Specifications and Manual Rev 1.3
Mhdt Laboratory USBridge Taipei, Taiwan True USB2.0 High Speed Audio Processor http://dhost.info/mhdtlab/
USB Audio Class 2.0 is a very innovative technology and standard. Mhdt Laboratory is happy to announce the USBridge, a true USB2.0 high speed audio processor. USBridge is a true high speed USB Audio Class 2.0 to standard S/PDIF digital signal converter. With this standard S/PDIF output, you can connect to any hi-end DAC even that your audio system doesn’t have USB input. With Windows® XP, Windows® 7 and
Windows® Vista, you need to install driver provided in the disk or download latest deriver from Mhdt Labs’ web site. Moreover, USBridge is powered by USB line itself, so no further power input is needed.
1.Description of the core
USBridge use the latest USB2.0 audio chip CM6631 from C-Media as a core. C-Media CM6631 is the world’s first USB2.0 true high-speed audio processor that can support the latest USB Audio Device Class Definition V2.0 and high-definition audio processing capability up to 192KHz/32bit(*). CM6631 provides the industrial standard I2S and HDA audio interface and also integrates 192KHz/24bit S/PDIF transmitter/receiver and MIDI I/O device. It’s suitable for versatile, high-profile, typical 2-channel I/O audio applications. Furthermore, CM6631 has an embedded 8051 microprocessor that can enhance the best flexibility and functionality with external upgradeable F/W codes. CM6631 would be the most high-fidelity and powerful audio core for high-value USB2.0 audio products.
2. Features
USB Spec. Rev.2.0 high-speed/full-speed mode compatible Latest USB Audio Device Class Definition Release v.2.0/1.0 compatible Auto detection for high-speed/full-speed USB Human Interface Device (HID) Class Definition Release 1.1 compliant Supports USB suspend/resume/reset functions Supports control, interrupt, bulk, and isochronous data transfers I2S serial audio output interface through RJ45 jack
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Built-in 192K/96K/48K/44.1KHz and 16/24-bit S/PDIF transmitter HID interrupts can be implemented via firmware codes
Supports USB Audio Class 2.0 and high-speed mode on Windows® XP, Vista,
and Windows® 7, Mac OS X 10.4 (or later version) with C-Media vendor drivers, Linux embedded USB audio drivers (ALSA) Default runs USB Audio class 1.0 and full-speed mode to be compatible with Windows® 2K, XP, Vista, 7 UAA driver and Mac OS X, Linux embedded USB audio drivers (ALSA)
User selectable sample rate settings (not applicable for Windows® XP) Additional oscillators are used for USBridge as the more accurate clock sources and to achieve lower digital signal jitter. 49.152MHz is for 48/96/192KHz sample rate data and 45.1584MHz is for 44.1/88.2/176.4KHz data.
*32bit may need the customized firmware/driver to support. It’s also possible for USBridge
to support extra 88.2/176.4Khz I2S output.
3. Operation System and Driver
3.1 Operation System
Since USB Audio Class 2.0 is a very innovative technology and standard, not every popular PC operation system has supported this kind of audio devices so far as USB
Audio Class 1.0. USB Audio Class 2.0 is not standardized by Microsoft Windows® yet.
Apple Mac® OS X was the first one that adopted USB Audio Class 2.0 device in-box driver since its Leopard version 10.5.7. However, the Mac® in-box driver has some structural problem need to be solved now. To provide you turnkey total solutions, Mhdt Labs provides complete software drivers with the hardware for the following operation systems:
1. Windows® XP 32/64bit
2. Windows® 7 32/64bit
3. Windows® Vista 32/64bit 4. Mac OS X 10.5.7 or later versions
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As said above, USBridge could also be configured as audio class 1.0 devices. The following table shows the current driver availability and compatibility on various OS comparing the USB audio class 2.0 and 1.0 modes:
Operation Systems USB Audio Class 2.0 USB Audio Class 1.0 Windows 2K N.A. Windows UAA Driver Windows XP Cmedia driver Windows UAA driver Windows Vista Cmedia driver Windows UAA driver Windows 7 Cmedia driver Windows UAA driver Mac OS X 10.5.7 or later Cmedia driver Mac in-box audio driver Linux Linux ALSA driver Linux ALSA driver
3.2 Drivers and installation
The drivers of our USBridge have been long time modified by C-media staffs to satisfy the users of high-end audiophiles. This driver provides only 2 channels PCM format for hi-ended usage and once it installed, USBridge will be the defaulted device for PC audio digital output when USBridge is plugged.
For Windows® XP, Vista, W7 Please install driver before use.
Find subdirectory in supplied disc: Plug in USBridge then execute setup.exe
The driver itself will install USBridge according to your Windows® O.S. Restart your computer after installation. Plug and play!
Latest version of driver can be download from our website: http://dhost.info/mhdtlab/
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4. Operation
4.1 Front Panel
1) S/PDIF output - Optical Toslink™ Connect to DAC or receiver with a Toslink™ optical fiber. The maximum supported format of toslink is about 170Khz, so if you are setting on 192Khz, please use coaxial output jack and cable.
2) S/PDIF output – RCA (BNC upon request) Connect to DAC or receiver with a 75 Ohms digital cable terminated with RCA male plugs. Gold plated RCA female connector
3) I2S output Direct I2S ouput for connection to a board or DAC provided with I2S input.
4) Indicator LED Green when device is proper installed and ready, blinking indicates outputting S/PDIF digital signal normally.
S/PDIF output (Toslink and RCA) and I2S output are outputted simultaneously.
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4.2 Rear Panel
5) USB input Connect to host with a suitable 2.0 USB cable w/Female B USB connector.
The USB Input must be connected directly to the USB interface of a computer. Function can be disrupted when a USB hub is in the connection line. USB 2.0 has a raw data rate at 480Mbps, and it is rated 40 times faster than its predecessor interface, USB 1.1, which tops at 12Mbps, so please use true USB 2.0 cable for proper operation.
4.3 Connection and Operation
For Windows® XP, Vista, W7 Please install driver according to procedure described in 3.2 Drivers and installation before use.
When driver is properly installed, restart your computer to let this driver function. Use certified USB 2.0 cable connecting to your PC and USBridge. You will see the green led located in front panel lights up.
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The example of connections is as follow:
DAC
Receiver, Pre USB 2.0 Cable Coaxial Cable w/SPDIF In
Toslink Cable DAC Chip RJ45 Cable
For Windows® XP The format of outputting S/PDIF can’t be changed by O.S. itself. But it can be set up by player like foobar2000 or Winamp.
For Mac and Windows® Vista, W7 The output S/PDIF is according the format set by control panel or by player like foobar2000 or Winamp.
4.4 Windows® W7 as an example
Installing driver in different O.S. and PC may have slightly different names and appearances during and after installation. Here are the procedures and names as well as appearances work with Windows® W7. The procedures are similar in other O.S. and PC.
Check if the USBridge and driver have been proper installed. Under Control Panel and select the Manage Audio Devices tag. Open control Panel and select Hardware and Sounds. Under Sound, select the Manage Audio Devices tag.
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The following windows will appear.
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As you can see, the USBridge is proper installed with name of “Mhdt Labs USBridge USB2.0 S/PDIF Converter”.
Connect USBridge to your DAC, and check what your DAC can handle with USBridge.
Execute the program in provided disk: WaveGen3.8.exe Choose the output Device to be “Mhdt Labs USBridge USB2.0 S/PDIF Converter”. The WaveGen3.8 is a direct sound producing tool. By using this tool, you can test the ability of you DAC.
More test and setting: Back to sound devices selection: Double click and launch the Digital Output/ “Mhdt Labs USBridge USB2.0 S/PDIF Converter”:
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Now you are in section of “Digital Output Properties”.
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Select Supported Formats tag to test and set like following:
Select Advanced tag to set and set default format like following:
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5. Configuring for ASIO, Kernel Streaming, WASAPI
USBridge can handle Direct Sound (DS), Kernel Streaming (KS) and WASAPI with specific player such as FooBar or Winamp etc. Take foobar as an example:
5.1 Kernel Streaming (KS) and WASAPI
Download the DLL for Kernel Streaming and WASAPI from the FooBar2000 website http://www.foobar2000.org/components/view/foo_out_ks http://www.foobar2000.org/components/view/foo_out_wasapi
These are zip folder which contains the DLL. Extract it from the zip and copy to the Components folder of Foobar2000. Then, restart FooBar2000, go to the File/Preferences/Playback/Output window as following:
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The device been selected is the default device to run as a core of Foobar. After USBridge is plugged in, the devices can be chosen is:
ASIO : Mhdt Labs USBridge USB2.0 S/PDIF Converter ASIO (see 5.2 ASIO) ASIO : ASIO4ALL V2 (see 5.2 ASIO) DS : Digital Output (Mhdt Labs USBridge USB2.0 S/PDIF Converter) KS : Mhdt Labs USBridge USB2.0 S/PDIF Converter WASAPI : Digital Output (Mhdt Labs USBridge USB2.0 S/PDIF Converter)
5.2 ASIO
5.2.1 C-Media ASIO Driver (Recommended)
Our ASIO driver was developed especially for C-Media CM6631. You can download these drivers from Mhdt Labs’ website: usb20asiop.dll usb20asiop.ini usb20asiopx.dll (64 bit) usb20asiopx.ini (64 bit)
Copy these ASIO drivers to the Components folder of Foobar2000 if you are using Foobar. Restart FooBar2000, go to the File/Preferences/Playback/Output window as following:
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Select ASIO Virual Devices and then select Edit Mhdt Labs USBridge USB2.0 S/PDIF Converter ASIO to get ASIO Virtual Device Editor like following:
Launch in Configure then you will see available WDM devices list like following:
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Select Bit-Depth (16-32 bit) and suitable Latency (system dependent)
Back to ASIO Virtual Device Editor:
Select Device channel to its proper mapping, one left and one right. In FooBar2000, go to the File/Preferences/Playback/Output and select ASIO : Mhdt Labs USBridge USB2.0 S/PDIF Converter ASIO Now, you are playing foobar2000 with ASIO driver.
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5.2.2 ASIO4ALL V2 ASIO Driver
There is an universal ASIO driver which also supports USBridge. Download ASIO4ALL universal ASIO driver version 2.10 or later version from: http://www.asio4all.com/
Install universal ASIO driver version 2.10 by executing ASIO4ALL_2_10_English.exe
Download the DLL for ASIO support from the FooBar2000 website http://www.foobar2000.org/components/view/foo_out_asio
As described in section 5.1. Extract it from the zip and copy to the Components folder of Foobar2000. Then, restart FooBar2000, go to the File/Preferences/Playback/Output window as following:
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Select ASIO Virual Devices and then select Edit ASIO4ALL V2 to get ASIO Virtual Device Editor like following:
Launch in Configure then you will see available WDM devices list like following:
Select Mhdt Labs USBridge USB2.0 S/PDIF Converter to power on and turn off the other WDM devices
Back to ASIO Virtual Device Editor:
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Select Device channel to its proper mapping, one left and one right. In FooBar2000, go to the File/Preferences/Playback/Output and select ASIO: ASIO4ALL V2 Now, you are playing foobar2000 with ASIO driver.
5.3 Sampling Rate
In FooBar2000, go to the File/Preferences/Advanced window as following:
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In Decoding section, you can set sampling rate. Set the best rate for your DACs.
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6. Specifications
Size: 90x3.2x95mm (w x h x d, case) 90x3.2x115mm (w x h x d, total) Weight: 200g (7oz)
Sampling frequencies (kHz): 44.1, 48, 88.2, 96, 192 Resolution (bits): 16, 24, 32(*) bits Inputs: USB 2.0, Outputs: S/PDIF x1 (RCA) (BNC upon request) Optical Toslink™ x1 I2S (RJ-45)
S/PDIF transmitter: 3.3V LVCMOS with 24mA current capability EIAJ CP1201, IEC-60958 interface standards I2S output voltage: 3.3V CMOS with 35mA current capability on each line
Power consumption: Standby:141mA Operating:148mA
I2S (RJ45) Pin definition:
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16 bits/ 48kHz THD+N
16 bits/ 48kHz Dynamic Range
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24 bits/ 192kHz THD+N
24 bits/ 192kHz Dynamic Range
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TIPS AND HINTS
USBridge was designed for audiophile usages and so it is in asynchronous USB2.0 operation. Please use USBridge as priority device and remove or uninstall any other devices if possible. Since Windows® is not a real time system, so the lower DPC latency value will result the better sound quality. Please examine the DPC latency status of your Windows® system.
DPC Latency Check
USB2.0 audio is a very high speed and sensitive device. If any kernel-mode device driver in your windows system is implemented improperly and causes excessive latencies of Deferred Procedure Calls (DPCs) then probably drop-outs, crackling will occur when using audio applications such as USBridge. High DPC Latency is a problem since it causes audio and video lag.
We strongly suggest you to run DPC latency check before using or purchasing USBridge. The DPC Latency Checker tool, dpclat.exe, determines the maximum DPC latency that occurs on your Windows system and thus enables you to check the real-time capabilities of your computer. dpclat.exe can be download from: http://www.thesycon.de/eng/latency_check.shtml
Windows® XP has lesser DPC latency problem. Windows® Vista and Windows® 7 have considerable serious DPC latency problem.
Make sure that there are no red spikes in your windows system before using USBridge.
In many cases DPC latency problems are caused by specific types of devices such as: z Network adapters for Ethernet and Wireless LAN (W-LAN), WIFI z Internal modems z CPU acceleration, booster programs z Hard disks RAID storage drivers
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z Battery control program of Laptop computers z Power saving programs (Ex, Intel EIST…) z Other Video or Sound drivers (especially Nvidia, Creative and Realtek) z Antivirus or Firewall programs z BIOS update
The setting of Foobar, Winamp…etc.,
Keep the buffer or latency as small as you can, smaller value give you more realistic sound. However, this value is PC dependent, an old word, please remove or uninstall any other devices if the audio performance is your goal.
USB Connecting Cable
The USB 2.0 Input of USBridge must be connected directly to the USB interface of a computer. Function can be disrupted when a USB hub is in the connection line. USB 2.0 has a raw data rate at 480Mbps, and it is rated 40 times faster than its predecessor interface, USB 1.1, which tops at 12Mbps, so please use true certified USB 2.0 cable for proper operation.
For Mac users
The driver of USBridge for mac:
USB2.0 High-Speed True HD Audio Install Package.dmg
This driver is provided by C-Media. Device name is “USB2.0 High-Speed True HD Audio” rather than “Mhdt Labs USBridge USB2.0 S/PDIF Converter” as seen in Windows. However, functions are the same.
Latest version of driver can be downloaded from our website: http://dhost.info/mhdtlab/
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