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Sony DPS-D7 Digital Delay

The Return Of The Single Effects Unit?

Article from Sound On Sound, November 1991

David Mellor looks at an effects processor which can't produce three dozen effects simultaneously. Is this the start of a new trend?



One day, mark my words, white will be the new black. Or perhaps it will be a subtle shade of off-white, but sooner or later manufacturers will tire of spraying their front panels with that particularly light absorbing non-colour which may have looked chic in the designer '80s but is being regarded as unnecessarily impractical in the user-friendly '90s. Just imagine having front panel legends that you can actually read rather than the current fashion of grey lettering on a black background!

The colour scheme of equipment won't be the only thing to change. Since the introduction, by Yamaha, of the multi-effects unit in the shape of the famous SPX90, and the later introduction by other manufacturers of units which could provide several effects at the same time, multi-effects units have become more and more powerful but at the same time they have tended to become more and more difficult to use. I'll make an exception in the case of the Zoom 9030 because for a multi-effects unit it is very easy to deal with, but by and large I think that multi-effects units have gone as far as they can. You can see what I'm leading up to, but I'll just add another point by saying that if you are already the owner of a multi-effects unit, why might you want to buy another one? The only reason can be that it has a better chorus or distortion or whatever. In that case wouldn't you be better off if you could buy a unit that was dedicated to the function you wanted?

I predict that we will see more and more single effects units coming onto the market. Not that the multi-effects unit will go away, but manufacturers will soon be trying to persuade us that their XYZ100 is the ultimate reverb, or the ultimate chorus. If you are in the manufacturing business, just think how many extra boxes you'll be able to sell! And I for one will love it because I do want a choice of dedicated units which I can add to my personal studio and use in conjunction with my existing multi-effects unit and sundry toys. And I want to be able to run my fingers across the control surface and edit the parameters of my chosen effect quickly and with a satisfying response from the machine - that could mean a knob interface. Shock, horror, jump in the air and do a double back somersault!

What we have here, the DPS-D7, is interesting on two counts, well three if you include the fact that it's a damn good piece of equipment. Count number one is that the DPS-D7 (there's also a DPS-R7 reverb on the way) looks like being the first in the new order of single effects units. It's a digital delay, and apart from some more esoteric functions it does everything, and provides every accessory as we shall see later, that a digital delay should. The other point is that it is made by Sony. Sony, that well known Japanese electronics company, has acquired something of a reputation in televisions, video cameras, hi-fi, portable stereos - pause for breath - compact disc players, digital tape recorders, digital multitrack recorders and the odd one or two other items. But for some reason Sony has not really entered whole heartedly into the effects unit market, although you will find Sony effects and even mixing consoles tucked away in professional catalogues. But if Sony have the expertise to design everything else in their impressive product range, then undoubtedly they must have something to offer to users of digital effects. Will they do a Yamaha and start making musical instruments and motorcycles next?

This single effects unit from Sony doesn't quite go all the way towards what I'm looking for in the equipment of the future, in its panel legending and operation, but it justifies its rack space by providing one quality effect, and by adding the 'accessory' effects that one would naturally want to use in conjunction with digital delay.

DELAY — THE EFFECT



Delay was one of the original effects, produced by a tape echo in the olden days. Many studios would have a varispeed Revox available with a reel of long play tape purely for that purpose. When digital delays first became available the tedious chore of turning the tape, or two tapes if you wanted stereo echo with different delay times on each channel, around every half hour or so was eliminated. This was a wonderful step forward in studio technology, if not quite comparable with that of landing a man on the moon. Ironically, almost as soon as delay became easy to use, it went out of fashion. That's life really; you only want what you can't have. My theory is that delay was mainly used to beef up the sound of mechanical plate reverb units, which gave a very smooth and dense reverb, but offered little variety of effect. As more versatile digital reverb units became common, the need for delay units lessened, to the point where delay is now mainly to be found as a 'stocking filler' among the other goodies in multi-effects units.

The simplest application of a delay unit is to provide a single echo, where the signal ripples through the memory of the device for a couple of hundred milliseconds before emerging in a hopefully unchanged form. If this single echo is fed back into the delay unit, either internally or via the mixing console, then a repeating echo is produced which gradually dies away (or builds up into distortion if there is a positive gain in the feedback path). This was sometimes known as spin echo. If the feedback path is EQed, then the character of the echo will change as it decays. For example if a little top cut is supplied, then the echo will lose a little more of its high frequencies as it goes round. This doesn't sound too exciting when you read about it, but the difference in the sound of the echo makes it well worth doing, if that's what you want of course. It follows from this that any self respecting delay unit will have control over the amount of feedback applied internally, and also an EQ stage, at the very least this will be a variable high frequency cut.

Of course one could add so many 'accessory' effects that a digital delay turns into a complete multi-effects unit, but we shall see as we go along how far the DPS-D7 follows this route. One effect that digital delays are naturally suited to, but which is not provided here, is sampling. If a delay unit has a certain amount of memory through which an audio signal moves, then it isn't too complicated to 'freeze' the audio and read it out at the push of a button. Samplers of this kind, as opposed to keyboard orientated samplers like the Akai S1000, are particularly useful for capturing a section of recording on multitrack tape and spinning it back in at another point in time. Ease of use is important here and the facility to read material in continuously, freeze it at the push of a button then recall it at the push of another button, or on receipt of a timecode value, characterise this type of sampling. But although the DPS-D7 can't do this, it leaves room for my theory of single effect units to come into action; Sony's next effects product could be a sampler perhaps. Isn't speculation fun?

DPS-D7 — THE DELAY



One is tempted to speculate whether the name of this unit originates from a mis-spelling of DSP, which as you must know by now stands for Digital Signal Processing. (Did you know that a committee of the European Parliament has decreed that 'DSP' is to be the new buzz word to replace 'Workstation' next year? Every audio product will have to carry it in large letters). Anyway, whatever it stands for, the unit's prime specifications are 18-bit analogue-to-digital conversion, 1-bit pulse digital-to-analogue conversion and a 48kHz sampling rate with up to 2.73 seconds of mono delay (half this for stereo). This ought to indicate that it's a serious unit, but one thing I tend to question when I see equipment boasting more bits than the CD standard 16, is why does the signal-to-noise ratio hardly ever shape up as it should? In theory, 18-bit resolution ought to give a signal-to-noise ratio of 18 x 6dB = 108dB. The specification here claims only 94dB. Are Sony, and other manufacturers who are in a similar situation, being conservative or is there a problem in translating theory into practice and getting the extra performance out of the XLRs on the rear panel? The subjective sound quality of the unit is, of course, excellent, with no problems for the pro user. Perhaps 18 bits give audible improvements over 16 that don't show up in the specs.



"The DPS-D7 is, I predict, the first of a long line of specialist boxes from all the major manufacturers that will concentrate on doing one thing, and doing that one thing very well."


Physically, the unit is a relatively weighty 1U's worth with a combination of analogue controls, buttons and a rotary control for adjustment of parameters. On the rear panel we find both XLR and jack inputs and outputs. The balanced XLRs operate at the higher level of +24dBu maximum, the unbalanced jacks at a maximum of +10dBu. Sony's spec states that the nominal levels are +4dBu and -10dBu respectively, but I would question the value of continuing to use this hangover from the analogue days of soft tape distortion. The only level that should concern users of digital equipment is the level at which it clips. Just leave the amount of headroom you consider appropriate for the type of signal you are dealing with. The input sensitivity is governed by a dual concentric front panel potentiometer, which is what we want, and there are similar, but not dual concentric, controls for the dry and effect output levels. Output level controls are a must if Sony is to be able to call the DPS-D7 'professional'. In professional use, life is much simpler if you can align input and output levels to the studio's standard, and set so that the device has unity gain. You can alter input and output levels in digital equipment via software, but this can only be achieved at the expense of digital headroom. Good old fashioned analogue controls are a must.

I hope you won't be disappointed that something is missing in the input/output department - there is no digital interface, either AES/EBU or S/PDIF. OK, so they are not really necessary in 1991 since all-digital studios are still rare. But the DPS-D7 you buy today will still be ready and waiting in your rack in 1992, and in 1993, and by then equipment which can't interface digitally will be at a disadvantage. I think Sony should have taken the opportunity of providing a digital input/output now, but I suppose we must allow them the opportunity to market a DPS-D7 Mk II at some future date.

Since the DPS-D7 uses a display/rotary control/button interface, it is desirable that the display is clear and informative. Actually, I think Sony let someone from the design department loose on this one because rather than a table of words and numbers it uses clever graphics and does look rather 'arty'. I'm all for it as long as it is helpful. For instance, when the help information is active, there is an icon of what to me looks like a barking dog on the left hand side of the display. The help information is useful, although it scrolls rather slowly.


OPERATION



The DPS-D7 comes ready packed with 100 delay programs with delights such as 'Feedback delay 2, 5th double tone', and plainer offerings such as delays of one frame and one field suitable for NTSC or PAL video and suchlike. The preset delays fall into seven categories: Stereo Delay, Feedback Delay, Double Delay, Tap Delay, Long Tap Delay, Panpot Tap Delay and Multiple Delay. To give you some idea of the depth of this unit, the Tap Delay gives you 38 independent taps to play with.

The idea seems to be that you will select a preset, modify it to your taste and then store it in one of the 256 user locations. In fact, there doesn't seem to be any way of starting absolutely from scratch since you can't access user locations until they have been programmed by copying a modified or unmodified preset. One question which might arise is just how do you select from a total of 356 possible programs with a rotary control? Do you need the dexterity of a circus plate spinner? Thankfully no; the rate of change of display seems to accelerate so that if you spin the control quickly, the parameters will change faster still.

Going into edit mode the basic functions are listed: Delay; Input; Output; EQ; Autopan; Local MIDI; System; Memory. Under Delay there are five parameters which of course include the delay time for each channel. One important parameter is Delay Time Sync. This means that both channels are set simultaneously. In fact all of the parameters throughout the unit which could be applied to either channel or both have a sync function, which you can see will save a lot of time.



"I think Sony should have taken the opportunity of providing a digital input/output now, but I suppose we must allow them the opportunity to market a DPS-D7 Mk II at some future date."


The next interesting topic is EQ, obviously for EQing the delayed signal, and perhaps more importantly for EQing a repeat echo as described earlier. The bass EQ ranges from 16Hz (which should be low enough for most purposes) to 6.3kHz (which is high enough to stretch most peoples' definitions of bass). Cut and boost is up to 12dB. High frequency EQ is from 400Hz to 20kHz with a similar range of level control. Most people would be happy enough with these two ranges, simply for the purposes of doctoring their echoes, but Sony have provided a third mid-range band for those of us who just may in time yearn for a little more control. This centre band is parametric with a frequency range of 63Hz to 20kHz with +/-12dB level control. The Q ranges from 0.267 to 34.62. Most people would regard a range of 0.5 to 5 to be adequate, so Sony have certainly been generous here.

The next group of parameters is for Autopan. Some might question the inclusion of Autopan on a delay unit, but it is nice to have repeat echoes bobbing around the stereo stage. If you don't need it, it doesn't get in the way, and I would regard it as an 'accessory' effect to delay, as mentioned earlier, although it's just possible you might want to use it as an effect in its own right. An impressive range of panning options is available.

Every effects unit needs MIDI control of the parameters. Call me cynical if you like, but I don't know of anyone who actually uses MIDI control once the novelty value has worn off. Do you? Is this the fault of the effects unit designers who make MIDI control too difficult to use, or the users who can't recognise a good thing when they see it? No. I would say that what we MIDI enthusiasts need most of all is an automation system for MIDI controllers built into our sequencers. I know that many sequencers allow such tricks as drawing controller 'curves', or you can enter controller data using a MIDI fader unit, such as the JL Cooper Fadermaster, but recording controller data is one thing, getting it right is another. We need an update system as found on all the best mixing console fader automation systems. How about putting it on Cubase, Steinberg? Anyway, now that I've got that off my chest I can say that the DPS-D7 allows up to four parameters to controlled by any MIDI controller from 0 to 121, and by note number, channel pressure and velocity. Someone please use this feature!

After MIDI control, we come to System. The input mode can be either mono or stereo, and is relay switched. By the way, there is also a relay switched bypass, as there should be, but unfortunately it didn't work for me. I can't think why, and if the important bypass function requires the instruction book (which I didn't have) to understand, then it has been wrongly designed. A proper relay bypass is vital for all types of live use. Next under the heading of System is Auto Help On/Off. Believe me, you'll need this switched off because otherwise practically every time you press a button you'll get that barking dog with his help message that scrolls ever so s-l-o-w-l-y. Good idea, but let's have the software update please. Among other functions are options to display the delay time in milliseconds (for engineers), quarter notes (for musos), metres (for PA system operators) and words (for lexicographers - sorry all you digital enthusiasts). I might have liked to have seen an option for feet since it's a well known rule of thumb that sound travels at one foot per millisecond, but I suppose it's about time we all became fully metricated. Along the same lines, the Q parameter of the parametric equaliser section can be displayed as Q (which equals the centre frequency divided by the bandwidth of the EQ curve) or, more usefully, as the number of octaves the bandwidth of the EQ covers. Beyond the next feature, the setting of the remote control channel, we get into crazy country. Did you ever want to set the clock on a digital delay? I mean time clock not system clock. I can understand that you might want to program in the user's name, but how about his or her date of birth? I won't rise to the bait, and I have to say that I don't know what's going to happen when your birthday arrives. I'll leave it as a surprise.

BASICALLY



Basically, the Sony DPS-D7 can be used in a very basic way without fuss or bother. Those people who have to use a digital delay for simple stereo delay purposes, like broadcasters and PA engineers, will like the simplicity with which such tasks can be handled. Musicians and studio engineers will like the fact that all the best tricks you could want a digital delay to do have been thoughtfully packaged into a unit which does the job to a high standard and without the bother involved when you want to set up a simple echo on a multieffects unit. With 100 varied, and very high-quality, factory presets to choose from and 256 user memory locations, you can take it that this latest rack toy has an incredible range of effects (some of which you simply won't believe are coming from a unit which is itself merely a digital delay). The DPS-D7 doesn't look like being the last effects unit from Sony, nor is it a throwback to the time when effects units could only perform one trick each. The DPS-D7 is, I predict, the first of a long line of specialist boxes from all the major manufacturers that will concentrate on doing one thing, and doing that one thing very well.

Thanks to The Synthesizer Company for the loan of the review unit.

FURTHER INFORMATION

£816.63 inc VAT.

Sony Pro Audio, (Contact Details).

SONY DPS-D7 SPECIFICATIONS

Quantisation: 18-bit linear
Sampling Frequency: 48kHz
Inputs: 2 channels, balanced XLRs (+4dB) and unbalanced phonos (-10dB).
Outputs: 2 channels, balanced XLRs (+4dB) and unbalanced phonos (-10dB).
Frequency Response: 10Hz to 22kHz (+0 -1 .0dB)
Signal-to-noise Ratio: >94dB
Dynamic Range: >94dB
Total Harmonic Distortion: <0.0035% (1kHz)
Memory: 100 presets, 256 user memories



Previous Article in this issue

Akai/Linn MPC60 II

Next article in this issue

When Things Go Wrong


Publisher: Sound On Sound - SOS Publications Ltd.
The contents of this magazine are re-published here with the kind permission of SOS Publications Ltd.


The current copyright owner/s of this content may differ from the originally published copyright notice.
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Sound On Sound - Nov 1991

Gear in this article:

Studio/Rack FX > Sony > DPS-D7


Gear Tags:

Digital FX
Delay

Review by David Mellor

Previous article in this issue:

> Akai/Linn MPC60 II

Next article in this issue:

> When Things Go Wrong


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