Mackie 1604, DOD 1642 Mixers
Mackie's 1604 mixer head to head with DOD's compact 1642. The result may surprise you.
When it comes to producing high quality at a realistic cost, Paul White finds the American mixer manufacturers right on the ball...
From time to time, manufacturers obviously feel in need of a bandwagon to jump on, and one of the current favourites is the compact, rackmount mixer. There's nothing new about rackmount mixers as such, but it seems that ever since Mackie Designs started to capture the imagination with their 'cuddly but powerful' little mixers, other manufacturers have started to turn out products along similar lines.
No two mixers ever offer exactly the same facilities, but I think you'll agree that the two reviewed here invite comparison in several key areas. Both are compact, have sufficient gain range to work at either the pro +4dBm or -10dBv operating levels and both are suitable for a variety of live sound, home recording and MIDI studio applications. And both boast a technical specification to rival many pro studio desks. Don't be fooled by the compact format — these are most definitely not toys!
DOD's 1642 is both simple and flexible, yet it is surprisingly small when you consider its complement of features. It is powered from a fairly substantial, external regulated power supply, which is fine for fixed installations but an unnecessary complication when working live. Ruggedly constructed from sheet steel, the mixer comes with rackmount ears fitted, but for desktop use, these may easily be removed by taking out a few cross-head screws. All the connections are located on the back panel, with the exception of the phones outlet and a 12v BNC connector which can be used to power a small light. Apart from the mic inputs, which are standard XLRs, all other audio connections are made by means of quarter-inch jacks.
As the title 1642 suggests, this is a 16-channel mixer, though it couldn't really be described as a 16:4:2. The routing arrangement is more like that of the Alesis 1622, where each channel may be routed to a stereo Main output, a stereo Sub output or both. The stereo 'Sub' mix may also be routed into the main stereo mix via buttons on the master section.
As is becoming increasingly common with small mixers, not all the channels are equipped with microphone inputs; in this case, the first eight channels have both mic and line inputs,while the remaining eight are line only. Phantom power may be applied globally by means of a single pushbutton switch located in the master section, and all 16 channels have insert points on stereo jack sockets, as do the Main and Sub stereo outputs.
As stated, only the first eight channels are equipped with microphone inputs, but in all other respects, the 16 channels are identical. The microphone inputs are low impedance and balanced with switchable phantom power which can only be selected globally and not on an individual channel basis. The mic input impedance is 2kohms and the line input impedance is 10kohms.
Unlike most mixers, which tend to use discrete microphone preamps, the DOD 1642 uses the SSM2017 low-noise mic amp chip, which also functions as the line amplifier when the line input is used. The channels not blessed with microphone inputs use a more humble op-amp as the line input amplifier. A single gain control is used to set the mic or line gain, and the gain range is from 10dB to 58dB on channels 1 to 8 and between -20 and 30dB on the line-only channels (9-16).
The equaliser is a straightforward three-band affair with shelving high and low filters, offering plus or minus 15dB of boost at 80kHz and 12.5Hz respectively, plus a fixed frequency mid control giving up to 12dB of cut or boost at 2.5kHz. There is no EQ bypass, but the controls are all centre-detented, making it easy to find the neutral position.
"DOD 1642: The mixer has a useful three-band equaliser on each channel and there are more aux sends than most people can find effects units to plug into them."
The aux send section comprises four controls, the first two being dedicated to aux sends 1 and 2. The remaining two controls can be switched using the Shift button to feed aux busses 3 and 4 or 5 and 6, though they can only be switched together and not independently. As supplied, sends 1 and 2 are set for pre-fade (foldback) operation, while 3 and 4 are post-fade for use as effects sends.
From the circuit diagram, it is evident that internal links may changed to individually select pre or post-fade operation for any of the four controls, though the manual says this should only be attempted by qualified factory personnel. However, it seems a simple matter of making or breaking solder bridges and the locations are shown in the manual.
Interestingly, the aux pots are wired in reverse, a measure intended to reduce mix buss noise. This doesn't affect the control operation as far as the user is concerned, other than introducing a slight degree of non-linearity, but it does help keep the feed to the effects units nice and clean. I first noticed this simple but effective technique in the Mackie Designs mixers, but I believe it is a well-known circuit ploy that has been used before.
A conventional pan pot is used to position the signal between the left and right outputs, and each channel has its own Mute and Solo buttons, as well as routing buttons for the Sub and Main stereo busses. An overload LED is also fitted; this comes on when the signal at the output of the EQ section is in danger of clipping. The channel faders have around 50mm of travel and are fitted with what appear to be hard rubber knobs. All other knobs on the console are made from a similar material, with inset coloured caps and marker lines to show at a glance how each control is set.
The master section includes six master aux level controls complete with peak overload LEDs, and pan pots for the four stereo aux returns. This number of stereo returns is very welcome, but no provision is made for level control — it is assumed that the effects units used will have their own output level controls. Aux returns 1 to 4, like the input channels and the left and right Subs, have solo buttons, the solo'd signal being shown in stereo on the bargraph level meters.
The Sub arrangement itself is quite flexible, in that the left and right Sub busses, known as Sub 1 and Sub 2, can be individually panned when they are fed back into the main stereo mix. Both Sub 1 and 2 have mute and solo buttons as well as individual buttons routing them into the main stereo mix. Because of a lack of panel space, the Sub levels are controlled by rotary controls rather than faders, and a selector switch allows the user to flip the meters between monitoring the main output and the two Subs. The Master level is controlled by two short-throw faders similar to the channel faders.
The phantom power button is accompanied by a yellow status LED, while a further yellow LED below the meters shows that a Solo button is down somewhere on the mixer. There's also a choice between Solo and PFL operation, which is a welcome sophistication on a mixer in this price range. In PFL mode, the desired channel or aux is solo'd in the headphones but the main output remains unchanged — which means you can solo signals during a live concert or while mixing a recording.
In the Solo mode, the solo'd signal is still fed to the phones, but the main output is also affected and the unsolo'd channels/auxes are muted.
The DOD 1622 is a very well engineered and versatile little mixer; the mic inputs are at least as quiet as you'd get from a good, mid-priced studio console, no doubt due in part to the adoption of SSM's mic preamp chips. Throughout the rest of the mixer, the sound quality is generally very good, with minimal noise, negligible hum and no obvious crosstalk, while the high and low EQ controls are smooth and predictable in operation.
The number of aux sends is also welcome — many larger consoles do no better in this area — while it is reassuring to see insert points fitted to the Main and Sub outs as well as to the individual channels. I particularly liked the ability to pan the individual Subs when mixed back into the main stereo mix, but I did find the lack of channel mute LEDs a little disconcerting, as it's easy to lose track of which switch is up and which is down.
Ergonomically, the mixer is compact but not unduly cramped and the knob markings are very clear. All connections are easily accessible and clearly marked, but being around the back, they help keep things tidy. In providing four sets of stereo aux returns and a full complement of insert points, DOD have equipped their little mixer with just about everything you could hope to get on a mixer of this size.
Mackie pioneered this particular mixer concept and DOD are making an unashamed attempt to break into this market — and judging by their final design, they have come up with a worthy contender.
DOD 1642 £999 including VAT.
John Hornby Skewes and Co Ltd, (Contact Details).
In the short time since its introduction, Mackie's little 1604 mixer has attracted an immense amount of interest both in recording musician and pro-audio circles. By combining innovative manufacturing techniques with highly proficient circuit design, the company has managed to produce a rugged, good-sounding console with very few compromises, yet at a surprisingly low cost.
The CR1604 is, essentially a 16-in, 4-out mixer, though only the first six channels are fitted with mic inputs. This is an acceptable compromise for most users, but an additional 10 mic preamps may be added in the form of the XLR10 expander, which employs the same balanced, phantom powered circuitry as the mic inputs in the CR1604.
Powered from an internal power supply rather than by an external adaptor, the mixer may either be rack mounted via the inclusive rack adaptors or used free standing. A novel feature is that the rear part of the mixer which houses all the input and output connections can, with the aid of the optional Rotopod mounting bracket kit, be rotated to put the connections on top rather than in their more usual place at the rear. All casework is constructed from heavy-gauge sheet steel and tastefully finished in grey enamel. For those users wanting more channels, up to three CR1604s can be connected together by means of the optional Mixer Mixer and this has a connection facility for yet another accessory, the Master Fader, which is basically a fader in a box that can control the overall level of the mixed signal coming from the three mixers.
Though the channel topogrophy is fairly conventional, there are a couple of little twists that deserve special attention. Unusually for a mixer of this type, the mic amps are exceptionally well designed and are quieter than those used in many professional multitrack consoles. If the input pod is mounted in its rear-facing position, the input gain control trims are also located on the back panel, which is a little unconventional. The mic amplifiers also have a generous amount of more signal than most other designs without distortion. Signal insert points are provided only for the first eight channels and master outputs, and these may also be used as direct output points by inserting a mono jack halfway into the socket. Phantom power is provided but it may only be applied globally.
The attention to headroom and gain structure is maintained throughout the mixer and, interestingly, the channel faders have a centre 'click' or detent at the unity gain setting, above which is another 20dB of gain rather than the more usual 10dB. This is particularly useful when working with such sources as guitar effects pedals or home keyboards, which tend to be a little short on output level.
Four aux send controls are provided, Aux 1 being switchable between pre-fade (foldback) and post-fade (effects send) operation. If the pre-fade Monitor position is selected, the signal comes out of the Monitor socket on the rear panel, while selecting the post-fade Aux option routes the signal to the Aux 1 output. The remaining three sends are all post-fade, while sends 3 and 4 may be switched as a pair to feed aux busses 5 and 6 — an unusual refinement on such a small desk. There are no master send level controls, so it helps if your effects units have input level controls — which most do. A useful touch is that the aux send pots have a detent at their unity gain position and offer an additional 15dB gain. This means there is enough level to feed budget effects pedals as well as dedicated studio processors. By wiring the aux send pots slightly unconventionally, Mackie have significantly reduced the aux mix buss noise.
The EQ section is a fixed, three-band affair but the frequencies seem well chosen for the majority of applications; the high and low shelving controls provide plus or minus 15dB of gain at 80Hz and 12.5kHz, with the mid offering plus or minus 12dB of control at 2.5kHz. There is no EQ bypass button but the controls are centre-detented, making it easy to set them in neutral.
"Mackie CR1604: Sound quality is excellent; the signal path is exceptionally clean with a very low noise floor, the mic amps being particularly impressive in this respect."
Most pan controls use a single-ganged pot, which doesn't produce an entirely accurate pan characteristic, whereas Mackie have gone for the more professional dual-pot approach, producing a constant overall sound power output from the two speakers, regardless of the pan position.
Interestingly, the routing and muting is handled by a single, dual-function button. This mixer has two sets of output busses — the main Left, Right mix and the Alt(ernative) 3,4 outputs. This is one of the compromises of the format; the mute button doesn't actually mute the channel signal at all, but rather re-routes it to a secondary pair of outputs which have no level controls. Solo buttons are also fitted to the channels, allowing signals to be monitored in isolation in the headphone mix without affecting the main output. This is a true stereo monitor arrangement and also extends to the four stereo aux returns in the master section.
As might be expected from such a straightforward mixer, the master section is pretty basic, but it still manages to offer no fewer than four stereo effects returns, each with their own pan pots and mono buttons. A single Solo button allows all four aux returns to be Solo'd simultaneously, though the way in which the Solo'd signals are presented on the bargraph meters needs a little explanation. In this case, the sum of all the line signal levels is displayed on the right hand meter, while all the mic signals come up on the left hand meter.
The meters themselves are simple 10-LED ladders; directly below them are power and Solo LEDs. It is possible to monitor the Alt output via the headphones simply by pressing the Alt Preview button, while selecting Solo to Main presents the Solo'd signal at the main stereo output as well as on the phones. This is useful for studio applications when setting up a mix. A Mute button allows the main output to be silenced, and the Solo and Phones level is controlled by an independent fader located to the right of the master Left and Right faders. Incidentally, the phones output is very powerful and surprisingly clean.
Some of the features which at first appear quirky, such as the centre-detented faders and aux send controls, are actually quite useful, while the additional gain available is a definite advantage when professional and consumer equipment is used in the same system. At first it may seem remiss to omit insert points from the line inputs, but the reality is that any device that can be connected to an insert point can also be run in series with the input line signal. This isn't true of mic inputs, which is why these have inserts at a point in the circuit path where the mic signal has been boosted up to line level.
The combined routing and muting button is a bit of a compromise but is unlikely to be a problem in practice. When running signals to tape, it is quite possible that all four outputs will be used, but it is unlikely that the mute buttons will be needed at this time. Conversely, when mixing, signals tend to be mixed directly to the stereo buss, in which case the buttons can be used as mutes with no problem.
There's no dedicated facility for using the Alt output as a subgroup; patching the Alt output jacks to either a couple of input channels or one of the stereo aux returns would do the trick, but an 'Alt to Master' button would have been more convenient.
The more you try to outwit this mixer, the more you realise that what appear to be compromises have actually been the subject of a lot of thought — there's nearly always a way to do what you need to do, even though it might not be the most conventional way. The EQ is also very smooth and musical in operation, the slightly non-standard choice of shelving frequencies obviously having paid off.
Both technically and subjectively, the Mackie CR1604 is a good-sounding mixer with a wealth of applications in professional, PA and home-recording circles.
Mackie CR1604 £839; XLR10 expander, £249; Mixer Mixer, £229; Master Fader, £85. Prices include VAT.
Key Audio Systems, (Contact Details).
For those needing a general purpose, compact mixer with exemplary mic inputs, musically useful EQ and lots of aux sends, both the the Mackie 1604 and DOD 1642 are superb choices. Deciding which one to choose is not quite so easy, as there are differences between the facilities offered by the two mixers which may sway the choice one way or the other depending on the requirements of the user. DOD's interpretation of the concept provides slightly more conventional signal routing, insert points on all channels and a more conventional solo system, whereas the Mackie 1604 has an arguably more versatile gain arrangement, the physical layout can be customised using the Rotopod kit, and several mixers can be cascaded using the Mixer Mixer if the need for inputs increases. DOD's mixer has eight mic inputs to the Mackie's two and provides inserts on all the line inputs plus the four main outputs, but the Mackie desk has a significant cost advantage and has the option to expand to a full 16 mic inputs. It also has a slightly better paper specification, especially in terms of audio bandwidth and crosstalk, though in practical tests, both mixers perform exceptionally well.
Review by Paul White
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