Did you know that the term ‘bucket brigade’ comes from a style of fire fighting, in which buckets of water would be passed down a line? Me neither. It makes perfect sense, though, when you think of what a bucket brigade device, or BBD, actually does: sequentially ‘filling’ and ‘emptying’ a series of capacitors with a signal.
“We love BBD circuits for their imperfection,” say Morphor on their website. ‘Imperfection’ is certainly the word — in essence, imagine those firefighters as simply being rather... sloppy. But needless to say, that’s what we love about them. Now Morphor enter the BBD delay arena with the Echo, a 4096‑stage bucket‑brigade‑based module in capacious 20HP.
With delay times ranging from a super‑quick 10ms to a languid 2.4 seconds, the Echo is a proper piece of analogue outboard goodness, with a raft of extra features and options thrown into the mix. The module’s full name, ‘Echo Analogue Quad Tap BBD Stereo Delay’, refers to its impressive array of eight different outputs for various applications of its four taps. Those four taps quarter the set delay time: if that is set to two seconds, for instance, tap 1 will be half a second, tap 2 one second, tap three one and a half seconds and tap 4 two seconds.
While the Echo isn’t the first delay module to offer discrete tap outputs (Xaoc Devices’ Sarajewo and Doepfer’s A‑188‑2 are two examples that spring to mind), it does arrange its outputs in a distinctive way: taps 1, 2, 3 and 4 get discrete mono outputs, but there’s also a stereo mix output for tap 4 and an overall stereo mix output for all taps together.
Not only is it therefore possible to send individual stages of the delay line to all manner of destinations; the final two sets of stereo outputs involve the Echo’s wet/dry mix, stereo spread and panning mode controls. These modes consist of Ping Pong, Traverse and Chaos: Ping Pong alternates repeats across the stereo image, Traverse progressively pans them and Chaos places them at random.
The delay itself sounds as smooth and warm as I could hope it to, though fair to say I would perhaps have liked the input to offer a little more gain before things start to clip. As it is, I did need to ‘work’ combinations of the input gain, wet/dry mix and input level on my mixer a bit to achieve a really healthy gain structure in various instances, but fair to say once in a sweet spot the Echo performs marvellously.
One predictable challenge with any BBD‑based design is these devices’ inherent tonality and noise. Longer delay times, for instance, will have a duller tonal character, which must be balanced with what can be a fairly prominent noise floor. To this end the Echo places a choice of two low‑pass filter modes in the delay line: early‑tracking or late‑tracking. These ostensibly amount to different cutoff settings: early‑tracking is less noisy but darker in tone, while late‑tracking risks more residual noise but affords a tonally richer signal.
I also found myself creating some gorgeous, pseudo‑quantised melodic patterns from the simplest input signal...
The Echo felt most alive and exciting to me with pinging, shorter delays, particularly when sent skittering across the stereo image, and from here it’s not a leap to the obvious point that such things can be used for far more than just a delay effect. A variety of lovely analogue chorus sounds are quick and easy to achieve, from subtle to extreme, and I occasionally found myself in harmonically rich Karplus‑Strong territory. With Sync mode activated, the delay time snaps to different clock divisions when changed or modulated. This not only makes for fun polyrhythms; I also found myself creating some gorgeous, pseudo‑quantised melodic patterns from the simplest input signal, since changing the delay time of course also affects pitch.
A few other functions add further excitement: there’s a switch to invert the polarity of the wet signal so that sonically it interacts differently with the dry, and also a tempo output, which fires useful clock pulses in time with the delay time setting. More off‑kilter is an additional input for breaking the internal delay feedback path with an external signal. This made for some pleasingly wild, multi‑input delay chaos, to say the least, and while it wasn’t hugely useful on a fundamental level, it is a welcome addition all the same.
The Echo doesn’t give you instant results on a plate, but that’s the nature of the BBD beast. “We love adding features that make people think,” says the developer, and to that end the Echo is an undoubted success, not to mention a worthy addition to the already formidable Morphor range. It’s got all the substance — and idiosyncrasies — of analogue, but it’s reliable everywhere it needs to be. I recommend it.