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DeltaLab Effectron ADM 64 | |
Article from Electronics & Music Maker, May 1983 |
The ADM 64 provides effects based round two delay ranges, selected by a central push switch on the front panel for Flange or Double. Six rotary controls allow wide variations to be made in both modes, especially with the provision of an envelope follower in addition to the more usual periodic modulation.
Although there are only a few controls, they all need careful selection during processing to get the most out of the unit.
The input signal can be between 100mV and 2V and a green 'Active' LED remains on if a suitable level signal is present, while a red 'Limit' LED indicates 0dB onset of clipping and/or slew limiting. Plenty of headroom is available in practice.
Once the delay range is selected by the Flange/Double switch, a delay control adjusts times from minimum to maximum at centre and then to envelope follower mode in clockwise half of the control. Flange range is 1-4mS and Double range is 16-64ms. In the envelope follower mode, the delay automatically follows the amplitude envelope of the input signal.
Feedback control is unusual in that it provides negative as well as positive feedback from 0 to almost 100%.
The Modulator section is an LFO that modulates the internal clock from one cycle every 10 seconds to 10Hz using the Speed control. The size of the flange or doubling delay sweep is set by the Width control, with maximum clockwise position giving the full 3-octave sweep. Other settings allow the Delay control to set the sweep 'centre' delay time and there is useful interaction with this and any external control CV in all but the minimum positions of Delay and Width, so some 'playing' with the controls is necessary to get the desired result.
Output level is dependent on the input signal level and simply has a Delay Mix control for adjusting direct output (at centre) with amounts of in or out-of-phase processed signal.
Three main types of effect can be produced. First, 'doubling' which delays a voice or instrument by 16 to 64mS. When this delayed signal is mixed with the original it produces a more 'full-bodied' sound. The Envelope Follower can add transient detuning for more natural effects on vocals.
The straight delay can also be used for sending to a separate reverb device to give a feel of early reflections (known as pre-reverb delay). A third effect is called Haas-Effect Image Shifting which can be used to stabilize images in a stereo field, since the ear does not relocate an echo in a different spatial position from the original sound if the delay is less than 40mS.
Comb Filtering lets you dramatically alter the overtone structure and tonal quality of any steady sound.
Flanging is a result of modulating the short delay with or without feedback that makes the comb filter effect. The familiar 'metallic' sweeping and shifting of harmonics is heard from different notes.
Using in or out-of-phase feedback will give different colouration to the signal, and with maximum feedback, a tuned resonance or ringing of 'peaky' sounds at a definite pitch will result (that's different with feedback polarity changed). It's particularly good with percussion.
Manual pitch shifting is easily done by turning the Delay knob. Automatic control is done with the Modulator to give smooth sweeps of pitch similar to vibrato. The Envelope Follower also modulates the clock for effective pitch 'time domain' changes from percussive envelopes like piano, guitar and drums.
This is an extremely efficient Flanger/Doubler unit that should find its way into many budget studios for creating specific effects.
On minimum delay setting the treated signal was very clean, but with some slight 'edge' ringing on a raw synth square wave input at maximum delay, which is hardly likely to affect most music inputs. The LFO modulator set at minimum still has a slight effect unless Delay is set to minimum. The review machine's LFO had a rather sharp triangular wave that was fine except for the full 3-octave sweep. Anything above the lowest Speed settings produced an unpleasant 'squelch'. At reduced sweeps below maximum there was no problem.
Above all, the ADM's clarity from the wide bandwidth, plus the wide modulation range makes it very acceptable for its reasonable cost.
The Effectron range is distributed in the UK by Scenic Sounds Equipment Limited, (Contact Details).
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