Korg Soundlink DRS 168RC

Though digital technology has transformed the nature of synths, effects, and even multitracks, project studio mixers have largely remained steadfastly analogue, breaking the chain which, if complete, would allow your music to remain in the digital domain from sequencer to master. Korg's 168RC forms the heart of a system designed to all but eliminate the analogue signal path, and Paul Wiffen wonders where it's been all his life...

It's about time. For the last 10 years I've been assembling a collection of digital audio gear which I steadfastly refuse to put through a conventional mixing desk, simply because I hate what happens to the clarity and transparency of digital audio once you start going backwards and forwards between the digital and analogue domains. You know — source sounds sampled into high quality‑samplers, then turned back into analogue to go into the mixer, then re‑digitised into an effects unit, then back to analogue for the tape return, then back into digital to for your final mix to DAT... However good the A/D and D/A converters on each item in the chain, I hate the 'blurriness' which creeps in after several conversions. The situation has become worse since everyone started to use PCM‑based synths, because everything has been digitised once before you even start.

So instead of recording through a conventional mixing desk, I've spent the last 10 years moving audio around, in the digital domain, between samplers, hard disk recorders and effects units, without the flexibility of mixing multiple channels of audio in real time. Obviously, the amount of real‑time mixing and effects processing possible within software has increased phenomenally over that time, from off‑line EQ and normalising of stereo in the original Sound Designer, to the automated eight channels of 3‑band parametric EQ I currently enjoy in Cubase Audio on the Falcon. But, as I found earlier this year, when a friend let me mix down one of my Cubase Audio recordings on his Yamaha 02R via the ADAT‑format optical interface, there really is no substitute for a proper hardware mixer, especially when the mixer has the quality of effects and automation that the 02R has. The only thing standing between me and the mixer of my dreams was that little thing called money. Of course, if your music is your livelihood, the 02R is a very sound investment, but unfortunately, I've never been quite able to get the knack of making money out of my musical efforts. In Germany, there are several companies modifying ProMix 01s (more in my price range, and an excellent mixer apart from its lamentable lack of digital I/O) for S/PDIF, AES/EBU and ADAT input/output, and I was able to use one of these for some Frankfurt Musikmesse Falcon demos I did. I seriously looked at the possibility of bringing one of these back to the UK, but the warranty and service issues become so complicated when you export units from one country to another that I had to give it a miss.

So imagine my joy when I discovered that Korg were planning the mixer I had dreamt of: an automated (with snapshots or MIDI‑controlled automation) digital mixer/effects package that not only had the capability for multi‑channel digital I/O, but came with the ADAT interface as standard, not an optional extra! (The problem with optional extras is that they often take a product within your budget outside of your budget.) Of course, I wanted some analogue inputs on this mixer — microphones and analogue synths can't be interfaced digitally — but what interested me was not one, but two ADAT inputs, and two ADAT outputs.

ADAT I/O Without ADAT?

I can already hear many among you asking what use an ADAT interface is without an Alesis ADAT recorder. Well, as much use as S/PDIF (Sony/Philips Digital InterFace) without a Sony or Philips product. Just as you can use S/PDIF to connect a Roland product to a Fostex, so you can connect a Kurzweil synth or an Emu sampler to a Yamaha mixer using the ADAT interface. More and more companies are using the ADAT interface for multi‑channel digital interfacing, and there is absolutely no reason why there has to be an ADAT in the setup (unless you want to record to it, that is).

Of all the automated mixdown systems I have ever used, the 168RC offers the simplest and most glitch‑free operation...

"But", I hear you cry, "why use the ADAT interface instead of S/PDIF or AES/EBU?" The answer to that, my friends, lies in the term 'multi‑channel'. Unlike AES/EBU, which sends stereo down XLR‑terminated cable, the ADAT interface sends eight independent channels of digital audio down the same optical connection with which S/PDIF can only achieve stereo. Of course, much of the time you only need stereo, when taking the final mix to your DAT machine, or sampling a stereo drum loop, but when you connect a multitrack digital recorder (tape or hard‑disk based) to your mixer in the digital domain, wouldn't it be great if you didn't need half a dozen cables and connectors to do it?

This is exactly what the ADAT interface gives you. Eight channels of audio down one filament of optical cable — unbelievable when you first think about it, maybe, but then "any sufficiently advanced technology is indistinguishable from magic", as Arthur C. Clarke put it. The first time you get eight channels from your digital audio recorder independently EQ'd and mixed on the separate channels on the desk in front of you, when they're only connected by a single insignificant optical filament, it's a pretty spooky feeling. Of course, we've been sending 16 channels of MIDI down a single MIDI cable for years but that's a lot less information than eight channels of 44.1kHz 16‑bit words.

Once you've got your head round the concept, you'll realise how incredibly useful this is going to be. Not only can you get shot of all that spaghetti from the back of your gear (analogue looms start to look like antiques), you can also stop worrying about earth hums and buzzes (optical cables isolate equipment electrically, eliminating the differences in potential between units which cause earth loops, and which occasionally blow gear up and kill people). Once you have a surfeit of digital connections on a mixer instead of a dearth of them (and digital outputs as well as inputs), you can start using them as effects send/returns and inserts, as well as straight inputs and outputs.

For me, the ADAT optical link is the most exciting interface since MIDI, and I think it will revolutionise the way audio is moved around studios in the very near future, especially home and project studios based on digital recording. I'm pleased to see Korg making it the audio interfacing standard for all their digital products (see sidebar on the Soundlink family) and I hope that other manufacturers will follow this lead. There are already signs of this happening, with Akai, C‑Lab, Digidesign, Emu, Kurzweil, Roland and Yamaha all shipping ADAT interface options for various digital audio products, but I can't wait for the day when this interface is fitted as standard rather than an option (remember the days of MIDI upgrades?).

The 168RC has two optical inputs and two optical outputs, giving a total of 16 channels of digital input and 16 channels of digital output. The 16 digital inputs (together with the eight analogue inputs) can be freely routed to the 16 channels (ie. they're not hard wired 1‑1, 2‑2, 3‑3, and so on) and to the aux returns. The first set of eight digital channels (the first ADAT Out), is used to output the eight busses the mixer features (which allows multiple 168RCs to be cascaded). The second set is freely assignable for channel outs and aux sends. Korg's engineers haven't forgotten S/PDIF completely, though; the main stereo output of the desk is also available on a co‑axial S/PDIF connector, so you can mix digitally direct to DAT (as there aren't many DAT players out there yet with ADAT inputs).

Analogue Inputs: Why So Few?

Conventional mixer users may be shocked to learn that the 168RC only has eight analogue inputs (complete with inserts). This might seem like a bit of a shortcoming, and certainly, if you only have analogue gear to record, this makes the 168RC on its own a little limiting. However, if you read the sidebar on the new Soundlink family, it will become clear how you can expand the 168RC to be a 24 analogue input desk using two 880A/D racks.

I found the EQ sounded extremely sweet, without any of the harshness that can sometimes characterise digital EQ.

The reason for keeping the number of analogue inputs down is a simple one: cost. These days, the most expensive section of any digital device is the Analogue‑to‑Digital Converters (A/Ds). Each analogue input requires its own A/D converter. So by restricting the number supplied as standard, Korg have been able to keep the starting price of the 168RC below £2500. If you need 16 analogue inputs, it will cost you £3294 including VAT (24 will set you back £4093). Of course, because of the digital interfacing, if you have other equipment with high quality A/Ds, you may well be able to use these and save yourself some money. If you own an ADAT XT, for example, you already have eight 18‑bit A/Ds which you can use to supplement the eight on the 168RC. Of course, this sharing approach works the other way too. For example, you might use the 168RC's converters to improve on the quality you can record to tape with the original ADAT recorder, by using the second ADAT output to route the eight analogue inputs of the 168RC to the ADAT's digital input. Suddenly, this digital interfacing starts to make real economic sense, allowing us to share expensive A/D converters and upgrade the quality of our recordings without making old gear redundant.

More interestingly for those using computers for hard disk recording, the eight analogue inputs of the 168RC can be used for digital audio devices which don't have their own multiple inputs. I used this facility to great effect by routing the 168RC's eight inputs to the ADAT input of my Falcon MK X, and was able to record eight tracks simultaneously for the first time, using the new ADATREC utility, which comes free with version 2.06 of Steinberg's Cubase Audio for the Falcon. In fact, the 168RC makes the perfect production partner for the Falcon with an ADAT interface, as the only connections you need to achieve eight ins and eight outs are two optical cables between the two units. When recording, the 168RC's inputs become the Falcon's inputs and when mixing down, the eight channels of the Falcon appear on eight separate channels of the 168RC, all in the digital domain.

There are many other applications where the 168RC can save you money. Instead of having to buy a box like Digidesign's 882 or 888 with Session 8 or Pro Tools, to add eight channels of high‑quality I/O to a Macintosh running your favourite audio/MIDI software, you can combine the extra functionality of the 168RC mixer with the Korg 1212 I/O PCI card, and obtain more EQ and effects for less money (see the sidebar on the Soundlink family of products). This applies to any system which can integrate an ADAT interface into its digital I/O. More and more ADAT interfaces are being announced every day, so check with your manufacturer for availability on your digital audio recorder.

In case this talk of economy has worried the purists out there, there is no cause for alarm. The A/Ds used on the 168RC show no sign of cost‑cutting in their spec or quality, only in their number. The 18‑bit converters sound as sweet as any I've heard, with a transparency which differentiates them from their 16‑bit counterparts.

However, quality conversion is not all you need from a digital mixer. Mixers need to be able to cope with a variety of input types and levels. Inputs A, B, C and D on the 168RC are designed to cope with mic or line level, thanks to the provision of 20dB pad switches. Inputs A and B are provided with balanced XLR connectors and a common 48V phantom power switch. Inputs C and D are on standard jack sockets, making them ideal for connecting low output‑level instruments like guitars and basses. However, they are still balanced stereo connectors, in case you want to connect a balanced source, though an unbalanced signal can also be input on a mono jack. These first four inputs are provided with insert jacks too (a stereo socket with the conventional ring/tip setup), allowing the signal to be routed through an external analogue effect before it is digitised. This is one of the most vital provisions on a digital mixer, and is far more important than on its analogue counterpart, for the following reason.

For me, the ADAT optical link is the most exciting interface since MIDI, and I think it will revolutionise the way audio is moved around studios in the very near future...

While it may be desirable, on an analogue mixer, to patch vocals, guitars and other signals with highly variable levels through a compressor, with a digital mixer it's absolutely vital to do this before the signal is passed through the converters. The reason for this lies in the nature of the digitising process. To achieve the optimal performance of any given converter, the signal must be supplied at 0dB. For every 6dB the signal drops below this, one bit of resolution is lost. So if a vocal phrase enters the converter at ‑30dB, the quality of the conversion will drop from 18 to 13 bits. Don't make the mistake of thinking that this is something which can be fixed later, using a digital compression or 'normalisation' algorithm. Once a signal has been digitised, the signal‑to‑noise ratio is set in stone. So normalising a signal recorded at ‑30dB in a system with a measured ratio of 90dB will bring the noise floor up to ‑60dB when you boost the signal to 0dB. The only way to avoid this problem is to compress the signal in the analogue domain before you digitise it. The 168RC makes this possible with its pre‑converter insert loop on the first four channels.

Inputs E, F, G and don't have the 20dB pad or insert loop, but they do have the balanced stereo jack socket and, like the first four inputs, they also have trim controls, allowing the input level to the converters to be optimised. Like the settings of the pads and the phantom powering, these trim controls are not memorised in the 168RC's automation 'Programs' (more on these shortly). In fact, none of the controls mentioned so far are, but this is how it should be. These controls should always be 'live' for instant adjustment. The last thing you want is a setting of phantom power or a pad changed by a snapshot being recalled.

Wot, No S/Pdif In?

Strictly speaking, it's inaccurate to say that the 168RC only has eight analogue inputs, because there's also a stereo input on coaxial connectors for Tape In. However, I didn't mention this at the same time as the other inputs as it is hard‑wired to the analogue monitoring circuitry, and cannot therefore be routed through any of the digital mixer channels. It can only be used for monitoring a stereo tape machine back through the desk, presumably for checking your recording after having mixed down to DAT in the digital domain (at least, I hope you'll want to keep the final mix all‑digital — otherwise what would you be doing with a desk like the 168RC?).

Of course, if you're only using this Tape In to check back mixes and the like, it doesn't matter that it is analogue, and it certainly saves you listening to your mix through an extra A/D‑D/A conversion (as you have to do on a certain all‑digital desk I could mention), but this does highlight what I consider to be the most serious omission on the 168RC: the lack of S/PDIF input. It will be some time before everyone has routing boxes to convert multiple S/PDIFs to ADAT interface format, so you might well have to run a source DAT or CD signal into the mixer in analogue form (thereby defeating what I take to be the point of the 168RC's other generous digital connectivity). Similarly, there is no way to connect the S/PDIF output of a synth or other sound source, to allow it to be mixed in through digital.

I got around this by using the Falcon's S/PDIF input, and then routing this inside the Falcon to two of the eight channels on the Falcon's ADAT output, and into the 168RC from there. This allowed me to route the digital output of my Roland S760 sampler into the 168RC for mixdown (although it did tie up two of the Falcon's audio channels during mixdown). I assume that you'll be able to do the same thing if you're using Korg's 1212 I/O card with a Macintosh or PC, but I suspect with the same limitation (loss of two hard disk recording tracks).

The ideal solution would be if Korg came up with another 1U rack box like their 880 interfaces, but which converted four S/PDIF inputs into one ADAT output. This would then allow you to mix and match multiple S/PDIF signals, from synths, samplers and CD or DAT, for processing through the main channels of the 168RC without A/D conversion. I think you may be able to use the Alesis AI‑1 interface to do this, but it does cost over £900, and you might need a BRC in your setup. I'm sorry to make such a big thing about not being able to plug an S/PDIF signal into the 168RC, but surely this is the raison d'être of the Soundlink series — to keep signals in the digital domain as far as possible.

24 Into 16 Does Go

The biggest question raised by the preliminary spec I saw on the168RC was how its 24 inputs related to its 16 mixer channels. In fact, this is handled very elegantly, using a programmable patch system. Pressing the button marked 'Input', to the right of the LED display, calls up a screen which shows you which input is feeding each of the 16 channels. Using the Up and Down buttons, you can move between the four rows of channels and then use the knobs below the screen to alter the input source for the four currently‑selected channels. The parameter field for each channel lets you select inputs ANAL A‑(analogue), DIG A1‑8 or DIG B1‑8 (the two ADAT inputs). This means that you can route any input to the channel of your choice for mixing, EQ and effecting. Unfortunately, there is no way to utilise whichever eight of these inputs remain unassigned in the mix output. It would have been nice if spare inputs not going through mixer channels could have been used as external effects returns for processors connected to Aux 1 and Aux 2. As it is, if you're using external effects, you have to bring them back through channels 13‑16 (assuming you don't want to EQ, otherwise you will tie up some of channels 1‑12, which are the ones which have EQ).

The two ADAT outputs on the mixer have separate functions. The first is hard‑wired to the eight busses on the mixer, so that busses 1‑8 appear on digital channels A1‑8. This means that you can pick up the eight busses in the digital domain on another device with the ADAT optical connector. The fact that the 168RC is a true 8‑buss mixer makes it the ideal tracking mixer for use with an ADAT (especially the original one, whose converters are starting to sound a little tired). In fact, the first Program on the 168RC is called 'Rec adat 1', the second 'Mix adat 1' and the third 'Mix adat 2' (ie. for mixing down two ADATs to DAT). Something tells me that the Korg guys had the ADAT in mind when designing and configuring.

...for those using computers for hard disk recording, the eight analogue inputs of the 168RC can be used for digital audio devices which don't have their own multiple inputs.

ADAT output B is fully assignable, and this is the one you would use if you were cascading 168RCs together to build up the number of channels and effects available (you can use up to six 168RCs in cascade). Again, there are master and slave Programs included for using more than one 168RC. You set the signals to be sent on this second ADAT output by pressing the 'Ex. Bus I/O' switch to the left of the LCD display: a screen then appears, showing the eight digital channels and parameter fields, where you can select the sources. As well as mixer channels 1‑16, you can also select any of the eight busses, Aux 1 and 2, or the main left or right outputs. I found this to be a fantastic feature in conjunction with the Falcon, as it allowed me to use the 168RC as a super Falcon 8‑input converter box with mic preamps, inserts and effects, all with the 18‑bit conversion and 24‑bit processing quality of the 168RC. Obviously, Korg designed this particular usage for the ADAT or their own Soundlink 1212 I/O card for Mac or PC users, but Falcon owners can take advantage of it straight away by using SoundPool's ADAT interface. When companies like Steinberg and Emagic add support for the 1212 I/O card in Cubase and Logic Audio, Mac and PC owners will get exactly the same fantastic capability (of course, if you want to record just audio, the OSC Deck 2.5 software bundled with the 1212 I/O will give you this facility straight away). This mixer (and any others which implement the ADAT digital interface) could spell the end for those add‑ons to hard disk recorders, the 8‑input/output expander boxes. Why go through extra conversion stages when you can pipe eight channels at once into your mixer in the digital domain and get rid of the spaghetti at the same time?

16 Channels, But Only 12 Faders?

Channels 1‑12 are full mixer channels with their own dedicated faders. They feature 3‑band semi‑parametric EQ, two aux sends and two effects sends, pan, mute and solo. The mute and solo buttons are directly above the faders and have LED indication to show their status. A final switch selects the channel currently being edited in the display. All aux and effects sends, pan, EQ and buss settings are edited in this way, with the knob below each parameter field in the display adjusting that parameter. These parameters cannot all be shown at once in the display and so are split into three groups: Input/Send/Pan, EQ controls, and bus assignments, which are selected by the buttons immediately above the fader channels. Channels 13‑16 do not have their own faders, nor any EQ, so they cannot be used as full input channels. Their primary purpose seems to be for external effects returns and so on. A single Select switch cycles around these channels, presumably because you will not need to keep adjusting them as often as the 12 primary channels.

The biggest question raised by the preliminary spec I saw on the 168RC was how its 24 inputs related to its 16 mixer channels. In fact, this is handled very elegantly, using a programmable patch system.

The I/S/P (Input/Send/Pan) display for each channel shows the individual input routing (duplicated from the overall input screen I mentioned above) with a level meter and phase switch. Next to this are the four sends, two to the external Aux 1 & 2 and two to the internal Eff 1 & 2, each with its own Pre/Post switch. The right‑hand side of the screen shows the pan setting and (for channels 13‑16 only), the level control and solo/mute switches.

There are also global screens for all 16 channels, which can be selected by the Aux Send, Eff Send, Pan and Meters buttons to the right of the LCD. These allow you to visualise the status of one parameter for all the channels simultaneously. The Meter screen is obviously particularly important, as many people are so used to being able to see levels on all 16 channels on a conventional mixer. This screen also features a Peak Hold parameter which allows you to determine how long (or even if) peaks are held in the display.

Pressing the EQ button below the LCD displays the seven EQ parameters available on each of the first 12 channels (this button does not respond if you press it while you have channels 13‑16 selected). There are Frequency and Gain controls for Hi, Mid and Low, plus a Q control for the Mid range; the parameters beside the Gain control actually tell you the amount of cut or boost you currently have set, in dB. I found the EQ sounded extremely sweet, without any of the harshness that can sometimes characterise digital EQ.

The 168RC comes with 20 preset EQ settings, which I found incredibly useful starting points for getting a sound (especially on drums). Coming, as I do, from the world of keyboards and MIDI, I have very little experience of EQing raw sounds from scratch (I lasted one week as a tape‑op at Matrix Studios back in 1980 before I realised that this was not my route to stardom) and I think others with my background will really appreciate this 'starter for 10' approach to EQ. Of course, those with the training can just set the EQ flat and do all the work themselves.

The final group of parameters is found under the bus button, which calls up a screen for setting which of the eight busses the selected channel will be assigned to. This works in exactly the same way as on a conventional mixer (except, of course, that you can automate it using snapshots or external control). Once assigned, you have pan, level and on/off control of each of the eight groups — and don't forget that these are available on ADAT output A for sending directly to a digital recorder. If you need analogue outs for these, you'd simply put an 880 D/A on this ADAT output.

MIDI Automation VS Snapshots

A hundred internal snapshot memories, for snapshot‑type automation, are available within the 168RC, but the desk can also send all parameter changes out over MIDI, for automation via a MIDI sequencer. You can choose whether the automation uses continuous controllers or SysEx, depending on what works to the best advantage for your software and the number of MIDI ports you have available. I found continuous controllers best, as this data can be displayed and edited graphically by most sequencers. The on‑board Programs (Korg's term for snapshots, static pictures of the desk status at a given time) allow you to re‑configure the mixer completely for specific applications — routings, effects and all — but they can also be used to make smaller changes to levels and settings in mid‑mixdown, via MIDI program changes embedded in a sequence. This is obviously ideal for complete scene changes, but for less radical alterations, especially those which don't need to be instantaneous, using MIDI SysEx or Continuous Controllers for automation gives much better results. If you were using the 168RC for live shows, 100 Programs would not last you for a full set, unless you used MIDI to make the necessary small alterations in level and EQ, and saved the Program (snapshot) changes for when you need to alter many parameters simultaneously — if you used SysEx or Continuous Controllers in this latter situation, they might clog up your MIDI stream anyway.

I found that using Cubase (though other sequencer programs will obviously work too) to automate EQ settings was great fun, and allowed me to obtain the sort of effects on a synth bassline which you would normally have to create with a synth filter as you were recording it. People doing dance music are going to love this automated EQ facility as, unlike synth resonance, you can put it on anything — vocals, drums, whatever you're mixing down — and on 12 channels at once. One word of caution, though. During very fast sweeps and resonance boosts, a certain amount of stepping could be heard, so the most radical effects need to be moderated a little to maintain the smoothness of operation you'd get from analogue EQ. However, this is more than compensated for by the automation facility and the ability to edit after the event, using your sequencer's functions. I soon found myself trying things that would be impossible without Cubase's tools for editing continuous controllers.

Summing In Digital

Although Korg were not able to supply the full manual with the review 168RC, I found the preliminary documentation covered the rare thing I couldn't work out from first principles. Overall, the 168RC is a breeze to use, and most parameters can be accessed from several different screens (ie. as part of one channel's parameters, or as part of the global display of one parameter for all channels).

In conjunction with Korg's forthcoming 1212 I/O PCI card for the Mac and PC, the 168RC would make a killer digital recording studio using the bundled Deck 2.5 software, but the real interest in the combination of 168RC and 1212 I/O will come when companies like Steinberg and Emagic support the Korg PCI card from within their software. Once you have the ADAT I/O on that card, the 168RC is the only way to go for mixing. The 12 inputs and outputs match up perfectly with the 12 faders on the 168RC, and you can use the remaining four faderless and EQ‑less channels as two external stereo aux returns.

It goes without saying that a mixer with eight busses and such generous ADAT I/O provision has to be a natural choice for recording and mixing with ADATs. If you have two ADATs, or an ADAT and an 8‑track hard disk recorder with ADAT I/O, this is the only game in town. The people who will be most disappointed in the 168RC are those who compare it with the Yamaha ProMix 01. It is a totally different beast. The 168RC is an 8‑buss mixer designed for integration into a digital system. It is not a 2‑buss mixer with motorised faders and the ability to take 16 analogue inputs as supplied. If that's what you need, buy a ProMix 01. If you want the features of the 168RC, particularly in conjunction with digital sources, and you need 16 analogue inputs as well, you'll need to budget for an 880 A/D.

This mixer breaks so much new ground that it is easy to forgive its few omissions; my only real criticism is the lack of an S/PDIF input — it would have been nice to be able to plug a DAT, CD or S/PDIF‑equipped synth in directly. I think in 1996 all mixers should have more digital inputs than analogue; one day all mixers will, and it's nice to see a new company to mixing being first to reach this important milestone. Of all the automated mixdown systems I have ever used, the 168RC offers the simplest and most glitch‑free operation, and the three Falcon mixes I did while I had the desk are amongst the cleanest and sweetest I ever managed without the help of a qualified engineer. This really is the mixer I have been waiting for all these years.