Driving Out the Dreaded Demons of Mic Preamp Hiss

Electrons are noisy little guys. As they rub against each other and frolic within their subatomic superhighways, they generate hiss. No, not a lot of noise. But amplify it by 60dB or so, and unavoidably, the Curse of the Mic Preamp (or other high gain stage) appears. And even a little bit of hiss can be annoying.
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You can’t eliminate all noise, but you can reduce it — often to inaudibility. So, we’ve chosen five low- and mid-priced noise reducers (under $1,000 list) to see if they’re up to the task: Adobe Audition, BIAS SoundSoap Pro, Creamware Osiris, Enhanced Audio Diamond Cut 6, and Sony Noise Reduction 2.0.


The most popular DSP technology for reducing noise is spectral subtraction. The process has three steps:

1. Isolate a part of the signal that contains only the noise you want to reduce (usually at the head or tail of a file).

2. Sample this noise, and optionally save it as a noise profile.

3. Use the noise reduction plug-in/program to subtract anything in the file that fits the noise profile. Poof! Noise gone!

The technique is effective, but if you need to remove a lot of noise, the overall sound may take on a “warbling” or “robotic” quality. (Sonic pervert alert: “Wrong” settings can make some great special effects.) Although the subtraction process is standard, each company takes their own approach to minimizing these artifacts. Another difference between programs is the roster of noise-reducing tools (just spectral subtraction, click and pop removal, clip restoration, etc.), and whether they’re stand-alone programs or plug-ins.

All the programs were surprisingly effective at nuking normal hiss levels with spectral subtraction. I figured I’d up the ante, so I turned up the mic pre gain all the way, talked very softly, and turned the air conditioning on full blast in the background. I also processed a piano recital by Janet Montgomery, which had been recorded live under less than optimum conditions. Surprisingly, all the products still did a credible job — even the lower-cost programs gave the higher-priced ones a run for their money.

Let’s look at the five contenders.

(adobe.com, $299)
Yes, it’s an outstanding editor and fine multitrack recorder — but the suite of noise reduction tools (Auto Click/Pop Eliminator, Click/Pop Eliminator, Clip Restoration, Hiss Reduction, and Noise Reduction) truly overachieves for this price point. For preamp hiss, Noise Reduction (Figure 1) beats Hiss Reduction: More natural, less artifacts, more effective. Audition also offers Frequency Space Editing, a goodie that lets you do things like remove a single cough from a concert, or only the kick drum from a drum loop.

Ease of Use: It’s neither particularly difficult nor easy. The interface is the usual Audition “scientific-looking” type of window, with a bunch of parameters and boxes. Confused by field names like “Precision Factor” and “Transition Width”? Just go with the defaults. However, the help file explains what these do in a straightforward manner, and a little tweaking can be beneficial.

Distinguishing characteristics: Audition is a complete stand-alone recording, processing, mastering, noise reducing, and editing solution. It’s the most feature-laden and versatile software covered here.

Downside: Although you can make adjustments in real time using a preview mode, you can’t navigate the file while you do this. Also, the noise reduction seems a teeny bit less transparent than OsirisXP; but this is a subtle difference that came into play only with certain material.

Upside: Some people buy Audition just for the noise reduction tools, and when you use them, you’ll see why. This is about as cost-effective as it gets, the defaults hit the spot 95% of the time, and perfectionists can do lots of tweaking.

(bias-inc.com, $599)
This versatile plug-in works with VST, AU, RTAS, AudioSuite, and DirectX. It’s also cross-platform. As befits BIAS’s strong Mac background, SoundSoap Pro has the slickest interface and graphics (Figure 2). But it’s not just a pretty face; its modules (hum and rumble, click and crackle, broadband noise, and a noise gate) work individually or connected together in series.

Ease of use: SoundSoap Pro is extremely easy to use, despite its sophistication. It’s 100% real time, and you can navigate, loop, or otherwise check out any part of the waveform being processed. There’s a helpful spectrum display (it also impresses clients!), and you can set up presets for easy comparisons of different settings.

Distinguishing characteristics: The software has a great “feel” — looks good, easy to use, works well. Although it can’t run stand-alone, the compatibility with so many different platforms on Mac and Windows is unique among these five programs.

Downside: It’s the second most expensive option here, although in the world of noise reduction software, it’s still in the mid-price range. However, SoundSoap, a stripped-down version that still does excellent hiss reduction, lists for $99.

Upside: This and OsirisXP are the easiest programs to use, although I’d give SoundSoap Pro the advantage in terms of graphic feedback and number of adjustable parameters. While it lacks Audition and DC6’s complement of tools, it provides the ones you’ll use 95% of the time.

(creamware.com, $730)
Osiris was the Egyptian god of the dead, which I suppose is a fitting name for a product that kills noise. Algorithmix supplies the algorithms, as they do for their own products and other companies (e.g., Magix Samplitude and Sequoia). Many consider their algorithms some of the best available, and for getting rid of noise, OsirisXP delivered big-time. The package includes DeClick, DeCrackle, and DeNoise modules, useable individually (Figure 3) or as a single, integrated plug-in. (Note: OsirisXP, the Creamware PSY-Q enhancer, and a sound card are also available as the REstore bundle for restoration work.)

Ease of use: You move the sliders in a specific order until the noise goes away. These are somewhat interactive, so you may need to go back and forth. Being part of Creamware’s Scope platform, Osiris “patches” into your signal connections. I found it easiest to bring the file into a host, patch the host out to Osiris, then patch the Osiris out to a host track input. This also allowed easy comparison between the original and processed sounds.

OsirisXP can be used in “XTC” mode, where the Creamware processors become available as VST effects. However, not all programs work well with XTC (e.g., Cubase SX does, Wavelab does not); so I preferred using it with the Scope platform, which I think is fabulous anyway.

Distinguishing characteristics: The Algorithmix algorithms seem particularly adept at minimizing artifacts when using large amounts of noise reduction.

Downside: It works only with Creamware hardware, and it’s not cheap — especially given the weak dollar.

Upside: It makes the Scope platform even more powerful; better yet, the software is effective and easy to use. Furthermore, OsirisXP uses very little power from the Scope DSP card, so you could easily use it on several sequencer tracks. And it’s realtime — tweak while the signal plays.

(enhancedaudio.com, $199)
This stand-alone program incorporates a big-time processing toolset: Spectral subtraction noise reduction (Figure 4), various filters (including brickwall filtering and a dynamic noise filter), sample rate conversion, CD preparation (but not burning), CD audio track ripping, the ability to put multiple processes in series, de-clipping, and even effects (reverb, echo, tube simulation, standard and multiband dynamics, time compression/expansion, and more).

Ease of Use: DC6 is reasonably user-friendly, and its separate preview mode accommodates realtime adjustments. But to exploit the program’s full capabilities, expect to spend some time experimenting and reading the help file; there’s a lot to chew on here.

Distinguishing characteristics: DC6 is nothing less than an all-in-one mastering/noise reduction solution — and given the $199 list price, its low profile is a bit of a mystery.

Downside: The interface is somewhat clumsy. For example, you can’t just drop the cursor where you want to play and hit the space bar; you have to right-click and select “Play from Here.” Uh . . . okay.

Upside: There’s an eclectic collection of all kinds of noise reduction tools, not just the usual ones. It’s the least expensive option here, but provides tons of features. If you’re on a tight budget and handle a wide variety of noise types (impulse, continuous, etc.), this is a fantastic deal.

(sonymediasoftware.com, $279.97)
The original Sonic Foundry Noise Reduction package brought affordable noise reduction to the masses. This update is a suite of DirectX plug-ins for vinyl restoration, noise reduction, clipped peak restoration, and click and crackle removal. For noise reduction, version 2 has updated, natural-sounding algorithms.

Ease of use: The user interface is nothing fancy — just the usual sliders, check boxes, and numeric value fields (Figure 5). While the defaults will take you where you want to go, a little tweaking can improve results. For example, there are four noise reduction modes that trade off less noise removal for fewer artifacts. And because it’s a plug-in, you can navigate the waveform in real time while tweaking parameters.

Distinguishing characteristics: These plugs will run on just about any computer with a pulse; the noise reduction has very low system and CPU requirements, making it useable on multiple tracks of a DX-compatible sequencer.

Downside: The price is almost the same as Audition, which includes the same tools as Noise Reduction 2 but also adds a bunch of processors and doesn’t require a separate digital audio editor. However, you can’t use Audition as a plug-in.

Upside: The program looks plain; the results are anything but. The modules are all highly effective, and the noise reduction also includes a high-shelf filter for hiss. And of course, realtime tweaking is great.


All these program do the job of removing hiss. It’s your particular needs that would favor one over the other.

For the most generalized, cost-effective noise reduction tool, it’s a tossup between DC6 and Audition. Clearly, if you need editing and multitrack recording options, Audition would get the nod. But if you already have a host you like, don’t care about the Frequency Space Editing, and need some of the tools that Audition doesn’t provide (brickwall filter, dynamic noise filter), then DC6 would be a solid choice.

However, neither of these work as plug-ins. This is fine if you just want to import stereo material, but to reduce noise with several tracks of a multitrack, you’d need to render each track, apply noise reduction, then import the cleaned up version into the host. For this, the plug-ins (BIAS SoundSoap Pro and Sony Noise Reduction 2) are a better choice. Noise Reduction 2 is less than half the price of SoundSoap Pro, but works only as a DirectX plug-in. If you need multiple plug-in formats, SoundSoap Pro justifies the extra bucks.

For Creamware Scope system users, OsirisXP is the logical choice. It’s easy to patch into the system, simple to adjust, and the Algorithmix algorithms are excellent. But you pay for these amenities. Those on a tight budget will likely render files and bring them into Audition or DC6.

The bottom line is that regardless of which software best fits your needs, it will get the job of exorcising preamp hiss done without killing your budget — and that’s a truly welcome development when you want the cleanest possible sound from your tracks.