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Korg SDD3000 Digital Delay

Digital Delays have been around for some time now and the main problem experienced time and again when reviewing and using various models, is the basic fundamental question of 'what market is the equipment designed for; studio or live band?' So many manufacturers have tried to please too many people all of the time and have effectively come up with a piece of equipment that has operational bugs in both environments. Korg have, however, produced a machine with many features ideal for studio use with ease and practicality of operation that make them accessible in live performance also.

Basic features of the Korg include, a 17kHz delay signal bandwidth with delay time continuously variable from 0 to 1023ms. User programmable presets store nine complete settings that can be recalled at the touch of a button with full editing facilities. The built-in modulation generator has four switchable waveshapes including an unusual random waveform, an envelope follower as well as an external control voltage input which can be used to directly vary delay time. Foot switch controls for 'bypass' and 'hold' modes and also delay time up/down, allow for extra flexibility in the live stage situation and the companion front panel switches are still operational, which definitely adds to the all round versatility of this machine.


Either front or rear panel input jacks can be tailored for maximum input, without distortion, by a three-way attenuator switch selecting from -30, -10 or +4dB nominal input. A level control makes final adjustments and the total input is displayed by a five segment headroom indicator, calibrated in 5dB steps from -20 to +3dB.

Besides a rotary control, governing the amount of feedback of the signal to the input stage, the Korg also offers high and low cut filters which are active on delay (regenerating) signal only. The low cut filter can be set at 125Hz, 250Hz or 500Hz giving minus 3dB/oct roll-off to each regeneration, and the high cut filter can be set to 8kHz, 4kHz or 2kHz cutting minus 6dB/oct in a similar fashion. This feature opens up some quite interesting possibilities, creating combined timbral and spatial effects. The Regeneration section of the Korg also has a pushbutton control which switches feedback to inverse phase. This takes the regenerating signal out-of-phase with the direct input, which produces a much richer, fuller sound, particularly noticeable on chorus and flanging effects. The infinite Hold mode can be operated either by a pushbutton control on the front panel or by a remote foot-switch plugged into the back of the unit. When Hold mode is selected delay time is automatically set to maximum (1023ms), but filter, invert and modulation controls can still be changed to create sound sampling of very high quality.

Time domain variations are created successfully by good modulation controls and Korg have given us plenty to choose from. Three controls are mounted on the front panel selecting Waveform, Intensity and Frequency. Waveform is selected by a four-way switch which offers triangle, square and an unusual random wave which works like a sample and hold effect clocked by Frequency rate. For general related effects such as flanging, chorusing etc, the triangle wave is well suited, and square wave can produce some special effects such as echo and pitch shift at lower delay rates whilst the random wave can give very effective ADT along with some very interesting effects at lower delay rates. The frequency of these waveforms can be varied between one cycle every 10 seconds to 15 cycles per second. This frequency rate is indicated by a flashing LED next to the modulation controls. The final setting for the modulator waveform is Envelope, which varies the delay time according to the amplitude of the audio input signal, as volume increases delay time becomes shorter. This system allows for heavy transient treatment when used at high intensity, and is therefore very effective when used for touch responsive flanging and chorusing, but can also be used for subtle Doppler effects when used at lower intensity.

These four waveform possibilities can be further supplemented by an external control to the Delay Mod input jack at the rear of the unit. The jack accepts a standard 0-5 Volt supply which directly varies the delay rate (high voltage - low delay rate, low voltage - high delay rate) where the maximum delay is indicated by the normal LED setting.

The Intensity control determines the degree (depth) at which the delay will adopt the characteristics of the modulating waveform. Maximum intensity slows down the delay rate to a ratio of 2:1, therefore at modulation wave peaks, delay time will be reduced to 50% of the value indicated on the LED display.

Output facilities of the SDD 3000 have been particularly well worked out and allow for a very good range of output options, both mono and pseudo-stereo. The 'Effect' control determines the mix of dry and delayed signals sent to the output amplifiers, and the front panel standard jack output can be attenuated by -20, -10 or +4dB to match input ratings of other equipment, while the three rear output jacks are all +4dB to match most studio and PA equipment. All outputs are unbalanced and can drive 600ohms to full output level (+21dBm). The output stage is also fitted with a phase inverse switch, which inverts the phase of the signal to the front panel output and +MIX/MONO jack at the rear only. Two other outputs are provided for direct signal only, and inverse phase MIX of the direct and delayed signal (set by level balance). A Bypass switch completely turns off the delayed effect and can be operated if you prefer by a footswitch.

There are two ways to produce a pseudo-stereo effect, using a mixer with two outputs from the Korg, set to opposite pan settings. Using the +MIX/MONO and -MIX outputs gives an extremely good effect for live sound on stage. However, when recording this setting is usually unsuitable, due to phase cancellation of the normal/inverse signals. It is therefore best to use Direct and +MONO/MIX signals, when recording.


Nine separate effects programs can be stored, recalled and edited at anytime. All controls on the front panel are remembered (apart from input/output settings) making the programming very versatile.

Underneath the LED display on the front panel are four momentary pushbuttons, Write (red), Program (yellow) and Delay time up/down (white). Programs can be stepped through in numerically ascending order, by simply pressing the Program button continuously. When the Program button is pressed while the Write button is held down, all the front panel settings (excluding input/output information) is stored in the program number memory, presently selected. This overwrites any program information previously stored at this location. New programs are best created from scratch using the manual mode, this way you are absolutely certain of the position of all the switches and controls. However, previously stored programs can be copied to a different location or edited then stored again. When a program is being edited a decimal point appears behind the program number on the LED display.

The standard delay-related effects are generally very good, with natural-sounding decay and quite faithful reproduction of sound quality. However, I did find that, especially at higher delay rates, effects such as flanging were a little noisy and a low sweep effect was quite noticeable. I am also a bit dubious about the stated 17kHz bandwidth, as even at short 400ms delays there is an apparent drop in high frequency content.

The inclusion of the Random modulating wave and the Envelope Follower, make the Korg extremely versatile with great creative potential. These features are normally only found on the particularly expensive units and are a great bonus here, and the external control voltage facility is something that I personally would make quite a bit of use of.


Design, construction and finishing of the Korg SDD3000 are quite simply excellent. The switches on the front panel, for inverse feedback and output, hold and bypass all have a light, positive action with LED inserts in the centre. These give a clear indication of the state of the controls. The cabinet itself has a two-piece metal shell screwed directly to a strong steel framework. The front panel has an attractive hard-wearing blue finish and the control knobs are generally smooth and quiet in operation.

Inside, two large PCBs are mounted back to back, separated by a metal plate and sheets of card as extra protection against shorting out of components on both sides. In all 58 ICs are peripheral Interface Adaptors which assist with DAC/ADC and generally run the show. The rear sockets are mounted on a separate PCB which is joined to the main boards via modular connectors, keeping wiring length to a minimum. All boards and components are used including two 8255 very securely mounted to the framework and soldering and finishing are of excellent quality.


The Korg SDD 3000 is certainly a well made machine which is a pleasure to use. A few little quibbles I do have would include: the noisy operation of the delay time switches (but considering the programmable presets this should not really be any problem), also the operation of the jack for external control voltage which has to be physically removed from the back panel to allow return to normal internal modulation facilities. Every Digital Delay unit of this type I have seen, has suffered this problem and I'll say it again; features like this must be switchable from the front panel before the full value and versatility of the unit can be realised in live work, and in the studio this feature could not be controlled from a patch bay. Despite these small problems, the SDD 3000 proved to be a particularly good device with some very fine features for both studio and live work.

The price of the SDD 3000 is £999.95 including VAT.

Further details from Rose-Morris, (Contact Details).

Also featuring gear in this article

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Korg SDD3000
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Browse category: Studio FX > Korg

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Using Microphones

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


Home & Studio Recording - Feb 1984

Donated & scanned by: Mike Gorman

Gear in this article:

Studio FX > Korg > SDD-3000

Gear Tags:

Digital FX

Review by Glenn L. Hughes

Previous article in this issue:

> Interconnect

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> Using Microphones

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