Great Eastern FX has unveiled the latest limited edition stompbox in its Obsolete Devices series, and it is a distortion pedal inspired by the iconic hard-clipping performance of the MXR Distortion+ and DOD Overdrive/Preamp 250 – only this does something very different, applying a powerful band-pass filter that allows players to dial in some cocked wah electric guitar tones.
And it is also packing some stompbox gold in its circuit, a trio of NOS germanium diodes. The Distortion Filter D312A is named after the Soviet-era diodes that might otherwise have ended up in a walkie-talkie.
Hey, now are secreted in a metal box that could add some serious firepower to your pedalboard. Life comes at you fast when you’re an NOS germanium pulse detector diode.
Every guitar effects pedal designer worth their salt wants to get their hands on a stash of NOS germanium transistors. Great Eastern’s David Greeves is no different. The whole idea behind his Obsolete Devices series is he finds a cache of OOP parts and then designs something with them.
“These rare and unusual components lead the design process,” he explains. ““Instead of starting with a particular sound or concept of what I want the pedal to do and then figuring out how to get there, it’s more a case of looking at a particular transistor or diode and asking, how can I make this really sing?”
Greeves found a box of 500 the D312A diodes. It was time to cook. What he came up with was not going to stretch this supply out but it does mean he’s got a distortion circuit that behaves exactly how he wants it do.
“I’ve always loved this kind of hard-clipping circuit as it’s really responsive to playing dynamics,” he says. “As soon as I tried three of these diodes in an asymmetrical arrangement instead of two, I knew that was the way to go – even if it meant I couldn’t make as many pedals from the diodes I had!”
Yes, 500 diodes, three per pedal. That means he is only making 165 of these, and once they are gone they are gone. The pedal itself is a four-knob design with Level and Gain self-explanatory, and Frequency and Depth where the magic of this circuit really lies. After all, it’s one thing finding these NOS components but it’s what you do with them that counts.
If the DOD and MXR units were a ballpark inspiration for the kind of hard-clipping drive Greeves wanted to produce, he would take the idea and run with it, adding a band-pass filter that allows players to select a frequency and wail on it.
“To my ears, these diodes have this incredibly expressive quality in the mid-range,” he says. “I’ve described it as ‘vocal’ or ‘vowel-like’ – a sort of roundness and singing character to bends and sustained notes. I wanted to draw that out even more by incorporating a wah-style filter that you could set to emphasise a particular frequency.”
The press materials mention the Queens Of The Stone Age sound, and that’s a good shout, but whenever you think cocked-wah, you think Mick Ronson and Michael Schenker, and maybe even Frank Zappa and Pete Townshend.
As anyone who has parked a wah pedal’s treadle in a fixed position will tell you, it will tease out some more harmonic content and can be just as effective for rhythm as it is for leads.
Definitely more interesting than a common or garden variety tone knob (not that there’s anything wrong with that), more imaginative than just a straight-up clone of an old design, and the kind of pedal we should expect from the designer behind the superlative Focus Fuzz.
The Distortion Filter D312A is available now, priced £249/$319. See Great Eastern FX for more details.
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