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What is the Sound of Shadows?

The Sound of Shadows (SoS) is a voltage-controlled (VC) digital delay module based around the PT2399 echo IC1 from Princeton Technology – which was, by the way, originally designed for Karaoke equipment.

The SoS is essentially two separate modules: a delay and a voltage-controlled amplifier (VCA). The focus of the SoS was the delay while the VCA was thrown in because half of an LM13700 IC was unused, so the VCA is very basic.

As with all f(h) products, the SoS was engineered towards maximizing functionality while keeping cost as low as possible. If some aspects of the unit seem awkward, it is most likely due to this. The goal is to make unique, useful, enjoyable, and affordable instruments, not just hoover2 out your bank account.

And remember: every instrument has its quirks and unexpected aspects, so RTFM! All the way through! Specific quirks are mentioned in the description of the particular feature they apply to, so please read this through before emailing!

*Details, samples, updates, and discussion can be found on the SoS thread on*

Technical specifications:

Supply Voltage ±12VDC
Supply Current (max draw @ ±12V) +12V: 51mA -12V: -21mA
Max. Input Voltage (@ ±12V) 10Vp-p
Max. Output Voltage 6Vp-p
Input & Ouput (I/O) coupling Direct*
Output Impedance 1kO
Control Voltage (CV) inputs ±Vsupply
CV input coupling Direct
CV input impedance 100kO
Mounting Depth 50mm (~2″)
Delay Length Min: ~31.3ms Max: ~342ms

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