The following describes a rather extensive process for mastering songs to CD. The mastering process is often a long one, and musicians spend lots of hours and dollars to achieve that ‘commercial studio’ sound. With the help of Cool Edit, a good set of ears and the following step-by-step tips, you are preparing yourself to enter the realm of professional music making. Where applicable, we’ve listed some details regarding suggested frequencies or ‘settings’, but please note that each song is different, so use your judgement and above all, use your ears!
1. Sample Rate/Bit Rate:: If you’ve already recorded into Cool Edit at 16-bit and you’ve remained in the digital domain, there isn’t really any reason to bump up to 32-bit unless you have extensive noise reduction to do. Working in 32-bits to simply add some minor EQ and/or Limiting isn’t really going to benefit most recordings (apart from some extended dynamic range) particularly if you are unfamiliar with the noise shaping curves and dithering selections, but it can’t hurt, and if you have the HD space…why not?. Certainly, if you begin at 24+ bits, stay there until the final stage.
2. Pre-Dynamic EQ:: This relates to whether or not you are going to use some type of limiter (as per the Hard Limiter) or mild compression on your final mix to give it that much adored PUNCH! If you plan on doing so, you may consider tweaking EVER SO SLIGHTLY some key frequencies that may be accentuated in the compression process. Key frequencies are 60hz-80hz (bass, 45hz and below for sub-bottom) 250hz (muddiness/low mid) 1.25k-2.5k (vocal fundamental) 5.8k/6.3k (sibilance) and 8k-14k (presence and shimmer). By boosting or cutting (at very small increments) you can really tailor your sound like a pro, using a variety of narrow and broadband Q. Don’t boost/cut more than 3dB in any one band, except perhaps in the 250hz range if your sound is very muddy.
3. Limiting/Ceiling:: Make it loud. That’s what everybody wants. With the hard limiter, you can set the “Limit Max Amplitude” to -.5dB. Use the ‘Boost Input By’ to really drive your signal. Be careful not to drive it too hard, as you will start to hear audible artifacts, though they are sometimes pretty cool effects. You can also use a simple compressor from within the Dynamics Processing menu. A compressor preset with a ratio of 2:1 is pretty standard for giving a mix ‘punch.’ Typically, you would not exceed a 3:1 ratio.
4. Stereo Expansion:: Totally optional. Lots of mix engineers use expansion already in the mixdown process; ie, your background vocals may be mixed with some stereo reverb, the drums may have some type of presence/ambience effect, electric guitars bouncing left to right. All of this can sometimes create a wash of stereo leaving you with no center at all, so use with caution. If you are simply trying to WIDEN a rather narrow stereo field, try using the Pan/Expander to give you a bit more depth and dimension. You can even move the center image around, but be careful, as that can often ‘unbalance’ your already perfect mix.
5. Post-Dynamic EQ:: See Pre-Dynamic EQ. You may not need any. If you didn’t use any before the limiting stage, use lightly to do the final tweaking. Very minimal boost and cutting; just shaping.
6. Normalizing:: Now, if you’ve hard limited with a max amplitude of -.1, you don’t have much room to work with. However, if you’ve added/subtracted EQ, you may want to boost the signal to peak amplitude. Some say normalize 98% just to be safe. There is really no harm in normalizing to 100%, so long as you are using a good CD burner and adequate software. The levels, as far as Cool Edit, should be painstakingly accurate.
7. Convert back to 16-bit, 44100, Stereo. The preset dither depths and noise shaping curves (pdf=triangular, Noise Shape A) are pretty good, but not necessarily for 32-bit 96k audio. You may want to experiment on shorter files before you find one that best suits your music. There is an explanation in the help file that better defines what curves work best with various sample rates.
8. Saving as Windows PCM Wave and doing it right:: When preparing your song, you want to make sure that when you’ve made your wave files that you have about 100-150ms of space BEFORE the beginning of the song. This will ensure that all CD players will capture the ‘start-ID index’ and play the beginning of the song properly; this value has actually gone down now, as newer CD players need very little (if any) space before the beginning of the track, but it’s always a good idea; and what’s 1/10 of a second anyway? Of course, if it’s a live recording and there is in effect ‘no stopping’, this is not so much of an issue. But you may want to experiment.
9. Using the CD Burning Application:: The first track on your CD must have a 2-second pause. This is related to the CD burning software itself, not something you do within Cool Edit or to the actual wave file. This 2-second gap is written right after the table of contents on your disc to ensure proper indexing and playback. After the first track, you don’t need to have any pausing at all. And, if your software/CDR supports DAO (disc-at-once) it will set up this default for you.
10. Burn baby, Burn (speed):: Always burn at 2x or slower (1x, realtime burning) if it is for duplication. 4x is fine for personal use. The reason being, you will inevitably have fewer CRC/burst errors, and most plants can detect what speed your disc was burned at and won’t even accept a CD premastered-cut at 4x or above…too many errors, too many chances for error during duplication. You also want to use a higher-grade CDR. There are many arguments as to what ‘dyes’ work better, etc. Most plants prefer the green or gold dyes over the blue…but you’ll want to check that out first.
The other, most obvious things to consider when mastering are that in this final ‘make it or break it’ stage, you are solely relying on one thing and that is your ears. Try (if you can) a different set of speakers, use speakers and headphones (ones that you know the sound of pretty well) to A-B and listen for boominess or tinniness. Make a ‘reference’ CD of a few tracks and audition it on a car CD player, boombox, home theatre, whatever you have available. And be sure to give yourself a break! Ear fatigue can set in fairly rapidly during this process, so don’t try and ‘beat the clock’…make sure you have ample work time but also adequate break time. Mastering is truly an art form, and to ‘master’ the artform itself takes lots of work, persistence and time. Rock On!!