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Accessit Sound Processor Units

Dual Sweep EQ & Stereo Reverb


The Accessit range of modular effects were introduced a few years ago to satisfy a growing need for low cost sound processors. Designed for the semi-professional and budget-conscious market, the Accessit units come in a smart compact plastic case with clearly laid out front panels. The units may be used either free standing or packed in three side by side, and mounted in a standard 19" rack using an optional rack kit.

At around £50 per unit they're not going to worry your wallet too much and will allow you to build up a useful range of sound processing units, as you require them, and when you can afford them. Accessit produce seven units in the range, all are useful and should help you to produce interesting and creative recordings.

We kick-off this month with two of the units: the Dual Sweep Equaliser and the Stereo Reverb.

As this is a modular system, we must, before looking at the individual units, go straight to the heart of the system, namely the power supply unit. This unit enables you to power up to four individual sound processors, power being distributed to each unit via a 5 pin DIN lead. The use of this external power supply helps to keep annoying mains hum down to a minimum, resulting in good clean signals. This is sadly, all too often not the case in many other budget sound processing units which use internal power supplies.

Dual Sweep Equaliser.


Dual Sweep Equaliser



As the name suggests, you're getting two of something, that something being a tone control. Small basic mixers are normally equipped with only simple treble and bass tone controls but the Dual Sweep Equaliser offers an additional versatile tone control that allows you to home-in on a specific frequency band and either cut or lift the volume of the sound occupying that region. This means you can set the frequency control fairly high up on the range and, for example, cut the hiss a little on a noisy recording or alternatively, by adding lift, strengthen the harmonics in a guitar sound to add some extra bite.

Operation



The equaliser is a unity gain device ie. it doesn't affect the volume of the sound going through it. Being of this nature and without any input level control it therefore requires a good healthy input signal, something around -10dBm to 0dBm, as provided by the auxiliary sends on your mixer for example. Microphones cannot be plugged directly into the equaliser but require a pre-amp to boost the signal up to a reasonable level.

The two equalisers contained in the unit, labelled A and B, are identical. Each contains a frequency control for sweeping through the audio range, this range being divided into two parts and selected via the front panel pushbutton. In the low position the sweep control operates over the 60Hz to 5kHz area, and in the high position over the 1kHz to 16kHz range. Unfortunately there seems to be a little confusion between the figures quoted in the specification sheet and the numbers printed on the front panel. However, in practice there's no real problem as few people are capable of recognising the frequency of a sound unlike trained musicians who can name musical pitches.

The final control on the front panel is the gain, which provides 12dB of either cut or lift to the sound. In the centre position it has no effect, turning it to the left will start to cut the volume at your chosen frequency and turning to the right will lift the volume. Using the frequency and gain controls together you can adjust the tonal quality of any sound with reasonable precision. These controls allow you to get down into the woolly and thundering bass areas, amble around the middle or sweep up to the bright highs! Having experimented with the use of this single sweep equaliser it came as an added bonus to find out that you can link the A and B sections together to produce a two band equaliser. This allows even greater control of the sound.

Rear connections on the Sweep Equaliser.


Round The Back



All input/output and power connections are to be found on the back panel of all the Accessit units. The Dual Equaliser uses standard jack sockets, one input and one output on each of the A and B sections. As previously mentioned the unit can be used as a two band equaliser, which is achieved by plugging the input signal into section A and taking the output from section B. When using the device in this mode an internal link is automatically made between the output of A and the input of B. To use both the A and B sections independently you just plug signals in and out, treating each section as a separate unit.

Application



The Dual Equaliser was definitely found to be a useful little device. Other than patching it into your mixer to expand its tone controls, the equaliser was equally at home being used as a stand-alone unit. On synthesisers, it proved to be very useful in shaping sounds in the areas where the synth's own low pass filter started to become ineffective.

One of the beauties of the Accessit units is that it's quite simple to link several of them together. The equaliser was particularly well suited to the stereo reverb unit, allowing additional tonal control of the reverb sound. Tonal adjustment of this kind can help simulate different acoustic environments eg. church-like acoustics by boosting the bass frequencies, or a lively hard room-type effect by lifting the upper mid and treble. Overall the Dual Equaliser was found to be of good quality and not too noisy in operation.

Stereo Reverb Controller.


Stereo Reverb



This unit comes in two parts, the Stereo Reverb Controller and the Spring Unit. Having plugged the power in and linked the controller to the spring unit the Stereo Reverb is ready for use. Unlike the equaliser, the reverb can be used with microphone or line level inputs patched into a mixer echo/auxiliary send or used as a stand-alone unit. Before describing the features and controls it's worth saying a little about reverb in general.

All environments can be categorised into various acoustic types, each with it's own reverberation factor. Outside in an open field there's no reverb at all, if you shout the sound you make will emanate from your mouth and travel away from you never to be heard again. If you put an object in the way eg. a wall, then a proportion of the sound will be reflected back and heard again at a lower volume. By continuing this theory, the more surfaces there are, the more reflections will build up. These reflections combine to determine the acoustic quality of the 'room'.

Everybody has experienced the sound quality found in a church or that of a tiled bathroom. Each of these rooms has it's own individual characteristic. The simulation of 'room types' has been achieved in a number of ways throughout the history of recording. The first method was to use a hard-walled room with a loudspeaker and microphone in it. The sound is then fed into the room via the loudspeaker, bounced around and then picked up again by the microphone.

Another method is the 'plate reverb' which is a large metal plate vibrated by the sound, (See HSR March 84). Other than the electronic methods of analogue, digital and tape reverb the other traditional way of producing reverb is with a spring line. This type of spring reverb is most commonly found in guitar and PA amplifiers, due to its low cost.

The Accessit reverb unit employs this spring method to produce a passable reverb treatment. The unit features six separately tuned springs suspended within an inner metal box, which helps to eliminate external vibrations from shaking the springs.

The sound, once applied to the input, travels through the springs and is then mixed together again at the output and because each spring is under slightly different tension, a varied delay time is produced. It is this cluster of delays that produces the reverb quality. The type of effect produced by this method depends wholly on the length and number of springs used. Many basic reverb units only use two springs, and the inclusion of six springs does produce an audibly superior effect from the Accessit unit.

Internal layout of the six reverb springs.


Controls



A mono input jack socket and two output jacks labelled left and right for the stereo output are mounted on the rear panel. The front panel controls are divided into two parts, the input/reverb mix and the reverb equaliser. The input gain operates in conjunction with a peak overload LED to help you set the optimum input level, whilst the mix control allows you to select the amount of reverb sound (wet) being mixed with the direct sound (dry). The maximum reverb decay time in the all wet position being 3.5 seconds. It is advised that you experiment with the setting of the mix control particularly when the reverb unit is connected to the echo send of a mixer.

Finally the equaliser controls. There are two of these, gain and frequency. Both are similar to those found on the sweep equaliser unit but with a more selective range. Here you can only sweep the frequency between 1kHz and 7.5kHz, and as before, by using the gain control, you can either cut or lift the selected frequency.

As mentioned previously, reverberation characteristics vary depending on the type of environment. The equaliser will help you to simulate these effects by cutting or lifting the upper middle and treble frequencies. In practice, it was better to cut the level of a selected frequency rather than lift it for the addition of lift made it very easy to overload the reverb unit as the equaliser boosted certain resonant frequencies.

In The Mix



As this is a stereo reverb unit you should utilise that facility to its fullest. If you use the unit with a mixer you can use the echo send output to feed signals into the reverb, then by returning the stereo output back into a couple of spare channels on the mixer you can pan the reverb and achieve a wider spatial effect. Once the unit is patched in, it's then a simple matter of turning up the echo send level on the relevant channel to add instant ambience to any selected signal or group of signals, creating 'warmth' in your recording as well as a sense of space.

Conclusions



In use, the Accessit reverb was found to be a fairly quiet unit. The little noise it did produce did not present too much of a problem as the effect would normally be used quite low in the mix anyway. As with almost every spring line reverb unit that I have used, the Accessit suffers from 'splashing'. This is a characteristic problem and is particularly noticeable on sounds with fast attacks such as percussion. Careful adjustment of the reverb mix control should help to eliminate most of this problem though.

To sum up, the reverb unit, like the sweep equaliser is a very useful effect, if not a basic necessity, for reverb should be one of the first effects you buy when setting up a studio. The Accessit Stereo Reverb is a fine little unit and well worth considering if you're working to a tight budget. Having said that, I do feel that the price is a mite too high and should really have been kept under £100 when one considers that the whole Accessit range is aimed at the budget conscious market.

Prices of the reviewed units are as follows: Dual Sweep Equaliser £51.69; Stereo Reverb £132.50; Power Supply £33.00. All inc. VAT. Further details from: Bandive, (Contact Details).


Also featuring gear in this article



Previous Article in this issue

Tascam 38 Eight Track Tape Recorder

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Home Studio Recordist


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

 

Home & Studio Recording - Apr 1984

Donated & scanned by: Mike Gorman

Review by Paul Gilby

Previous article in this issue:

> Tascam 38 Eight Track Tape R...

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> Home Studio Recordist


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