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Yamaha MC1604

A mixer that is equally at home on the road and in the studio.

Simon Bateson reviews this mixer from Yamaha and finds that first impressions can deceive...

Yamaha are not a completely unknown company in the musical equipment field; in fact they manufacture almost every musical device, (with the possible exception of nose flutes and thumb pianos). Their competence is undoubted, witness the world domination of the DX7, the keyboardist's Stratocaster. Mixers, however, are a slightly different affair. Since mixer technology is quite comprehensible, anyone with a warehouse full of pots and op-amps can make a mixer of sorts. Consequently there are many different brands of mixer on the market, of which Yamaha is just one. So regardless of the name, the purchaser's choice lies in merits of the individual mixer.

Having decided on such basics as number of input and output channels, price limitations and so on, one has three main areas to examine and approve before making a purchase.

Firstly, facilities are a matter of taste and intended area of application. Models typically vary in routing facilites, in the number of auxiliary busses (can you have too many?), in channel monitoring and muting controls and in EQ design. A good compromise avoids costly and unhelpful complexity without imposing frustrating limitations.

Secondly, anyone can make a mixer, but good technical design is a little less common. Excess input noise, unnecessary earthing problems, outputs which cannot drive long cables without losing treble or oscillating wildly, nasty EQ sections...

Thirdly, general style, construction and ergonomics are essential qualities. Is the mixer comfortable to work with? Do the controls fall to hand easily? Your first encounter with a good mixer should be easy.

The Yamaha MC1604 is one of a range of economical mixers, also available in 12- and 24-channel versions. Although primarily designed as a PA mixer, it has much to offer the home or rehearsal studio as well. So, to coin a phrase, wossit like?

"It's a capable PA desk for those heady occasions when you venture on stage."

Channel Format

Starting from the top, (and where better?) each channel has a balanced input preamplifier, which is normally fed from an XLR connector (pin 2 hot, as with most European and Japanese equipment). The input impedance is 8K here (4K unbalanced); plugging in a balanced or unbalanced jack disconnects the XLR and associated shunt resistors to give the same input sensitivity at 20K impedance (10K unbalanced). A switchable 20dB pad follows to lower the basic input sensitivity from —60dB (0.775mV) to -40dB (7.75mV). These are for 'rated' output which I will confuse you with later. Flat out with all hands on deck the mixer will give its all for 0.195mV input, which is enough. Naturally you will want to put more than this in occasionally, hence the 'Gain' control. This provides a further 40dB of control and is scaled from -20 to -60dB. The scale should really be entitled 'Sensitivity', but anyone who has wondered about the completely arbitrary labelling of guitar amp 'Hi' and 'Lo' inputs will feel quite at home. Anyway, what all this means is that you have balanced, low noise inputs which will accept sources ranging from little to large (-20dB, 7.75V before clipping) with the minimum of switching and fiddling. For recording purposes, the lack of a 'Mic/Line' or 'Remix' switch might be inconvenient but a patchbay would solve this, (and you should really have a patchbay anyway). Input gain adjustment is guided by an LED which turns on 3dB before clipping occurs. That's plain silly, because the mixer standard internal operating level of 300mV gives a wonderful 30dB overload margin, yet if set up so the LED flashes quite frequently, which we all like to see ('Oh yes there's some input there') the channel gain is certainly too high. Turning on 10dB before clipping is more like it. At least the indicator is post-EQ, so it will indicate the genuine operating limit.

The channel insert point follows the pre-amplifier. The nominal send and return level here is -10dB, suitable for the majority of affordable or semi-professional effects including pedals.

Next in line electronically, comes the EQ facility.

The EQ section must be the thorn in the side of mixer designers. It never quite does everything you want, however many knobs you are burdened with. This mixer carries the common compromise of fixed treble and bass controls, called 'High' and 'Low' with a sweep mid-range ('Mid Freq'). Treble and bass I have so called because they are like wide ranging hi-fi tone controls, providing up to 15dB of boost or cut at 100Hz and 10kHz. The frequency response graphs provided disagree slightly with the figures, showing a more honest (and sensible) HF limitation of +13dB which slopes off above 20kHz. As you may have guessed, you cannot make a bass guitar deep but not boomy, nor give vocals presence without feedback, but find me an economic EQ where you can! The midrange control can be centred anywhere between 350Hz and 5kHz, and is not too peaky but pleasantly smooth. One feature I particularly liked was that the centre frequency knob was half the size of the others. Consoles with indistinguishable controls make me seethe! My only regret about the mid control was that it would not sweep down to the 150-250Hz 'boom' region.

Four auxiliary sends are provided on each channel and that's luxury! These are arranged as FB1 and 2 and Echo 1 and 2, and are post-insert, (pre-EQ) and postfader, respectively. Internal links are provided to modify the auxiliaries as required (for instance, making FB1 and 2 post-EQ) but modifications should be arranged through a dealer since they're not obvious. The four controls are half-sized like the mid frequency knob and arranged in a square. They are a little cramped but this is a small price to pay for the versatility of four auxiliary channels. In a studio you can set up complex yet easy effects patches, and live you can have two effects and two different foldback monitor mixes.

"...this mixer provides ample facilities and quality performance, at an affordable price."

Just below lies the Pan control, which performs the usual function, albeit with a dual pot to give an approach to consistent loudness while panning. Next come the channel control switches which, like all the others, are dinky oblong plastic bi-coloured buttons like Liquorice Allsorts. The top colour differs for each function, while the lower white section disappears when the button is in, making a simple and effective status indicator. These buttons seem to be the latest Japanese fashion and a practical one at that. First in line come the group assignment switches which send the fader output to groups 1-2 and 3-4 respectively. You cannot send direct to the stereo master outputs: a silly omission for the price of a switch. The next button is marked 'Cue', meaning Pre-Fade Listen. This routes the channel output (post-EQ) to the mono cue buss and is a simple additive system. Lastly the red-topped 'On' button is a channel mute. This is sensibly designed to mute both the post- and pre-fade outputs, preventing mysterious echoed signals from supposedly unused inputs. Not all is muted however, for the insert output is still available.

Light, long-throw (100mm) faders are fitted. These are graduated in dB, and the graduations are accurate! I found it quite pleasing to be able to adjust levels precisely. Interestingly, Yamaha are trying to foster good mixing practice by setting standard channel gain marks at -6dB (about 80% up), ie. not with the fader full up so you can't turn things up quickly. Next in the signal's perilous journey we have the groups.


All signals must pass through one or more of the four group sections. These are simple but useful. In each group, the bussed input channel signals are mixed and amplified to the internal operating level of -10dB and sent to the group insert socket. This is so you can put the entire drum kit through a Kay fuzz pedal (or perhaps something less tasteful). On returning, the signal goes two ways. Firstly, via the 'Group Out' control, it passes to a balanced line amplifier and emerges at a nominal level of +4dB from the appropriate 'Group Out' XLR connector. Secondly, through the group fader and 'Group Pan' control, it is sent to the stereo master channels. The group control switches include 'Group On' which is post-insert but turns off both outputs; and the 'Cue' button for headphone monitoring. The home straight comprises two red master faders, each with 'On' and 'Cue' (prefader) buttons. As with the groups, balanced outputs appear at +4dB on XLRs.

Auxiliary Channel Controls

Above the left master channel controls are all four auxiliary send masters, each with a 'Cue' button. With the masters at 8 on a 0-10 scale, the outputs are nominally +4dB, unbalanced. Echo returns 1 and 2 are provided, above groups 1 and 2 respectively. The standard input level here is +4dB, although the maximum sensitivity, with the input controls and group faders full up is -8dB (echo returns appear on groups 1 and 2). I would have liked a higher sensitivity here, since many digital delays operate at -10dB. A 'Cue' button lies below each return control, while above is a pan control (1, 3, L and 2, 4, R) and assignment switches for 1-2, 3-4 and Stereo, just like all the input channels should have had.

The only remaining input is a talkback system, fitted above the right stereo master. An unbalanced XLR input for low impedance mics works in conjunction with an 'Input Level' control, a 'Talkback' master on/off switch and six routing buttons, 1, 2, 3, 4, FB, Stereo. These six buttons are cleverly placed next to the headphone controls so as to look like monitor switches but actually define the destination of the talkback. This is very useful, enabling the engineer to hurl selective abuse. The master button enables one to mute more penetrating comments.

"The input devices are evidently special low-noise types, and practical tests with dynamic and ribbon mics gave very acceptable results."

Metering and Monitoring

Metering is straightforward, with six large illuminated R45 style meters. These are supplemented by LEDs which light regularly to indicate +8dB peaks and remind you how misleading VU meters are. Two serve the stereo outputs, displaying 0VU for +4dB out, while the other four display the post-fader group levels. Two small slide switches by the meters alter their functions to read the post-auxiliary master signals. Left to right, the meters then show FB1, FB2, Echo1, Echo2 output levels respectively. No direct channel or cue metering is provided, but then it's not really essential with channel peak indicators.

The monitoring system I did find irritating in some ways. As mentioned above, all the cue buttons are latching types and the monitor signal is a simple mix of whatever buttons are pushed in, with no priority. Consequently, if you're listening to the stereo output channels using the stereo cue buttons (the only ones to give left/right, rather than mono, headphone signals) and wish to check another channel, then you must select the appropriate channel cue button and switch off both stereo cue buttons, or otherwise you will end up hearing the lot. Correct operation is just adopting a habit. The designer's justification would lie in the economy of the system, I imagine.

So, that's what it's got. How well does it work?


Three essentials in a good mixer are wide dynamic range, good sound quality and the ability to perform in the real world, (ie connected to myriad horrible high-capacitance cables). Yamaha quote an impressive -128dB input noise, with a realistic 150 ohm source impedance (I make that 0.31μV equivalent input noise), but if you follow the asterisk you find it is quoted for a 12.7kHz bandwidth. Now, knowing that noise goes away if you turn the treble down, this might sound like cheating. However, noise measurement is often done according to the 'A' weighting filter curve, which is a method of assessing noise according to its apparent loudness. (You can hear quiet midrange noise much better than high frequency hiss.) Measurement over a 12.7kHz bandwidth gives a figure approximately equal to the 'A' weighted figure. I don't know why they bothered though, because the full bandwidth noise figure is only 2dB worse, and that beats the majority of affordable mixers. I measured -124dB equivalent input noise from one channel to a group output. The input devices are evidently special low-noise types, and practical tests with dynamic and ribbon mics gave very acceptable results.

Dynamic range is the difference between the noise floor and clipping, and by adopting -20dB as the internal operating level, this mixer has 30dB (31.6x) overload margin (bearing in mind my comments about the channel 'peak' LEDS). This is sensible and makes operation relatively uncritical. Sound quality (beyond distortion measurement) is best judged with ears and a good monitoring system, so I sat down with music and a bypass switch. Taking the longest route, that is from channel input to stereo output, the signal emerged surprisingly unmangled. In hi-fi magazine terms the sound was more confused and less airy at the high end but this was only just detectable by direct comparison. The headphone output was almost as good, which is important for untiring monitoring. My last workshop test was to connect lots of assorted open cables and 22n capacitors to the outputs and inputs to try and incite oscillation but, beyond some loss of treble, nothing happened at all. How boring.

Construction and Ergonomics

This is principally a PA mixer, and thankfully is relatively portable whilst remaining solid. This is due to extensive use of a lightweight yet sturdy natural material they call 'wood'. The whole base is made from 1" chamfered plywood, the sides from 3/4" veneered board. Two recesses are cut into the base under each side which makes it very easy for two people to carry, although one can manage all but the 24-channel version unaided. Front panel construction is semi-modular, with input channels removable in groups of four and the remaining sections on another module. The power supply, a large and liberally rated device with five regulators, is integral but causes no detectable hum. Service access, for instance to replace modules or meter lamps, is simple; more major circuit repair less so.

With the miniaturisation available in modern components, mixer size is really a compromise between the operator's arm length and finger size. In general this product is well proportioned. The pots feel sturdy and reliable (although this doesn't always follow; the most reliable pots I have used are conductive plastic types which always feel ready to fall to bits) but are a bit stiff. In contrast, the buttons are very light, which is unfortunate because they are easy to operate accidentally. No 'scribble strip' as such is provided although an area is marked above each fader for labelling. This is better than scrawling all over the thing anyway. Paper masking tape is a useful medium here. Overall the presentation is clear and self-explanatory with the possible exception of the monitor system, and of course the high quality of finish is what one expects from Yamaha.

Conclusions — What Price Two Functions?

You might pass this mixer over in a shop. It has too few output groups to be a 'real' multitrack mixer. It looks nice but not outstanding. But in a 4-or 8-track studio (routed via a patchbay), this mixer provides ample facilities and quality performance, at an affordable price. For instance, the 1204 and a new or used 4-track will give you sound quality and versatility that cassette multitracks simply cannot match. Furthermore, it's a capable PA desk for those heady occasions when you venture on stage. This mixer warrants attention.

The Yamaha MC1604 costs £1685.00 including VAT. Further information is available from: Yamaha Kemble, (Contact Details).

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At Home in the Studio

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The Scintillator Strikes Back

Home & Studio Recording - Copyright: Music Maker Publications (UK), Future Publishing.


Home & Studio Recording - Feb 1986

Donated & scanned by: Mike Gorman

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Mixer > Yamaha > MC1604

Review by Simon Bateson

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