Cayin N3 Ultra (Pre-Order)

Cayin N3 Ultra Vacuum Tube DAP

Gen3 Vacuum Tube Circuit

This is our second DAP using JAN6418. The N3Pro was our first attempt and we have spent a lot of effort to install a pair of JAN6418 into a relatively compact DAP chassis. Unfortunately, we need to accept the following two limitations at the 2020 implementation:

• JAN6418 is a Subminiature Pentode tube; we need a pair for the stereo circuit, a set of 4 for the balanced circuit. Since we can only install a pair of JAN6418 in N3Pro, the tube timber circuit can only facilitate single-ended phone out, the balanced phone out is solid-state only.
• While we have passed down the Suspension installation technique from N8 to N3Pro, the filament of JAN6418 is a lot more sensitive to vibration when compared to the LED filament in Nutube, so the N3Pro is optimized for some scenarios but still suffers from ringing in other scenarios such as knocking on DAP, holding the DAP and then place it on a table or knocking on the table when DAP is placed on it.

With 4 years of portable vacuum tube R&D in our arms (since N3Pro) and the Gen3 Vacuum tube circuit after N30LE, we have improved the JAN6418 implementation by

1.Anti-shock Anti-vibration Installation

A newly designed custom-built shock absorption silicon housing that enables vertical suspended mounting. We incur this design from N8ii and provided significantly improved shock and vibration absorption. You can now shake it, tab on it, and even run around with it, the ringing effect is very minimal even with sensitive IEM. Make sure you try this in CanJam New York if you have the opportunity.

The 2024 version JAN6418 installation involved a custom-designed CNC-machined center frame, revised shock absorption silicone housings that provided better protection to each JAN6418 independently, and a “screwless” vertical-mounted installation.

2.Balanced phone output with two JAN6418

How can this be done? This is technically impossible, so we cheated. The DAC circuit and headphone amplification circuit of N3Ultra are fully differentiated but the timbre circuit, since we are using a pair of JAN6418 only, is singled-ended. We need to perform Balanced to Single-end before the timbre circuit, and Single-ended to Balanced after the timbre circuit. While N3Ultra is not a fully differentiated design from source to output, we have included some serious engineering to handle the correction properly. We are so confident that we even explain the constraint in advance.

Can we install four JAN6418 into N3Ultra to achieve a genuine fully-balanced design? This will involve more space and we can easily achieve that by increasing the width of N3Pro by 10mm. Unfortunately, using a quad-set of JAN6418 will consume more power, shorten the duration, generate more heat, and increase background noise, those are the real problems that stop us from using four JAN6418 in U3Ultra.

3.JAN6418 as Voltage Amplifier

The N3Pro employs JAN6418 as a buffer in its timbre circuit, it offers beautiful tube sonic characteristics to single-ended phone output. The Gen3 Vacuum Tube Circuit delivers a fuller tube sound to both single-ended and balanced phone out and lines out of the DAP, and we need a stronger output from the timbre circuit to achieve this goal, the JAN6418 is not connected as a low gain voltage amplifier in N3Ultra and we added a FET buffer immediately after the JAN6418 to enhance the output. Last but not least, since JAN6418 is a Pentode tube, we can connect it in triode and ultra-linear modes and use them as Classic and Modern tube timbre respectively. If you have heard the dual tube timbre of N30LE, you’ll be amazed that this is a simple circuit design that can achieve a similar dual timbre effect cost-effectively.

DAC circuit

The N3Ultra uses two pieces of AK4493S from AKM as DAC. A powerful FPGA has enabled the DAC can decode up to 32bit 768kHz in PCM, and 22.5792MHz (DSD512) in DSD.

Parametric EQ

This is a feature that has been on our To-Do List for several years. Yes, we heard you, and late is better than never.

We are still working on the PMEQ UI so the final control might be slightly different from the screen photo I showed below. You can add up to FIVE bands in the PMEQ section, each band is equivalent to a digital filter that enables you to shape the sound output of the DAP. To properly specify the characteristic of each band (filter), you need to specific

• Frequency: the center frequency that you want to apply the adjustment in each band (filter)
• Q: the ratio of center frequency to bandwidth, and when you fix the center frequency, then bandwidth is inversely proportional to Q, meaning that as you raise the Q, you narrow the bandwidth.
• Gain: control the aptitude (boost or cut) for the center frequency specified in each band (filter)
• Type: Choice of three types: Low Shelf, Peaking, and High Shelf
• Enable or Disable a particular band, this will allow you to hear the difference of one particular band (with or without) specifically.

The Low shelf is typically the left-most (bass) frequency that you want to adjust, and the High shelf is the right-most (treble) frequency that you want to achieve, and the remaining bands should defined as peak type. The low-shelf filters and high-shelf filters act like a Low pass filter (LPF) and a high pass filter (HPF) respectively, but shelf filters can be used for boosting and cuts in the gain setting, while the pass filters can only be used for cuts.

As you set up the bands, the implication of each set will be stimulated in the FR graph above the band controls. This will help you to visualize the effect of your PMEQ settings.

System Configuration
The N3Ultra is powered by a Snapdragon CPU and operated under Android 8.1. While the system hardware is capable of running common music-related applications, the JAN6418 vacuum tube is extremely sensitive to wireless interference. We can’t quantify the difference between JAN6418 and, for example, the KORG Nutube 6P1 scientifically, but saying the JAN6418 is 10 times more sensitive is a conservative guess in our experience, and yet Cayin is probably the most experienced team on this issue in the portable audio industry. As a result, we make the N3Ultra puritans DAP without Wi-Fi or Bluetooth capability.
Can we include a WiFi feature and direct our users to use Wi-Fi while the DAP is not playing back? Yes, been there, and done that with the original N8, we received lots of user complaints over the years, and occasionally returned machines for warranty and repair service simply because users forgot to turn off the WiFi after turning on the WiFi "accidentally" or after the OTA firmware update.
Can we remove the WiFi feature and keep Bluetooth for wireless DAC? Yes, been there, and done that with the N3Pro, and we received user complaints that their sensitive IEM can’t use the wireless DAC features because of Bluetooth interference, in their opinion, when we provide the feature, we have the responsibility to make it workable for everyone.
From a business perspective, we want to sell more N3Ultra, and adding streaming support is the way to go, especially when we have the hardware and operating system to do just that. This is a tough decision because we are limiting streaming support through USB DAC only, but this is our choice to become a responsible brand. If we can’t provide noise-free streaming, we better take that feature away and make sure the JAN6418 timber circuit is performing satisfactorily.