YULONG DA1: Flagship All-in-One with AK4499, 5W Class A BAL headphones and Pre-Amp
Mar 23, 2021 at 7:46 AM Thread Starter Post #1 of 49

YULONG Audio

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YULONG DA1 Sales Guide - 01.jpg


Product Detail

YULONG DA1 is our TOTL All-in-One for Personal and Home Audio applications. It can function as a DAC/preamplifier/head-amp independently or stack up with the optional 240W Power Station that we developed alongside the DA1 from the very beginning. The chassis of the DA1 Main unit and DA1 Power Station are CNC milled from solid aluminum alloy, the seamless case is elegant and solidly built, and they can disperse heat effectively to keep DA1 in an optimal operating condition.

We have dug deep into the AKM flagship 32-bit AK4499EQ DAC chipset and designed an exotic supporting circuity and power supply system from the ground up. We have also further improved our well-received proprietary Jitter and Control (JIC) FPGA solution. This will enhance audio performance by optimized data integrity, de-jitter, and minimized digital artifact before the digital signal transmits to the DAC chip. We passionately believe a high-quality DAC chipset will only be meaningful when the pre-conversion digital processing is also top-notch.

With both digital and analog inputs in place, YULONG DA1 can serve as your personal audio hub for varieties of applications. We have designed the circuitry independently and developed four different circuit switching modes to maximize the performance of the DA1. The analog section is a fully balanced design with discrete components. The Class A circuit can be configured as a headphone amplifier or pre-amplifier depending on the user application. The headphone amplifier offers an exceptional driving capability and can handle headphones with different impedance, sensitivity, and design. Rated at up to 5 watts per channel (at 32 Ohm), you can expect a stellar dynamic range and headroom, even when fed with a difficult load.

The DA1 measures exceptionally well, and it also sounds stunningly refined and musical because we have devoted a lot of resources to fine-tune the audio performance through repeated audition and modifications. We have also paid a lot of attention to small details. The DA1 operation is controlled intuitively through a single high precision probably damped volume knob. All playback and setting information are clearly displayed on the large IPS wide-angle LCD screen.

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Outstanding digital audio capability

  • Proprietary 4th generation high precision low tolerance YULONG Jitter and Interface Control (JIC) FPGA solution.
    • Receive and convert all input digital signals into low-jitter I2S bit-stream.
    • De-jitter by FIFO digital signal buffering while synchronizing with the built-in Femtosecond Oscillators.
    • Pulled in and locked the signal by a dual PLL;
    • Distribute and synchronize the signal and then output high-quality low-jitter I2S bit-stream through FIFO.
  • Design around AK4499EQ chipset with industry-leading 32Bit/768kHz and DSD512.
  • Independent circuit buffered with high output current and built by discrete components.
  • Cross-examined in numerous speaker and headphone sound systems to safeguard adaptability with different playback environments.
  • Choice of 1x or 2x Clock Sync to personalize sound signature.
  • Widely recognized XMOS XU208 solution with customized (with license) Thesycon driver to enhance sound quality and stability.
  • Choices of 3 digital filters to fine-tune your system for different music genres and personal preference.
  • USB Audio supports MS Windows, macOS, and Linux. Special attention to enhance support to Android and iOS mobile and tablet devices.

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State-of-the-art analogue implementation
  • Class A headphone amplification circuit composed of 12 high output audio grade power transistors, delivers up to 5 watts per channel output.​
  • Amplification circuit can switch over to become a very strong Class A preamplifier, ready for active speakers or power amplifiers with ease.
  • 99 steps digitally controlled analog volume for Preamp and headphone output.
  • Fully balanced design, low impedance DAC line output, high current preamp, and headphone amplification.
  • The main unit power supply is an in-house developed fully discrete voltage regulator circuit that provides constant current power supply to reference regulator, delivers outstanding transient current up to 15A, lots of headroom even at demanding condition.
  • Heavy-duty exotically built 240W external power supply to enhance the audio performance for the most demanding users.
Circuit Switching Modes

We have designed and laid out the circuitry independently in order to minimize the ripple effect and developed four different circuit switching modes to maximize the performance of the DA1 in different scenarios.
  • Pure DAC: When used as PURE DAC, the power supply to the headphone and preamplifier circuit will switch into parallel regulator automatically, this will maintain the circuit in optimal temperature and audio performance.
  • Pure Headphone Amplifier: When used in HEAD AMP mode, the pure DAC output will be switched off.
  • Pure Preamplifier: When switch to PRE-AMP mode, the headphone output, and DAC line-out circuit will be switched off, and the Class A amplification circuit will switch over to Class A preamplifier operation.
  • All-in-One: Best overall performance when all signals are optimized for internal distribution, minimize interconnects in your system, and reduce external interference significantly.

The suggested retail price of DA1 is US$2,499, and the DA1 Power Station is US$1,599. They can be purchased separately and are expected to available by end of April 2021.

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DA1 Functional Diagram.jpg


DA1 Specification FHD.jpg
 
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Mar 28, 2021 at 6:20 PM Post #4 of 49

project86

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I personally find this thing very intriguing. The massive outboard PSU will most certainly contribute to the overall SQ, and is beyond anything we've seen from Yulong before. I also love that buyers can stagger the expenditure by starting with the DAC and then later adding the upgraded power supply down the road. Makes the path to ownership more appealing.
 
Mar 29, 2021 at 9:33 AM Post #5 of 49

Slim1970

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This looks very intriguing Andy!
 
May 11, 2021 at 12:21 PM Post #7 of 49

YULONG Audio

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Always optimized is the essence of our product development, we want to make sure our users will always enjoy the best performance when they use our product. While it is important to design proper audio circuit and use high quality components, dedication and attention to detail is the key to get everything right.

Audiophile is not about using expensive equipment, it is an attitude to pursue best audio performance within our resource, and we follow through this concept wholeheartedly when we develop DA1.

YULONG DA1 Sales Guide - 07.jpg
 
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May 14, 2021 at 3:57 PM Post #8 of 49
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I have known YuLong, the founder of YULONG Audio for 8 years already, DAC has always been YULONG's core business. With a strong engineering background from communication industry, YuLong spend a lot of resource on testing and measurement since his early day in this industry. His emphasis was slightly different, while he wants to identify the weakest link and improve his product though measurement, and he'll also explore why some design didn't sound good but measured well.

I remember in one occasion when we sit down and review one of his prototype of a newly received DAC chipset, I noticed it was very different from the reference design he showed me earlier on. I asked what have been changed and did he improved the parameters significantly. To my surprised, the reference board measured better than the prototype by quite a bit. YuLong told me that the reference board was optimized to measure well at 1kHz, on the expense of below par performance at certain less obvious frequency range. It might looks good on paper but it didn't sound balanced when playback music. The first thing he do is to redesign the circuit to perform stably across the complete frequency range. His design might compromise on measurements when compare to reference design, but it will sound significantly better in real life.

On the other hand, we have discussed this same question over and over again: since there are very limited choice when come to high quality DAC chipset, so what makes our DAC better than DAC of other brands? Power Supply and Pre-DAC Digital to Digital processing were the two areas that YuLong has been focused in past few years, and for the later, he developed the Jitter and Interface Control (aka. JIC) FPGA solution.

JIC (Jitter and Interface Control)

This is YULONG's proprietary FPGA solution to enhance audio performance by optimized data integrity, de-jitter and minimized digital artefact before the digital audio signal transmits to the DAC chip. It is composed of the following process:
  1. Receive and convert all input digital signals into low-jitter I²S bit-stream.
  2. De-jitter by FIFO digital signal buffering while synchronizing with the built-in Femtosecond Oscillators.
  3. Pulled in and locked the signal by a dual PLL;
  4. Distribute and synchronize the signal and then output high-quality low-jitter I²S bit-stream through FIFO.

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YULONG started off with off-the-shelf solution in the pre-DAC processing of their earliest products, but when they improved their DAC handling and audio design in subsequent products, they feel the need to improve the Digital Audio processing BEFORE they feed the signal into DAC, especially when users are using less capable computer or mobile devices as their music source. They have noticed these high jitter music sources reduced the musicality of their DAC performance. Every so often when customers complaints the DAC sounds very “digital”, the quality of music source is frequent the focus of attention.

YULONG started to work out FPGA applications on pre-DAC processing since 2017 and by 2019, they have developed their first JIC (Jitter and Interface Control) FPGA solution. This is an accumulation our 15 years of digital audio experience and was first implemented in their reference DA10 All-in-One DAC headphone amplifier. They were amazed by the improvement over previous non-FPGA model (i.e., DA9). They have revised their JIC and passed down the technology to other products. The JIC in DA1 is their 4th generation FPGA and it improves the accuracy and compatibility of their algorithm in this revision.

Customers who have experienced our JIC-based product are all amazed by the natural sound signature, especially on the holographic soundstage. This is the technology that differentiate YULONG from other boutique audiophile DAC manufacturers.
 
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May 15, 2021 at 12:02 AM Post #10 of 49
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Thanks for the info Andy, definitely looks like DA1 is the "flagship" I've always hoped Yulong would design/release.

I know YuLong when I was an audiophile looking for a new DAC, and we maintained a close relationship after I joined Cayin and become his "indirect" competitor. Sometimes it's frustrated to discuss with YuLong because he is a very stubborn Engineer, always insist to solve a problem from the ground up, but seeing the DA1 develops from concept to a real flagship is an amazing experience.
 
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May 23, 2021 at 3:25 PM Post #13 of 49
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YULONG Reference System with DA1.jpg


Power is the foundation of High Fidelity Audio. This is a statement that experienced audiophiles will recognize from the bottom of their heart. After all, the game of high fidelity audio is ultimately transformation of electrical energy into sound wave.

YULONG Audio takes power supply seriously, not only as a commodity, but as an important lesson in their journey of audiophiles. They devoted a lot of resource to facilitate their audition room, and spent considerable effort and time to improve the power supply to the reference sound system. They have built a massive power distribution center to handle power supply for source, DAC, pre- and power amplifier separately. They have sourced different transformers and adopted it for different purpose in the power distribution centre.

Power Supply R&D.jpg

In the course of three years of continuous experiments, YULONG has accumulated a lot of experience in power supply optimization, and DA1 is the first platform where they can apply their knowledge and experience freely.

When YULONG planed for a new All-in-one flagship, power management was the top priority during product conceptualization. Among several alternatives proposed, two-box designed with outboard power supply was selected when YuLong was working on the supporting circuit for AK4499 DAC. This is the first time he work with current mode output of AKM DAC chipset and he has designed an 8 channels Current Voltage conversion circuit to cope with that. This complete DAC circuit was very demanding and sensitive to power supply, a properly designed, fully integrated All-in-One can meet all the power requirements of the circuit, but a high quality external power supply will certain bring out the best of the DA1.

The DA1 internal power supply employs a customized 50W toroidal transformer with a fully discrete voltage regulator circuit. It can provide constant current power supply to reference regulator, and delivers up to 15A current to the DA1 circuit. This is a very decent power supply to all-in-one headphone amplification, provides lot of headroom to the DAC and analogue audio circuit at demanding conditions.

DA1 Main Unit Power Supply.JPG

The external power supply is a big step from the internal power supply of the DA1 main unit, after all, high-end audio is about transformation of electrical energy to sound wave, so the most important upgrade of your DAC and amplifier is to upgrade the power supply.

The DA1 Power Station uses two bigger toroidal transformers to facilitate digital and analog power supply separately. Having the transformer and the discrete power supply circuit in a separated heavy duty CNC machined aluminum alloy chassis will also minimize interference with the DAC and amplifier circuitry. The energy reserve has also increased significantly, the 240W power supply offers more voltage headroom and better electrical transient. All these improvements will result in improved dynamic and control, music become holographic with a much darker background.

When a lot of DAC or All-in-one focused on digital capability or rated power with different headphones, YULONG DA1 put power supply as priority, and we go all the way to exotic level implementation to fully explore the DA1 for the most demanding users.

DA1 Power Station.jpg
 
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May 24, 2021 at 9:30 AM Post #15 of 49
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I can afford the DA1, saving for the PSU.
Take your time, we are working on some final adjustment before we start mass production. We have upgrade the internal clock (crystal oscillator to be exact) at last minute for better performance, and we should proceed to production once we complete the adjustment of the new oscillator.

You can go ahead with the basic DA1 setup, and upgrade to two-box configuration later. Given the weight of the DA1 Power Station, I don't think you save a lot on shipping even if you buy them together. Therefore I'll suggest you take the DA1 first, I am sure you'll find the DA1 a perfect all-rounder and come back for the power supply upgrade.
 
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