Soundcraft 6000 Mixer
The Ideal 24-track Partner?
It may not be a new product, but recent events in the world of 24-track recording look like giving the Soundcraft 6000 console a newfound popularity. David Mellor investigates.
Once upon a time, 24-track recording used to be the province of two types of studio owners: those with plenty of money to buy a new Studer, Otari or similar, and those with the sense of adventure necessary to grapple with the ups and downs of a secondhand machine. Out of all studio equipment, it is absolutely essential for the multitrack to be reliable. If the mixing console develops a fault, chances are that it is isolated to one module and you can take it out and carry on running. But if the 24-track goes down, it's more likely to be something major like the transport mechanism itself. Not having a working multitrack recorder obviously equates to no income for the studio, in hard business terms.
The arrival of Tascam's MSR24 24-track recorder [reviewed SOS January '90] has changed all this. Now it is possible to have a new 24-track for the price of a modest car. If you can run to this, 24-track operation is now an entirely practicable proposition, and I would estimate that there are a large number of people on the verge of taking the plunge right now.
Since the Tascam MSR24 is, in multitrack recorder terms, so cost-effective ('cheap' is not the right word), it needs to be partnered with a similarly cost-effective mixing console. Although there are by now quite a number of consoles suited to 16-track working on the market, affordable 24-track compatible consoles are as yet a bit thin on the ground. Price-wise, the Soundcraft 6000 seems close to being an ideal partner for the Tascam machine, all that remains is to investigate a little further to see whether it matches up in terms of facilities and performance.
The Soundcraft 6000 has a nicely conventional presentation in the 'split' - as opposed to 'in-line' - monitoring configuration. By 'conventional', notice that I don't mean 'old-fashioned'. I just mean that the console has all the facilities you would expect, in the places you would expect, and no 'designer's conceit' functions that in some consoles only hinder the process of music making. If you have had any experience of a couple of other consoles, learning the operation of the Soundcraft 6000 would take all of about five minutes - it's that sensible and straightforward. Let's explore the features...
Going straight into the input module, the first thing to notice is that the module seems to be a bit on the short side, as consoles go. Is there a bit missing? Well of course there isn't; Soundcraft have packed everything in tightly and have still managed to use full-size knobs. Although engineers with short arms will appreciate the 'reachability' of the controls (and to many people this is not a trivial matter), as we shall see this leads to a couple of drawbacks. But starting at the top, let's look at the input module bit by bit and see what the 6000 has to offer.
The Gain control offers a range from 2dB to 70dB mic gain and -10dB to 20dB line gain. Soundcraft are rather pleased with their mic amp design, which does away with the need for an attenuation pad to cope with high level signals from bass drums and the like. The mic amp is electronically balanced and Soundcraft claim a good CMRR (Common Mode Rejection Ratio - a measure of the amp's ability to sort out the signal from the interference) down to 100Hz. Turning to the line input, it is a relief to find that Soundcraft have not joined other manufacturers in doing without control over gain. Not only does a variable line gain allow matching to various odd types of equipment, it also lets you work the fader at a convenient level, especially with signals that you want to keep fairly quiet. The line input here uses part of the same circuitry as the mic input stage, but it is an honest-to-goodness line input in its own right - unlike the dodgy and still evident practice of simply attenuating the line signal and feeding it to the mic amp.
Before I leave the input stage, let me mention the switchable Phantom power on each channel. I have never been convinced that a switch is necessary if you stick to the right types of microphone and DI boxes, but it's here if you need it, as is a Phase Reverse button.
Equalisation is one of Soundcraft's strong points. The EQ section provided here is obviously not on the same level of complexity as you would find on an SSL or Neve console, but what it does it does well. A 'musical' EQ you might say. Not strictly part of the EQ section (ie. it functions even when the EQ is switched out) is a 100Hz filter with a 12dB/octave characteristic. Ostensibly, this is for removing the low frequency rumble that our ears ignore but mics pick up very well indeed, or for rolling off the bass boost which occurs when a directional mic is used close to the sound source. This filter is also very useful - more useful? - in conjunction with the LF EQ control. Adding level at low frequencies often adds too much very deep bass content which, far from having the 'gut wrenching' effect desired, just makes the track sound murky and ponderous. A simple click of the Filter switch lets you have all the bass boost you want, without these problems.
The actual curves of the LF and HF EQ controls are shown in Figure 1. As you can see, they have a shelving characteristic, meaning that the boost reaches a maximum and stays there, rather than continuing on up, or rolling off again. These curves, plotted at maximum cut and boost, show that both the LF and HF controls affect every frequency on the appropriate side of about 750Hz. This is particularly noticeable in the HF, where you can clearly hear the effect the control is having on the high midrange frequency band, when perhaps you only wanted to adjust the highs. I would have preferred an extra switch to control the frequency at which the HF control begins to bite, but of course this would cost extra, and what Soundcraft have provided is done well.
"Equalisation is one of Soundcraft's strong points."
Figure 2 shows the effect of the low - mid EQ control (there is also a high mid which works in the same way). The scale is more compressed than in Figure 1 but, if you work it out, you can see that there is a full 15 decibels' worth of cut and boost available with a 'Q' (at maximum boost) of 1.5. The frequency ranges of the low mid and high mid controls are, respectively, 150Hz to 2400Hz and 600Hz to 10kHz, giving a useful degree of overlap.
One interesting point about the design of the 6000 console is that Soundcraft have paid attention to the quality of the earthing. Earth is, in electronic circuitry, used as a zero voltage reference and a place to get rid of unwanted currents. In practice, these unwanted currents can pop up again just where they're not wanted. However, when the EQ section is switched out of circuit, the actual signal input to the EQ is also removed. This helps to minimise the generation of unwanted currents in the earthing system of the console.
Six auxiliary sends are provided - with options. Aux 1 and Aux 2 are switchable, as a pair, to either prefade or postfade. There is also an internal jumper to allow the prefade selection to be pre or post EQ, depending on what arrangement is most popular in your studio. Aux 3 and Aux 4, similarly, are switchable between prefade and postfade but there is no pre/post EQ jumper for these. Auxiliaries 5 and 6 are set permanently to postfade operation. The only drawback I can see here concerns the paired nature of the switching. It is always much nicer to have complete freedom of pre/post switching on individual auxiliaries, but once again cost rears its ugly head - and if I can't afford SSL prices, then I'd rather compromise on facilities than on sonic performance. Incidentally, there is a slight confusion in the legending of Auxes 5 and 6. There is a white line drawn from the 'Aux 6' label to both the knob below (which is Aux 6), and the knob above (which is not). Strange.
Another of Soundcraft's strong points is their panpot design. There's not much to a panpot, you might think, but there may be more than meets the eye. As on many consoles, the routing switches select pairs of buses and the panpot is used to send the signal either to the odd-numbered or even-numbered bus. This implies that unless the isolation of the panpot from the unselected bus is very good, there will be crosstalk between the buses. Crosstalk can be defined as 'the unwanted contamination of a wanted signal by an unwanted signal', just like your flower bed gets contaminated with weeds. It can be a major problem, so let me give you an example: Suppose you are recording several instruments simultaneously onto the multitrack recorder and you have the guitar and bass parts on adjacent tracks. Later on, you decide that the guitar part wasn't up to scratch after all and decide to remove it from the mix. Unfortunately, crosstalk has allowed it to seep into the bass track and there is now no way of killing the guitar without also getting rid of the bass.
There are many ways in which one track can spill into another, but crosstalk in the mixing desk is something that should be dealt with by the manufacturer, leaving the engineer to get on with his task more freely. Soundcraft's pan control is simple, component-wise, but they claim an isolation of greater than 90dB, which is very good by any standards. They also claim that the law of the control more closely approximates the ideal, giving a smooth pan across the stereo image. The centre drop of the panpot is 4.5dB, which is a compromise between the ideal 6dB for correct mono summing and 3dB for constant level in stereo.
The switching arrangements of the input module are a definite source of interest on the Soundcraft 6000. The 'On' switch uses FETs (Field Effect Transistors) to fade the signal rapidly up and down rather than abruptly cutting it in and out. The benefit of this is that there is less likely to be a click generated. In practice, there is a slight click, but you would have to have the monitors pretty high to hear it. FETs, being electronically rather than mechanically controlled, make other things possible. One possibility is a mute bus, which allows the engineer to assign any number of channels to a master mute switch, making instantaneous channel muting right across the console possible - good for clever tricks during mixing. (Just one note to Soundcraft: two mute buses are more than twice as good as one, but thanks for this one anyway.)
The other interesting facility is solo in place (SIP). This is a great function when you can get it in the recording studio (but don't allow it within a mile of any live work!). Conventional PFL (Pre Fade Listen) is provided, but a master switch converts the entire console to SIP operation. Briefly, what happens is that when you PFL a channel, that channel is routed directly to the monitors leaving the mix unaffected. When you SIP a channel, all the other channels are muted, letting you hear that one alone but completely disrupting the mix! The benefit is that in the 6000 you can set internal jumpers to a 'solo safe' position, which means that they won't be muted during a SIP operation. This would typically be done on any channels used for effects returns. The upshot of this is that when you SIP a channel you hear that channel with its correct fader and pan settings, together with any effects applied, and it's possible to flick back to PFL in a moment if you need to. Very nice.
Moving down to the fader, we find what I think is the 6000's worst feature - the positioning of the routing switches next to the fader. Obviously this saves space, but many engineers would agree that the fader is best situated centrally in the channel module and the surrounding space left uncluttered. The principal drawbacks of the Soundcraft implementation, apart from the congestion caused, are twofold. Firstly, the routing switches are so small and tightly packed to fit into the available space that you have to operate them with your fingernail; using the pad of the finger will as likely as not push down two buttons. Secondly, space is very limited for marking the fader position with a Chinagraph (which, to be absolutely fair, not every engineer does). Still, in other respects the 6000 has such a lot going for it that these points will not make the difference between a sale and no sale, but it isn't a direction console manufacturers ought to pursue.
To complete the input module, let me mention the peak LED, with detector circuitry positioned sensibly post EQ, which illuminates when the channel is within 8dB of clipping. Essential and effective.
"Soundcraft's pan control is simple, component-wise, but they claim an isolation of greater than 90dB, which is very good by any standards."
Moving to the right along the console, we come to the output module. On a 24-track bus version, you would expect to see 12 of these, each with two group faders and two monitor sections.
Starting with the group faders, the problem of lack of space for markings crops up again. If anything, the inclusion of two faders in a module the same width as an input module makes the congestion worse. But as I said, if I wanted the console for the other things it can do, I would be prepared to accept this. Group output metering uses 20-segment LED bargraphs with green, yellow, and red colour-coding.
Moving up to the monitor sections, which are also useful as extra inputs during the mix, the topmost button is the Group/Tape switch, selecting either the group output or tape return to be the monitor source. There is a small but useful EQ section which the engineer, if he is sufficiently bold, may allow the producer to play with. HF and LF controls are provided, having a similar effect to the controls on the input module. There are two Aux sends, feeding Auxes 1 and 2, prefade or postfade. 'Postfade', in this sense, means after the monitor volume control. A Pan control is of course present, as is an On switch. Solo In Place is not provided on the monitors, probably because it isn't quite as applicable here. PFL only is available.
Subgroups being as handy as they are, it's not surprising that there is a Subgroup switch included here. This one little switch actually does such a lot, it's surprising it isn't stiffer to press. When Sub is selected, the output from the group fader passes through the panpot to the stereo mix bus, via the monitor section panpot - but not through the monitor volume control, as happens on some consoles. At the same time, the monitor section becomes an extra input to the group, its level being set by the monitor volume control, like a dedicated auxiliary return for just that one subgroup. Subgroup switching is an area where operator confusion can quite easily creep in, particularly as an engineer often has to be able to learn to work an unfamiliar console at very short notice. On the Soundcraft 6000, subgroup switching is nice and simple and straightforward, just as it should be.
The master module is twice the width of the others, and keeps facilities down to a sensible minimum. The six auxiliary masters are located here, with AFL (After Fade Listen) soloing. An oscillator provides 700Hz and 10kHz tones (but why no low frequency tone?) to all groups and auxiliaries but not to the mix output(?!). Internal jumpers allow the oscillator, and talkback, to be removed from Auxes 1 and 2 and/or from Auxes 3 and 4. It's a pity that the oscillator and talkback are linked in this way, because while you are very unlikely to want tone to go to headphone foldback, you are very likely to want to be able to talk to musicians over cans. When the oscillator is not in use it is disabled, meaning that tone cannot leak anywhere it isn't wanted. Talkback is routed in a similar fashion to the oscillator and has an associated internal mic, on/off switch, and level control.
There are two outputs available for routing to monitor amp and speakers, for both the control room and studio (only one monitoring system for the control room, unfortunately). Monitor sources are four in number: mix, 2-track A, 2-track B, and 2-track C. There is a Dim button for the control room and that important Mono switch. Headphone listening overrides the control room output and employs circuitry which is sensitive to the impedance of the headphones in use, keeping the level fairly constant. Also on this module are the Solo In Place and Mute master switches. Metering is via VU meters with peak LEDs.
The Soundcraft 6000 is a solid workmanlike console with a few minor drawbacks. Certainly these drawbacks are not going to compromise the quality of the results obtainable, but fall more under the category of 'niggles'. One point I have saved until now will emphasise just how suitable the Soundcraft console is for use with Tascam's new 'budget' 24-track recorder - that is, the liberal provision of internal jumpers to set various combinations of inputs and outputs to match Tascam's -10dBV operating level. These include the monitor inputs and outputs, mix outputs, all of the stereo tape returns or just Return C - a useful combination. Furthermore, there should be no problems nor compromises working at Tascam's chosen operating level.
Would-be 24-track studio owners would do very well indeed to check out the Soundcraft 6000, because even if it isn't the newest, flashiest, most feature-laden console in existence, it is ready for hard work and is very easy to operate.
Many thanks to Marco Perry at The Beat Farm for allowing us to use his studio and Soundcraft console for this review.
"...the inclusion of two faders in a module the same width as an input module makes the congestion worse."
Soundcraft Electronics Ltd, (Contact Details).
Review by David Mellor
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