Newbie Question.  Recording my band.  Not sure what levels to record at.  Should I set peaks at 0db?  -3db?  -6db?  What is a good level to target?

If you are recording at 24 bits, then peaks around -6 - -4 dB or average around -12 dB or even lower are OK (depends on the material, too, obviously).
24 bits offers so good dynamics, that it's no use recording any hotter. It makes your life much easier not having to be afraid of clipping.

Wow Thanks.  Last Time was recording at 0db average with peaks higher.  Had some clipping too.  I had no idea about peaks -4 -> -6db or average -12db - Thanks!!!  I check if I am at 24 bits too.  Thank you!

Lower, probably.  Every instrument is different, especially between peaking and average.  Peaking shouldn't go over -6.  That leaves you some headroom when the guitarist turns it up to 11.  You'll probably find the "real" takes tend to be louder than practise takes, so set the input gain lower.

Higher peak/average recording was the norm in ye ole analog days.  Noise was an issue then, and analog saturation and distortion was a tool.  Digital doesn't do saturation and such distortion is ... unwanted.

So keep the levels sane.  Peaking at -6 is the outside edge of acceptable and safe.  By the time you are at -12 or so you should have plenty of sound level captured (and there are easy, reversable steps to raise the level).  And unless you have superior analog hardware, pushing the average home recording interface is less likely to deliver a solid sound.  One of the reasons people pay money for preamps/etc. is you can run it closer to the max w/o it crapping out on you when the singer finally lets loose and you lose that perfect take to distortion. 

@

Here we go again!
You will find the mother of all threads on the subject here.
In general -16 or -18 dbfs (what you see in Sonar) is 0vu (your analog signal); BUT it depends on your equipment.
YOU have to test and calibrate it for your system.
"Record as close to 0dbfs as possible" was the mantra in the 16 bit days.
It was BAD advice then, and is worse now when working at 24 bits.
0vu is/was still -16dbfs at 16 bits (and 24 bit).
Most, if not all, prosumer gear gets "brittle" at high gain levels (the gain necessary to get a 0vu signal to 0dbfs).
Even LOTS of pro gear is running out of usable headroom at that point.
Read the linked thread, there's a wealth of knowledge there...

Tom

-18 dbfs rms. That's what most most interfaces have the converter filters calibrated to. Of course, you don't want your peaks to go over zero, but Sonar is capable of showing you both rms and peak levels at the same time.

My key is, get a "good" signal that shows up on the meters. You want all your meters to be fairly busy, but no reds. The only time you should ever accept a red LED light is occasionally on a drum hit, and ONLY when using a completely analog mic-pre. On your A/D converter and in Sonar, you should never see any reds, but your loudest signal should be approximately 75-80% of the meter.

Nevermind how it's mixed going into the DAW or recorder. It's how you mix it later that's important. 

Question: I levels on the Audio Interface (Octacapture) Preamps and then Levels show in the track meters in Sonar.  The advise on levels (above) - is it for Audio Interface or for levels in Sonar?  Sorry for Dumb questions.

Really both. No overs on either of these. The OctaPre is likely also your A/D converter, so you don't want any Reds on that, either.

One important thing to remember is that you cannot affect the levels coming into Sonar from within Sonar - it's all done at your interface/pre

Correct adjustment of your pre/interface gain should show a healthy level on both sets of meters: as long as you're leaving sufficient headroom you're ok to hit the red button!