#re201

Space Island

10″ x 8″

mixed media on wood

The Roland RE-201's preamp was once again the topic of gently heated forum posts after Boss released two new Space Echo pedals earlier this year (the RE-2 and RE-202). On the original RE-201 Space Echo, the preamp was an analog circuit that boosted and filtered the input signal, preparing it to be written to the magnetic tape used to create the infamous echo effect. This meant that the “direct” signal had some coloration from the preamp even when the echo was not in use. The new pedals include a digital emulation of the preamp, and most forum posters seem happy that the emulation can be bypassed (as a secondary function). But these forum posts also revealed that few players seem to understand the way the preamp works on Boss’s older Space Echo emulation: the RE-20 pedal. That’s understandable, because the RE-20 has a bypass arrangement that I’ve never seen on another pedal....

The RE-20 is easily the most-used delay pedal for Thom and Jonny. During rehearsals last December, Thom had three of them spread across his pedalboards for use in his independent guitar and vocal signal paths.

Volume Controls

One must admit that the single “input volume” control on the RE-20 pedal is a bit unusual. On most pedals, the “input gain” control only has an effect when the pedal is active. That’s the reason most pedals also have “output volume” control: you can set the gain control however you like, then adjust the output volume control to match the volume when the pedal is on and when it’s off. So on a standard preamp pedal, you can crank the “gain” for some clipping, then back off the “volume” to avoid shaking the windows.

On the RE-20 pedal, the “input volume” control effects the volume even when the echo effect is turned off. This design decision has some benefits: it allows Boss to leave out the “output volume” control, making the pedal easier to use and cheaper to manufacture. It’s also reminiscent of the input gain control on the original RE-201 tape echo. The downside is that if you want to give the echos a gritty, compressed sound, you have the boost your output volume even when the echos are turned off. So if you’re carefully gain-staging your effects and how you hit your amp’s input, the RE-20 can really throw a wrench in the works. Not only that, if your input signal is boosted too much, you’ll get harsh hard clipping even when the echo effect is turned off. Boss addressed this on the new RE-202 pedal by offering a “saturation” knob that only affects the direct volume if you activate the preamp emulation. But the RE-20 pedal has other bypass oddities too...

With a loud input (such as this synth oscillator), the Boss RE20 can add some harsh hard clipping even when the echo effect is turned off. The clipping only gets more extreme as you turn up the input volume control. Many describe this clipping as “digital”, but there’s nothing inherently digital about hard clipping. Analog distortions like the Proco Rat and Marshall Shredmaster use hard clipping for an aggressive sound. However, the RE-20 pedal′s hard clipping is very different from the multi-stage transistor clipping on the original RE-201.

The RE-201′s Transistor Preamp

The on/off footswitch on the RE-20 pedal may not bypass the “input volume” control, but it does change the sound of the “direct” signal! This is what makes the RE-20 really unusual. But before we delve further into the RE-20, we should first understand more about the input stage on the original RE-201 Space Echo. On RE-201, the input passes through a transistor preamp that is always active. This is great for folks who like the preamp’s coloration: a gentle rolloff of the highs and lows, plus a bit of transistor clipping. But if you wanted to bypass the unit entirely, you’d need a separate bypass loop box.

Most folks, Jonny Greenwood included, decided to embrace the preamp’s sound and instead used a footswitch to disable the echo. A footswitch connected to the “echo cancel” jack actually stops and starts the RE-201’s motor, disabling the echo effect. In an added quirk of analog electronics, the sudden change in speed when the motor stops creates a bend in the echo’s pitch as heard on live version of In Limbo, but that’s another story (and note that “tails” on the RE-20 works differently). When the “cancel” footswitch is used, the direct signal is always passed through the input volume control and the transistor preamp, regardless of whether the echo motor is running.

And for the curious, this info is only true for the RE-201 and RE-101 Space Echo units. Roland’s later Space Echos such as the RE-301 (famously used by Brian Setzer) and RE-501 feature different preamp circuits.

Here's a simulation of the frequency response of the transistor preamp in an late-period RE-201 Space Echo with a buffer before the input (the treble basically disappears if you connect a guitar directly to a Space Echo, so most people put a buffered pedal in front to correct the impedance mismatch). On a real vintage Space Echo, the frequency response could be more dramatic if the aging capacitors haven't been replaced in the past ~40 years.

Jonny with two of his vintage Roland RE-201 Space Echo units during the recording of Radiohead’s In Rainbows (radiohead.com/library).

The RE-20′s Preamp Bypass

Boss understandably wanted to recreate the tone of the original RE-201 unit, so the RE-20 pedal includes an emulation of the RE-201′s transistor preamp. That faithfulness to the original is also the reason the RE-20 has such a gritty, tinny sounding reverb effect (whatever you think of it on its own, the reverb blends beautifully with the echo). But the engineers at Boss must also have realized that many modern players want their direct tone to be unaffected when a pedal bypassed. So when the RE-20′s echo is turned off, the preamp emulation is turned off too. Many folks don’t seem to realize this, since the volume control suggests that the preamp is always active, like it was on the original RE-201. But when you turn off the RE-20′s echo, the “direct” signal is instead passed along with minimal filtering. To sum it all up: when the echo is turned off, the signal is still buffered, and its level is still set by the “input volume” control (which can still cause hard clipping), but the coloration from the preamp emulation is disabled.

To test this, set the volume of the echo and reverb on the RE-20 to zero, and turn the effect on and off with the footswitch. It’ll depend on your setup, since a mids-heavy amp might already cut those frequencies. Even so, you should notice a some cut to the lows and highs, and perhaps a tiny dip in volume.

Here’s a the frequency response of “direct” signal through a Boss RE20 pedal. For the “Effect ON” setting, the echo and reverb volume controls were set to zero.

When the effect is turned on, the high end takes a serious hit above 10kHz. In addition, the direct volume is lowered by 0.5dB, presumably so that the overall level feels the same even when the delay signal is mixed in. In contrast, when the effect is turned off the frequency response is basically flat (there’s a reduction of 0.5dB at 15kHz, but you’d probably never notice it running through guitar cabinet). Notice that the high-end rolloff begins later than on the RE-201 preamp (at about 2kHz instead of 1kHz) but cuts the high-end much more dramatically above 10kHz.

Modern Versions

It’s worth noting that the newer RE-2 and RE-202 pedals do not replicate this behavior. Instead, the transistor preamp emulation can be turned on or off as a secondary function. And when the preamp is selected on the new pedals, it stays active even when the echo is turned off. In that sense, it’s more faithful to the original RE-201. But I find it a shame they didn’t include the RE-20’s style of bypass as an additional option, especially since they offer multiple bypass options. That said, if they did add another bypass option, nothing would beat an emulation of the motor stopping when the echo is “cancelled”! For now we’ll have to make do with the twist feature.

Winter set-up :