The phrase "Digitally Remastered" is supposed to make an old recording CD friendly, but how much power does the remastering engineer have and how is it exercised?

With the death of vinyl, and the introduction of DCC (Digital Compact Cassette) and Minidisc (the Sony recordable CD format) imminent, the digital revolution is almost complete - as far as the average record buyer is concerned, anyway. And with the current emphasis on record companies capitalising on their back catalogues, the reformatting of past masters has become a more profitable business than ever before. Take last year's Remasters or the soon-to-be-released Elvis - The King of Rock 'n' Roll (The Complete '50s Masters) and you'll get some idea of the breadth of what's going on.

Since the introduction of CD, the skills of the digital remastering engineer have sometimes come into question. Does digital processing of old masters actually improve the originals? If so, why do so many remastered albums seem to have "lost something" in the transfer? How much power does the digital engineer actually have to change the classics? And what of the technology involved?

Peter Mew has been an engineer at Abbey Road Studios for 27 years, working in post-production for the past seven. He has been using the American-developed Sonic Solutions system for the last two years, remastering everything from Josef Locke to the aforementioned Led Zeppelin. Some transfers are relatively straightforward involving just a little equalisation being applied to the analogue audio signal as en route to the industry-standard Sony PCM1630 - as was the case with RCA's tribute to Elvis.

One of the more powerful alternatives is the system Mew uses - the American Sonic Solutions' NoNoise, which uses Sonic Solutions' hardware and software and an Apple Macintosh platform. The alternative is a British development, CEDAR (Computer Enhanced Digital Audio Restoration). As well as the DeScratch, DeNoise and Digital EQ features which CEDAR offers, NoNoise is a supremely powerful editing tool with its 3.5 gigabyte hard disk memory (over four-and-a-half hours' worth of sound).

Originally Sonic Solutions' system was run on a mainframe system in the States, and if you wanted to do something with it you had to go there. And since all the functions needed one hundred times real time processing, you had a long wait... In contrast, CEDAR was developed in conjunction with the British Sound Archive at Cambridge University (see feature in MT, November '89).

Topically - since it is the 25th anniversary of Sgt Pepper's Lonely Hearts Club Band, Mew has recently finished remastering 13 mono Beatles EPs from quarter-inch tape. At the time when the entire Beatles album catalogue was mastered for CD a few years ago, Sonic Solutions hadn't been installed at Abbey Road.

"It'll be interesting to hear the difference", says Peter, "because obviously some of the tracks are the same versions as on the original albums. Most were in mono, but some of the later ones like 'Magical Mystery Tour' were in mono and stereo."

Part of the task of remastering is dictated by the original masters, part by the objective of the exercise - are you simply "tidying up" an old recording for modern consumption or are you trying to make it sound as if it was recorded yesterday? In the case of the Beatles, the objective was one of respectful realism.

"The masters were fairly hissy" says Mew. "There were a few dodgy edits and stuff to improve, but the idea was just to improve the overall sound quality, not to change the EQs or re-edit or anything drastic like that."

Often Mew works from old 78s. This afternoon he's completing a Josef Locke compilation for EMI Records, something which he likens to art restoration. He demonstrates how a heavily crackling 78 can be cleaned up using DeScratch, then reduces the background noise before doing an overall EQ. But how much of the demon equalisation is released in the remastering process?

"Depends what it is", comes the answer. "With old stuff like 78s, quite a lot, because you're trying to balance the amount of noise you can get rid of with still trying to retain an equal amount of high fidelity in the material. With more modern stuff like The Beatles, I won't use too much.

"Anything that you do you try to enhance rather than change. You have to look into the mind of the engineer who originally recorded the master, and think 'Did he actually want that to be bass light there or would have he preferred a bit more bass?'. So you think 'Well, what sort of speakers would he have had - pretty thin sounding?', so you add a bit more bass in. It's effectively trying to get it to sound the way the original sounded."

Some of the work Mew does with 78s is for people with private collections. He remembers the ultimate challenge in this field - the broken record.

"We've literally had records which we've glued back together and they've went 'clunk' at every revolution. For the most part, the machine will automatically recognise something as radical as that, but sometimes it'll miss things and then we have to go and do it manually."

"It's nice to be able to work with things like Beatles tapes because they're a part of history and a pleasure to listen to."

The clicks appear as dramatic peaks on the system's waveform editing page. Then if a section is irreparable it can be reprocessed using the Interpolation function.

"It's possible to tell the machine to rebuild this part of the sound based on the sound that's on either side. It thinks for a few seconds, and the spike is no longer there. Unfortunately this isn't a real-time process, it's about 15 times real time, so you have to set it to reprocess longer sections for a few hours. Usually overnight!"

Over at Cedar in Cambridge, in-house remaster engineer Clive Osbourne is explaining what he sees as being the differences between the two systems.

"I think essentially the Sonic has been designed primarily as an editor", he says, "and they've sold a whole lot of systems for that purpose. Cedar's angle is that we're mainly restoration. In fact we were basically a restoration service for record companies before we began selling systems - but we feature most of the same things as Sonic like scratch removal, crackle removal and noise removal which takes out hiss and any other hums or buzzes in the signal. The biggest difference, I suppose, is that our DeScratch and DeCrackle are both real time, and that isn't the case with Sonic. The DeNoising parts of the system are pretty much the same."

Osbourne thinks that remastering should be done as tastefully as possible. In fact, he very rarely uses EQ at all.

"We don't use much EQ because the record companies like to EQ to their own taste. The EQ we use here is to get rid of problems - for instance, you may be able to take a very narrow notch out just to remove a particular hum or something. We use EQ for restoration rather than colourisation. Also, when you use EQ in conjunction with the noise reduction, you're actually EQing noise-free, which means that if you're going to do a boost at 10k or something, you just boost the signal, you don't boost the hiss."

The length of time it takes to remaster an album obviously varies depending on the amount of work involved, but on average it takes around two-and-a-half days. While using DeNoise on Sonic Solutions, Peter Mew will take a sample of the noise he wants to remove for the left and right tracks of each passage he's cleaning up, and so albums with longer sections of music, like soundtrack or classical, tend to take less time than rock or pop.

In the case of the Josef Locke material, Mew is working from both 78 and tape. He talks about how, in some cases when remastering albums, sometimes the sound quality of a particular track may have to be slightly degenerated to make it fit into the collection.

"You have to, maybe, let some more noise through than you would otherwise to keep the high frequencies up on the stuff from disc, or degrade the tape stuff a bit, although that's obviously not the idea", he explains.

"I work from the point of view that sound comes first, and so if that means having more noise left in to keep the sound quality up, then that's the way it is. It does take something away if you try to clean up these 78s too closely, because their dynamic range is so limited anyway."

"The worst thing we get from vinyl is a swishy sort of surface noise which is realty hard to get out", explains Osbourne. 'In fact there's no system which will totally remove that because it's not a constant sound, so we just have to take out as much as we can with the hiss reduction. We don't ever claim to get all of that out because it's incredibly tricky.

"The main thing is to try to keep certain frequencies upfront on certain sounds - for instance, with classical you get that very edgy sound with the violins that you must try not to lose. In the same way with jazz or blues you get those really sharp screechy tones on the trumpets and you mustn't lose the sharp brightness on those."

So what, exactly, does rock remastering involve?

"Lots of different things", says Osbourne. "For example, Virgin are putting together a compilation album of some old Brand X material, and there was one particular track they wanted to put on which was fairly rare, and that was a monitor mix straight from the desk at a soundcheck. It was from a cassette, so it was incredibly hissy, and it was my job to get rid of that.

"Had the people who developed the equipment told us how different from analogue it was, then people might have reacted better to digital."

"Sometimes I'm doing stuff which is already out - like this punk compilation CD which had been in the shops for a while but the quality wasn't very good, so we cleaned it up. It was all Sham 69, X-Ray Spex and stuff, but it was all pretty ropey. The X-Ray Spex track was live and it was awful."

"Often people come in just to assemble albums rather than do it on a conventional digital editing machine", adds Mew. "Sometimes I'll be asked to de-noise stuff which is relatively recent. I did a couple of Squeeze and Joan Armatrading albums, just getting rid of analogue tape hiss. Some people are looking for the editing facilities - like we can do up to one hundred second crossfades and stuff. So it all varies."

With the Sonic Solutions system Mew uses a Drake 20-bit convertor, a Lexicon 480L for touches of reverb (which he rarely uses) and Sony 1610 Digital mastering. In his opinion, DAT is an unsuitable format for professional mastering.

"Totally unsuitable", he asserts, "never in a million years. One of the big drawbacks is that most of the DAT machines don't tell if they're throwing up errors. A 1610 will tell you because it has an analyser. I think DAT is a format which hasn't been proved basically. Tapes which we recorded on 1610 ten years ago, some of them won't play. Now that's on three-quarter inch tape, professional standard, so what's going to happen to a DAT in ten years? In a way, I suppose it's not too bad because pretty quickly the company will get a CD of the work, but then the same thing applies with a CD; it's not a perfect medium by any means. I think some people are going to get a shock in ten years time when they try to remaster stuff from DAT."

There are still those who feel that the digital format lacks warmth in the sound, and that certain remastered albums simply aren't as good as the original vinyl releases. Often though, this is entirely the fault of the engineer. Mew agrees: "I've heard a lot of things done by other people on these systems and they do sound terrible because they overdrive the functions to the point where you just lose the sense of what's going on. You can get rid of the noise, but at what cost?"

"There's a lot of user-colourisation involved in these systems sometimes", Osbourne adds. "With the de-noise and de-scratch functions, the process is almost automatic - you just sit back and let the computer get on with it. But the hiss reduction is where the real talent comes in. We've had people at exhibitions come up to us and say "Oh CEDAR, I've heard some stuff done on that that's rubbish', and really we can't help it if someone's used the system and done a bad job. There are some engineers working with this stuff who don't have very good hearing basically!"

There is, it seems, a certain amount of rivalry between remaster engineers. In Mew's opinion, the demonstration discs that CEDAR and Sonic Solutions supplied when they launched the systems were wildly over-enthusiastic in their use of the functions, making certain demo tracks sound hard and unappealing.

Does he think the original "harshness" of digital has put a lot of people off?

"Definitely. It can sound harsh but it really depends on which convertor you use. People have always levelled that accusation at 1610 - that it sounds harsh. Which it does to a certain extent, but when you compare the benefits... For instance the amount of digital copies you can do, with only a slight amount of difference is much more useful than doing analogue copies. You listen to the master copies of some albums I've had to work on and it's just 'ssssssssssssssssss'. That's why they bring them along to me, and that doesn't happen with digital.

"You're not getting an unbiased opinion here because I prefer digital, but it does take a lot of getting used to. I also think it's taken engineers a long time to get used to the different techniques required. A lot of it is the fault of the manufacturers because - equalisation particularly - doesn't behave in the same way that analogue does. So your immediate reaction if you're used to analogue EQ is that digital EQ doesn't sound as good. Once you've mastered it, you'll realise that it's just as good, if not better. Had the people who developed the equipment told us how different from analogue it was, then people might have reacted better to digital."

But the digital medium is here to stay. Which of course makes the likes of Osbourne's and Mew's jobs all the more important.

'Everything's a challenge", says Osbourne. "You've got to view every job in a different light. If you felt that it was like a sausage machine and you were just rushing things through, then it would be terrible. It's nice to be able to work with things like Beatles tapes because they're a part of history and a pleasure to listen to. You learn something different about sound with every new job you take on."

Osbourne remembers a time when he introduced NoNoise to a rather sceptical Jimmy Page. The initial Led Zeppelin CD reissues had been a disaster and the legendary guitarist was wary of the digital domain.

"He brought in this old Led Zeppelin track that had been done for a BBC radio session in the '70s" Osbourne recalls, "so we cleaned it up, and afterwards he said Aww, if only I'd known about this sooner, because we've just finished doing a boxed set of all the old stuff. And this is the last track, so it's too late!'. I think that taught him to keep up with the changes in technology..."

You see, keeping abreast of high technology is really just a matter of teaching an old Black Dog new tricks.