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Boss Micro Rack Series

For people with very narrow studios, Boss have introduced a very narrow effects rack... Martin Sheehan investigates.

From the Boss stable comes a complete rack system, comprising a phaser, a flanger, a digital delay, a compressor/limiter/expander and a graphic equaliser.

Arrival of this micro rack series was first heralded at the Frankfurt show earlier this year and they should be in the shops by the time you read this.

The Boss Micro Rack Series represents an alternative to the standard 19" rack mountable effects in that, although they are still 1U (1¾") in height, they are only 8½" wide. An RAD10 rack-mount adapter is available which enables any pair of units to be mounted in a standard 19" rack. Each unit requires a 9V DC supply which, it is recommended, be derived from the Boss PSA series AC adapter.

RPH10 Phaser

The RPH10 is a 12 stage phaser offering three basic modes of operation. The mode switch will select either 6, 10 or all 12 stages of phasing, which gives a progressively deeper effect by producing more notches in the frequency spectrum. The feedback control will further strengthen these sounds by tapping off some of the effect and feeding them back into the input, thus giving a pseudo-flange effect. The standard sort of modulation section is provided, offering Rate, Depth and a Manual control. The rate of modulation can be varied from 100 milliseconds up to 14 seconds which enables everything from a fast wobble to slow swoosh to be generated. By setting the depth to minimum the modulation sweep can be performed manually by (believe it or not) the manual control. This is a good way to apply effects such as the commonly heard timed sweep on a cymbal crash over the end of a bar. The manual control also adjusts the centre frequency over which the phasing operates when the depth control is set below its maximum position.

In common with the rest of this series of units there is a power on/off switch and an effect on/off switch, each with an associated rectangular LED indicator situated at opposite ends of the front panel. Although these look very smart, they also look very similar and it would be a shame to hit the wrong one just as you reach the climax of your master-work. One way to avoid this possible calamity, however, is to make use of the standard ¼" jack effect on/off footswitch socket provided on the back panel. Electronic switching is used here to avoid any pops and bangs.

Input and output connections - on all this range of units are duplicated on both standard jack and phono sockets. With the profusion of both types in the home studio industry, I'm always pleased to see this feature. There's nothing wrong with using phonos for semi-permanent connections. Another advantage of this duplication of input and output sockets is that they often prove a handy place from which to take a split feed. Boss have used a break socket for the jack input, thus giving the jack exclusive priority if both jack and phono sockets are connected. This is a good idea because it prevents you from misguidedly plugging in two pieces of gear which would short their outputs together and consequently risk damage to their circuitry. The output sockets, however, are paralleled and can be used simultaneously. Input and output level matching is taken care of by a push switch which is described in the manual in the following manner: 'If it is the noise that you wish to avoid more than anything, set the switch to -20dBm position, and if you are annoyed by the distortion, set it to the -10dBm position.'

I think that says it all rather quaintly, although it tends to sound a bit like they are running down their own technical specifications. In operation the phaser is actually very quiet, aided by the compression and expansion circuitry at each end of the phase shifting section.

Another feature uniform throughout the range, is the standard DC connector socket on the back panel. Sockets for both power in and power out are provided and units can be daisy-chained using the DC to DC plug leads which are supplied as standard with every model.

As with the phaser, two RBF10s can be linked via the modulation buss to produce true stereo flanging where the sweep direction is opposite on each side of the stereo image.

A modulation polarity switch and buss socket are provided at the rear of the RPH10. The polarity switch will invert the modulation sweep which, aurally, has the effect of turning the upward swooshes into downward ones and vice versa. On its own this switch would be a little pointless, but it comes into its own when two RPH10s are harnessed together via the modulation buss socket. This standard jack socket links the modulation sections of the two phasers together allowing a pair of them to be used as 'master' and 'slave'. In this way true stereo phasing can be produced and, when used in this manner, inverting the polarity of the modulation on one of the units will further dramatise the phasing effect.

The quality of phasing produced by the RPH10 can be varied between a gentle whispering in mode 1, through a spacey swirling in mode 2, to a deep sweep in mode 3. Mode 2 is my personal favourite as it can create a lot of effect without being too obvious, if that does not sound like too much of a contradiction in terms. For some of my tests, the units were used in-line rather than on an effects loop from a mixer and I would like to have had a direct/effect mix control to play with as the levels jump a little when switching between the dry sound and the effect. Also, an overload LED would not go amiss as a back-up for the ears. Overall though the quality of the phasing and the low noise level outweigh these minor niggles.

RBF10 Flanger

The flanger sports the same modulation and feedback controls as the phaser with the exception of the fact that the feedback control has a centre detent off position and generates in-phase feedback when rotated clockwise and inverted phase feedback when rotated in the opposite direction. It also offers a mix control which allows the direct signal through exclusively in the anti-clockwise position and the effect through exclusively in the clockwise position. The back panel differs from that of the phase in that two different outputs are available. One is the mixture of direct sound plus the in-phase effect whilst the other incorporates a phase inverted version. When both these outputs are used through separate amplifiers or panned left and right they will give an enhanced spatial effect but they cannot, however, both be summed back to mono because in this case they will cancel each other out, and produce an untreated signal.

The sound quality from the RBF10 is very clean and bright and again the unit is very quiet noise-wise. It incorporates a noise gate after the delay section which I tested by using very tiny input signals and turning up the gain on the mixer to listen for the opening and closing of the gate. Whilst doing this I came to the conclusion that the unit is acceptably quiet anyway even before the noise gate cuts in although it is good to know its there when using the unit with low level inputs such as guitar. The flanger produces good results with both 6-string and bass guitar indicating a good frequency response as well as a low noise floor. When the unit is switched to its -20dBm mode it presents a 1Mohm impedance to the input signal which is an advantage where guitarists are concerned, because it helps to preserve their valuable high frequencies.

With the feedback control set to its centre off position, the RBF10 can produce quite a convincing chorus effect which sounded especially spicy when tested on rhythm guitar. Advancing the feedback control clockwise produces the characteristic moving frequency peaks, and anti-clockwise, a more open hollow sound is created.

Again, I was not entirely happy with the effect on/off switch but it is less of a problem on this unit as the provision of the mix control allows for the flanger to be used on an effects send/return loop as well as in-line or via insert points.

RDD10 Delay

With the possible exception of its maximum delay time, the RDD10 will do everything that basic digital delays of twice its size will do. It has modulation and feedback sections to take care of all the phasing, flanging and chorus tasks, and a delay time which is variable between 0.75ms and 400ms, using a nine position rotary switch and a x0.5 to x1 fine adjustment pot. A delay output level control is provided together with a delay tone control. Now, a delay tone control is an unusual addition, but I found it very useful for one task in particular. When recording or mixing vocals, I often like to use quite long delays - about 200ms. To be able to get a decent amount of level without the sibilants and fricatives disturbing the rhythm, I usually return the delay via an input channel on the mixer and knock off some top. This tactic can achieve a rich sound without the delayed sound becoming too obtrusive. By using the tone control on the RDD10 the same effect can be achieved via the effect return on the mixer, which often will not have any EQ, thus economising on valuable input channels. The last part of the travel of this tone control will slightly boost the top of the delayed signal and this can be very effective for emphasising phasing and flanging. The tone control is also handy for dissuading the unit from screaming at itself if very large amounts of feedback are required.

Outputs, both jack and phono, are provided for delayed and mixed clean and delayed signals, so the unit can be used equally well in-line or in-loop. As with the phaser and the flanger, a modulation polarity switch and buss connector socket are provided for the linking of two digital delays.

The quality of the delayed sound from the RDD10 is very good and I'm inclined to believe that their quoted frequency response of 40Hz to 16kHz +1, -3dB is up to the mark. Certainly, a complete mix can be played back whilst monitoring the delayed sound only, with no obvious flaws evident. The phasing and flanging sounds produced on digital delays can often be less inspiring than those produced by their analogue counterparts but the RDD10 is quite convincing in this area. The maximum delay time of 400ms may seem a little stingy when the norm is now about 2 seconds, but this figure is often achieved with reduced bandwidth and in any case, apart from special effects, the vast bulk of delay work occurs at times of less than half a second, so high quality in this area should be regarded as more important than longer delays.

RCL10 Compressor/Limiter

Not just the usual common or garden comp/lim this, but an expander and noise gate as well, all in one box. The usual Attack, Release and Threshold controls are provided which offer attack times of 0.5 to 50ms and release times of 200ms to 2 seconds with a 30dB range on the threshold control. Somewhat less than common on budget units is the 'Ratio' control which incorporates a centre detent 1:1 ratio position. When rotated clockwise, this control sets the desired ratio of compression at infinity:1. When rotated anti-clockwise from its centre position it adjusts the expansion ratio up to 1:1.5. The noise gate offers control over both Threshold and Decay and the final control on the front panel adjusts the output level. At its centre position there is unity gain through the unit but it is variable from off to +14dB. All the ins and outs common to the Micro Rack series are present on the rear of the RCL10 with the addition of a key input and two stereo link sockets, one for the noise gate and one for the compressor.

There are many ways in which the RCL10 can be put to use in the studio. I tried all sorts of tricks with it, all of which it coped with admirably. The key input will control both the compressor and noise gate sections and I found that using the expander on legato keyboard parts whilst keyed by a drum unit, can result in a rhythmic feel being added to the keyboard without necessarily going for the choppy feel that can be achieved from a keyed noise gate. The expander also proves most useful for attending to noise where the more positive action of a noise gate is not necessary or desirable. The attack and release timings available are quite adequate; the most important aspect of which is that the fastest attack time does not adversely soften the punchiness of a rhythmic track. The physical layout of the front panel is good, starting on the left with the compression threshold and ending on the right with the output level control. It may sound a bit obvious to organise the front panel so that the signal can be followed through logically but not everybody does it this way. A very handy and flexible unit then that should find a host of applications in any small studio.

RGE10 Graphic Equaliser

The RGE10 is a 10-band graphic equaliser covering a frequency range of 31 Hz up to 16kHz in octave intervals. The slider for each frequency offers 12dB of boost or cut plus a master level slider. Each of the sliders has a miniature red LED recessed into its front which is permanently illuminated to give a clear indication of the relative slider positions. Input and output sockets, power sockets and effect on/off socket and switch all fit into the appropriate style for the Micro Rack range.

Everything appears as one would expect for the RGE10, ie. you don't notice any effect when all sliders are at their centre detent positions but when setting it up, each slider makes a positive contribution its allotted frequency band. The control for each frequency is quite selective but there is just enough overlap between them to give a smooth, 'musical' effect. The master level slider is useful for keeping the apparent overall level from shifting about too much when boosting and cutting bits of your sound and the effect on/off switch allows simple comparisons with the untreated signal to be made.

The only real drawback of the RGE10 is the shortness of the slider travel which makes fine adjustment more tricky. In its defence, however, usually a graphic equaliser does only need to be set up once at the beginning of each session.

The RGE10 operates quietly and would be ideally suited to use at the insert points on a mixer, although it will work well with a wide range of signal levels.


The whole Micro Rack series is manufactured to a good standard and is nicely finished: it is very solidly constructed, as I found out whilst trying to take one apart. (Use a sharper chain saw - Ed). It is so designed as to be fully screened from the outside world and the PCBs are grounded to the chassis by a devilish looking spiked washer which clamps down onto the PCB track and is bolted through to the main case. All the pots and switches are positive and smooth to operate and are sensibly colour coded. Although designed primarily for use at line level, they will all operate quite happily with low level signals and the 1 Megohm impedance input is a good sign that they will not hinder the guitarist who normally suffers from a curtailed high frequency response due to excessive pick-up loading by low or medium impedance inputs.

All five members of the Boss Micro Rack series are worthy competitors in the studio effects stakes and I must confess to being particularly impressed by the digital delay and the compressor/limiter. They retail for £125 each, apart from the digital delay for which you would have to part with an extra £75. I am tempted to single out the RCL10 Compressor/Limiter as being particularly good value for money with regard to home studio usage.

The overriding impression that these units leave me with is that they have been designed with good noise figures and the needs of the home studio recordist high on the priority list, and if this is so, Boss have not fallen short of their aim. I shall look forward to trying any additions that Boss might be planning to add to this very useful range of units.

The Phaser, Flanger, Graphic Equaliser and Compressor each retail for £125 including VAT. The Digital Delay retails at £200 including VAT. For further details contact: Roland (UK) Limited, (Contact Details).

Also featuring gear in this article

On The Rack
(ES Aug 85)

Browse category: Studio FX > Boss

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Alesis XT Digital Reverb

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Centre of Attraction

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


Home & Studio Recording - Aug 1985

Donated & scanned by: Mike Gorman

Review by Martin Sheehan

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