"Any Electrostatic Headphone Fan Needs to Grab One!"
iFi Audio's Pro iESL headphone amplifier excels at driving electrostatic headphones. Its defining characteristics are transparency and an ultra-wide dynamic range that is totally natural.
""I was very impressed with the iESL. It benefitted dramatically from a lowering of noise which opens up the upper midrange frequencies to new and complex detail… the iESL is packed with value too,"" raves Paul Rigby, The Audiophile Man. ""Any electrostatic headphone fan needs to grab one!""
""So much extra beauty bloomed with the Pro iESL. Thanks to the Pro iESL, you can now enjoy the best possible sound quality through electrostatic headphones,"" reports Poland's HiFi Philosophy.
Energize Your Electrostatics
Your electrostatic headphones are like a top-of-the-line Porsche. The Porsche engine requires a lot more power than your standard car. So do electrostatic headphones! They need to be 'charged' or more accurately, 'energized'. Traditional amplifiers do not deliver the either the EHT (extra-high tension) voltage or the required audio voltage that electrostatic headphones need, which is typically a maximum output of 300V.
The Pro iESL makes use of three core components: iFi's Pinstripe Permalloy Core Transformer, and a Capacitive Battery Power Supply with the Bias Voltage Generator. All of these components were developed using the very best classic approaches combined with the latest in cutting-edge technology, to deliver the 'perfectly matched' headphone experience.
Pinstripe Permalloy Core Transformer (PPCT)
Making a transformer with the wide bandwidth and low distortion needed in the iESL is very challenging. To attain this, the custom transformers used by iFi in its Audio Pinstripe Permalloy Core Transformer (PPCT) have complicated hand-wound, multi-section windings with both vertical and horizontal sectioning. They exceed the standards set by Siemans (Germany) and Peerless (USA). With a bandwidth of <5 Hz to >60 kHz (-3 dB), transformers in the iESL far exceed the requirements of even the JAS High-Res logo.
The unique transformer properties give the iESL an ear tingling transformer coupled-stage that is unsurpassed. So each and every flagship dynamic headphone when used through the iESL enjoys a whole new level of smoothness and airiness.
Capacitive Battery Power Supply
The Pro iESL's Capacitive Battery Power Supply is charged up to the required voltage and then the charger circuit is turned off completely, leaving the capacitor bank to 'float' at the required bias voltage. This results in an essentially perfect bias voltage source with no electronic noise whatsoever at any frequency. The headphones are, in essence, powered by the battery bank and not the mains.
Highest Quality Internal Components
The Pro iESl uses the highest quality internal components, including Wima Capacitors, which are perfectly suited for the capacitive power supply. These 1,000-volt rated capacitors are from Germany. The key is the very high insulation resistance and minimal current leakage, as any such leakage causes self-discharge. The whole capacitor pack has around 35,000,000 K Ohm insulation resistance, which means that the self-discharge time (to 30%) is around 100,000 seconds or 27 hours. So you are always listening on battery power, not AC mains power.
Vishay MELF resistors offer superior SMD resistor performance in terms of accuracy, stability, reliability, and pulse load capability. The cylindrical construction of MELF devices provides the optimal power rating and pulse load capability need for the iESL. MELF are more complex to make and therefore cost more. When assembling PCBs, MELF resistors require special machines and treatment. But iFi does not shy away from such complexities if it means higher component quality and ultimately far superior sonics.
