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To Pre or Not to Pre
Quality pres can focus sounds in your mix and give everything better definition
By Dan Richards

An important aspect of a quality microphone preamplifier is how much "space" in the soundfield a preamp takes up in order to have your ear accurately define a particular instrument or voice. People wonder how you can hear every instrument clearly on a well-recorded song — even if it's through a crappy little speaker. One of the secrets is in the mic pres.

Take the stereofield and within it place a sound — let's say an acoustic guitar. Now, how much space is that taking up? If it's an inexpensive preamp, it might "sound good" to you on that one track, but you have to add a lot more tracks in order to make a complete stereo mix of a song. Imagine the stereofield being the size of a dollar. That guitar through a cheap mic pre might take up the size of a quarter. So, how many quarters could you lay on a dollar before you started running out of room? Not even 18. Try it yourself.

On that same dollar, how many heads from a straightpin could you fit? Probably a couple of hundred.

The "dollar bill" metaphor and illustration in this article are still only two-dimensional. What keeps the "cheap" preamp from getting really big is that it's unfocused to start with so it never creates enough energy in a small enough space to allow it to be projected out into space with any real effectiveness. The metaphor is similar to a laser — in which a very strong light is achieved by continuously focusing and focusing finer and finer until it comes out into free space. An unfocused light — like a cheap pre — will have its energy dissipate quickly. When you listen to an individual acoustic guitar track that's well-miked running through a really high-quality preamp — the originating "focal point" of sound of the guitar will take up about as much space as the head on a pin.

We're currently testing quite a few of the mic pres available. There are newer mic pres coming into the market all the time offering stunning solutions well within reach of most project-studio budgets. Companies include API, Millennia, Speck Electronics, Great River, Sytek, John Hardy, FMR Audio, Grace, Vintech, Buzz Audio, Benchmark, A Designs, and Phoenix Audio. The great thing about many of these companies is that they are boutique operations. You will often receive superior service, a superior product, and it's not unheard of to have the actual designer of the mic pre answer the phone when you call.

A cheap lens, like a cheap mic preamp, doesn't focus the signal. The resulting image is unfocused and lacks definition.

The one thing all the higher-end mic pres have in common is that they focus the origin of a given sound in a very small and tightly-focused space within the soundstage. If you listen to a cheap-to-average mic pre and compare it to the higher-end mic pres, you'll hear the cheaper pres sounding as if they're swimming with a chorus effect. They are considerably less defined than their higher-end counterparts. And this starts to build up as you add tracks into the mix. All those parts take up so much space, and by the time you're ready to mix you wonder why you can't get a clear mix that sounds like it was professionally recorded.

On the other hand, with well-recorded tracks using good mic pres, you can often throw up the faders and the song is often 95% there.

Then comes something that in my book is often more important than EQ for making instruments sit in the right place in the mix — and that's panning. It's a lot easier to pan a specific sound if you can easily pinpoint in the stereo field just exactly where that sound is positioned. A great pre will show you, whereas a less-than-stellar pre will confuse your ears because the sound is literally taking up a less-defined area.

A quality lens, like a quality mic preamp, focuses the signal well. The resulting image is clear and defined.

In describing the qualities of a mic pre, Allen Burdick, President of Benchmark Media Systems, says, "Harmonic distortion and intermodulation distortion are both created by the same mechanism. This may be a narrowband amplifier, an amplifier that is slew rate limited, or an intrinsically flawed design element in the amplifier, such as the output stage. At low frequencies, the large amount of feedback in today's audio amplifier elements all but eliminates distortion products. However, at high frequencies the intrinsic gain of an amplifier element is significantly reduced and therefore the percentage of gain available for use in feedback becomes severely limited. Excellent high frequency performance requires a careful use of wide bandwidth, intrinsically clean circuit elements, and the proper amount of feedback. "

This is one of the many reasons you'll find for investing in the front-end rather than having the "DAW du jour". Almost any DAW made in the last few years will sound like any other DAW. There is surprisingly little difference sonically at the level of the digital medium itself — from very inexpensive DAW's to a full-blown Pro Tools rig. The real sonic difference is more in the choice of room, source, microphones, mic preamps, analog-to-digital converters — everything on the front-end before and at the point the signal is finally converted into ones and zeros in the digital domain.

Investing in the front-end is actually investing. Spending money on computer-based audio is the disposable trash of our age. There are $100,000 Sony digital multi-tracks made just a few years ago that are literally worth next to nothing now. I had someone offer me a Sony 3324 last year for free if I'd just take it from their studio. I said, "No thanks." I don't have room or the need for it.

People think nothing of spending thousands of dollars on the new DAW-in-a-box. Two years from now it won't be worth 25% of that. But if you invest in a high-end pre, it will still be worth nearly as much as you paid in five or even 10 years — and some of them will actually appreciate in value. Keeping that in mind makes a quality mic preamp not so expensive after all.

Sample rates are switching and rising a mile a minute. 96K today and 192K tomorrow. Hang on to your recording medium — whatever you use. Jumping to the next great DAW will not improve your sound nearly as much as a serious mic pre will add to your front-end and to your overall tool kit.

This article has been edited, amended and updated for Studio Reviews April 2005. Portions of this article were originally published by Digital Pro Sound in November 2002.

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