Sunday, 12 May 2019

Behringer VD400 Vintage Delay

"Roadrunner, roadrunner", sang Jonathan Richman in 1975, "going faster miles an hour", and then four years later there was a revolution in Iran, and just forty short years after that we both had a look at the Behringer VD400. Who knows what the future will bring.

What's the VD400? It's an delay pedal aimed at guitarists, although in this post I'm using it with a Korg ARP Odyssey synthesiser. While you read the following words have a listen to this short demonstration:

The VD400 is a clone of the old Boss DM-2, which came out in the early 1980s. The DM-2 was a "bucket brigade delay". It used a chain of capacitors driven by a clock circuit to generate the delay effect.

How do bucket brigade delays work? The first capacitor in the chain is connected to the audio input. Each time the clock ticks, the capacitor records a split-second signal from the input; when the clock ticks again it passes that value to the next capacitor in the chain, and when the signal has passed through all the capacitors it's sent to the output.

The DM-2's circuit had 4,096 capacitors, so it took a noticeable time for the signal to pass through the chain. That's how a bucket brigade delay works.

Bucket brigade delays use analogue components, but they have a fuzzy, digital sound that resembles bitcrushing, because the input is cut into tiny little time-slices. They aren't as smooth as 1970s tape echo units, but they're cheaper and a lot more portable. They were killed off in the late 1980s by digital sampling delays. Nonetheless they have a distinctive sound all their own.

The VD400 is particularly appealing because the price hovers around £20, so as with the Behringer Model D that I wrote about earlier in the year the VD400 is a cheap way of adding a bit of analogue grit to an otherwise digital setup. Original DM-2s hover around £200 on the used market depending on condition, although to my mind a physically-abused DM-2 would actually be more valuable than a pristine example on account of the patina. Boss re-released the pedal back in 2015 as the DM-2W, which actually sells new for less than a used DM-2. Is it any good? Probably!

The VD400 is powered by one of those square 9v batteries or a 9v power supply; it works best with mono audio cables. There are only three controls. The repeat rate varies from 300ms at the maximum to an unpleasant flange effect at the minimum value; the echo knob sets the volume of the delay signal; the intensity knob sets the feedback, which varies from light swirly to screeching feedback. The VD400 will self-oscillate, so even if you have no input whatsoever you can still use it to make odd sounds.

In the video further up the page I have my Korg ARP Odyssey plugged into the VD400; the ARP Odyssey is being driven by an Arturia Beatstep, which is being clocked by Patterning running an iPad Mini. It's all going into a MOTU 2048 connected to a Power Macintosh G5. An eclectic bunch of hardware spread across the last twenty years.

As mentioned, the delay has a crunchy sound. The VD400 applies a low-pass filter to the output, but the 300ms delay isn't really long enough for spacey dub effects. When you change the repeat rate, the echo momentarily changes in pitch. The short delay time means that you have to be careful with the intensity slider, otherwise you get a swampy soup of delay.

The VD400 has a separate direct output that bypasses the delay effect. It operates in parallel with the main output, so in theory you can mock up a stereo effect by routing the direct output to one channel and the effected output to another, although sadly there isn't a way of outputting only the effect.

Of note the unit won't turn on unless you have something plugged into the input. Physically it's made of plastic. The original DM-2 was made of metal, and was apparently indestructible. I can't imagine the VD400 surviving as well. It's very lightweight, and even then most of the heft comes from a metal plate screwed onto the base:

There's a simple mod you can do. If you open up the unit there's a trim pot inside that alters the maximum delay time. Opening the unit is relatively easy. There are only four screws, but you also have to pull the knobs off, which is awkward. Furthermore once the case is open there are a pair of very short wires connecting the pedal to the circuit board, so be careful not to snap them off.

The trim pot. There are two other pots. I have no idea what they do.

As the delay time goes up the graininess increases. In the following video my shaky white hands adjust the trim pot while trying not to destroy anything or scratch the table:

Despite years of dissolution I can still use a screwdriver in the official manner. In the video I've set the delay knob to the maximum value - I adjust the pot from the shortest value to the longest. Notice how it ends up sounding like dub delay, but put through a bitcrushing effect. The result is pleasant but has an irritating aliasing sound, although with a bit of filtering it would be a lot nicer.

In summary the VD400 is slightly awkward if you aren't a guitarist. You have to use mono cables. It's obviously nosier and more fiddly than a VST effect, and you could probably imitate it convincingly with a mixture of bitcrushing and low-pass filtering, but for £20 it's a fascinating little toy.