Inside the L3 – Design and Measurements
Design
The L3’s been in the works for a while now. In fact, before the original L5 was ever listed on the market, we were already in the process of hand soldering together an early test unit of the L3.
All three of our players use a 6-layer PCB stackup. The L3 and L5 Pro share many internal components, while also maintaining the same digital circuit architecture.
In our opinion, an important step of creating a high quality DAP is to separate the digital and analog signals cleanly. Digital circuitry is very noisy, whereas analog circuitry is vulnerable to noise. We accomplish this with different approaches in each of the devices.
In the LP5’s PCBA, the device separates the two parts, specifically in that the top half of the PCB is a digital circuit while the bottom half consists of the analog circuits. Between the two is a ground plane.
The L5 implements this slightly differently. One entire side of the board is completely digital, while the other is entirely analog, and the wires are kept apart by a ground plane.
The L3 is designed specifically for use with sensitive IEMs, and the most important thing is design a device that maintains a jet black background free of noise. Because the L3 has a smaller area to work with, the circuits on the device are all on one side of the board. To avoid interference between the digital and analog circuits, we implemented a similar design to the LP5’s vertical division with multiple ground planes: There are two layers of ground plane in the digital circuits that help block interference, and three layers of ground planes in the analog circuits. In addition, the analog portion is shielded so that there’s no chance of external interference.
Measurements
Let’s start this section off by saying measurements don’t tell the whole story. Numbers are just a part of the whole, and having impressive measurements doesn’t ensure that the music you hear from a digital audio player will be reproduced faithfully.
But relying only on subjective impressions without any insight into how a device measures would just be taking a complete stab in the dark. We prefer to marry the two – design something that doesn’t have any glaring measurement issues, but also sounds good to our team’s ears.
3.5mm unbalanced SNR
3.5mm unbalanced THD
2.5mm balanced amplitude
2.5mm balanced SNR
Re: DAC Chip Choice
If you compare the signal to noise ratio spec-wise to other high end players, the L3 isn’t best in grade. There are chips on the market that measure better than the CS4398, notably (and one that was previously up for consideration) the ES9018.
Here’s where human subjective impressions came in. The team didn’t like the SABRE house sound in the player, and thought that the DAC chip that was finally implemented (CS4398) was the one that made the player sound the most open and natural.
