E02 Fully Balanced Audio Motherboard
Cayin announced the E02 Audio Motherboard today (10 April 2020). This is the fourth Audio Motherboard for N6ii DAP with dual ES9038Q2M DA, fully balanced design, fully discrete headphone amplification and an unamplified, clean line out. The Audio Motherboard can decode upto 32Bit/384kHz and DSD256, and it will handle SACD-ISO and DST encoded directly.
Design and Features
The A01 and T01 are full-featured Audio Motherboard with versatile choice of outputs such as 3.5mm and 4.4mm phone out, and dedicated 3.5mm line out. From there on, we take a bit of risk and offered an Audio Motherboard with only ONE feature: ultimate single-ended headphone. We were skeptical whether this old-school “do one thing at a time and do it right” approach will work for the portable community, and we were overwhelmed by the response of media and users. So we shall continue our vision to offer ultimate solution for niche group users.
Inevitably, there are a lot of users preferred balanced amplification, some of them want to stick with their existing earphones (or aftermarket cables) that are terminated for balanced application. For this reason, we decided to develop an Audio Motherboard that share the same “best of the best” vision of E01 with fully differential design.
E02 deploys dual ES9038Q2M in mono mode (configured to current output), each DAC chipset decodes one channel independently. Since the complete circuit is in fully differential design, so we have installed 4-channels IV convertors, two dual channels LPF, two dual channels line drivers. The headphone amplification circuit is Cayin’s another ultimate solution for DAP users: 4 channels high power discrete components Class AB amplification.
Fully Discrete Balanced Headphone Amplification
We have implemented 4-channels, fully discrete, high power low noise headphone amplification circuit in E02 Audio Motherboard. The R&D effort to develop an discrete component based circuit is a lot more tedious and time consuming because that involve a lot of fine tuning to select and manipulate the operation parameters of each components. By adjusting the gain and operation current of the low-noise audio grade JFET (Junction gate Field-Effect Transistor) and BJT (Bipolar Junction Transistor), we have a lot of flexibility to tune the performance and sound signature of the circuit.
The E02 is rated at 600mW @32ohm loading, this is a lot of power for portable DAP, even higher than the corresponding output of A01 and T01. The N6ii (E02) can drive relatively demanding load, and handle complicated music with ease. Music with wide dynamic range will be reproduced with authority and amazing details. The outstanding frequency extension and transient, wide and holographic soundstage will offer a whole new experience on selected music genres.
Please be reminded that the JFET and BJT of E02 required 5-10 minutes (depends on room temperature and playback setting) to settle down in optimum operation condition. This is more or less a given requirement for discrete components based audio circuit.
A Line-level Balanced Line Out
As indicated in the block diagram below, the output from line driver is optimized for balanced line out. In fact, the balanced line out of E02 is the first 10kΩ output impedance unamplified balanced line out among N6ii Audio Motherboard lineup. This is significantly different from the balanced line out of A01 and T01, as they are merely fixed level output from amplified headphone output. If you intend to use N6ii as balanced line source for desktop or speaker-based audio system, or want to bundle N6ii with portable balanced headphone amplifier as “exotic” portable rig, the E02 is your long awaited solution.
Last but not least, the Line out of E02 is adjustable among 2.2V, 3.2V and 4.1V. The final 4.1V is the de facto standard and is the setting we recommend if you want to connect N6ii(E02) to most desktop audio products. We are aware that portable amplifiers span over a very wide range of amplification gain, and a lower line out level might better with these high gain high input sensitivity amplifiers, therefore we offer selectable line out level to enhance connectivity of E02.
Interchanging phone out and line out and setting output level of line out are available through pull down user manual.
Battery Duration and Specification
The suggested retail price of E02 is
US$419 and is available by 13 April 2020. Unfortunately we are facing major difficult in arranging shipment to our International dealers, there are serious delays in logistic all over the world right now, so the actual availability might vary, please consult your Cayin dealer for more detail.