Cookie-Cutter ‘Sub-Sonic Filter’

Tom Evans who makes very nice phono stages made the following astute comment:

A rumble filter simply adds to the bass cut making your already “cut” records sound bass light. Plus, it “time-steps” the bass in relation to the higher frequencies (where our hearing is most sensitive) so much so it can confuse the ear into believing the bass is playing out of tempo.

iFi solution:

Since the very first iPHONO launched in 2012, we have used our own in-house ‘Subsonic Filter’. It made it into the iPHONO2 and the iPHONO3 and now, the ZEN Phono which is the very first time this filter is seen in such an affordable price level.

As there is only minimal vertical modulation remaining at very low frequencies with an an actual cut LP that is playable, we know that “vertical modulation” at low frequencies must be warp.

So we designed a filter to take advantage of this.

This is not artificial but real knowledge. By understanding fully how LPs are cut and replayed,  it is possible to filter record warp strongly without at the same time attenuating low bass or adding group delay.

GND Defender
GND Defender
GND Defender from iFi audio
GND control.

Take out speaker hum.

Ground control to Major components.

The optimum configuration for each system is one Ground/Earth for the whole system. If a system has multiple Grounds/Earths, then it often creates unwanted ground loops. These systems will then have an annoying low-frequency hum (emitted from the speakers).

Current solutions either jeopardise (i) both safety and EMI shielding (e.g. cheater plug), or (ii) EMI shielding. And most are single country (US) uses only.

The GND Defender in the correct way, intelligently detects a ground loop and will cut the ground for that component.

AI ground detection.

With a GND Defender at the IEC power input, it will intelligently detect and remove the ground loop at the component.

Behind this, the GND Defender:

  • Intelligently breaks DC ground loops to eliminate ground loop hum
  • EMI shielding is retained
  • Equipment Safety is unaffected (not a ground lift – so maintains equipment safety ground)

If multiple ground loops exist, more than one GND Defender may be required.

The GND Defender is smarter than the average ground lift. By a long way.

GND Defender from iFi audio

Battleship build.

The GND Defender is not only at the cutting-edge in terms of technology but also safety:

  • High-performance glass passivated semiconductor
  • High Case Dielectric Strength of 1500VRMS UL Listed
  • X7R Capacitor
  • High-temperature stability
  • Flame resistant IEC socket/connector/chassis
  • Fireproof polymers UL94-V0

Remember that best practice is to always keep at least one direct power cable connection.

Surge overload rating of 220A. With a maximum rating >10A, continuous current rating 7A, it handles all voltages around the world from 90-240V.

Intelligently block DC voltages from the mains to eliminate transformer hum. Equipment safety is unaffected.

EMI shielding is retained.

Support

AI Ground DetectionEach unit will automatically disconnect the ground on that device
Ground SafeAuto reinstatement of ground connection to pass current if a fault is detected
Voltage rating90 – 240 volts
Surge overload rating220A
Continuous current rating10A (1100W – 2400W)
Universal IECHospital-grade IEC connectors
Dimensions68 x 37 x 32 mm / 2.7” x 1.5” x 1.3”
Weight61g / 2.2oz

Reviews

Great product – it solved a back to earth brilliantly

Produced perfectly in line with expectations, it solved a ground loop that was affecting my sub very well. I had already tried to solve differently but without success, with this simple device the problem is gone.

(Click name to read original review)
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