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Roland Digital Delay SDE2500

More MIDI magic from Roland.

Paul White gets his hands on the new programmable delay unit and arrives at some interesting conclusions.

It certainly seems that this is the year of the MIDI controlled effects unit and this new offering from Roland allows the user to create and store up to 64 delay effects which can be addressed by means of the panel controls or by MIDI patch change information in the range 0 to 127. As you would expect, a modulation section is included so all the standard delay related effects can be generated and the bandwidth of 17kHz combined with some rather sophisticated high resolution converter electronics means that this unit should be capable of satisfying most professional requirements. Curiously though, the delay time at full bandwidth is a modest 350mS and this only increases to a maximum of 750mS in the Time x 2 mode where the bandwidth is reduced to 8kHz. In real life however, this restriction on delay time is not as serious as it might first appear to be as most delay effects, including straight echo, can be set up using delay times of 350mS or less; really long delay times are only ever necessary if you intend to produce Brian May style sound on sound guitar excesses.

No prizes for guessing how many units of rack space this machine takes up so let's get straight into looking at the controls.

Panel Functions

A glance at the photograph will show you that all the normal delay line controls are located to the left hand side of the front panel. The first of these is the obligatory and very necessary bypass button which is a nice, big, easy to use affair with a neat little status LED located just above it.

Again, the input level control works just as you would expect and your endeavours in this department are monitored by a six section LED meter.

"In this age of computer based equipment, it's really very nice to see that the designers have gone out of their way to adapt the machine to the user and not vice versa."

The Modulation controls, Rate and Depth hold no surprises and the same is true of Feedback and Delay Level except for the fact that they actually exist as separate knobs rather than as increment/decrement buttons or a single assignable controller. In this age of computer based equipment, it's really very nice to see that the designers have gone out of their way to adapt the machine to the user and not vice versa.

All these controls, with the exception of the input level control (which should only need setting up once each session), are linked to the programming electronics and so all their settings can be stored and recalled as patch information - the fact that the level of delay relative to the direct signal level can also be stored is particularly useful.

Bang in the middle of the front panel is the Memory No button which is really a type of rocker switch and this does work in an increment/decrement fashion to step through the patches or memories. By pushing down both sides of this button, the rate at which the memories step through is greatly increased, the direction of stepping being dependent on which side you pressed first. This button also doubles as the MIDI Omni Mode on/off switch. To the right of this switch is the display window which houses five seven segment numeric LED displays. Under normal circumstances, the first two display the patch number whilst the last three indicate the current delay time in milliseconds. In true Roland style, the display is dual function and may also serve to indicate Omni on/off status and MIDI channel number. A further two additional LEDs indicate delay on/off status and the LFO modulation rate, the latter by flashing at the oscillator frequency.

"...this produces echoes which become softer as they die away..."

The right hand side of the panel takes the form of a keypad containing nine buttons and the first of these is another of those ingenious rocker switches which in this instance allows the delay time to be incremented or decremented. The remaining buttons are arranged in two rows, the top row for programming and MIDI functions and the bottom row for modifying effect parameters, these being Time x 2, Delay Phase, Filter and Hold, each having a built in status LED. Time x 2 is fairly self explanatory (it doubles the maximum delay time to 750mS) and Delay Phase as might be expected gives you the choice of feeding back signal in normal or inverted phase. This option only has any significant effect at very short delay times and is most useful for changing the character of flanged sounds where the change in colouration is quite distinct.

Filter comes next, but there is more to this than meets the eye. This control gives the option whereby the high frequency content of any signals fed back is progressively reduced. In the context of straight delay with feedback, this produces echoes which become softer in tone as they die away and it is thought by some that this duplicates the characteristics inherent in tape loop echo units which gives them a subtly distinctive sound quality preferred by some musicians. Certainly this feature is useful for treating vocals where the repeat echoes can be made less obtrusive and consequently more natural than simple full bandwidth repeats.

Hold is the familiar feature that allows anything captured in the machine's memory to be constantly looped giving an infinite repeat effect, but with no triggering facility, this function is of very limited use. I really did expect to find a triggered sampling system on a unit of this price and sophistication, especially one from Roland who usually have a pretty good idea of what the end user really wants, but if you are going to buy one of these machines for it's programmable facilities, it's possible that you'll already have a cheaper delay line to take care of such mundane tasks.

"...I was particularly intrigued by the socket labelled Playmate, so I eagerly connected my footswitch and waited for the scantily clad bunny girl to appear..."

Rear Panel

On peering round the back of the unit, the usual array of connectors is present with the addition of one or two new ones. MIDI is catered for in the form of In and Through DIN sockets.

Operating levels may be switched to match +4dBm or -20dBm systems and both delay only and mixed outputs are provided as now appears to be common practice. Having remote jacks for Delay on/off and Hold is also par for the course but I was particularly intrigued by the socket labelled Playmate, so I eagerly connected my footswitch and waited for the scantily clad bunny girl to appear but alas, I had once again mistaken Mr Roland's intentions. This function is really a rather clever timing device which means that you can set the delay time via this switch such that the delay time is the same as the time elapsed between two consecutive depressions of this pedal. In effect, this means that you can tap your foot on the pedal in time to the music and automatically set a new delay time that fits the tempo of the piece. Of course the maximum delay time can't exceed the maximum capability of the unit (750mS), but this mode of operation could be very useful in a live situation enabling you to instantly set up a suitable delay time without having to touch the front panel controls. Two further sockets allow for the connection of footswitches which may be used to increment or decrement the programme number if MIDI is not being used to handle this task. In this event, it is probably wise to programme your effects in the order in which you intend to use them to avoid unnecessary complications.

Also present is a CV input jack. This is not designed to allow the unit to be controlled from a synth but rather to make possible external control over the pitch modulation, for example, by connecting an external LFO. Inserting a plug into this socket disconnects the internal modulation oscillator.

"As a straightforward high quality delay unit equipped for MIDI control, this unit has no real faults but some may feel that it has omissions."


The SDE2500 can be set to operate in the MIDI omni mode or to respond to any discreet MIDI channel in the range 1-16. When one of the 64 memories is allocated to a MIDI programme number in the range 0-127, this information is stored as part of what Roland call a number table. Four such number tables may be stored and recalled and when the unit is powered up, the last number table used is operative. This is made possible by the battery backed up memory system which is responsible for preserving all other program information when the machine is switched off and this battery is intended to last for at least five years.


Fortunately, the manual for this piece of equipment is very thorough and clear, so you shouldn't have any trouble in learning to drive your SDE2500. This is worth a mention, as many oriental manuals - even some Roland ones - are less than perfect to say the least, and may be of little more help than the original Japanese manuscript. As this manual is 29 pages long and contains a great number of explicit diagrams (no, not that type of explicit diagram!) I shan't attempt to reproduce it all here. Buy an SDE2500 and you'll get one of your own. As the essential controls are real knobs, setting up a sound is really very straightforward if you've used any kind of DDL before and a simple ritual involving the programming buttons locks your desired sound into the memory of your choice. Existing memories may be edited but in order to have your cake and eat it too, you can first copy the patch into a spare memory location so that way, you still keep the original intact.

And Subjectively...

Once you've tried out a lot of different DDLs, you cease to be surprised by the type of effects that can be created and this Roland model doesn't do anything to break with tradition with the possible exception of the Filter parameter. What it does do however, is to produce all these standard effects to a very high standard with exceptional clarity and a marked lack of background noise which is an obvious advantage in any studio environment. With the unit set to Time x 2, the reduced bandwidth is not as detrimental to the sound quality as you might imagine, and though there is obviously a perceptible difference in high frequency response, this would not be serious for most applications.

Both chorus and flange effects work well and the phase invert switch does give a genuinely useful choice of colouration in the flanging mode. One thing to bear in mind though is that the delayed sound is muted for up to 400mS whenever the program is changed or the delay time altered, so don't expect to be able to program a composition that needs one delay effect to switch instantly to another without any form of discontinuity. To keep matters in perspective, this problem is inherent in the design principles of DDLs and is in no way confined to Roland.

For those not entirely au fait with the setting up of different effects, the manual contains a complete section on sample settings, all of which are clearly illustrated by means of front panel drawings showing the appropriate control positions.


As a straightforward high quality delay unit equipped for MIDI control, this unit has no real faults but some may feel that it has omissions. The new breed of MIDI controlled delays could reasonably be expected to incorporate sampling and keyboard pitch control as there is presently a huge demand for this kind of equipment, and if such a sampling device also functions as a DDL, then it makes good commercial sense to the musician or recordist working on a budget to go for that model. Whether longer delay times are necessary or not, the maximum delay time is a strong selling point, and for a unit of this price, I would really have liked to see at least a one second delay at full bandwidth.

This is a very stylish and well behaved instrument with exemplary credentials in the way of noise, distortion and dynamic range. If what it offers is capable of satisfying your requirements, then you can be confident that this unit will impress both you and your clients. If you need more however, then you have to decide whether to spend an extra couple of hundred pounds on an all singing, all dancing machine or whether to go ahead and buy the Roland regardless and spend the change on one of the many fine, low cost sampling delay lines currently available. Despite my occasional niggle, this really is a very desirable piece of equipment.

The SDE2500 costs £600 including VAT, and further information is available from:- Roland (UK) Ltd, (Contact Details).

Also featuring gear in this article

Previous Article in this issue

The TDK Competition Results

Next article in this issue

TAC Scorpion 16:8:2 Mixing Console

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


Home & Studio Recording - Sep 1985

Donated & scanned by: Mike Gorman

Gear in this article:

Studio FX > Roland > SDE-2500 Digital Delay

Gear Tags:

Digital FX

Review by Paul White

Previous article in this issue:

> The TDK Competition Results

Next article in this issue:

> TAC Scorpion 16:8:2 Mixing C...

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