Digital Home Recording Tips, Part 2
Pages: 1, 2, 3

Mixers, Preamps, Converters, and More

My Alesis MultiMix 8 combines the functions of a mixer, mic preamp, effects box, and computer audio interface into an absurdly inexpensive box.

To get the microphone signal up to line level and then into your computer, you'll need a mic preamp and an audio interface. (Although most computers have microphone inputs, they're insanely noisy and not sized for XLR mic cables.) If you're running multiple mics, you'll need a mixer as well. I tackled all three problems at once with an Alesis MultiMix 8 USB mixer. At $149 street, the MultiMix is a great value. Not only does it provide multiple preamps with phantom power, it also digitizes the mix and sends it to your Mac or PC over USB. It even includes some zany signal-processing effects. (However, I recommend not recording with effects to your computer, because it reduces your options during final mixdown. You can always add effects in the mix (either with software or with hardware), but you can't remove them.)

The Alesis MultiMix 8 USB mixer is an incredible deal, but has a design flaw: the bottom gets too hot. Two friends of mine have burned one out in six months. I put mine up on old calculators to allow airflow, and have run it 12 hours a day for two years with no problem. The mics I mentioned above, recorded through this mixer into your audio program on your computer, can give you amazing sound.

Which audio program? There are untold choices. A popular one is Audacity, which is free and quite robust. Here's a tutorial on recording and editing in it. Also see this O'Reilly tutorial on podcast vocal editing, which uses Audacity as well.

Dirt and Vacuums

Now that you've got your digital signal clean you might wanna dirty it up a bit — with "good" dirt, that is. Good dirt usually involves old-school technology, specifically, vacuum tubes, which can add a pleasing distortion. You can spend five grand on a tube preamp, but you don't need to. And only the most discerning ears will be able to tell. I've also gone the other way, and tried the $30 ART tube preamps, but they added a lot of undesirable noise to the signal, so I don't recommend them.

Whatever you get, make sure it has XLR inputs and outputs; they will add a lot less unwanted noise. I use and love the SM Pro Audio TB202 rackmount mixer/compressor/EQ. It's an amazing stereo unit that does a lot, and does it well.

The TB202 lists for $250. I bought my TB202 for $125 on Craigslist — not to save money, but because they're so in demand that every online store I tried was back-ordered a month. The one I got had all the red paint on the front worn off from years of use, but was otherwise in great shape.

My TB202, glowing creepily in my studio at night, comforting me and guiding me.

The TB202 has a warm tube sound, is low-noise (for analog gear), and has some nice (if limited) compression and EQ. Compression reduces dynamic range (making loud sounds softer and soft ones louder), which can be useful, especially for voice or drums.

Mess around with the compression settings. I recommend starting with the Attack and Release buttons enabled (pushed in), and the Compression knob at about 1/3 (ten o'clock). Try adding a little more compression while speaking or singing into a microphone and wearing headphones to monitor the effect. Compression is damn nifty, and most professional recordings contain some. But don't overdo it; too much compression makes things sound fake and crunched.

Here are some audio tests I did with mine. Although this is a stereo preamp, it only uses one tube, because the tube has two channels. I'd recommend you replace the factory tube with a Tesla/JJ 12AX7/ECC83, which has much nicer sonic qualities and costs only ten bucks.

Tip: Getting Good Levels

Although compressors can even out levels to some extent, you want to capture sound at the right level. The best levels for recording are not too loud, and not too quiet. That seems like a no-brainer, but it's crucial. Too-quiet levels in analog recording made the tape hiss louder than the program material. In digital recording, you end up with a signal that isn't strong enough to do much with, and when you raise it up to "normal" listening levels, it just doesn't sound good. The noise increases, and sound gets gritty.

Conversely, record too loud, and the signal distorts. In the analog days, producers sometimes used that as an effect, particularly on drums. But whereas moderate analog tape distortion can sound pleasant, digital overload distortion is just hideous.

You want your average volume to be somewhere in the middle of the level scale in your recording program, and your peaks (loudest parts) never to go outside the bottom and top of the scale. You can see what this looks like in these waveforms. Notice how the too-loud signal is squared off, indicating clipping.

This Audacity screenshot shows a visual representation of the recording below. Note the too-low (A), too-high (B), and just-right (C) levels.

• Too Low, Too High, Just Right (289KB MP3)

Volume Pad and Low-Cut Switch

To prevent overload distortion, most mixers (and some mics) include a pad switch. This lowers the volume by 10dB or more, which is useful for recording in high-volume situations. For instance, you should engage it when recording a guitar through a Marshall stack, but not when recording a spoken voiceover.

Another handy control is the low-cut switch (sometimes called "high-pass filter" or "HPF"). The low-cut switch eliminates everything below a certain frequency (usually somewhere between 75Hz and 150Hz). This is useful when recording voice, as there's little useful information lower than 150Hz. All you'll cut out is the UPS truck pulling up outside to deliver you more gear from Musicians Friend, and the wall-penetrating sub-bass of the Hummer with the spinners and bumpin' stereo that the rich kid up the driveway blasts because he's bored with his nice life and longs to live in the ghetto.

Use the HPF on voice, but not for bass guitar, keyboards or drums, as they all produce frequencies below 150Hz that you (and your audience) won't want to miss.

Conclusion

Digital recording technology has changed the face of music and brought the capacity of the studio to anyone with a little bit of disposable income. But the part of the signal chain before the computer doesn't really need changing. They got it "right" a long time ago. Microphone technology hasn't changed much in 50 years (though manufacturing improvements, and globalization, have brought the price of an entry-level condenser microphone down). And the technology for mounting and using a microphone (having a pop filter and a shock mount) haven't changed in nearly a hundred years.

It doesn't take an engineering degree to get a good sound, but it does take a bit of care. Love your audio like you love your best friend. Nurture it, pet it, tell it "good girl" (or "good boy," depending on your kink), and it will get where you need it to go.

Take notes with each experiment, see what works and what doesn't, and remember this: people only truly begin to get old when they become unteachable.

So teach yourself. Listen to your audio, and let it guide you. The world will give you its ears if you make something great that fills a void. And if it sounds great, all the better.