SET TO CLEAN UP?

Steinberg Clean! PC Audio Restoration & CD burning software

Published in SOS July 1999
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Now that PC-based CD burners are so cheap, transferring old vinyl records and cassettes to CD is easier than ever before -- but do you really want the noise of your ageing vinyl preserved for posterity as well? Martin Walker checks his stylus, adjusts his tracking angle, and tries out a software solution to the problem.

Many people still have an extensive collection of music on vinyl records, although these days their vinyl is probably being used less and less. Putting on a CD is a simple matter, and the sound quality of audio CDs remains extremely high throughout their long life. Vinyl, on the other hand, is fiddlier to use, demands more care and attention, and the quality of the audio it reproduces can be seriously affected by rough handling, dust, spillage, and bad storage.

For reasons like these, many people (aside from those hi-fi listeners who still regard the 16-bit 44.1kHz sampling standard of CD audio as insufficient for audio reproduction purposes) would happily trade their existing vinyl collection for the CD equivalents, were it not for the expense involved. Thankfully, there is now a much cheaper way to do things. Any PC with a modest spec, a soundcard and a CD-R burner can be used to transfer not only vinyl tracks, but also any selection of tracks taken from cassette tape or other CDs. You just re-record each track onto your hard drive using

STEINBERG CLEAN! £80 pros Very effective noise reduction. Excellent value for money. Wavelab Lite is also included. cons No way to hear transitions between tracks. Only 44.1kHz stereo material can be cleaned. You have to go through the business of processing each track before you can burn it to CD -- even if you don't want to use any of Clean!'s effects. summary At this price and with these features, there is no competition from any other noise-reduction package.

either the analogue or digital soundcard input, and then use the software supplied with your CD burner to place these tracks into the desired order before burning your own audio CD. You can create your own compilations, resurrect band demos recorded years ago, or create easier-to-use CD versions of any other existing material. This technology has been available to home users for some years, but is far more affordable now that CD burners can be bought for under £200.

Of course, when you transfer audio from cassette or vinyl to CD without carrying out any further processing on it, you also transfer the limited top end and added hiss of old cassette tapes, and the ticks, pops, and general surface noise from vinyl. It has been possible for several years to greatly reduce or even eliminate such problems digitally, but until a few years ago, such audio treatments were expensive, non-real-time processes, solely for high-end mastering purposes. Fortunately, on the high-powered home computers of today, the application of advanced audio restoration algorithms is something that can be handled in real time, and the latest addition to the home recordist's audio restoration arsenal, Steinberg's Clean!, removes the final obstacle -- that of price -- by retailing for a mere £80.

Clean! combines all the features needed for transferring any type of audio file to CD. Files are handled in groups, and all their data is stored in Project files. Installation of the software is easy, and it runs from a single well-designed window (one per Project file -- but only one can be open at any one time). The window is divided into four main areas (see screenshot, see previous page). At the top left is the tracklist for the Project, which is where you assemble the files to be included in your CD. Three buttons at the bottom let you Import new WAV files, Remove them from the list, or Delete them altogether from your hard drive (there is also an 'Import Tracks from CD' option in the Import menu for digital audio extraction, if your drive supports it). Once imported, tracks appear in the list itself, and you can then use the familiar set of transport buttons (Stop, Play, Rewind, Previous Track, Fast Forward, Next Track, Record, and Cycle Playback) to audition tracks or record new ones directly to your hard disk.

You can directly edit the Author and Title entries (these are saved in the Project file), and adjust the size of the gap between tracks on the finished CD from zero (no gap) to four seconds (the default value is two seconds). A vertical fader lets you scroll through long track lists, and the two Sort buttons beneath this let you move the currently highlighted track up and down to re-order the Tracks.

Clicking on the Record button starts the recording process, as well as automatically adding a new item at the bottom of the Tracklist. Both Record and Playback levels are displayed to the right of the Tracklist, and beneath the level display are faders to control these levels. It is vital to set up a healthy input level when recording from analogue media to achieve the optimum audio quality in the digital domain, but the Playback level does not affect signal levels, just the output volume from your soundcard.

At the bottom of the window is the Waveform display, complete with zoom In/Out buttons, and a horizontal slider to view different sections of a zoomed waveform. Also neatly integrated into this window are the mouse-grabbable Start and End Markers (which allow you to leave out unwanted material before and after the desired recording), and Fade In and Out markers (dragging these creates a variable-length fade that you can hear in real time). Unfortunately, the transport buttons only seem to work on individual tracks -- you can't hear the transition between one track and the next, which would have made setting up fades easier in the overall context.

The Effects section at the top right of Clean!'s window is certainly comprehensive, and the algorithms owe their origins to the excellent (but expensive) DeClicker and DeNoiser plug-ins developed by Spectral Design. Each effect has just one amount fader and an on/off switch. The Declicker aims to remove single short clicks, the Decrackler works on the more continuous background crackles found on many vinyl records, while the Denoiser reduces constant broad-band background noise. All of the algorithms on offer take considerable processor power for their calculations, and you will need a fairly powerful PC to hear them in real time (see later for more details). The current CPU load is shown in an indicator underneath the waveform display.

During my tests Clean! proved surprisingly effective for such a low-cost application, the noise reduction being particularly good at removing unwanted noise without taking a chunk of the music with it as well (a common

Software Noise Reduction     You can reduce noise in existing recordings in a variety of ways, some of which are more effective than others. Expansion (the opposite of compression) can widen the dynamic range, and normally in the case of noise reduction the majority of the signal passes through unaltered -- only when the signal level drops below a user-set threshold does expansion occur. This technique can be effective, although as with compression, it can give rise to pumping effects if over-used. Another way to reduce noise is to use a variable low-pass filter such that the cutoff frequency is reduced during quiet passages, although this time over-use can result in deliberately low-level passages becoming muffled. A better way is to analyse the audio by separating it into various frequency bands, and then expanding them individually. Generally, the more bands in the analyser algorithm, the more expensive the product, and the more effective the results, but this is not always the case. Most noise-reduction software finds it easier to distinguish background noise from music if you can first feed it a short section containing just noise (which can often be found between tracks on cassette or vinyl). The software can then use this as a noise 'signature' (or noise print), and remove noise with the same frequency spectrum as the signature from the entire recording. However, Clean! uses a similar noise-reduction algorithm to the much more expensive plug-ins designed by Spectral Design, which works in real time, constantly adapting its noise print during the course of the track. More than five years of research went into the original algorithms, and it shows, even on the cut-down versions included in Clean!

problem with budget noise-reduction algorithms).

Three additional effects are provided to improve the overall sound of elderly recordings suffering from limited bandwidth, high-frequency loss, and narrow stereo images. Bass Boost is a simple EQ centred on 60Hz, and Brilliance works above 5kHz. Stereo Spread uses the common technique of adding out-of-phase components to widen the image -- if used to excess, however, this technique can cause problems when processed material is replayed in mono, so the Stereo/Mono switch at the top of the effects section is useful for checking this. There is also a global on/off button to bypass the entire effects section, which is handy for checking that you haven't been too enthusiastic with the effects controls and removed useful programme material.

When you have found the best settings, you can apply them to individual tracks using the 'Process Single Track' button. This creates an additional WAV file with a similar filename to the original, but with the effects added permanently. The Track Number in the Tracklist window also changes from red to green to show that processing is complete for this track. Before you burn your CD each track must be processed in some way (the software won't let you proceed to the burning stage if any remain unprocessed, which suggests that the processing is not just adding the effects but readying the files for transfer to CD in some other way -- adding the between-track gap information, for example). Fortunately, you can deal with all of your tracks at once, provided you're happy to have the same effects settings for each track, by clicking on the Process button. If you have already processed some tracks individually at this stage, only those which have not yet been processed are affected by the overall settings. Whether processed individually or in one go prior to CD burning, the new files created take up about 650Mb of hard disk space in total (for a full-length CD) -- so you need to have room for this before you start. As a benchmark, it's also worth bearing in mind that if the CPU Load window registers 50 percent processor load, then a full CD's worth of material lasting an hour is likely to take 30 minutes to process. However, you can use the Cancel button to abort processing at any time if you change your mind. Following processing, if you want to normalise your track audio levels (ie. bring them up to maximum), you can do so from the menu option at the top of the window. All processing introduces level changes to some degree, so it's best to leave overall normalising until last (ie. after all other processing is complete).

Once every track has been processed (either individually or together), you can burn (or simulate a burn) to your CD-R recorder at 1x, 2x, or 4x speed, depending on the model you have.

According to Steinberg, Clean! will run on a Pentium 200MHz MMX processor with 32Mb of RAM. However, restoration algorithms are notorious processor-hogs, and even on my Pentium II 300MHz machine I couldn't enable all of the options simultaneously. This doesn't really matter, as you can apply each desired effect in turn, off-line, creating a new file on each pass (it is often easier to get the best results from audio restoration algorithms by setting each one up in isolation anyway). If you really want to hear the combined effect of several denoising algorithms in real time but have a less powerful PC, you can reduce the processor load by temporarily monitoring in mono (with the aid of the Stereo/Mono switch) while you find the optimum position of each control, and then return to stereo before clicking on the Process button.

Steinberg claim in the manual that only SCSI-compatible drives are supported, whether for grabbing CD audio or burning the final CD-R disc. However, when I followed this up by visiting their web site, I found the up-to-date list of supported drives to be identical to that of Wavelab, which does support IDE CD drives. The best solution is to check the web-based list before buying Clean! (or ask your dealer to do this if you don't have web access) to see if your particular drive is supported.

The printed Operation Manual is well written, the sensible advice on how to get the best quality signal from your vinyl even including various ways to clean your records. There is no help file, but an electronic copy of the manual is also provided in PDF format on the CD-ROM, along with a selection of templates for CD labels and booklets. Finally, a copy of Steinberg's Wavelab Lite audio editor is also included, making the Clean! package even better value for money.

Clean! is not the cheapest option for transferring vinyl to CD -- that distinction probably belongs to the Deluxe version of the Adaptec Easy CD Creator to which you can upgrade from the more basic version that is bundled with most CD-R drives for about £60. However, the Adaptec package's noise reduction is easily outclassed by Clean!, especially as the latter offers separate declicking and decrackling algorithms. Although you never quite know how an algorithm will respond with a particular problem until you try it out, those offered by Clean! seem very effective, particularly at the price, and are also far less likely to remove wanted programme material at the same time.

This is by far the cheapest solution if you want a high-quality, all-in-one way to transfer a variety of audio material to CD. I suspect that Steinberg would sell even more copies of Clean! if they also provided a DirectShow plug-in version for more general cleaning duties, but you can import stereo 44.1kHz WAV files for processing and then resave them if required. The only restriction is that they must comply with Red Book track specifications, and must therefore be at least four seconds long. Mind you, this isn't a big obstacle either, since you could pad out the end of a shorter sample with digital silence and then remove it after treatment. However, I doubt that this restriction will worry Steinberg, and at £80 Clean! deserves to sell by the bucketload. Highly recommended!

information

£79.95 including VAT. Arbiter +44 (0)181 970 1909. +44 (0)181 202 7076. Click here to email www.arbitergroup.com www.steinberg.net