Spectrum Editing with Steinberg Wavelab

Get "inside the waveform" when you need to do sophisticated editing

By Craig Anderton

Did you ever wish you could “get inside” a piece of digital and edit out just one specific element? For example, suppose you have a great drum loop, but the kick is just plain wrong and you wish you could substitute a different one. If only you could delete the kick and leave everything else alone...

Actually, you can—with results that range from stunningly effective to, well, not so stunningly effective. With Spectrum Editing, you don’t just alter amplitude, but can define specific frequency ranges and process only those selected ranges. We’ll show how this process works by eliminating the kick from a drum loop, but the same principle applies to emphasizing or de-emphasizing particular frequency ranges. This is particularly useful with drum loops, due to the drum hits often being fairly isolated, and occupying different frequency ranges. It’s possible to do things like emphasize only a drum’s transient, accent the snare backbeat, and in some cases, remove a sound entirely from a part.

Start by selecting Spectrum in the waveform window. The usual amplitude display will be replaced by a multi-colored display that shows lower frequencies at the bottom, higher frequencies toward the top, and uses color and brightness to indicate levels (Fig. 1).

Fig 1: Wavelab’s Spectrum display

To the right of the Loudness tab, there’s a wrench; you can click this to edit the spectrogram display. Unless you’re working mostly with high frequencies, click on this and select Logarithmic Frequency Scale (Fig. 2). Then click Apply and OK. This will make it easier to see the kick drum.

Fig. 2: The log scale makes it easier to edit lower frequencies.

Type S to choose the Spectrum Selection tool (it’s also available on the toolbar, to the right of the time selection button). Zoom in if needed to see what’s happening at the various frequencies more easily.

Study the waveform while playing it to correlate sound to shapes and colors. For example with Wavelab, red is the loudest level, then it goes through the spectrum (orange, yellow, green, blue, indigo, violet) to softer levels, with dark violet being the softest. So in this example, a yellow blob at a low frequency (toward the bottom of a window) shows a kick drum.

Draw a rectangle around the part you want to delete (Fig. 3)

Fig. 3: Isolate the kick.

In the edit area above the waveform, Surgery should be selected so you can choose the desired “Processing of the selection.” In this case we want to Damp the level; here the level will be dropped by -48dB. Under Filter Settings, Bandpass is the right choice because we want to remove only the selected frequencies. You can also choose the filter steepness, and a crossfade time between the processed and unprocessed sections (Fig. 4).

Fig. 4: This is where you specify how you want to process the area you’ve selected.

After making the desired settings, click on Apply. As if by magic, the kick is pretty much gone; repeat for additional kicks. Note that because the selection tool is a rectangle, you may need to “carve away” at various frequency components rather than expect to delete the entire kick with one rectangle (Fig. 5).

Fig 5: The yellow blobs indicating the kick are gone, and the loop sounds virtually kickless.

Spectrum Editing has many other uses. You can isolated just a transient, and increase its gain to give more attack. Also note you have processing options other than Damp, like Dispersion and Fades, and you can play around with the filter as well—there are options for low-pass filter and high-pass filter as well as pass-band filter. You can even set fthe filter steepness (in dB/octave) and adjust the crossfade time.

If you have some particularly demanding editing to do, like removing a single cough in the middle of a live acoustic performance, it can take some time to juggle all these parameters appropriately. But when all else fails, Spectrum Editing can accomplish if not miracles, at least feats that seem pretty miraculous.

Craig Anderton is Editor Emeritus of Harmony Central. He has played on, mixed, or produced over 20 major label releases (as well as mastered over a hundred tracks for various musicians), and written over a thousand articles for magazines like Guitar Player, Keyboard, Sound on Sound (UK), and Sound + Recording (Germany). He has also lectured on technology and the arts in 38 states, 10 countries, and three languages.