to do, I believe, is follow the meters on the Duet, and set you record inputs in Logic to unity gain (zero boost/zero cut, usually about 2/3rds of the way up a simulated fader control.) This will let the Duet set the proper volume and let Logic record it at that volume unimpeded.

As far as the switchable +4dbu/-10dBV on the Duet, that's for plugging in devices other than microphones into the Duet's inputs. The switch let's you pick which line level to expect from that device. When you switch to "XLR Mic", it no longer expects line level in, but rather a microphone, and will route that input through the built-in mic preamp instead.

HTH,

G.
 
Thanks for the clarification, Glen. It seems I've been making this more complicated than it has to be!

Cheers,
Drew
 
oboedrew said:
Thanks for the clarification, Glen. It seems I've been making this more complicated than it has to be!

Cheers,
Drew
Click to expand...
Well, Drew, you're just lucky in that you have a very simple signal chain and that you happen to have a decent box in that Apogee that actually has some metering on it. Change either of those factors, and the knowledge you have already accumulated would become far more necessary.

Once you get used to it, it's really not all that complicated; but hang on to what you learned, it'll probably come in handy in the futire.

And like fraser said, you can always come here and let us confuse you even more :D.

G.
 
Alright, here's another question, which may or may not be related to my original query... not sure, really.

When recording my oboe in the past, using a PreSonus Inspire (before my recent upgrade to the Apogee Duet), I used to turn the gain dial up as high as it could go without clipping. Now I'm reading in a few articles that that's not necessarily the best way to record. I've read that I should record at -18dBFS. I see the dBFS meter in the channel strips in Logic. But should I be setting the gain on my Duet so that the peaks in volume come up to to the -18 point? Or should the middle of my dynamic range fall at the -18 point?

Again, thanks in advance for any clarification or explanation you can provide!

Cheers,
Drew
 
oboedrew said:
When recording my oboe in the past, using a PreSonus Inspire (before my recent upgrade to the Apogee Duet), I used to turn the gain dial up as high as it could go without clipping. Now I'm reading in a few articles that that's not necessarily the best way to record. I've read that I should record at -18dBFS. I see the dBFS meter in the channel strips in Logic. But should I be setting the gain on my Duet so that the peaks in volume come up to to the -18 point? Or should the middle of my dynamic range fall at the -18 point?
Click to expand...
The latter is closer to the truth. The whole idea is that -18dBFS should in most converters be close to (give or take a dB or three) what they convert a line level (0VU) signal into on the digital side. So, assuming that you've been a good boy and are averaging about 0VU on the analog side, as long as you have your software input gain set to zero (unity gain), that should mean that your signal will come in averaging around -18dBFS on the digital meters.

The first key is that you don't want your peaks clipping by trying to exceed zero. If you have to turn down the gain slightly and drop your average below -18 to accomplish that, that is just fine.

And if at an average of -18, your peaks still fall well below 0dBFS on the digital scale, that is perfectly fine also...in fact that can be preferable down the road when mixing. You're right, the old advice of pushing your gain so that you are always peaking near the top of the digital meter is no longer the good advice it may have once been with older digital technology.

If you haven't already found it, Drew, check out the IRN website at www.independentrecording.net. Jay Walsh (known here as Farview of Farview Studios fame) has part 1 of a series of articles he's presenting on "gain staging" (the art and science of setting gain levels). Plus I have an interactive applet there called "Metering and Gian Structure" that goes into a whole lot of detail on - what else? - metering and gain structure ;) :D.

G.
 
Glen,

Those articles are so helpful! It's a lot of information to digest, but I think it's starting to make sense. So, basically, to find the ideal recording levels for my oboe, I need to use the gain dial in the apogee control panel (which can be set from 10dB at the bottom to 75dB at the top), and turn it up until the average volume is around -18dBFS in the Logic channel strip. Does that sound about right?

If so, what about the meters that are on the top of the actual Duet (not in the software control panel)? Do these serve any useful purpose?

Also, I'm on the lookout for good articles to help me understand mixing/mastering. Any recommendations?

Thanks again!

Cheers,
Drew
 
oboedrew said:
Glen,

Those articles are so helpful! It's a lot of information to digest, but I think it's starting to make sense. So, basically, to find the ideal recording levels for my oboe, I need to use the gain dial in the apogee control panel (which can be set from 10dB at the bottom to 75dB at the top), and turn it up until the average volume is around -18dBFS in the Logic channel strip. Does that sound about right?
Click to expand...
Yeah, that's pretty much it to get you started. Remember to make sure that your input record levels in logic are set to zero gain; this will ensure that the meters in Logic are giving you a true reading of what's coming off the Duet.

But to get the best sound, you'll probably have to do some fiddling around, especially with mic placement. Distance and,location of the mic, the actual sensitivity of the mic itself, how loud you play will all determine the actual volume and quality going into the Duet to begin with. Get those sounding the way youwant first, and then adjust the levels to the plan above after that.
oboedrew said:
If so, what about the meters that are on the top of the actual Duet (not in the software control panel)? Do these serve any useful purpose?
Click to expand...
I'm not that familiar with the Duet and the pics and description on the Apogee website don't help me much there. I don't know whether they're giving you a VU meter on the input or a dBFS meter on the output. Best I can recommend there is to check their manual and see what they say about it.

HOWEVER:There is a tendency for many manufacturers to say in their manuals, "record as hot as you can without clipping". This is as you have probably realized by now, not good advice. If you read that, ignore it.
oboedrew said:
Also, I'm on the lookout for good articles to help me understand mixing/mastering. Any recommendations?
Click to expand...
For some good mastering info, check out John Scrip's website at www.massivemastering.com and Tom Volpicelli's site at www.masteringhouse.com. They both have a few good articles on the art and science of mastering.

Frankly there's not a whole lot of stuff I've seen online that does all that great of a job on mixing techniques. There are some great books out there, though. Feel free to head back to independentrecording.net and pull up the Studio Reference Book Catalog. Once in the catalog, select the "Audio Production & Technique" category for a custom-selected list of what's available from Amazon.com.

Just for starters, I'd recommend taking a look at these titles, but there are many others also:

The Mixing Engineer's Handbook
Mixing, Recording and Producing Techniques of the Pros
Mixing Audio: Concepts, Prectices and Tools

G.
 
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