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Yamaha RM602 Mixer

Brother to the MT44D multitrack recorder, this little mixer has stood the test of time.

Though we have looked briefly at the RM602 mixer as part of a package including the MT-44D recorder, it stands up well in its own right.

Yamaha's RM602 mixer is no newcomer. It's about a year old and exists in a market where the competition is becoming increasingly fierce. Manufacturers of equipment in any field learn a lot from the successes and failures of their counterparts. In relatively new fields such as the booming budget end of the recording industry, new ground is being trodden and the pioneers have to make their decisions based as much on prediction as on experience. Has Yamaha's undoubted experience in the music and audio industry helped it to predict successfully for the RM602? A year should be a long enough period to tell in a market which is growing as rapidly as this one.

The RM602 did, in fact, have a predecessor whose weaker areas of performance could be learned from and avoided during the design stages of the new model.

What's it Got?

The RM602 is a 6:2 mixer with the facility to route to and from a 4-track tape deck. It's small and light, measuring 340mm x 73mm x 325mm and weighing 3.2kg, but robust enough to survive being carted around for mobile work. It sports six inputs, effects send and stereo effects return, RIAA equalised phono inputs for a record deck, four tape ins and outs, stereo auxiliary inputs, stereo outputs both jack and phono, stereo inserts and stereo monitor outputs. 2-band EQ of the shelving type is provided together with switching facilities for routing input signals to tape tracks. LED bar graph type metering is also provided on the stereo outputs.

What it Does

The six inputs are all unbalanced standard jack connections. The first bit of circuitry encountered is the input level selector switch. Four positions are available offering -50, -35 and -20dB input levels with the fourth position designated Tape. The input levels correspond generally to mics, guitars and keyboards respectively with the -20 position being used for any nominal line level signals. The Tape position (on channels 1 to 4) routes the respective tape input into the channel concerned.

On channels 5 and 6 the Tape position is replaced by a Phono setting. In this position channels 5 and 6 will accept inputs directly from a stereo record deck cartridge.

The EQ on each of the six input channels is of the shelving type. It is 2-band operating at 10kHz and 100Hz and offers 15dB cut or boost at each frequency. The effects send buss operates in the usual manner with a send pot for each channel, the overall output level being governed by a master effects send control. A nice touch here is the provision of stereo effects returns. This takes the form of a pair of mono jack sockets one of which is summed to mono if used on its own. A dual ganged pot is then used for control of the overall effects return level.

"...the additional ins and outs make it surprisingly versatile."

Following the effects send pots on the input channels are the monitor sections. These are stereo consisting of a level and a pan control together with a tape/post selector switch on channels 1 to 4. The labelling is not quite as clear as it might be here. Basically this switch selects whether the signal to the monitor buss is derived from the tape input or the channel input. The signal is taken pre-fade in the Tape position and obviously post-fade in the Post position. It would have been more straightforward to label it Input/Tape to make it more obvious as to exactly what is being monitored. It is also not the norm to have post-fade monitoring, however, this can offer some operational advantages as we shall see later. The monitor switches on channels 5 and 6 select between post (post-fade input signal) and either the left or right stereo busses respectively. This arrangement allows for easy monitoring directly from the main stereo buss.

Below the monitor sections are the pan controls followed by the channel faders, all of which operate in the accepted fashion and require no explanation. Not so, however, the tape out switching which does require a little delving into.

The switches themselves are a pair of 3-position slide switches situated one above the other and operating horizontally. With each switch in its centre position input channels 1 to 4 are routed to tape outs 1 to 4 respectively. However, moving the top switch to the left will route anything on the left stereo buss to tape out 1. Moving it to the right will route anything on the same left stereo buss to tape out 3. Similarly when the lower switch is pushed to the left anything on the right hand position signals on that buss routed to tape out 4. This may sound a little confusing on paper but works surprisingly well in practice. For instance, bouncing tracks 1, 2 and 3 onto 4 would involve sliding the lower switch to the right and panning channels 1, 2 and 3 to the right. Using the stereo buss in this way allows channels 5 and 6 to be used to add extra inputs during the bounce. It also allows the input channels to be mixed down to stereo on the recorder connected to the tape out sockets.

Below the tape out switches are the auxiliary in and master monitor pots, both of which are conventional dual gauged rotary, and below these are the master left and right faders. These have the same 45mm travel as the channel faders and are also felt lined to help deter dust and hence lengthen fader life. Apart from the power switch and a conveniently positioned (right hand, front edge) stereo headphone socket, the only remaining item on the unit is the metering. This dual, tri-colour 13-segment LED bar graph meter indicates the signal levels leaving the mixer. It is placed after the stereo insert points so that it gives a true representation of the levels leaving the mixer regardless of whatever device is patched into the insert points. This does mean though that it's important to remain aware of probable internal signal levels which may vary from those shown on the meter whilst an external signal processor is patched in. This point is made all the more important due to the fact that there are no other level metering devices on the mixer. Peak level indicators on the input channels would have been welcome in this respect.

How they do it

Returning to the top, the input stages of budget mixers can often be the source of unwanted noise. This becomes most noticeable when using low level inputs such as dynamic microphones. Tests with the RM602 showed that there should be no problem here given the close-miking techniques most often used in multitrack recordings. For PA work, noise level is never so critical so no problems here either. The record deck inputs on channels 5 and 6 give a clean input direct from a turntable cartridge and are a great asset for anyone with a need for dubbing from disc.

One aspect I was not too keen about with regard to the input stage was the switchable input gain. This doesn't allow a variable enough adjustment of the input signals in order that the faders may be lined up to give a visual representation of the audible levels. It also makes it difficult to optimise signal to noise levels through the mixer. This is a compromise often seen on budget mixers and can be overcome to a large extent by adjusting the input level at the source where this is possible. However, the advice that Yamaha give in their brochure suggesting that microphone input levels should be adjusted by altering the distance of the microphone to the sound source is not, I think, to be followed to the letter!

"I feel the stereo monitoring to be something of a luxury and I would have preferred to see in its place continuously variable input gain controls rather than switches to allow easier optimisation of levels."

The EQ section is about as standard as you will find and the chosen frequencies of operation are suitable for the usual corrective jobs of reducing hiss and rumble or increasing brightness and weight. It's often a good idea with small scale multitrack to increase the top slightly on recording thus allowing the option of reducing it again during mix-down to achieve a primitive form of noise reduction. The shelving actions of this form of EQ lends itself well to this technique.

The only disadvantage of the effects buss is that there is only one of them. But as mentioned earlier this is the area where the post-fade arrangement of the input channel monitor sections can come into play.

If the output is monitored from one of the two pairs of stereo outputs provided, although it will not allow an independent monitor mix, it will allow for the monitor output to be used as another effects send. In fact because the monitor buss is stereo it's possible to have three almost independent effects sends at your command. There are plenty of places for these sends to be returned using the stereo effects return, the stereo auxiliary in and input channels 5 and 6.

And is it all Worth it?

The RM602 mixer turns out to be surprisingly flexible for its size. The options available would make it suitable for live sound reinforcement, stage submixing and audio visual work as well as its obvious role as companion to a 4-track recorder. There are a range of units from Yamaha specially designed to work with the RM602 but it will work just as well with almost any make of recorder currently on the market.

The criticisms I have of the RM602 are none too serious, but I think still worth mentioning. This would make my other criticism less important: the length of fader travel. Although the faders provided operate smoothly and quietly, the fact that the input gain is not continuously variable means that the fader positions will often vary to quite an extent thus rendering smooth fades rather tricky. Providing longer faders, however, would be a rather impractical answer. The cost of longer faders, plus the increase in overall case size that would be necessary to accommodate them, would defeat the object of producing economically designed equipment. It is necessary than that care is taken with levels at source to avoid the limited fader travel causing any problems.

"...because the monitor buss is stereo it's possible to have three almost independent effects sends at your command."

The comprehensive spec, block and level diagrams given in the operating manual make interesting reading for a reviewer, however, I think some of the space may have been better taken up by providing some practical tips for the prospective RM602 purchaser. Some areas of the mixer's operation are painted a little roughly and a typical RM602 purchaser would, I expect, be more interested in tips than figures.

...and Finally

Having go the gripes over, I think this mixer is a neat little piece of equipment. I've tested the RM602 over a period of some months (apologies to Yamaha) and during that time I have used it quite successfully on one or two pieces of work. Its routing system works well and the additional ins and outs make it surprisingly versatile.

At a price of £249, anyone buying this mixer today should be just as pleased with it as someone who purchased one when they were first introduced over a year ago. That says something for any product existing in a market which develops as rapidly as this one.

The Yamaha RM602 retails for £249 including VAT.

For further details contact: Yamaha, (Contact Details).

Also featuring gear in this article

Previous Article in this issue

Fader-Panner Project

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APRS 1986

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


Home & Studio Recording - Jun 1986

Donated & scanned by: Mike Gorman

Gear in this article:

Mixer > Yamaha > RM602

Review by Martin Sheehan

Previous article in this issue:

> Fader-Panner Project

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> APRS 1986

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