Analog Obsession: Dimension D Chorus and Roland SDE Delays

After the Analog Obsession article we did back in June about the Roland RE-201 Space Echo, I started thinking about more cool tools that Roland made for the studio. I've always been a big fan of devices that do one thing (or just a few things) and do it well. They almost always equate to easy use, and therefore quick results, which is always conducive to the creative process.

SDD-320 Dimension D
The Dimension D is a studio gem that adheres to the principle of doing one thing, but doing it extremely well. Its one and only function: some of the best sounding stereo chorus ever made. However the Dimension D is more than a chorus, it is really a sound enhancer for adding spatial effects to stereo or mono sources. The Dimension D gives a new "dimension" without the apparent movement of sound produced by other chorus devices. The strength of the Dimension D is in its subtlety. It was clearly designed not to create a dramatically new sound, but to enhance the sound of any instrument, preserving the instrument's own sonic qualities. Furthermore, the Dimension D was not built to a price; it was an expensive, heavy, well-built unit for the studio. A Dimension D will put you out around $1200 on the used market--if you can find one of these rarities. They were built to last, and rarely require servicing.
Roland’s SDD-320 Dimension D

"Its one and only function: some of the best sounding stereo chorus ever made."

The front panel controls are as you might expect: Simple. It has 4 pushbuttons (much like an 1176) for four different levels of effect intensity. Interestingly, there are no controls for rate. All four settings sound fantastic, and are all very useful. Another pushbutton turns the effect off. The only other controls are a bypass and power button. It has a 10-LED segment for output level, plus a front panel jack for a remote bypass switch.

The Roland Dimension D is built around two "bucket brigade" type analog delay lines with companders (compressor/expanders) and pre/de-emphasis for noise reduction. The delayed signal is mixed into the stereo channel it was derived from, and also cross-mixes to the other channel with opposite polarity. Normally this would result in a loss of lower frequencies, but the cross-mixing is high pass filtered, and the direct signal is slightly bass-boosted. When you switch it on, not only a delayed (and equalized) signal is added, but the direct signal is altered, to be "complementary" to the delayed signal.

The result is that the overall tonality is almost unchanged when the effect is switched on or off. The 4 presets all have somewhat slow modulation of the delay time, which helps to keep the periodic nature of the modulation in the background. To achieve the desired depth, comparatively long "bucket brigades" are used: 1024 stages for each channel. Most bucket brigade chorus circuits work with 512 or even fewer stages.

SDE-1000 Digital Delay
The SDE-1000 was my staple delay before transitioning to the world of DAW recording and plug-ins (and also before I discovered the joy of tape delays). With its simple and well laid-out controls, the SDE-1000 is easy to understand without ever cracking the manual.

Roland’s SDE-1000 Digital Delay

Delay length is displayed in milliseconds via the blue fluorescent display, and is set easily by holding down the +/- toggle button. The Time x2 button allows the user to quickly double the delay time (up to 1.5 seconds). The number of repeats is set with the Feedback control. When pushed past 12 o'clock, the Feedback control can allow the user to drive the signal back on itself as well, albeit not as stylishly as a tape delay--but still very useful for adding spice to a mix.

The SDE-1000 also has a good sounding Modulation section with Rate and Depth controls for flanging and chorus. Also present is a button to switch the phase of the delayed signal, as well as four memory presets to store your favorite settings; just hold 'em down to save--just like a car stereo!

The Roland SDE delays were launched in 1983; among the other models were the SDE-2000, SDE-2500 and the SDE-3000 all adding or subtracting various bells and whistles. It seems the SDE-1000 and the rest of the line was directed at the "pro-sumer" and live market of the day, with its unbalanced connections and low output levels. But despite this, and its early low-bit converters, the SDE-1000 still holds its own twenty years later, and is still found in many studios. It is a good sounding delay, couldn't be easier to use, is built to last, and can be found for reasonable prices on the used market.

Roland’s SDE-3000 Digital Delay

-Will Shanks

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