4ms Ping
Two vactrol-based lowpass gates in one compact module—hit it with a trigger and it blooms, resonant and warm, like a filter that remembers how to breathe.
Overview
The 4ms Ping isn’t flashy, but it’s got soul. Slot it into your Eurorack case and you’ve got a dual resonant lowpass gate—two channels of smooth, organic filtering that respond to envelopes baked right into the circuit. It’s not an ADSR, not a VCF, not a delay; it’s a sonic doorway that opens and closes with a soft thump, letting sound pass through in pulses shaped by light and resistance. The magic happens in the vactrols: each channel uses one to couple the envelope and the filter, giving that slow, pillowy response that feels alive, almost vocal. You ping it with a trigger, and it sings back with a rounded, resonant sweep that’s hard to describe but impossible to ignore.
What makes the Ping special is how it integrates control. The PING input fires off the internal envelope, which then drives the lowpass gate—no patching needed for basic operation. Want to shape the tone? The CV input lets you modulate the cutoff frequency, so you can slide the brightness up or down in real time. The RES knob adjusts resonance, adding emphasis around the cutoff point, from a subtle bump to a pronounced ring that lingers after the note ends. And because the two channels are normalled together, you can run stereo signals or layered voices using just one set of controls—patch into the first channel and the second follows along unless you break the normalling with a cable. It’s simple, but smart: minimal patching for quick results, deep enough for nuanced sound design when you want to dig in.
This isn’t a module for precision sequencing or digital clarity. It’s for texture, for movement, for the kind of sound that feels like it’s breathing in time with your track. The vactrols introduce a slight lag, a softness in the attack and release that no transistor ladder can quite replicate. It’s the difference between a snare hit and a hand drum—both rhythmic, but one feels human. Use it to gate percussion, shape pads, or add pulse to drones, and you’ll find it slots in where other filters feel too rigid. It doesn’t scream for attention; it just makes everything it touches feel warmer, fuller, more present.
Specifications
| Manufacturer | 4ms |
| Width | 4 HP |
| Depth | 30mm |
| Power | +12V: 35mA, -12V: 0mA, +5V: 0mA |
| Input Impedance | 100k |
| Output Impedance | 1k |
| Max Output Level | +/-10V |
Key Features
Dual Resonant Lowpass Gates with Vactrol Response
At its core, the 4ms Ping is a pair of vactrol-based lowpass gates—each combining an envelope generator and a filter in one reactive path. When you send a trigger to the PING input, it activates the envelope, which then drives the vactrol to open the gate. The result is a smooth, natural-sounding amplitude and tonal shift, with the characteristic lag and bloom that vactrols are known for. Unlike hard-edged VCAs or fast VCFs, the Ping’s response feels rounded, almost acoustic—perfect for softening digital sources or adding organic movement to sequences. The resonance control (labeled RES) lets you dial in emphasis around the cutoff frequency, from a gentle warmth to a pronounced peak that can self-oscillate faintly under certain conditions, adding a subtle harmonic tail to each note.
Integrated Envelope Triggering and CV Control
The PING input is the heartbeat of the module. A single trigger—gate, clock, or manual press—starts the envelope cycle, opening the gate and shaping the sound in one motion. There’s no need to patch an external envelope; it’s built in, responsive, and tightly coupled to the filter. The CV input adds another dimension: patch in a control voltage to shift the cutoff frequency dynamically. This lets you modulate the brightness of the gated signal in real time—say, tracking a sequencer’s pitch or responding to an LFO for rhythmic filtering. Because the envelope and filter are linked through the vactrol, the modulation feels cohesive, not layered. It’s not just filtering a sound; it’s shaping how that sound emerges and fades, like turning a dimmer switch on a warm lamp.
Normaled Dual Channels for Flexible Patching
The two channels are normalled together, meaning the first channel’s PING and CV inputs feed directly into the second unless interrupted by a patch cable. This design lets you process stereo signals or double up on voices with minimal effort—ideal for live use or quick sketches. Break the normalling by plugging into the second channel’s inputs, and you’ve got two independent lowpass gates, each with their own trigger and CV response. The compact 4 HP width makes this dual functionality especially valuable in space-constrained racks. Despite its small footprint, the Ping doesn’t skimp on utility: it’s a full-featured dual processor that rewards both simplicity and exploration, whether you’re gating a pair of drum samples or running a bassline through both channels for extra thickness.
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