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Echo Unit Supplement

MXR Delay System II

Over the past years MXR products have earned themselves an enviable reputation for reliability and versatility both in the studio and on stage. Walk into almost any professional recording studio, inspect their equipment racks and you're bound to see at least one MXR device; their distinctive blue front panels being instantly recognisable. However, the introduction of a new range of products heralds a new image slightly less distinctive than the previous one but still recognisable from the blue and white MXR logo.

The Delay System II is part of this range and supercedes the previous digital delay unit. It is available in either half or full memory configurations giving maximum delay times of 1600mS or 3200mS respectively. The unit under review had the full memory specification and came with the optional road case. The standard model is 2U 19" rack mounting with a black plastic coated front panel that houses all controls. Logical function grouping and clear, white labelling make for convenient operation. A large, red digital readout is provided for delay time in milliseconds and is well sited directly above the Fine delay time control for clear visibility, even in bright lighting conditions.

Switching on the power illuminates the Delay Time display and the unit remains switched out of its delay mode for almost four seconds whilst the digital memory is cleared. The input Level control to the right of the panel and its associated LEDs are used to match the input signal level to the operational level of the delay unit, and a limiter is incorporated to prevent harmful input overload conditions from occurring. These LEDs are clearly marked -12dB and Limit and the former should remain lit for optimum signal to noise ratio. This proved a simple enough task in practice.

Delay Set

A 32 position click-stop rotary switch is provided on the right of the display for delay range selection. This knob is fairly large and easy to turn from a short to a long delay quickly, without having to step through each position. Clockwise rotation increases the delay time and the digital readout gives a visual indication of your selected delay time and helps when duplicating a previous delay value. This is beneficial on repeat session work for example, when you may need to drop-in on an overdub whilst matching the previously recorded delay. The 32 delay ranges span the full 3200mS delay time available and proved to be well chosen in terms of their effect.

Three centrally positioned LEDs labelled 16kHz, 8kHz and 4kHz give an indication of the delay bandwidth in use; the bandwidth changeover points occurring automatically at 800mS and 1600mS delay times. In order to permit accurate setting of a delay value, the Fine delay set control may be used to reduce the value set by the main selector switch up to a value 20% less, when turned anticlockwise. Observing the display readout whilst tuning the delay time simplifies this task.

Once a delay has been set up, the Regen control next to the Level knob can be used to adjust the amount of delayed signal that is returned to the input for further processing. Short delays with regeneration give basic metallic reverberation treatments whilst longer times give multiple echo. Smooth clockwise movement of the Regen control increases regeneration from Off to Full. According to MXR the unit has been adjusted to prevent self-oscillation at maximum setting. This is not the case, however, when very short delays are chosen and full regeneration employed, as runaway feedback results.

Internal construction.


Time delay alone produces reverb or echo effects only, but the inclusion of a triangle wave LFO for automatic modulation of the time delay allows flanging, vibrato and chorus effects to be produced. The vibrato was particularly appealing, gently enhancing a rather mundane vocal performance. The chorus sound achieved by this unit is one of the better ones being extremely rich. Naturally, you need to experiment to find the effect that pleases you in particular.

Manual rotation of the Fine control gives a random modulation effect which may find a use on more esoteric music, or as a special treatment. The amount of modulation is determined by the Width control which is labelled 0% to 100% with oscillator sweep frequency being controlled by Speed. The sweep frequency ranges from 0.1 Hz to 20 Hz allowing slow flanging, variable vibrato rates and Leslie speaker effects. The latter was particularly realistic, with Speed on full and Width at 50%. It proved difficult to achieve the characteristic 'skying' effect on electric guitar, until the Invert Delay button was pushed. This has the effect of interchanging the peaks and notches in the comb filter, making the flanging sound even deeper and richer.

When modulation is selected, especially on slow settings, the Delay Time readout gradually changes with the sweep. This is a fascinating feature which helps clarify the actual operation of the LFO and Width control, as you can see the effect of increasing the Width control by observing the changing display.

Selection of delays greater than about 400mS enables the Repeat Hold function to be initiated by depressing a small pushbutton on the front panel or activating a footswitch connected to a rear panel jack socket. An LED lights up on the front to indicate the status whichever method is used. The Repeat Hold button causes a portion of the input signal, equal in duration to the selected delay time, to be stored in memory and continually cycled. With the maximum delay of 3200mS available from this unit, the Repeat Hold becomes a very attractive feature indeed, and excellent for producing tape loop effects with no annoying noise build-up or consequent degradation of signal. The Hold is enabled by playing a phrase and then pushing the button in. A new phrase can then be 'overdubbed', so to speak, by disabling the Hold button, playing a new phrase and then reselecting Hold. With care, a short, multi-layered piece can be constructed and repeated indefinitely.

The final front panel controls deal with the balance between dry and delayed signals. Advancing the Mix control clockwise decreases the dry signal level as the delayed signal increases. The 12 o'clock position gives an equal balance of both signals. A Dry Defeat button shorts out the dry signal, effectively turning the Mix control into an output level control for the delayed signal. Finally, a Delay Bypass button with LED, cuts out the delay circuitry completely, the input signal passing through the system with unity gain. Footswitch control is also provided on the rear panel for this function.

MXR with Optional Roadcase.


The rear panel offers two sets of audio input and output connections, both ¼" jack and XLR, but only the XLR input is balanced which is strange on a unit of this calibre, designed for professional studio use. A white Level button permits the jacks to be switched from instrument level to line level, the latter being most appropriate for connection to mixing desks, having a maximum output level of +16dBm. A handy feature is the inclusion of an XLR pin diagram above each XLR connector - saves you the trouble of looking up pin numbers on the specification sheet! Additional connections are provided for linking an external signal processor using the Aux In and Out sockets.

The sturdy construction of the Delay System II could not be faulted. The chunky controls are extremely easy to turn with a positive feel to them. They were well laid out ergonomically with clear labels. Internal construction is up to MXR's usual high standards having socketed ICs for easy maintenance. A ground shield is provided for the double-sided PCBs which contain components of the highest quality and all circuitry suggests that the unit should give very reliable performance. The optional road case is a recommended investment if you intend using the device in live performance or transporting it a lot.


The Delay System II is a very flexible unit capable of producing the full range of time delay effects. The 16kHz bandwidth right up to 800mS means that the discrete echo effects remain clear, crisp and bright. MXR describe the unit as 'surgically clean' and it certainly leaves you with this impression. Some digital delays suffer from a 'halo' effect caused by the background quantisation noise, but this was not apparent on the MXR device. Longer delay times and wider bandwidth for the delayed signal requires additional circuitry, and this is reflected in the price. All in all, this is an impressive unit, befitting of the MXR name.

Recommended Retail Price is £1,199 inc VAT. Optional road case is £35 inc VAT. For further details contact Atlantex Ltd., (Contact Details).

Also featuring gear in this article

Previous Article in this issue

Yamaha R-1000 Digital Reverb

Next article in this issue

Echotec ET-100

Electronics & Music Maker - Copyright: Music Maker Publications (UK), Future Publishing.


Electronics & Music Maker - May 1983

Echo Unit Supplement

Gear in this article:

Studio FX > MXR > System II

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Previous article in this issue:

> Yamaha R-1000 Digital Reverb...

Next article in this issue:

> Echotec ET-100

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