Considering the large number of delay units currently on the market it is pleasing to see a product that is slightly different. The HD 1000 Harmonics/Delay from Ibanez is a combined unit containing both a digital delay and a harmoniser at a very modest price.

The instrument is a 19" rack mounting system designed to match the DM 1000 Digital Delay. It is sleek and good looking, measuring just 1¾" (1U) high and has a smart metallic grey and bronze finish.

A liquid crystal display shows the state of the system at all times and manages to offer a great deal of information without being needlessly complicated. The mode of the system (either Bypass, Delay or Harmoniser) is shown, together with the delay time in milliseconds or the amount of pitch shift. A useful feature is the inclusion of a simple linear VU meter which shows the level of the signal after it has passed through the input buffer amplifier. This amplifier may be switched between Line and Mic to match the input. The display is permanently back-lit, a thoughtful touch which is vital for stage use and unobtrusive in normal light.

Controls

Six colour-coded push buttons are used to select the mode and the delay time. In delay mode the delay time is permanently displayed. It may be incremented and decremented (in steps of 2ms) using two of the push buttons over the range 0-126 ms. Three ranges are available - x1, x2 and x4 - giving a maximum possible delay of 504 ms. A further push button steps successively between the ranges. These three controls have been carefully thought out and any desired delay may be quickly selected. The controls allow wrap-around (i.e. decrementing from 0 ms gives 126 ms) and fast autorepeat if held down.

An internal modulation voltage is available with variable range (Width) and repetition rate (Speed). This can be used to obtain flanging, chorus and vibrato. A feedback pot determines the amount of the output signal which is allowed for regeneration.

The pitch shift may be adjusted over a range greater than ±14 semitones and is shown on the LCD (when in harmony mode) in 'cents', 100 cents being equal to 1 semitone. Coarse and fine adjustments are provided to allow the interval to be set up accurately. The tuning on the review model was stable and trouble free.

Finally three level potentiometers control the input amplifier gain, the dry output level and the processed output level.

Construction

The unit is well made and reasonably rugged. The bottom panel, which is held in place by four screws, may be removed to reveal the component side of the large single-sided PCB. Construction is to a very high standard and the board contains many fine tracks closely spaced. The circuit comprises some 29 ICs - analogue, TTL and CMOS. A note attached to the rear panel warns that there are no user-serviceable parts inside the case and so there will generally be no need to open the unit.

The circuit employs 8-bit A/D and D/A converters which are cheap and readily available. Companding is used to reduce the noise which is inherent in an 8-bit system. This is vital since the theoretical optimum S/N ratio without companding is only about 48 dB. The alternative is to use higher resolution converters (say 12 bits) which give reduced quantisation noise but are rather expensive.

All connections to the unit are situated on the rear panel and are made by mans of standard ¼" jack plugs. Dry and mixed (i.e. dry + processed) signals are available separately. Also, buffered 'send' and 'receive' connections are provided to allow for an additional feedback loop. Finally a socket is provided to allow a Bypass foot-switch to be added. This was not provided with the review model but would be very helpful in serious use, especially to a guitarist.

Problems may arise if the unit is used freestanding since the display is difficult to read unless placed roughly at eye level. This could generally be overcome if a rack were used but is worth bearing in mind.

Effects

The unit is, first and foremost, a harmoniser and should be judged as such. A diagram of various control settings is attached to the top panel. This also carries a block diagram of the system. Example settings include:

Flanging

This proved rather disappointing. When fed directly with an electric guitar or vocals there was little noticeable effect and severe treatment was necessary with a fuzz box (connected between the guitar and the delay unit to create a signal rich in harmonics) before the characteristic sound was obtained. Even then the effect was poor since the excursion of the modulation waveform is not sufficiently great to produce an acceptable flange ratio. The tone may be varied slightly by adjusting the delay.

Chorus

Chorus is obtained by using a slightly longer delay than that used in flanging. The effect enriches the sound but tends to be too thin to be really useful. A much better thickening technique is to use the harmoniser, set to give little or no pitch shift, giving the effect of two instruments playing in unison. A little modulation may be added to improve the effect further, giving a rich, pleasing sound which is free from any noticeable glitches.

ADT

Automatic double tracking may be achieved by using a delay of 30-80 ms with little or no feedback. The delayed signal is not distinguishable as a separate echo but is perceived as a thickening of the sound. The effect may also be achieved in harmony mode by selecting a pitch shift of 10 cents. The detuning is sufficient to create the impression of two sources and the harmoniser itself always introduces a slight delay. Therefore the shifted output arrives momentarily after the application of the input. This effect is particularly noticeable if the 'dry' level is turned down to remove the original signal from the output. It may be used to advantage with a guitar signal to add a 'click' to the attack of each note which is extremely effective with bass notes.

Reverberation

A 'hard reverb' is available using the same delay as above but, this time, with feedback. This has the effect of producing multiple repeats although they are still not distinct. Unfortunately the reverb is rather unnatural - a simple spring line would be far better - and would benefit from greater feedback than is possible with the unit as it stands. The addition of an external feedback path, making the total loop gain approach unity, would be useful and would allow slowly decaying reverb and echo to be produced. A loop gain of exactly unity would allow sounds to circulate indefinitely without the degradation introduced by an analogue system and would extend the versatility of the unit considerably. To be fair to Ibanez they do not claim the effect to be a true simulation and, if carefully used, it is not unpleasant.

Echo

Echo is produced using delays above 100 ms. Short delays allow slap-back echoes to be produced whilst longer delays can give echoes of up to half a second. With feedback set at minimum just one repeat is given. As the feedback is increased the number of repeats increases until, at full delay with full feedback, the sound continues for around 4 seconds.

As for reverb, better results would be possible if greater feedback were readily available. However the unit comes as a refreshing change after using a bucket brigade system.

The echo effects show the delay mode to its best advantage. On vocals a slapback echo with heavy feedback produces a realistic echo/reverb reminiscent of a large hall. I would have liked to have seen a longer delay possible. 64K RAM chips are available nowadays for pennies rather than pounds if you are prepared to buy in bulk and so the inclusion of extra memory would not increase the cost of the unit significantly. An echo of 2 seconds or more is perfectly feasible (whilst still retaining an adequate bandwidth) and would be useful for special effects if nothing else. Such an option would not be out of place in a unit which clearly aims at versatility.

Harmony

The harmonics mode is likely to be that most frequently used. All harmonisers are subject to 'glitching' (i.e. colouration of the sound due to the splicing process involved). A full description of this is given in E&MM Sept. '82. Modern harmonisers are designed to keep the colouration to an absolute minimum and, bearing in mind the price of the unit, the designers have been reasonably successful in this.

Upward pitch shifts are impressive. Shifts of over an octave are perfectly usable and should cause few complaints unless prominent in the final mix. This is not to say that a signal which has undergone such a large shift remains totally faithful to the original. However the colouration is not particularly unpleasant or obtrusive and noise is not severe. Generally shifts within ±4 semitones may be relied upon to remain reasonably true to the original although a little 'lumpy'.

Downshifts are slightly less successful. The output is decidedly flawed and contains occasional 'hiccups'. Also the output level appears to drop as the shift is increased. This makes a signal which has been shifted up by an octave far more prominent than one which has undergone an equivalent shift downwards.

With vocals the harmoniser really comes into its own. The entire range of shifts may be used successfully, giving sounds ranging from ludicrously high pitched squeaks at one extreme to grumblings from the depths (which eventually become almost unintelligible) at the other. Of course, large shifts of pitch are of limited use outside the field of special effects. However, such shifts compare favourably with professionally produced results. Using more modest shifts harmony may be added to a vocal track, although the usefulness of a fixed interval for more than a few notes at a time is questionable.

The feedback control may be used to add the shifted signal to the original at the input to give a further shift. In this way the unit may be set up to produce a chord from a single note, giving interesting results when processing a guitar. When set to give a shift of one octave up both the first and second harmonics are clearly audible. With vocals the effect produces very rapidly rising arpeggios which seem surprisingly familiar!

Vibrato

True vibrato (genuine frequency modulation) is obtainable by selecting zero pitch shift and adding a little fast modulation. An acceptable vibrato effect is available in either mode simply by modulating the signal slightly. The results are warm and natural for subtle settings although a deeper vibrato tends to sound slightly synthetic.

Conclusions

The instrument is well made and well presented. The controls are logically laid out and make the unit easy to use and quick to set up. It is very versatile and represents good value at £325.

The harmoniser section works well and may be used to generate a wide range of effects. The delay is disappointing in some respects although the echo effects are very respectable. The noise reduction circuitry works well and the unit introduces little noise of its own into the signal. Most of the controls operate over a sensible range although a wider modulation sweep would greatly improve the flanging effect. More feedback would have been welcome to allow the unit to be driven almost to oscillation but this may be overcome by using an external loop.

Many of the above problems are minor and somewhat subjective and do not detract particularly from the performance. Overall, a nice piece of equipment for stage or the budget studio.