Waldorf 4-Pole
A rack unit that does one thing. It filters anything you feed it, and it does it with the analog warmth digital filters kept chasing.
Overview
The pitch for the 4-Pole is simple. Take the 24 dB-per-octave lowpass filter out of Waldorf's Microwave and Wave, put it in its own box, and let people run any signal through it. Sound on Sound (June 1996, p.146) put the appeal this way: no matter how good digital filters had become, the old analog filter still had a certain something that stayed tantalisingly out of reach of the digital domain. That is the reason this unit exists, and the reason people still hunt for one.
The 4-Pole is a filter, not a synth. You patch audio in, shape it, and get the sound back out. The magazine coverage describes it as the Microwave/Wave 24 dB lowpass filter, freed from the instrument it was born in and offered as a standalone processor. If a favorite sampler or sample player lacked that special quality, you could give it a sonic boost through the 4-Pole. A lot of digital gear from the mid-'90s had functional filters that didn't sound like this.
The editing system is what makes the 4-Pole interesting to anyone who has programmed Waldorf gear. A letter to Sound on Sound (September 1996, p.12) took issue with the June review's description of the interface as awkward and tedious. The letter pointed out that the Pulse uses exactly the same editing system and that the 4-Pole is in fact more straightforward, with only 22 parameters available rather than the Pulse's 55. Whether you find it tedious depends on how much time you've put into Waldorf's menu-driven approach. Twenty-two parameters is not a lot. It's a filter with attitude, not a modular in a rack.
By late 1998, Sound on Sound (November 1998, p.52) was reviewing the D-Pole. It noted that the Microwave had set the scene back in 1989, the Wave followed in 1994, and the Pulse monosynth arrived in 1996. All three had excellent-sounding analog filter sections, and those made the company's reputation. The 4-Pole follows from that: if the filters are why people bought the synths, sell the filter on its own.
One practical limitation: the review notes that no wet/dry mix control is provided, though a Bypass button lets you switch the filter out quickly. It can be used as a channel insert (mono in, mono out), but doing so renders many of its stereo options redundant. It works best as a stereo processor rather than a mono insert. With no blend control, you're committing to the filtered signal rather than dialling in a taste of it.
For collectors, the 4-Pole sits in an odd niche. It isn't a synth, so it doesn't command synth money, but it is a piece of Waldorf's analog-filter lineage, built when the company was at the height of its reputation for filter design. The people who want one tend to want it for a specific job, like warming up a digital source or adding character to a sampler, rather than as a collectible to sit on a shelf.
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