ICF (In-Cable Filter) looks as regular eurorack power ribbon cable, but really it's not like any other cable. At
the middle of its length there's LC filter inserted, which cleans up a lot of noise and ripple from
power bus board, more efficiently than NKP. Not to mention Swiss-made plugs and thicker than
usual, 26AWG wires. It can isolate sensitive module from noisy power bus, or noisy
module from the rest of the system. It also minimizes ripple on entire power distribution board if it's the kind of low impedance bus like for example
POWDIS, although NKP being slightly more efficient at higher frequencies.
Here are few examples from spectrum analyzer. Because it's ribbon cable of about 30cm, there's
no point in measuring it over wide spectrum, because above 300MHz its characteristics are mostly
determined by the shape of the cable, and usually power cables in eurorack cabinet are twisted in
every imaginable way. And besides, even if we provide possibly the cleanest power at the bus,
there's always the cable going to the module that can easily pick any electromagnetic interference.
So attenuation of high frequencies should be really provided on the module itself, which sadly is
not the case most of the times.
All measurements are normalized to regular ribbon cable of the same length, with the same plugs
and same 26AWG wire.
Here's overall look at 300MHz bandwidth of ICF. Two notches at higher end are caused by nonperfect test environment, and the ribbon cable acting as additional rosonators.
With better setup it might be possible to make measurements over higher bandwidth, but as mentioned earlier, this will all be invalid in real world use of ICF.
A closeup at 30MHz bandwidth. Attenuation at 30MHz is lower than in case of NKP, by about 5dB
Again, slightly less attenuation than NKP, although lower end attenuation clearly starts to appear
as in favor of ICF
This is where ICF starts to kick in. Between 70 to 80 dB attenuation in most of the 300kHz
bandwidth! While NKP can go only up to 40-55dB.
NKP and ICF are made to keep the noise and ripple low on any system when needed, either
because noisy modules, or noisy power sources. They are somewhat different in operation, NKP
being better at higher end, and ICF at lower end. So it seems that the best results can be achieved
combining their features. It is possible and of course we did that too! Here are the results of ICF
plugged to NKP, this time for 5MHz bandwidth showing good few dB improvement:
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