Mastering made easy - use the volume knob in your truck. I've heard more songs ruined by bad mastering than I care to hear again, esp. in home mastering. Why anyone would want to match many commercial releases to the .1 dB is beyond me, other than as an academic exercise.
Most mastering engineers in the past have gone through the gamut - learning tracking, learning mixing and then graduating to mastering w/ a fine ear and knowledge of what needs to be corrected - and what doesn't. The first lesson was like the Hippocratic Oath - "first do no harm." Originally, mastering was the process to prepare a tape (usually) for mass production on LPs, which didn't have the bass or dynamic range of tape. That is where all that cool and expensive hardware came in - Pultecs and Fairchilds. Tape was ususally recorded hot, not just for the sound but to overcome the noise inherent in tape. It is different in the digital world, where bass can be as loud and low as you like, and noise is not an issue really. Rather than taking advantage of larger dynamics, many modern productions squeeze the very breath out of songs. When I comp my old LPs or CDs, volume is all over the place between them. Since these are for my personal use, I quickly and roughly adjust the volume between them, and leave the fine tuning for the vol. knob. Gee, I even use it when the washer in the other room kicks in to the spin cycle, or the car hits a more knobby stretch of road, or the kid next to me at the light is blowing his subwoofers on a flat-line CD in his car.
But if you want to go academic, you just take common mixing procedures and go anal w/ them to produce a hot mix. Go in and vol envelope all the main elements (hell, if they were paying me by the hour I'd go into the backing ear candy, too!). They sound level, now, pretty much? Good. Now but a compressor on every track. An opto L2A2 emulation on many things, but percusive and lead on an 1176. On lead vocals, both. Now route your tracks to buses. On the buses put another comp - probably an SSL emualtion. As well as your master. That is an easy way to serialize your comps, using less compression but more compressors. Yes, it does usually sound smoother, more natural than hitting the all button on an 1176. Your mix still not hot enough? Follow the comp with a limiter and crank up the output on the comp, squeezing the bejebbers out of dynamics so every sound is an on/off affair.
Still not loud enough but still hitting the red at points? Open Sound Forge or another editor and start looking at your tracks. On vocals, drums, acoustic guitars you'll find spikes. 1, 2 even 3 dBs louder than the majority of the sound. Use the pencil editor to bring these down towards the rest of the level. Oh, suddenly you have a few more dbs to play w/ on several tracks. Cool. Raise the bus or track comp output. Just be careful that you haven't muffled your punch, which was what those spikes were.
Now you have a mix track that sits at -3dB or higher. Surely you can squeeze a few dBs in mastering easy, right. First, open it in your editor. Any more spikes where the bass, kick and guitar all hit the downbeat. Be ruthless - prune those spikes, too.
Now comes the fun part of mastering. You throw another compressor (and EQ, tho that is another subject - you probably have eqs on tracks and buses to high pass bass wasted bas energy in the triangle, vox, etc.). Put a limiter on the master so you can really slam those levels w/o going over. It is best if you go buy some really expensive hardware. Yes, I know software is almost there - but commercial CDs usually go through pricey analog. The fine hairs you get in analog saturation live there. Close is -.1 dB - you want exact. Even w/ the +$1000 a channel mastering compressor (and that is low end in this game) you'll still want digital compression before, or use SF to render it before mixing it out through hardware. One can't be too careful there there might be any air left in your song.
While you are buying hardware, invest $5000-10,000 in some "pro" speakers, kick everybody out of the biggest, non-square room in the house and spend several thousand dollars treating it. I know my wife would understand, tho I would have to find a completely new home not to master in, but live. Now you can hear all these little tweaks you are making - once you gone through the above processes a couple hundred times and your ears can hear them. Don't worry, it will get faster once you get the hang of it.
Those are some of the tricks the pros use. But be warned, most of the effort above will be wasted on people who don't have trained ears, who are listening on ear buds etc. The . whatever dB differential between home mastering and pro mastering is mostly hype. That little difference can be heard, sublimely. Studies have shown people like the louder version of anything (well, maybe not jackhammers or wrecks at night outside your window - I'm talking about music). But there ain't that much difference. You shouldn't try to not make your music competitive, but 1 dB isn't going to be a deal breaker. If you like your song, you'll probably turn it up anyway.
A good song (after all, you will be listening to it many, many times), well recorded and mixed on typical home recording systems, and home mastered to w/in a dB or so of a commercial recording, will sound fine. Once you get your basic techniques down. Until then, don't worry about the last few dBs. You are more likely to do harm than any good.
You can use most of the techniques above - but not on every track of every song. Unless you want to. But I prefer to leave a little breathing room the music I do. It sounds better than cranking every step to 11. Back in the day, I could seldom get my analog stuff to sound harsh. Digitial, easy as pie. You can feel tracks straining against the limits of sound. And vocals easily become harsh, the T's sound like Derek Jacoby in "I Claudius" and the S's sound like the singer is speaking Slitheren. That bugs me a whole lot more than reaching for the volume control.
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