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Quloos QU02 USB Bridge

USB Digital Audio Interface to SPDIF AES/EBU I2S

Amanero Combo384
Supporting DSD512

A full isolation to isolate PC EMI

Both ends of isolation are powered by local
Generating I2S signal by CPLD
Using Hi-End special oscillator AS338
Using multiple Linear power chips
Four kinds of cable sequences of I2S

Can of driving Length=10m coaxial cable

For optimization of car audio system
Can be powered by 12V battery power supply

Supporting multi-platform operating system

Whats the USB Bridge?
For QU02, It is a digital audio converter for USB convert to coaxial, optical, AES/EBU, I2S (IIS) digital audio output.

Briefly speaking, USB Bridge can also be deemed as an external high-quality digital sound card that can connect to mobile phones, computers and tablets.

The purpose of USB Bridge is to improve the sound quality of DAC, so that the sound quality of DAC connected to computers, mobile phones and tablets can reach or even exceed that of many digital players.

How to use?
Its simple. QU02 can be connected to computers, mobile phones and tablets (mobile phones and tablets need an OTG converter to convert to USB-A port) through USB cable, and then output connect to DAC, active speakers with digital audio input, power amplifiers with digital audio input, and DSP of car audio through digital audio cable. The methods of connecting backend devices include coaxial, optical, AES and I2S.
Why to design QU02?

[Replaceable sound quality/exceeding many digital players] Whether we are designing the QA661, or the designing the a better sound quality QA662, we reached a conclusion that as long as the USB Bridge was excellent enough, the sound quality was replaceable or even exceeded many digital players.

[Playing online streaming music easily] There is a certain threshold for using online players, which increased users difficulty on using them, especially if they wanted to use them well. However, there is almost zero threshold when using USB Bridge to listen online streaming music. No matter is mobile phones, tablets or computers, its easy to play online streaming music.

[The best choice to improve the sound quality] For most DAC, or HiFi devices with DAC, the simplest and most effective way to improve the sound quality is to add an excellent USB Bridge in front of it, with small investment, but realizing a significantly improved sound quality.

New Isolation Technology
When both ends of the isolation are powered by the local pure power supply, we can hear the sound that is smoother, with cleaner background and more details.

To effectively eliminate the ground loop noise introduced from the computer, the standard USB Bridge are equipped with complete ground isolation, such as INT204, Hydra Z+, Alpha, A.B.C, as well as some excellent USB Bridge in China. Its obvious that a lot of efforts have been accumulated in this aspect.

The isolation design of QU02 is also unique. The CPU part of the USB Bridge, the audio output processing part and the clock part are completely isolated. The purpose is to isolate the interference caused by the computer, so that the sound is more pure and accurate.

However, for almost all similar designs that adopted complete isolation, partial power supply of CPU of USB Bridge is by 5V power supply from USB inputted, so the sound will be greatly influenced by 5V power supply from USB inputted.

How about QU02? It directly abandoned 5V power supply from USB inputted and uses local pure power supply at both ends of isolation.
    Because both ends are designed with complete isolation, we made the isolation up to 3000 V DC voltage before and after isolation, through Murata isolation power module.
    Through isolating the power supply, we realized the couplings, which not only realizes the complete isolation, but also ensures that both ends are supplied with pure power supply with low internal resistance.

Clock circuit design regardless of the cost --- Clock is the Soul of Sound

A lower clock jitter can realize a better sound quality and significantly improve the medium frequency and low frequency quality that human ear is more sensitive. Make sound has toughness, the instrument and voice have a touchable real object sense. In addition, the low jitter makes the high frequency more delicate, exquisite and accurate.

QU02 selects wurths high-precision crystal oscillator for partial CPU of USB, because a poor CPU clock will bring a large EMI interference to power supply and surrounding space. The stability of Wurth crystal oscillator and low jitter will make the position of sound image more accurate, more three-dimensional effect, and more open sound scene.

The audio of QU02 uses two AS338 crystal oscillators (Accusalicon specifically launched for Hi-End audio applications). This crystal oscillator, with selling price more than US $50/pc, is a more high-end model of popular AS318B in Hi-Fi applications, whose phase noise and jitter performance are leading the similar products.


AS338 Jitter 38fs

AS318 Jitter 88fs


AS338 10Hz phase noise

CCHD-957 10Hz phase noise

The jitter of AS338 is as low as 38fs, much lower than the 88fs of AS318B. The 10Hz phase noise, which has a great influence on hearing, is lower than the popular crystal oscillator CCHD-957 by about 10dB.
Excellent Jitter With Coaxial Output

The above jitter test diagram is for QU02 engineering machine. About test screenshot under APX555 instrument, our parameters are marked as 80ps, because there will be some deviations on parameters of each machine.

Through applying low noise and pure power supply to power AS338 crystal oscillator, excellent digital signal processing circuit and excellent CPLD frequency division design, we successfully realized the incredible low jitter audio output.There is only 80ps with coaxial output jitter, which is only 40% of jitter 200ps of many single digital audio processing chips.

Coaxial Output THD and SINAD

Power supply is the source of sound, Taking the largest part of cost

The biggest cost gap between different devices generally lies in power circuit. For example, in terms of price, many Linear power chips are 10-20 times than that of general power chips.

In addition, for most machine designed, there only needs a few power chips. However, we will use over 10 or even dozens of power supply chips, which caused a huge cost gap. We will divide the power supply into several groups according to the major categories (including high-frequency and low-frequency, audio and non-audio). Then, during the second stage, we will divide into several groups according to different current sizes and different interference levels. Finally, during the third stage, we will supply power to each specific electric circuit independently. The advantage is that we realized countless independent power supply effects inside a machine, ensuring the independence of each other, isolating their influences, and ensuring the purity, refinement and accuracy of sound.

There are two main reasons that explains why Linears power chip is expensive. On the one hand, the parameters are excellent, rare low noise, and fast enough transient response. On the other hand, the actual performance of the sound is good. The sound of the linear power supply chip is exquisite and has many sound details. Compared with the conventional power supply chips, it is significantly improved.



LT3042 Noise: 0.8uV

ADP151 Noise: 9uV

LM7805 Noise: 75uV

How excellent are the parameters of Linear power chip? Let's just take a brief look at the noise index. The noise of LT3042 is 0.8uV, which is only 8% of the 9uV noise of the commonly used low-noise power supply chip ADP151, and only 1% of the 75uV noise of the regulator chip LM7805.

The Linear power chip used by QU02 includes multiple LT3042, LT1963 and LT3693.

To achieve excellent sound quality and actual hearing sense, QU02 uses not only complex power circuit design and expensive power chips, and also uses the Philips axial electrolytic capacitor, Philips 135 electrolytic capacitor, Philips 030 axial electrolytic capacitor, Murata power source isolation module, Murata common mode inductance, WIMA film capacitor, ERO film capacitor, Panasonic SMD film capacitor.

A perfect sound for Computer input and Mobile phone for input

For most of the independent USB Bridge on sale now, the power supply used in the circuit before isolation is the 5V power supply from USB inputted, which determines that the sound will inevitably be influenced by the quality of USB inputted power supply. When connected to a computer with a better power supply, the sound will be better. However, when connected to a computer or mobile phone with a bad power supply, the sound will be worse, which is manifested in that the sound tends to become hazy, thin, weaken details, unclean and lacking in three-dimensional sense.

Some user will try to add USB noise purifier to solve this problem. However, although most USB noise purifiers can bring a clean sound, but they also cause the loss of sound details or make the sound thin, which makes the original goal became impossible.

Because QU02 used Murata power isolation module and completely abandoned 5V power supply from USB inputted, realizing that the sound is completely free from the influence of power supply from USB inputted. The advantage is that when the mobile phone is used as the sound source, it will have better sound quality performance than similar products. The difference between the sound computer inputted and mobile phone inputted has been narrowed. Adopting mobile phone as the sound source can realize HiFi sound.

An OTG conversion cable to USB-A port is needed, If the QU02 is connected to Android or iPhone and tablets, so as to realize a convenient online streaming music playing and wonderful enjoyment of a high quality of sound.

It is can drive the coaxial cable with a length of 10M

When we conduct the actual test with 75ohm Canare coaxial cable in a length of 10m, there is almost no influence to sound quality. When the length of coaxial line is increased from 1.5m to 10m, the Jitter is only increased from 72ps to 74ps, so that such a slight difference can be ignored.

If needing a longer distance, it is recommended to use AES for connection. In theory, AES can support a long distance transmission of 100m.

Therefore, your computer and audio can be free from each other.

User-Friendly Audio Source of Car Audio

When using QU02, we find that not only the coaxial cable can be a length of 10 meters, but also the USB cable can be a length of 10 meters through our actual measurement, which is very friendly to car audio users.

No matter you plan to install QU02 in trunk of the car and use a long USB cable to connect the phone and tablet to the dashboard, or you plan to install QU02 under the seat and use a long coaxial cable to connect to DSP input of car audio in rear boot, both are achievable, which is more convenient and can experience better sound quality of Hi-Fi on car audio.

QU02 uses external 12V power input. Since the maximum power supply of car can reach 14V, it cannot be used directly. Therefore, we provide two vehicle power supplies for car audio users to choose (need to purchase separately). These two power supplies are equipped with noise filtering function, and the voltage will be stabilized to a fixed 11.5V to ensure stable use and sound performance. One of the two vehicle power supplies is the interface of the vehicle cigarette lighter, which can be directly plugged into the vehicle cigarette lighter. The other type of power input is connected by terminal blocks, and ACC is provided as the control input for power startup. (When purchasing the vehicle power supply, please find it directly in the store or kindly consult us)

Sample Rate Indicator

1X 2X 4X 8X
44.1kHz(PCM) 44.1kHz 88.2kHz 176.4kHz 352.8kHz
48kHz(PCM) 48kHz 96kHz 192kHz 384kHz
DSD DSD64 DSD128 DSD256 DSD512
Supports Multiple Port Output
QU02 has I2S, AES, Optical, 2 Coaxial digital audio signal output.

Sample Rate Supported By The Output Port

I2S 32Bit / 44.1kHz ~ 384kHz DSD64 ~ DSD512(Native)
AES 24Bit / 44.1kHz ~ 384kHz Dop64 ~ Dop128
OPT 24Bit / 44.1kHz ~ 192kHz Dop64
COAX 24Bit / 44.1kHz ~ 384kHz Dop64 ~ Dop128
Impedance and Level of The Output Port
Port Impedance Matching Output Level
I2S 100 LVDS
AES 110 3Vpp
OPT --- ---
COAX 75 0.55Vpp
Selectable I2S Cable Sequence
Four groups of switches can adjust four conventional I2S cable sequences, so as to realize the compatibility with DAC of different brands

K1: K1 to ON, DSD FLAG is PIN15, Set PIN15 as the FLAG Bit.

K2: K2 to ON, DSD FLAG is PIN14, Set PIN14 as the FLAG Bit.

K3: Phase setting of I2S interface, K3 to ON is Standard phase,K3 to OFF is Reverse phase.

K4: DSD channel setting for I2S interface, K4 to OFF is DSDR using LRCKK4 to ON is DSDR using DATA.

Note: After setting K3 or K4, You need to restart the device for this to take effect.

Note: Cannot connect with HDMI of computer, TV and set-top box
Local drawing of internal PCB

Statement: The above internal pictures and PCB plate pictures are for reference only. To continuously improve the sound quality and performance of product, materials or circuits are subject to change without notice.
Other Parameters
Input power: DC12V 2A (range: 11-13V, >500mA), 5.5 x 2.1mm, positive inside and negative outside
Power consumption of whole machine: <5W
Systems supported: Windows (ASIO driver), Mac, Android, iOS, Linux (drive-free)
Size of host: 197 x 197 x 45mm (Not including exposed sockets and foot mats)
Weight of host: 1.29kg
Size of package: 330 x 260 x 75mm
Weight of package: 1.72kg
Package list: QU02 host, USB Cable(USB-A to B, L=1.5M), Instruction Manual, DC12V 2A Power Supply (Input AC110~240V)

Price: QU02 USB Bridge US $389.99 (Not included shipping)

Payment methods 1: Direct remittance to PAYPAL, Our paypal account: cxqmcu@cxqmcu.com

 QU02 USB Bridge(Black) USD $389.99 + $50.00 (Shipping)

 QU02 USB Bridge(Silver) USD $389.99 + $50.00 (Shipping)

 Shipping by Registered Air Mail

ADD:Room A1502,NiuLanQian Building,MinZhi Road,LongHua Town,ShenZhen,GuangDong,China
Postalcode:518131   TEL:+86-0755-28187975   FAX:+86-0755-28187976