ADDAC 607 Crossover ()
A three-way audio splitter with analog circuitry. It sits behind a lot of Eurorack mixes and rarely gets noticed.
Overview
The ADDAC 607 Crossover doesn't modulate and won't scream through your speakers. It takes up six HP. It's an analogue 3-band crossover that splits incoming audio into high, mid, and low frequency ranges, each with its own output. Send in a full-range signal and the 607 can route the lows to a sub synth, the mids to a vocoder, and the highs to a granular processor, all at once and all in analog. It lives in the ADDAC600 Series, a family of utility and processing modules built around clean signal manipulation. This isn't a filter for shaping tone. It's a tool for routing, effects splitting, or multi-amp setups within the rack. It doesn't resonate or sweep, and it works a bit like a mixing console's insert point, with modular patching on top.
ADDAC System is known for no-nonsense Eurorack designs, and the 607 is a utility module that doesn't skimp on quality. It has two audio inputs, so you can blend or switch sources before splitting. That's handy for live sets or layered processing chains. The sum master output gives you a recombined version of the processed signal, so you can monitor the full picture while still sending isolated bands elsewhere. That's a lot of flexibility for such a narrow panel.
Specifications
| Type | Analogue 3-band crossover |
| Filter type | 12 dB Sallen-Key filter |
| Controls | Volume controls for high range, mid range and low range |
| Switchable crossover frequencies | 2 kHz, 4 kHz, 8 kHz (high range) and 370 Hz, 620 Hz, 1 kHz (low range) |
| Inputs | Two audio inputs |
| Outputs | Sum master output; Outputs for high range, mid range and low range |
| Power requirement | 60 mA (+12 V) / 60 mA (-12 V) |
| Width | 6 HP |
| Depth | 45 mm |
| Price | €299 |
Key Features
Three-Band Frequency Splitting
The 607 divides audio into three bands using a pair of switchable crossover points. The low-range crossover offers 370 Hz, 620 Hz, or 1 kHz, which suits separating sub-bass from punchy mid-bass. The high-range crossover offers 2 kHz, 4 kHz, or 8 kHz, so you can isolate presence, articulation, or sibilance. The points aren't continuously variable, but the stepped options cover most practical needs, from musical tone shaping to technical routing. The result is three clean bands that are non-overlapping or minimally overlapping, each at its own output. That lets you send different parts of the spectrum to different effects, like distorting the highs, compressing the mids, and leaving the lows alone.
Sallen-Key Filter Topology
The 607 uses a 12 dB/octave Sallen-Key filter design, known for its stability, low noise, and smooth phase response. Unlike resonant state-variable filters, the Sallen-Key circuits here are used only for clean frequency separation, not tone shaping. Coloration is minimal. What goes in comes out, just sorted. The 12 dB slope is steep enough to prevent bleed but gentle enough to avoid the phase artifacts that can plague higher-order designs.
Independent Level Control Per Band
Each frequency band - high, mid, and low - has its own volume control. You need these for balancing the outputs when routing to different destinations. Maybe your high-frequency processor needs less signal, or your sub oscillator is too dominant. The knobs let you adjust each path without touching the source. Combined with the sum master output, you can change individual levels while still monitoring the full mix.
Dual Inputs and Full Signal Access
With two audio inputs, the 607 can handle stereo sources or let you switch between signals on the fly. Because it has a sum master output, you keep access to the original signal, just processed and recombined. That helps for A/B comparisons or for feeding a main mix while still processing bands separately.
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