Noise is an inherent characteristic of any electrical component that is also found in audio interfaces, DJ controllers and headphones. Some devices produce less noise, while other devices produce more noise, which can arise within the device itself and/or from external sources, including USB interfaces, cables and power supplies.
Identifying the source of the noise can sometimes be tricky, which can mean having to try out different solutions. Fixing a loud buzz in the USB signal or ground loop from a motherboard or DAC can be addressed easily and affordably with a USB audio noise eliminator such as the iFi iSilencer+ and iDefender+.
Using SPDIF over optical connection is another way to break ground loops, although this workaround won't, obviously, work if the device doesn't have an SPDIF port. For audio interfaces, DJ controllers, headphones and DACs, the iFi iSilencer+ and iDefender+ are a good working alternative for filtering noise, while improving audio quality.
The "plus" symbol indicates that the iFi iSilencer+ and iDefender+ are upgraded versions of the previous - iSilencer3.0 and iDefender3.0, although it appears the iSilencer+ and iDefender+ might be intended as replacements since the iSilencer3.0 and iDefender3.0 are currently unavailable to buy.
The iSilencer+ and iDefender+ models integrate upgraded capacitors, which are now low-ESR tantalum capacitors, which seems to suggest the previous iSilencer3.0 and iDefender3.0 may have been using high ESR capacitors, which produce more heat and ripple voltage; hence decreasing the input and output filtering performance. The ESR rating is not included on the specs of the iSilencer+ and iDefender+ but a good ESR value for a capacitor is between 0.01 and 0.1 ohms.
Externally, the iSilencer+ and iDefender+ retain the same design with rubberized hard plastic outer shell and blue Standard-A USB, gold plated connectors. The wiring specification is the same too, using ‘SuperSpeed’ USB 3.0, which provides data transfer speeds of up to 5 Gbit/s (625 MB/s).
iSilencer+ integrates the same Active Noise Cancellation chip found in the previous model, which increases signal-to-noise ratio by dropping the noise down to 40dB, removing RFI/EMI noise and maximizing audio signal quality in the process.
The external design of iDefender+ has also been kept the same minus the 5V port for the power supply, which is now a USB-C port, instead of micro USB. The external power supply port is a useful addition for powering a USB DAC with clean electricity. A power adapter is not included but you can use any (ideally one with a 5V/2A rating) or you can buy the iPower low noise power adapter, which has a 10uV noise floor.
Both iSilencer+ and iDefender+ are also sold with different connector types so, you can use them with different devices such as a smartphone, computer or DAC. The connector types pictured on this review are USB-A to USB-A, which allows you to listen to audio from the USB-A port of a computer via a pair of USB headphones.
The USB-A connector terminal on both the iSilencer+ and iDefender+ supports both USB 3.0 and USB 2.0 connectivity; hence they will work with both USB 2.0 ports and USB 3.0 ports. While USB 3.0 has greater bandwidth (faster data transfer), the round-trip latency is the same as USB 2.0.
There is a DC to USB-C cable adapter included in the iDefender+ box. The included cord adapter cable has a female barrel jack plug to male USB-C jack with a short cord. The cord has the following specification written on the sleeve: 300V 22AWG CR1 AWM Type I A FTI.
The specification on the cable, essentially, means that the cable adapter uses 22 AWG - american wire gauge - covered with a PVC insulation sleeve that can withstand 80 degree Celsius temperature. The cable is designed for low amp devices; hence the 300V (volts pressure) rating on the cable, which is worth knowing if you plan to use this adapter for a different purpose since it won't be safe to use with high amp devices.
Both iSilencer+ and iDefender+ do the job they claim when used as intended to remove ground loop interference from a USB port and making music sound better by lowering ground floor and increasing the volume of the audio signal, which improves the overall frequency response.
These solutions won't work if the issue is coming from a "dirty" power supply so, it's worth checking this if you are using an external audio interface like a mic preamp or USB mixer powered by an external power supply. When using iDefender+, it does require the use of a 5V power adapter if you want to see a noticeable improvement. The iSilencer+ and iDefender+ are available to buy from iFi Audio amazon store.