|
Further, Gain is adjustable from 0dB/9dB/18dB. The Pro iCAN can output >10V in Single-Ended mode and 20V in Balanced-mode. The 20V mode is equivalent 100W into a 4 Ohm speaker. So the Pro iCAN can drive almost any headphone into very hard-clipping (protection circuitry typically kicks in under such circumstances). |
|
|
|
|
…and audiophile line-stage.
The Pro iCAN has at the core, a Japan Alps motorised rotary volume potentiometer. This is the ‘6-Track’ version with 4 tracks used for a true balanced volume control. This is the litmus test for any amplifier to see if it is truly balanced, or operates internally in single-ended mode. Those using ‘2-Track’ volume controls may offer balanced in and out, but are not true balanced designs. The Pro iCAN however is fully-balanced from beginning to end.
|
|
|
|
|
In terms of flexibility, 3 single-ended and 1 balanced inputs and 1 balanced and 1 single-ended output, the Pro iCAN is a full-function audiophile line-stage that is at home in many expensive hi-fi systems. Its user-selectable Solid-State/Tube amplifiers remain and so are 3D Holographic˚ for Speakers and XBass˚ for ultra-fidelity home audio systems. |
|
|
|
|
True Differential Balanced®
At the upper end of the headphone amplifier market, despite the best protestations of ‘balanced’ things are not always what they seem. This is a curious case of ‘Is balance balanced?’
For headphones, it DOES make good design sense to implement a balanced topology (the possibility of higher power, increase dynamic range and lower noise etc.) It goes without saying that the balanced design should be balanced all the way through, ‘end-to-end.’
|
|
1. The typical so-called ‘Balanced’ headphone amplifier
The majority of ‘balanced’ high-ended headphone amplifiers are actually single-ended amplifiers with balanced inputs and outputs. The balanced input will be converted into single-ended operation inside the amplifier, then converted back to balanced just before the output:
The following block diagram depicts the balanced input through to the amplifier (orange) which afterwards, reverts to single-ended and runs through many single-ended stages before then going to the balanced outputs.
|
|
|
|
In detail: The balanced input signal will first be converted into single-ended operation by extra circuitry added to the single-ended signal path. The volume control and actual headphone amplifier are formed by a pure, single-ended circuit.
To provide balanced drive to the headphone, the signal is inverted using more circuitry added to the single-ended audio path.
A sure fire giveaway of such circuitry is the use of a 2-Deck volume control (c.f. 4-Deck for true balanced circuitry), as well as having more than four gain/current buffer blocks among two channels.
At the input, the additional balanced to single-ended conversion circuit generates extra noise on top of the volume control pot.
At the output, the inverter circuit used to create the balanced signal simply doubles the signal, noise and distortion of the amplifier, nothing is reduced or cancelled, only added. So one gets double the signal but also double the noise and distortion.
Hence this is truly a case where MORE IS LESS. There is much more circuitry, but far lesser performance, both objectively and subjectively.
|
|
|
2. True Differential Balanced® – Pro iCAN
The Pro iCAN however, is true balanced end-to-end, from the input all the way through to the outputs. It operates with full-differential internal signalling, meaning the signal is always remains two separate signals of equal level but opposite polarity. This is what we call True Differential Balanced®.
|
|
|
|
|
|
In detail: The Pro iCAN circuit is fully-balanced with completely equal circuit sections for Positive (Hot) and Negative (Cold) signal phase of each channel. The Volume control has 6-Decks, two decks each control the volume of one channel, and the other two decks are used for monitoring the volume control operation. This exceptional volume control potentiometer is custom made for iFi by ALPS Japan and has no parallel from other makers.
But, as the two halves of the volume control and the two halves of the amplification operate differentially, they effectively become a single stage. So the circuitry is highly elaborate in actual implementation, yet it comes down to the simplest design possible for a headphone amplifier, that is a volume control, a gain stage and a current buffer*.
Compared to a single-ended design with exactly the same circuit, True Differential Balanced® lowers noise by 3dB and also lowers THD dramatically over the. Additionally, it allows the signal level to be doubled, so True Differential Balanced® circuitry also produces 9dB (or 3 times) greater dynamic range.
Note: In professional audio, ‘Balanced Amplifier’ only means the Input/Output connections are balanced, the internal circuits are actually single-ended (if the internal circuit is also balanced, it will be called differential).
But in the Hi Fi world, most people view a ‘Balanced Amplifier’ as balanced all the way, from end-to-end, and incorrectly assume even the internal circuits are balanced.
|
|
|
|
|
Tube/ Solid-State Real-time Switching
Compared to high-end headphone amplifiers, the tube stage of the Pro iCAN is different in two-ways. First, we don’t use good-quality 6922s or similar. Instead we use the very best; General Electric 5670 which is the premium variant with a different pinout.
Second and just as important is the circuit design. Unlike other headphone amplifiers that have the same circuit and just switch in/out the tube section, the Pro iCAN is the very first of its kind that has two individual input circuits – one tube and one Solid-State. This results in the best sonics of both worlds because the signal path is the shortest and there is no compromise to ‘shoe horn’ the tubes into an already existing solid-state circuit.
For the first time, one can enjoy both the sound of Solid-State and Tubes in a single package (rather than as an ‘Effect Type’ add-on within an otherwise conventional solid-state design) and be able to switch in real-time. For some recordings and headphones/loudspeakers, Solid-State may sound ‘more lively.’. For others, Tube and Tube+ (especially Tube+) will sound more ‘luxurious.’ Select the one that sounds best for that particular moment, be it the recording, the mood or even the weather. After all, enjoying music is an experience to be savoured and not a scientific research exercise.
|
|
We haven’t stopped there. We are tube lovers and we appreciate sometimes there is a need for even more tube-like sound, there are two tube settings – Tube and Tube+. The Tube+ position reduces overall loop-gain and thus negative feedback to the minimum. This gives a different trade-off between the tube’s natural harmonics and the transient performance. |
|