Stylophone CPM DF-8: Ridiculously Fun Filter – Review
From filter freak fun to modular madness, all in one affordable black box!
1,5 / 5,0 | 
Stylophone’s CPM DF-8 is a standalone and Eurorack-ready dual filter unit with eight filter types, envelopes, VCAs and effects. It’s flexible, affordable, and way more fun than it has any right to be. And no stylus in sight!
Stylophone CPM DF-8 Review
Stylophone CPM DF-8: The Highlights
- Two analog filter channels
- Eight filter types per channel (lowpass, bandpass, highpass, notch, bandstop)
Two ADSR envelopes with linear and exponential curves - Two looping Ar envelopes
- Four envelope trigger modes
- Two VCAs with envelope inverters
- Two white noise generators
- Sample and hold with adjustable slew
- PT2399 lo-fi delay with modulation
- 14 modular Patch Points
- Stereo outputs
- Built-in 2W speaker
Stylophone Compact Portable Modular
If you had told me a few years ago that Stylophone would transform into one of the more interesting brands in the synthesizer world, I would have suggested that you give the edibles a break. And yet here we are, with the company most famous for its toy-like and stylus-equipped instruments having now released not only a theremin but two Eurorack-ready modules from its Compact Portable Modular (CPM) series – with nary a stylus in sight.
The first to come out was the CPM DS-2. A dual oscillator drone synth with effects and modular patch points, it announced that an established company was heading in a bold new direction. And that glorious, military-style design, like a Polivoks crossed with a field radio. Or something. I’m not in the military. But you get my point. It’s decidedly non-Stylophone, and about the only thing that betrays its lineage is the onboard speaker and the fact that it takes batteries.
Now we’ve finally got our hands on the next entry in the CPM series, a dual analog filter device called CPM DF-8 that can be both companion to the DS-2 and its own thing. And while the most obvious use-case is as a filter unit, the fact that it has white noise generators and VCAs means you could even use it as an experimental sound device on its own (much like you can the dronetastic DS-2).
But is it any good? Very much so, and in many different ways. Here’s why.
The Filters
The logical place to start with the CPM DF-8 is the filters. There are two filter sections, Filter I and Filter II, each with identical parameters. The star is the filter itself, or should I say filters, as there are two types and each is multimode.
The first is the Gen R-8 type based on the circuit from Stylophone’s unique (and now sadly discontinued) Gen-R-8 synthesizer. This is a 12dB/Oct filter with selectable lowpass, bandpass, highpass, and notch modes. They’re all lovely and characterful, with resonance that isn’t afraid to self-oscillate.
The other filter circuit is the 2045, a reproduction of the SSM2045 as found in the Sequential Circuits Pro-One, Elka Synthex, and many others, but is probably most famous for its inclusion in the Mutronics Mutator, the filter unit favored by Daft Punk, and the sound of French touch filter house records of the 1990s. To extend the range of the 24dB/Oct lowpass, Stylophone has created additional modes that combine it with the Gen-R-8 highpass into bandpass+, notch+, and bandstop+ modes, each with two distinct filter peaks. These are all beautiful and fairly unique-sounding, and really make this unit something special.
Envelopes, Gates and VCAs
Along with the two filters, the CPM DF-8 gives you two envelopes. There’s the standard ADSR (controllable with knobs) plus an additional looping AR mode that can pull double-duty as an LFO (as there is no dedicated low frequency oscillator). You also get a switch to change between linear and exponential curves for the envelopes. Looping envelopes and different curve shapes? This is seriously nerdy stuff and very surprising for a Stylophone device – and I love it.
Envelope I affects Filter I, and Envelope II, Filter II. You can adjust the envelope depth on each filter both positively and negatively, and you can inverse the envelope from the get-go. You can even patch the envelopes out. Very flexible.
In terms of gates, the DF-8 lets you trigger the envelopes from external sources via the patchpoints, via a threshold based on incoming audio, or by pressing a manual trigger button. You can also control the VCA from an external source, or turn the envelope off and leave the VCA wide open.
S&H, Delay and Stereo
With its two filter channels and variety of envelopes and gate triggers, you’re probably starting to see how the CPM DF-8 can be used. There’s more, though. Somewhat surprisingly, this little black box also boasts a sample and hold circuit, with rate and source selection, either noise or the two envelopes. Interestingly, you also get a slew knob to flatten the effect, something that is not so common on modern synths but very welcome indeed. You can sync the S&H to an external signal and patch it out to control a different module or synth.
As with the DS-2, the DF-8 also has an effects section, although there’s no reverb, just the delay. I say “just,” but this is the same PT2399 lo-fi delay as the DS-2, the one originally developed for karaoke machines. It’s crusty and crunchy and adds bags of character to the already characterful filter sound. You can adjust the time and feedback (called repeats here), plus sync the modulation to either Envelope II or the S&H for additional rhythmic spankings.
Lastly, you can configure the CPM DF-8 to work in either mono or stereo modes, the latter panning each filter hard left and right (with the delay centered).
In Use
To put the CPM DF-8 through its paces, I grabbed my trusty Korg Volca Drum, which I use whenever I need to test a new mixer or effects unit. The DF-8 includes a variety of mini jack cables for patching, including two that you don’t usually get standard, a splitter and an attenuator cable, so I didn’t even need to reach into my bag of cords. I set it up on the floor, patched the two battery-powered devices together, and was instantly transported to a land of furious filter fun.
I used the splitter to get the Drum’s audio into both Filter I and Filter II, trying combinations of gate triggering via the Drum’s sync, and envelope following courtesy the DF-8’s audio threshold. With two filters, two envelopes (oh, those looping ARs!), sample and hold, and delay, there’s plenty here to play with. Before I knew it, I had entered a realm of audio madness.
I haven’t really mentioned the noise circuits yet. There’s a noise generator as part of each filter, and dialing them in adds additional percussive flavor. I also used it to accentuate the S&H, cranking the resonance and lowering the cutoff to bring out the pingy telemetry sounds. To bring some semblance of order back, I coupled the envelopes, syncing them both to Envelope I, and linked cutoffs as well.
What a blast.
In Conclusion
Stylophone’s CPM DF-8 is a real winner. While the DS-2 drone synth might be a little esoteric for some tastes, DF-8 has a much broader appeal. Even if you only ever used it as a stereo filter effects unit, it would still be worth the entry price. Especially with those 2045 filters. But it’s much more than that. It’s packed with lots of clever little things that encourage experimentation, particularly for rhythm. And the DS-2 really comes alive when you pair it with the CPM DF-8, turning the combination into two complete synth voices.
Newbies to modular synthesis will love it because it allows for patching and exploration without having to commit to a full Eurorack rig, although you will need a controller with CV and gate to get the most out of the pair. MIDI wouldn’t have gone amiss, but there’s only so much you can pack into one device. Honestly, I could have done without the speaker if it meant getting MIDI instead.
Overall, CPM DF-8 is a wonderful machine. Playing with it, I was taken back to the ‘90s and the age of hardware filter units, but also into uncharted territory thanks to its many odd and unusual quirks.
I still can’t get over the fact that this is a Stylophone instrument. I can’t wait to see what’s next in the CPM lineup.
Pros and Cons
Pros
- Eight filter modes and they’re all beautiful
- Both ADSR and looping AR envelopes
- Onboard noise makes it into a sound source in its own right
- Crusty lo-fi delay
- S&H takes things into outer space
- Use it to control external devices
- Very flexible
Cons
- No MIDI
- Speaker is neat to have but not particularly useful
Pricing and Availability
Stylophone’s CMP DF-8 is available from Thomann* for $249 / £229 / €259.
More Information
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