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در ادامه DAC و Computer Audio

چهار شنبه 27 جولای 2016
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اول این لینک هارو دقیق بخونید خیلی خوبن :

Thorsten Loesch

Gordon Rankin

John Swenson

Steve Nugent

Benjamin Zwickel

Pedja Rogic

این روزها در مورد DAC و موضوع حذف نویز و جیتر از PC میخونم. تورستن و گوردون و ژان و استو بیشترین تحقیقات رو تو زمینه گرفتن بهترین نتیجه از PC داشتند با ارتباط USB . دو مورد هست یک ایزوله کردن (Galvanic USB Isolation) گالوانیک نویز PC از DAC که هر چقدر ایزوله تر باشه بهتره اما با امکانات این صنعت (دو راه یکی کوپل نوری که جیتر بیشتری داره و دیگری استفاده از چیپ های Analog Device مثل ADUM4160 که هم محدودیت 96کیلوهرتز دارند و هم جیتر بیشتر) عملا هر چقدر ایزولیشن بیشتر بشه جیتر هم بیشتر میشه و موضوع مهم دیگر برای صدای خوب حذف و کاهش جیتر که اونم کار راحتی نیست.

First isolation is a good thing to have. I run a CG filter from my main power and put all the computer stuff on one side and all the analog on another. That way the switching computer noise has 2 filters to jump thru before it gets to the analog side.

I isolate at the I2S level. We found over the years that this was the best place for it. We reclock all the signals on the DAC side so the jitter is very low.

Using the Analog Devices ADUM series… well requires some engineering. First it is not setup to drive cables. These chips were meant to be on the board of the isolating endpoint. They also don’t sound that good… not sure why… maybe the same reason some USB cables don’t sound good. They are limited in speed to Full Speed or 24/96.

Most of the current asynchronous or even adaptive have no isolation. Anything that is self powered cannot have isolation…. well SPDIF converters can because they can have a transformer or optical output. But then again as pointed out above SPDIF leads to more jitter. This does not mean they are bad. These just may require a little more setup and adjustments than those that are.

I really would not get hung up on this as much as getting something that sounds good to you. Visit a dealer or have a dealer send you something to hear. Don’t buy by numbers or what people say here. Nobody listens the same or has the same system, room etc…

have fun!

فعلا با نتایج من تو اینترنت بهترین حالت Computer Audio گرفتن دیتا از asynchronous usb کامپیوتر هست.

DAC بهتره و شاید لازمه که True Multi-Bit باشه یعنی از سیستم R-2R استفاده کنه و نه از سیستم Delta Sigma و حتی اگر عبارت Multi-Bit رو قبل Delta Sigma دیدید بدونید اون دک مالتی بیت واقعی نیست.


So you have an Apple computer running OS X Yosemite and you want to optimize performance. I’ve got you covered. If you prefer to run an older version of OS X, I have another optimization blog that covers Snow Leopard through Mountain Lion.

Less is more…

It’s obvious Steve Jobs is dead. Forget about the fact that when Yosemite was first released it had so many bugs and conflicts you would think it was engineered by Microsoft. Apple was on the cutting edge of professional audio and video production, photography, and CAD, but has now redirected their marketing efforts toward the average social networking, iCloud using, multiple mobile device consumer.

Yosemite emphasizes a plethora of “eye candy” aesthetic features, automated multi-device and multi-platform integration, and organizational apps such as Mission Control, Dashboard, and Widgets.

The more of these optional processes you remove, the more you’ll improve Yosemite’s performance.

My company, Mojo Audio, manufactures and sells high-end computerized music and video servers for the home theater enthusiast and recording/editing professional. Though this blog was written to assist our customers in optimizing the performance of Yosemite running on their upgraded Mac Mini media servers, these same optimizations will work on any Mac running Yosemite.

I’ll walk you through exactly what you need to do to disable memory resident programs that automatically load by default when Yosemite boots up. And I’ll also show you how to turn off optional wireless control interfaces, such as infrared, WiFi, and Bluetooth.

When you disable these optional processes and reallocate system resources, your computer does less switching, swapping, interrupting, and error correcting. Freeing up system resources and turning off unused wireless control interfaces results in noticeably more efficient performance which translates to a more fluid and coherent audio and video presentation.

Warning! I recommend that before making any changes or updating software in any computer that you backup your drives. Using “cloning” software, such as Carbon Copy Cloner, creates a bootable backup.

It’s a perfect use of your time . . . you can clone your drives while you review the rest of this guide.

Start with a clean install of Yosemite:

It’s often easier to start with a clean slate than to figure out how to turn off and undo things we may have unknowingly turned on.

You did remember to back up your data and boot drives, right?

When you do a clean install you’re going to erase everything, so now’s a good time to make and test (yes, test) your system backups.

Warning! When doing a clean install do not activate any automated features. Activate only one web browser, preferably Safari. Don’t activate any optional features or plug-ins, such as Google Chrome. BTW, Chrome and Yosemite don’t play nice together, so I wouldn’t recommend using Chrome under any circumstances.

Here is a link to a guide on how to do a clean install.

Now that you’re back to clean, and nothing optional has been added, I’ll show you how to turn off a series of default resident processes that automatically boot up with Yosemite.

Improve Safari performance:

Safari does all sorts of things automatically to enhance your browsing experience. Of course, anything automatic consumes system resources. One option would be installing software, such as ClicktoPlugin, that prevents Safari from automatically loading plugs-ins.

Software like ClicktoPlugin not only speeds up browsing, but also reduces fan speed and extends battery life. It also improves performance of audio and video streaming.

The way it works is that it replaces any plug-in object with an unobtrusive placeholder that can be clicked on to load the embedded content of the plug-in. Now plug-ins only activate manually.

Another option you have instead of or in addition to using a plug-in management Application would be to uninstall Adobe Flash. Without Flash and plug-ins, Safari performs better.

Clear your desktop:

Remove any files, folders, or infrequently used Dock icons. These convenience and organizational options slow down performance by requiring the system to constantly redraw them on the screen.

Remove from Dock

For a minimized Dock, the only icons you need are Finder and Trash. The rest of the icons can be deleted. Some people like to keep Launchpad in their Dock for easier access to Applications.


To keep icons in your Dock, opposite click on the icon and select Keep in Dock. If you use an Application all the time and want it to open whenever you restart your computer, just opposite click on the icon and select Open at Login.

Other Keep 2

If you are optimizing for audio or video, you want your player and/or recording software to automatically open at Login. For desktop use, this could be accounting software, CAD software, and/or a web browser.

Applications automatically opening when the computer restarts is very important to restore function for media servers or home automation.

Close all Applications

Before applying any optimizations, make certain the only application running is Finder.

The Force Quit window will allow you to view all applications that are running.

Go into the  Apple Menu, drop-down menu, and select Force Quit.

Click to Enlarge

Click on and highlight an application. Press the Force Quit button in the lower right corner. Repeat until the only application shown is Finder.

Click to Enlarge

Disable pretty and automatic:

Disabling “eye candy” such as Transparency and turning off automated features such as Widgets will improve Yosemite performance.

Reduce Transparency:

Go into the  Apple Menu, select System Preferences, and click on Accessibility.

Yosemite System Preferences

In the Accessibility window, check the Reduce Transparency box.

Reduce Transparency

Change Minimize Windows to Scale:

Any effect that is used when minimizing windows unnecessarily consumes system resources.

Go into the  Apple Menu, select System Preferences, and click on Dock. Change the Minimize windows from Genie effect to Scale effect.


Uncheck the Animate opening applications box. You can check or uncheck any of these features. Remember: less is more.

Disable Widgets:

Widgets are cool looking and convenient, but they use quite a bit of system resources. Not updating Widgets significantly speeds up rebooting and improves performance. Click on the Widgets toggle in the upper right corner.

Widgets 2

Uncheck, deactivate, and remove as many items as possible from both the Today and the Notifications panels.

Disable the Extensions that you don’t need:

Go into the  Apple Menu, select System Preferences, and click on Extension.


Go to the Today options in the left column and uncheck any or all extensions you don’t require.

Disable sleep, Power Nap, and screen saver:

Go into the  Apple Menu, select System Preferences, and click on Energy Saver.

Energy Saver

Uncheck everything except Prevent computer from sleeping automatically and Start up automatically after a power failure. Move the Turn display off after slider to the far left set to Never.

Disable Notifications:

Go into the  Apple Menu, select System Preferences, and click on Notifications.


In the left column click on and highlight the Do not disturb option and uncheck as many boxes as possible.

Notifications 2

In the left column click on and highlight each of the features (Calendar, Face Time, Mail, Messages, etc) and uncheck as many boxes as possible. Change to 1 recent item for each feature.

Speed up new Finder window generation:

In the Finder pull down menu select Preferences.

Finder Preferences 2

Set the New Finder windows show to the place you go to most often. This could be Desktop, Documents, Music or your user home folder.

Finder Preferences

You can also control several other aesthetic features by checking or unchecking these features.

Removing unused languages:

Go into the  Apple Menu, select System Preferences, and click on Languages & Region.


Make certain that only the language(s) you use are listed. Highlight and delete unused languages and add any languages you may need using the + and – buttons.

Removing the presentation order for Spotlight:

Go into the  Apple Menu, select System Preferences, and click on Spotlight.

Spotlight 2

In the Spotlight control window, select the Search Results tab.


You’ll see a list of Applications with check boxes next to them. Uncheck all of the boxes. There is no point in leaving “Music” for a music or media server because your library/player software doesn’t access through Spotlight.

Disabling Login Items:

Ideally you want only one Application to automatically open when you login to your computer. If you use your Mac as a dedicated music server, you would want only your player software to open at Login. If you are a professional, you would want your accounting software, CAD software, etc. to automatically open at Login. At the same time, you want to disable any other applications that may automatically want to open at Login.

Go into the  Apple Menu, select System Preferences, and click on Users & Groups. To streamline the Login items click on the Login Items tab at the top.

Users & Groups 3

Note: This is the same window you can add guests and users with restricted access. For example, you could allow your children to log on to your media server and play recordings from your NAS drive, but not have access to change any of your administrative settings.

You’ll see all the Applications you’ve set to automatically open at Login in the main window. You can remove any optional automated fluff Apps, such as iTunes Helper, to improve system performance.

Users & Groups

I recommended that you upgrade iTunes with a high-performance music/media player Application.

Disabling Automatic Software Update:

Go into the  Apple Menu, select System Preferences, and click on App Store. Uncheck the Automatic Updates box.

App Store 2

Note: This is the same place you can manually check for updates.

I cannot recommend more strongly that before updating you always make and test (yes, test) a backup of your drives.

App Store

Often updates have bugs or conflicts with drivers. Having a bootable backup allows you to easily return to your former working system, when as is quite common, an update screws up your computer : P

Repairing disk permissions:

For optimal system performance, Repair Disk Permissions after you do OS X updates, do Application updates, or transfer large quantities of data. This is a good habit to get into.

You can find Repair Disk Permissions in your Disk Utility Application.


Activate your Launchpad. Disk Utility is located in your Other folder.

Yosemite Other

Note: use the Escape key on your keyboard to return from the Other folder to the rest of your Launchpad Applications.

Disk Utility 3

To Repair Disk Permissions, simply highlight the disk you want to repair.

Disk Utility 2

When repairing disk permissions is done, you will see Permissions repair complete at the bottom of the Show details window.

Disabling the Time Machine automatic backup:

Go into the  Apple Menu, select System Preferences, and click on Time Machine.

On the left side of the window, you’ll see a slide selector that has off at one end and on at the other. Make sure the selector is switched off.

Time Machine

Warning! Your drive will inevitably fail: back up often. Using a bootable backup will save you a significant amount of time when you have to reinstall your boot drive.

Disable the automatic journaling feature:

Just as before, launch Disk Utility by activating Launchpad, clicking on the Other folder, and selecting the Disk Utilities icon.

Individually select any drive on the list. Hold down the Option button on your keyboard and click on the File drop-down menu. Slide down the File drop-down menu and select Disable Journaling. If you don’t hold the Option button down while selecting the File drop-down menu, Disable Journaling will not be a selectable option.

Disable Journaling

Repeat this for all drives.

If you wish to enable the automatic journaling feature for a drive, simply repeat the above process and select Enable Journaling in the same drop-down menu.

Turn off wireless control interfaces:

Turning off unused wireless control interfaces, such as WiFi, Bluetooth, and Infrared, improves performance by freeing up system resources and reducing data corruption caused by EMI “noise” on sensitive internal circuitry.

Systems Mojo Audio sells with our optimized Yosemite have Infrared turned off because it’s rarely used and Bluetooth and WiFi turned on since they are often used to set up new systems. I recommend turning off as many wireless control interfaces as possible.

Warning! Turning off wireless control interfaces can disable control devices, such as your Apple Bluetooth keyboard/mouse/pad. I recommend a USB keyboard and mouse for setup and troubleshooting.

For highest performance use no wireless control interfaces:

  • Connect to the internet via Ethernet cable on a LAN.
  • Control your desktop computer with USB control devices.
  • Use your laptop’s integrated monitor/keyboard/pad.
  • Use cables to transfer data between computers and devices.

The second-best option is to use only one wireless control interface.

Let’s start by looking at what works with what so you’ll have a better idea of which wireless control interfaces you’ll want to turn off.

Control devices associated with wireless interfaces:

  • Most keyboards and mice = USB (wired or wireless)
  • Apple keyboard and mouse = Bluetooth
  • Apple and aftermarket remote controls = Infrared
  • iOS and mobile device remote control = Bluetooth
  • iOS and mobile devices remote desktop App = WiFi

The above list may differ from brand to brand or App to App and may even change over time. I recommend connecting a simple USB keyboard/mouse/pad and turning on/off wireless control interfaces one at a time and testing each of your control devices to confirm which works with which.

Note: Wireless devices that plug into USB have relatively low noise compared to WiFi or Bluetooth because they have external receivers, cause less EMI noise, and are better shielded from internal circuitry.

Turning on/off the infrared:

Go into the  Apple Menu, select System Preferences, and click on Security & Privacy.

System Preferences

Click on the Advanced button.

Security & Privacy

Off: Check the box next to Disable remote control infrared receiver. On: Uncheck this same box to activate the infrared receiver.

If a windows Lock icon is in the locked position, you must unlock it before making any changes. To unlock any window, click on the Lock icon; you’ll be prompted to enter your administrative password.

Note: The password for any Mojo Audio optimized system is “Mojo.”

Turning on/off the WiFi control interface:

Go into the  Apple Menu, select System Preferences, and click on Network.

WiFi Networking 2

Click on and highlight WiFi in the left column:

Off: Click on the Turn WiFi Off button. On: Click on the Turn WiFi On button.

Note: The color of the dot on the left of the networking interface goes from green to red when an interface is turned off and returns to green when turned back on.

Turning on/off the Bluetooth:

Go into the  Apple Menu, select System Preferences, and click on Bluetooth. Click on the Bluetooth status button. Note the status changes.

Bluetooth 2

Click on the Advanced button and additional Bluetooth options appear. Check or uncheck the options you want. Personally I uncheck them all.


Note: So that Apple keyboards/mice/pads work with our new systems we leave the Bluetooth on. I would recommend switching to a simple USB keyboard/mouse/pad and turning all the Bluetooth off.

Deactivate processes using Terminal:

Warning: incorrectly entering code in the Terminal Application can permanently disable your computer. It could require that you reformat and reinstall your entire boot drive.

Did you test your bootable backup? Always a good idea.

The Terminal application is a text-driven command-line interface that allows you to communicate directly with the Unix-based operating system at the core of OS X Yosemite. Unix is the lowest possible level of human interface above machine language, giving the most streamlined and direct control over Yosemite.

I’ll show you how to use Terminal to remove Apps and processes that are set running by default when Yosemite boots up .

To launch the Terminal application, activate Launchpad, go into the Other folder, and click on the Terminal icon. The Terminal interface will appear. Now you are ready to enter commands into the command-line.

Yosemite Other

Tip: To minimize the potential for error, I recommend you copy the commands and paste them into the Terminal’s command-line.


Remove Mission Control: copy/paste the following lines into Terminal’s command-line one at a time and hit the Enter key after each one:

defaults write mcx-expose-disabled -bool TRUE [Enter]

killall Dock [Enter]

Remove Dashboard: copy/paste the following lines into Terminal’s command-line one at a time and hit the Enter key after each one:

defaults write mcx-disabled -boolean YES [Enter]

killall Dock [Enter]

Remove Spotlight: copy/paste the following into Terminal’s command-line and hit the Enter key:

sudo launchctl unload -w /System/Library/LaunchDaemons/ [Enter]

In order for the following command to take effect you’ll be required to enter your administrative password and hit the Enter key.

Note: The password for Mojo Audio optimized systems is: “Mojo.”

Remove Automatic Termination: copy/paste the following into Terminal’s command-line and hit the Enter key:

defaults write -g NSDisableAutomaticTermination -bool TRUE [Enter]

Finder is the main organizer in Yosemite. Unlike most applications which you can quit or Force Quit, the default settings in Yosemite will allow you to relaunch but not to actually quit Finder.

Terminal 2

Resetting Yosemite to quit  Finder: copy/paste the following into Terminal’s command-line one at a time and hit the Enter key after each one:

defaults write QuitMenuItem 1 [Enter]

killall Finder [Enter]

Important! Quit the Terminal Application.

To maintain optimal performance, each time you reboot your computer, and each time you use Finder, you will need to follow the instructions below to manually quit the Finder Application. Since Yosemite needs at least one Application to be open before you can quit Finder, you’ll need to open your player or primary software first.

Click on the Finder icon in the dock.

Select the Finder column in the top drop-down menu next to the  Apple Menu in the upper left corner of your screen.

Quit Finder

Slide down to the bottom row and select Quit Finder.

You’ll know Finder is not running if the dot under the Finder icon in the dock is gone.

Reactivate processes using Terminal:

Reactivate Dashboard: copy/paste the following into Terminal’s command-line one at a time and hit the Enter key after each one:

defaults write mcx-disabled -boolean NO [Enter]

killall Dock [Enter]

Reactivate Mission Control: copy/paste the following into Terminal’s command-line one at a time and hit the Enter key after each one:

defaults write mcx-expose-disabled -bool FALSE [Enter}

killall Dock [Enter]

Reactivate Spotlight: copy/paste the following into Terminal’s command-line and hit the Enter key:

sudo launchctl load -w /System/Library/LaunchDaemons/ [Enter]

In order for the following command to take effect you will be required to enter your administrative password and then hit the Enter key.

Reactivate Automatic Termination: copy/paste the following into Terminal’s command-line and hit the Enter key:

defaults write -g NSDisableAutomaticTermination -bool FALSE [Enter]

Reactivate Finder: copy/paste the following into Terminal’s command-line one at a time and hit the Enter key after each one:

defaults write QuitMenuItem 0 [Enter]

killall Finder [Enter]

Important! Quit the Terminal Application.

Perform periodic maintenance:

To maintain the highest level of performance and security, you must periodically do a few tasks manually:

  • Turn off the Finder application every time you open or reboot.
  • Close applications other than your player or primary software.
  • Clone or back up your media and documents as they change.
  • Repair disk permissions every time you rip or download files.
  • Update software only as needed – if it’s not broke, don’t fix it.
  • Always clone or back up your boot drive before updating.
  • Repair disk permissions after updating or installing Apps.

If you like what you read in this blog and are interested in getting more free tips and tricks, sign up for Mojo Audio’s Audiofiles blog. Also, sign up for our e-newsletter to get more useful info as well as coupons, special offers, and first looks at new products.

Plus, don’t forget to “like us” on Facebook.


Benjamin Zwickel

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Asynchronous USB looks to be the perfect solution

پنجشنبه 21 جولای 2016
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این متن عالیه :


Universal Serial Bus (USB) is a serial bus standard to interface devices. USB was designed to allow many peripherals to be connected using a single standardized interface socket and to improve the plug-and-play capabilities by allowing devices to be connected and disconnected without rebooting the computer (hot swapping). Other convenient features include providing power to low-consumption devices without the need for an external power supply and allowing many devices to be used without requiring manufacturer specific, individual device drivers to be installed.

A nice story about the development of the USB interface: The D/A diaries: A personal memoir of engineering heartache and triumph by Hitoshi Kondoh.

USB is a computer bus like any other but for some reason it inspires people to make all kind of funny products.


USB wedding ring


USB audio is very popular.
One of the reasons is that USB audio is part of the USB standard and as a consequence native mode drivers are available in all the popular OS (Win, OSX and Linux).
Connecting a USB audio device is a matter of plug&play.

USB audio is a flexible solution as any PC offers USB.

If you use a laptop this is probably the way to go if you want to improve on the on-board sound card.

The audio is routed to the USB.
This is a matter of choosing the USB audio device in your media player.
The on-board sound card is bypassed; in fact you don’t need a sound card at all.

The USB audio device is your (outboard) sound card.


Today the resolution of USB audio ranges from 16 bit/ 32 kHz to 32 bit/ 384 kHz.
A lot of DACs are still limited to 16 bit/ 48 kHz max.


The data transfer from the PC to the DAC can be done in adaptive or in asynchronous mode.
In adaptive mode the DAC adjust its timing to the rate the data is pouring in.
In asynchronous mode the DAC keeps its timing constant and controls the amount of data send by the PC. By design asynchronous mode eliminates input jitter.


A lot of people think USB audio is limited to 16 bits/48 kHz max.
A lot of (cheap and sometimes not so cheap) USB DACs are indeed limited to this resolution.

This is because the manufacturer decided to use a simple and cheap of the shelf hardware solution.

Another common misunderstanding is the specification of the bus (USB 1,2 or 3) and the USB audio standard (1 or 2).

USB Audio Class 1 standard (1998)

This standard allows for 24 bits/96 kHz max.
The standard itself doesn’t impose any limitation on sample rate.
Class 1 is tied to USB 1 Full Speed = 12 MHz
Every millisecond a package is send.
Maximum package size is 1024 bytes.

2 channel * 24 bit * 96000 Hz sample rate= 4608000 bits/s or 576 Byte/ms
This fits in the 1024 byte limit.
Any higher popular sample rate e.g. 176 kHz needs 1056 bytes so in excess of the maximum package size.


All operating systems (Win, OSX, and Linux) support USB Audio Class 1 natively.
This means you don’t need to install drivers, it is plug&play.
All support 2 channel audio with 24 bit words and 96 kHz sample rate

USB Audio Class 2 standard (2009)

It is downwards compatible with class 1.
USB Audio Class 2 additionally supports 32 bit and all common sample rates > 96 kHz
Class 2 uses High Speed (480 MHz). This requires USB 2 or 3.
As the data rate of High Speed is 40 X Full speed, recording a 60 channel using 24 bits at 96 kHz  (132 Mbit/s) is not a problem.

From mid-2010 on USB audio class 2 drivers are available in OSX 10.6.4 and Linux.
Both support sample rates up to 384 kHz.
It is unclear if Microsoft is going to support USB Audio 2.
You need a third party USB class 2 driver on Windows.

Companies like Thesycon or Centrance have developed  a USB Class 2 Audio driver for Windows.

Using High Speed USB for playback  there are no limits in resolution.

USB Speed

  • Superspeed – 10 Gbps USB data rate (USB 3.1)
  • Superspeed – 5 Gbps USB data rate (USB 3.0)
  • High Speed – 480 Mb/s with a data signalling tolerance of ± 500ppm (USB 2).
    This means every 125 µs a SOF packet arrives with a allowed deviation of ± 0.0625 µs..
  • Full Speed – 12 Mb/s with a data signalling tolerance of ±0.25% or 2,500ppm. (USB 1&2)
    This means every 1ms a SOF packet arrives with a allowed deviation of ± 500ns.
  • Low Speed – 1.5Mbits/s with a data signalling tolerance of ±1.5% or 15,000ppm (USB 1&2)

USB receivers

The data send over the USB must be transformed to a format a DAC (the chip doing the DA conversion) does understand. This can be SPDIF or I2S.
This is the task of the receiver chip.

Adaptive mode 16 bit units often use the Cmedia or TI (PCM270x) based chip sets. These are not programmable and usually only support 16 bit  and 32, 44.1, 48 kHz sample rate.

An example of how this chip-set performs compared with asynchronous USB can be found below.

24 bit adaptive mode DACs needs a programmable design (TAS1020 or other USB Audio Controller).

This chip enables 24 bit/ 96 kHz over USB.

Chips like the TAS1020 are limited to full speed.

You can’t do high speed as needed for USB audio class 2.

96 kHz is the upper limit when using native mode USB Audio Class 1 drivers.

A USB audio class 2 or a custom driver is needed to run 176/ 192 kHz and higher.

An example is the Tenor TE8802L by Galaxy Far East Corp.


  • USB2.0 Audio Class v2.0 and v1.0
  • 2-Inputs support by one I2S pairs with 128/256 Fs.
  • 2-Output support by one I2S pairs with 128/256 Fs
  • Adaptive/Asynchronous Mode supported
    • High-Speed mode support Adaptive/Asynchronous
    • Full-Speed mode support Adaptive only
  • Resolutions support 16/ 24Bit with sampling rates support 44.1/48/88.2/96/176.4/192KHz
  • Built in one IEC60958 professional 24 bit/96KHz S/PDIF RX, with I2S pins as well.
  • Built in one IEC60958 professional 24 bit/192KHz S/PDIF TX, with I2S pins as well.


Today you can buy complete USB-receiver modules like XMOS.

Basically a USB to I2S or SPDIF converter.

A couple of these interfaces can be found here.

Transfer modes

Data is exchanged over USB using one of the four possible modes:

  • Control Transfers: command and status operations,
  • Interrupt Transfers: device requires the attention of the host
  • Bulk Transfers: large volumes of data like print jobs
  • Isochronous Transfers: time sensitive information, such as an audio or video stream
    • Guaranteed access to USB bandwidth.
    • Bounded latency.
    • Stream Pipe – Unidirectional
    • Error detection via CRC, but no retry or guarantee of delivery.
    • Full & high speed modes only

Transfer modes explained in detail.

Isochronous transfer

When the computer sends the audio stream to an USB port, if first reads the data from the hard disk and caches blocks of the data in memory.

It is then spooled from memory to the output port in a continuous stream (Isochronous mode).

Frames are sent out every millisecond.
This happens whether there is any data in the frame or not.
The rate at which the frames go out is determined by a oscillator driving the USB bus.
This rate is independent of everything else going on in the PC.
In principle this guarantees a constant flow of the frames.
In practice the frames might not be filled properly with data because some program simply hogs the CPU or the PCI.
Anti virus polling the internet at high priority are a well known example.


Isochronous transfer can be done with three possible types of synchronization modes in the USB audio device.

Synchronous, adaptive and asynchronous synchronization

There must be some kind of synchronization between the PC and the DAC to avoid buffer under/overrun.


The clock driving the DAC is directly derived from the 1 kHz frame rate.
This mode was used by the early USB audio devices.
They were limited to 48 kHz and pretty jittery.


In this mode the timing is generated by a separate clock.
A control circuit (sample rate guesser) measures the average rate of the data coming over the bus and adjusts the clock to match that.
Since the clock is not directly derived from a bus signal it is far less sensitive to bus jitter than synchronous mode, but what is going on the bus still can affect it.
It’s still generated by a PLL that takes its control from the circuits that see the jitter on the bus.



In this mode an external clock is used to clock the data out of the buffer and a feedback stream is setup to tell the host how much data to send.

A control circuit monitors the status of the buffer and tells the host to increase the amount of data if the buffer is getting too empty or to decrease if it’s getting too full.
Since the readout clock is not dependent on anything going on with the bus, it can be fed directly from a low jitter oscillator, no PLL need apply.
This mode can be made to be very insensitive to bus jitter.



The warm reception in the audiophile world of asynchronous USB as developed and promoted by Wavelength inspired other brands to offer asynchronous USB DACs .


Asynchronous mode is not better by design but by implementation because you can implement a top quality (low jitter) clock in the DAC.

There is actually a good example of this case of its the implementation of the clock thats important, not the asyncness itself that is important. The recent inexpensive Musiland devices use an asynchronous protocol but then use a frequency synthesizer to generate the local clock rather than use a fixed frequency oscillator. The result is jitter that is actually worse than some of the better adaptive implementations!

John Swenson

The best way to get the most out of a dac chip is to put 2 audio oscillators right next to the dac chip. Buffer the oscillators and send them back to the USB controller to use to create the I2S (or other audio data stream L/R justified, DSP whatever) and this will give you the best response and the lowest jitter.


What many companies are doing is using the Frequency Synthesizer to create the audio oscillators. Basically these are frequency multipliers that can create any frequency and in the case of the TAS1020 down to 4Hz resolution. The problem with a Frequency Synthesizer is that the jitter can be as much as 100x that of a fixed oscillator. When enabling the oscillator in the TAS1020 also adds noise to the audio data stream because of the noise it fixes to the power supplies.


So choose wisely what you buy and ask the correct questions.

It’s not about the code… though all of ours is different, it may have an effect on the sound. But more so it has to do with the hardware and how that functions.

J. Gordon Rankin


Not everybody agree that asynchronous is better.

Centrance, manufacturer of adaptive mode solutions, is one of them.

Some manufacturers may lead you to believe that Asynchronous USB transfers are superior to Adaptive USB transfers. This no more true than saying that you “must” hold the fork in your left hand. If you know what you are doing, you will feed yourself with either hand.

Michael Goodman, Chief Product Architect

Async USB provides a simpler way to implement a low jitter DAC relative to adaptive mode USB. For the cost of a small number of lines of firmware code, you reduce the amount and complexity hardware needed and potentially reduce the cost of the hardware needed for a high quality result. Most thinking engineers appreciate simplicity and the potential for low cost designs that deliver the goods.

You can find plenty of bovine excrement in the marketing of all kinds of high-end gear. Marketing products using buzz words without supporting detail or test results works when the audience is technically ignorant.

Old Listener

The perfect solution

Asynchronous USB looks to be the perfect solution.
You configure your PC for bit-perfect output and the DAC takes care of the timing totally independent of the timing of the PC.
But there are posts on the Internet claiming that even in case of an async USB DAC what is happening upstream is still affecting sound quality.


Almost all recent offerings of quality DACs have asynchronous USB input.


One issue with USB is that it sends regular bursts of info like the start of frame packet – “The SOF packet consisting of an 11-bit frame number is sent by the host every 1ms ± 500ns on a full speed bus or every 125 µs ± 0.0625 µs on a high speed bus”. If the timing of this shifts or is variable, this could elicit a different & variable reaction from the USB receiver & translate into a different & varying jitter or noise spectrum. Making the PC end as solid & stable as possible without undue processing could be one factor in ameliorating this variation. It might not be the low level of jitter that we notice but the variation in jitter – that’s one reason why I say that the measurements we currently run seem not to be capable of picking up these issues or we are not directing them to the correct target for measuring.


Vendor specific

Some companies don’t use USB audio in isochronous transfer mode.
They implement their own solution using bulk mode transfer.
Bulk mode is asynchronous by design.

As it is bulk mode,

  • No guarantee of bandwidth or minimum latency
  • Error detection via CRC, with guarantee of delivery.

In case of isochronous mode it is exactly the reverse.

As long as the DAC is the only one connected to an internal hub, bandwidth is in general not the problem using USB high speed mode.


Inherent to a vendor specific solution is that he either supports your OS or not.
The advantage of USB audio is that it is natively supported by Win, OSX and Linux.
However in case of USB audio class 2 on Win you need a third party driver too.

Anyway this solution does audio over the USB without using the USB audio of the operating system.



Jim Lesurf did a nice experiment.
He measured the analog out of a DAC Magic when feed by its own adaptive mode USB and by a asynchronous USB to SPDIF converter (Halide).

The differences between adaptive (USB direct) and asynchronous (Halide) are clear.

According to the author not only measurable but also audible. [5]

Archimago [11] measured the jitter performance of a adaptive mode USB and a async mode.

adaptive mode USB


Asynchronous mode USB (CM6631A

Indeed, the jitter performance improves with asynchronous USB

USB cables

Cable length between full speed devices is limited to 5 meters. For a low speed device the limit is 3 meters.

As the signal degrades proportional to the length of the cable, a short cable is often recommended.

Other says this can put a source of RFI (the PC) to close to the USB-DAC.

Audiophile USB cables

As file based audio is gaining momentum and many believe asynchronous USB the way to go there is a growing market for audiophile grade USB cables.

The question of course is why a cable can have any impact on sound quality.
Some say that improved jitter performance of a cable can make a difference.
Others say that the reason we use asynchronous USB is exactly to have zero input jitter at the DAC so all what is happening upstream is irrelevant cable included.[1]
Audiophile USB cables are becoming as controversial as high-end power cords.

The Limitations of digital audio processors and cables create timing errors known as jitter, which remove portions of the audio signal and replace them with noise and distortion. Cables tend to round off the square waveforms of the signal, making them less clear to the processor, thus increasing jitter. This rounding effect varies greatly among cables and a truly superior digital audio cable can make great improvements in sound quality.


Another manufacturer talking some marketing bull shit?
They do have a point.
Digital is indeed sending fully analogue electrons over a wire.
And indeed, the block pulse degrades with the length.
A good digital cable is one who minimizes this degradation.

The USB 2.0 specification lists a maximum cable length of 5 meters (~15 feet). This is marginal with the best of cables, and many “audiophile grade” cables will run into problems even with far shorter lengths. There have been many credible reports of improved sound quality with some cables, but these have almost all been in systems using Class 1 Audio, with a maximum data rate of 12 MHz. When the data rate is boosted by a factor of 40x to 480 MHz, there are very few “audiophile” cable companies that have the tools and experience to ensure good results.
Computer Audio Playback Overview – Ayre

This is an easy test.
Connect your high speed USB device, e.g. a hard disk using your audiophile grade USB cable. If hi-speed mode (480 Mbps instead of 12 Mbps, the old USB 1 standard) fails, it is a bad DIY digital cable not even compliant with USB 2 standards.


A clear and well written step by step guide to setup and USB DAC using XP, Vista or OSX can be found at the Ayre website.

Setup for Win7.

Setup for Vista.


You can check if your asynchronous USB DAC is really asynchronous.
Audio devices supporting asynchronous transfer mode should have an extra ‘endpoint descriptor’ with

Svyr has more

A simple way to find out is to use the Thesycon USB Descriptor Dumper

Drop out.

Some users complain about dropouts when playing USB audio.

This might be due to different devices sharing the same USB-Hub.

If your audio and your graphics card are on the same hub, the bandwidth required by the graphics might cause the audio to stutter.

Anti-virus programs polling the internet with high priority might interrupt the audio too.

Trouble shooting

Trouble shooting USB audio is covered here.

  1. Universal Serial Bus –
  2. USB audio spec and jitter – John Swenson
  3. How USB Works –
  4. USB in a NutShell – Byond Logic
  5. Time for a change? – Jim Lesurf
  6. Universal Serial Bus Device Class Definition for Audio Devices 1 – Universal Serial Bus (1998)
  7. Universal Serial Bus Device Class Definition for Audio Devices 2 – Universal Serial Bus (2006)
  8. USB audio standards – Computer Audio Asylum
  9. How can USB performance impact audio quality? – Computer Audio Asylum
  10. Confirming whether your DAC is asynchronous as claimed or not – svyr
  11. MEASUREMENTS: Adaptive AUNE X1, Asynchronous “Breeze Audio” CM6631A USB, and Jitter – Archimago’s Musings
  12. USB made simple – MQP Electronics Ltd
  13. Fundamentals of USB Audio – Henk Muller, Principal Technologist XMOS Ltd. -June 27, 2012
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CEC DA 0 3.0

چهار شنبه 20 جولای 2016
/ / /

این برند CEC آمده ایران و رومی از CEC استفاده میکنه به عنوان ترنسپورت. تو انگلیس هم Living Voice محصولاتش رو با این CEC دمو میکنه با Audio Note ژاپن.

ما هم این ترنسپورت رو شنیدیم و تفاوتش رو دیدیم چقدر زیاد بوده با ترنسپورت های دیگه.

حالا این CEC اومده یه Dac زده که روی کاغذ خیلی وسوسه کننده است. مالتی بیت ، R2R بدون هیچ چیپ تبدیل ، بدون فیلتر خروجی و …

نگاهی بهش بندازید جالبه :

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صداي Allan Taylor منتخب ركوردهاي اوديوفايلي

سه شنبه 19 جولای 2016
/ / /

Artist: Allan Taylor
Year Of Release: 1978-2016
Genre: Acoustic, Folk, Folk Rock

Allan Taylor is one of the last of the travelling troubadours who came through the social and artistic revolution of the nineteen sixties and carved out a career as a solo singer-songwriter. Born in Brighton, England in 1945 he experienced the Beatnik times, the Skiffle days, the Mods and Rockers and the early Hippy days, all played out on Brighton Beach. At the age of twenty one he left home and became part of the vibrant folk music of London, playing all of the major folk clubs of the time (for example, the famous Troubadour Club) and then to Greenwich Village, New York, playing legendary clubs such as Gerde’s, The Gaslight, The Bitter End, The Mercer Arts Center. He embraced the issues, images and emotions of his time and used these experiences as the basis of his songs. Signed to the international record company United Artists and recording in London, Nashville and Los Angeles his albums were released world-wide. By the mid-seventies he returned to Europe to live and then started on the second part of his career, having now established his modus operandi – collecting the stories for his songs in the bars and cafes of Europe and throughout the rest of the world.


1978 – The Traveller [Rubber Records – RUBCD026]
[01] Homestate [03:32]
[02] It’s Your Way [02:54]
[03] Running In A Crowded City [02:56]
[04] The Traveller [04:37]
[05] Lone Pilgrim [03:49]
[06] Land Of The North Wind [04:32]
[07] Cold Hard Town [02:34]
[08] The Ladies Are The Loving Kind [03:58]
[09] Lady Takes Your Time [04:06]
[10] Good To See You [04:25]

1991 – Out Of Time [T. Records – TCD.003] [Remastered]
[01] It’s Good To See You [04:48]
[02] Scene From A Corner Café [06:39]
[03] The Ladies Are The Loving Kind [04:13]
[04] Standing At The Door [04:36]
[05] Roll On The Day [04:15]
[06] Out Of Time [04:34]
[07] Choose Your Time [03:35]
[08] Piaf [04:05]
[09] “Boy” Is A Nation [05:05]
[10] We Must Journey On [05:03]
[11] Angelina’s Cantina [05:00]
[12] Middle Time [04:11]
[13] The Rose And The Briar [03:29]

1996 – Looking For You [Stockfisch Records – SFR 357.6013.2]
[01] The Traveller [04:58]
[02] So Long [04:28]
[03] Looking For You [04:28]
[04] Win Or Lose [05:04]
[05] The Veteran [04:34]
[06] The Dove [03:08]
[07] Restless [04:28]
[08] Joseph [03:56]
[09] Misty On The Water [03:37]
[10] Cold Hard Town [03:18]
[11] Crazy Man [03:39]
[12] Hard To Tell [02:13]

2000 – Colour To The Moon [Stockfisch Records – SFR 357.6021.2]
[01] Kerouac’s Dream [03:57]
[02] A House By The River [02:42]
[03] A Road Too Long [04:08]
[04] Back Again [03:27]
[05] Notes From Paris [04:49]
[06] Wheel Of Fortune [03:49]
[07] Brighton Beach [04:25]
[08] Colour To The Moon [04:34]
[09] Creole Girl [06:19]
[10] Whatever The Way [03:32]
[11] Crazy Amsterdam [03:34]
[12] Scotty [03:23]

2003) Hotels & Dreamers [Stockfisch Records – SFR 357.6028.2]
[01] The Beat Hotel [06:58]
[02] The Stranger [03:46]
[03] Frenchtown [04:49]
[04] Los Compañeros [06:11]
[05] For Those We Knew [03:55]
[06] Running On Dreams [05:22]
[07] The Mission Hotel [04:54]
[08] For What It’s Worth [04:53]
[09] Some Dreams [04:30]
[10] Pearls And Wine [04:01]
[11] When Time Is Short [05:54]

2007 – Old Friends – New Roads [Stockfisch Records – SFR 357.6047.2]
[01] Chimes At Midnight [04:06]
[02] For An Old Friend [03:23]
[03] Urban Love Song [04:35]
[04] The Meadow [04:15]
[05] Homestate [03:51]
[06] The Morning Lies Heavy [03:25]
[07] Syracuse And Albany [03:06]
[08] Now You Know [02:43]
[09] Let Me Be [03:28]
[10] Flower In The Snow [02:44]
[11] Like I Used To Do [03:58]
[12] Lady Take Your Time [03:51]

2009 – Leaving At Dawn [Stockfisch Records – SFR 357.4057.2]
[01] Winter [03:53]
[02] The Almost Man [06:31]
[03] Back Home To You [04:42]
[04] Provence [03:45]
[05] Firefly [06:07]
[06] Lay Soft On Your Pillow [04:05]
[07] New York In The Seventies [06:09]
[08] The Last Of The Privateers [05:42]
[09] Leaving At Dawn [04:19]
[10] It Could Have Been [03:36]
[11] Make Another Turn [05:07]
[12] Red On Green [03:45]

2010 – Songs For The Road [Stockfisch Records – SFR 357.9010.2]
[01] Dedicated To … [03:53]
[02] A Promise And A Porsche [06:31]
[03] Let The Music Flow [04:42]
[04] Dancing On A Saturday Night [03:45]
[05] Midnight Call [06:07]

2013 – All Is One [Stockfisch Records – SFR 357.4078.2]
[01] Endless Highway [04:49]
[02] Let The Music Flow [05:29]
[03] All Is One [07:31]
[04] We Stood As One [05:34]
[05] I Followed Her Into The West [04:31]
[06] One Last Smile [05:00]
[07] Plenty For The Few [04:36]
[08] The Sky [08:39]
[09] Like A Cloud (Canzone Del Ripensamento) [03:26]
[10] The Best I Can [02:22]

2016 – There Was A Time [Stockfisch Records – SFR 357.9015.2]
[01] Chimes At Midnight [04:59]
[02] For Those We Knew [03:53]
[03] Down The Years I Travelled… [04:55]
[04] For What It’s Worth [04:43]
[05] The Merlin Café [06:04]
[06] Provence [04:24]
[07] There Was A Time [04:28]
[08] Joseph [04:33]
[09] Win Or Lose [05:53]
[10] Winter [05:14]
[11] Red On Green [03:47]
[12] The Beggar [04:11]


1998 – Sometimes/The Lady [BGO Records – BGOCD390]
[01] Sometimes [04:58]
[02] Searching For Lambs [04:28]
[03] Nursery Tale [04:28]
[04] Robin Hood [05:04]
[05] Song For Kathy [04:34]
[06] Swallow Swallow [03:08]
[07] Scarlet And Grey [04:28]
[08] Our Captain Cried All Hands [03:56]
[09] Tudor Pop [03:37]
[10] The Leaves Of Spring [03:18]
[11] The Pied Piper [03:39]
[12] The Kiss [02:13]
[13] Belfast ’71 [02:13]
[14] Still He Sings [02:13]
[15] The Morning Lies Heavy [02:13]
[16] Something’s Changed [02:13]
[17] Let Me Be [02:13]
[18] The Boy And The Mantle [02:13]
[19] The Lady [02:13]
[20] Cain [02:13]
[21] Simple Song [02:13]
[22] My Lady [02:13]

2012 – Down The Years I Travelled … [Stockfisch Records – SFR 357.9013.2]
[01] Down The Years I Travelled [04:03]
[02] Win Or Lose [05:28]
[03] Choose Your Time [03:09]
[04] Golden Island [04:24]
[05] There Was A Time [03:15]
[06] Songdance [03:26]
[07] Jimmy’s Song [03:18]
[08] Gently Does It [04:06]
[09] Banjo Man [04:55]
[10] Chimes At Midnight [05:20]
[11] Boy Becomes The Man [03:43]
[01] Maybe Another Day [05:29]
[02] Cry From The Heart [05:31]
[03] Don’t Think Twice, It’s All Right [04:29]
[04] So Long [04:40]
[05] Let It Come, Let It Go [04:43]
[06] The Merlin Café [04:16]
[07] Carried On The Wind [04:28]
[08] Come Home Safely To Me [03:27]
[09] Let’s Go To Paris [04:30]
[10] Across The Borderline [04:14]


2013 – Old Friends In Concert [Universal Music Group – 06025 3726777]
[01] Heute Hier, Morgen Dort / Day To Day [04:41]
[02] Ansage [01:40]
[03] Los Compañeros [05:38]
[04] Schwestern, Brüder / What’s The Life Of A Man? [03:26]
[05] Banjo Man [05:10]
[06] Kleine Stadt / The Town I Loved So Well [05:03]
[07] Leaving At Dawn [04:35]
[08] Ansage [00:50]
[09] Es Ist An Der Zeit / The Green Fields Of France [05:32]
[10] Unterwegs Nach Süden [05:16]
[11] Kerouac’s Dream [04:22]
[12] Ansage [01:04]
[13] Gut Wieder Hier Zu Sein / It’s Good To See You [05:21]
[14] Sag Mir, Wo Die Blumen Sind / Where Have All The Flowers Gone [04:35]
[15] I’m Going Home [05:59]
[16] Dat Du Min Leevsten Büst / Night Visiting Song [02:57]
[17] Schon So Lang / Been On The Road So Long [04:53]

Wheel Of Fortune

There’s a drag queen preaching Jesus in the middle of the square
A young kid playing “Yesterday” on a Japanese guitar
There’s a loser on the talk show, he wants to be a star
And Sharon sings for Wayne in a karaoke bar

There’s a superstar who fell from grace, he has to tell it all
About the dizzy heights he rose to and his ignominious fall
Infamy or fame, it’s the same for one and all
We’re just trying to get attention in this suburban shopping mall

In this suburban shopping mall, another shopping mall
We’re just trying to get attention in this suburban shopping mall

Everybody’s got their price, in that there is no shame
Everyone will sell their soul for a minute or two of fame
We’re playing wheel of fortune, life is just a game
Some will win, some will lose, but we all end up the same

We will all end up the same, we will all end up the same
Some will win, some will lose, but we all end up the same

Will the drag queen find Jesus, and what will Jesus wear
Will the faded star redeem himself, become a millionaire
Will Wayne marry Sharon, will they make the perfect pair
Another joke, another tragedy, does anybody care

Does anybody care, does anybody care
Another joke, another tragedy, does anybody care


All Is One

One frozen smile, one dying fall
One crooked mile, one Wailing Wall
One broken vow, divides the few
Too late somehow to make anew

One bird in spring, come summer soon
Young lovers sing a simple tune
Too young to know how dreams are brief
And come to fall, one autumn leaf

One final dance unites us all
One grand romance before we fall
One stands alone when all is gone
When one is all and all is one

One river flows, one endless sea
One never knows how it should be
One hopeless love, one more lost cause
One velvet glove to close the doors

One backward glance, one fare-thee-well
One more chance in a wishing well
One helpless call, one road too far
We lose it all, for what we are

One final dance,

One grain of sand, one falling star
One crippled hand, one old guitar
One tune will end, one song begins
We fly again on broken wings

One traitor’s kiss , one twisted knife
One night of bliss, one wasted life
One final hour, one second more
One faded flower thrown to the floor

One final dance,

One letter burned, one memory lost
One gift returned, one lover crossed
One open wound, one bleeding heart
One comes around, one plaays the part

One life is short, one cannot stay
One must depart, one fades away
One runs the course, one tries in vain
One shows remorse and tries again

One final dance unites us all
One grand romance before we fall
One stands alone when all is gone
When one is all and all is one
And all is one, and all is one

Allan and Johnny at Skagen Festival 2009

One Last Smile

Red On Green

Now all is gone
Only words remain
Words I write to you my love
One last sweet refrain

When the order came
Early in the dawn
Soldiers into battle
Falling one by one

Then I stood alone
I knew it was my turn
Falling into darkness
Never to return

No more will I see the light that dances in your eyes
No more watch the flowers bloom when fleeting swallows fly
And the last light of the summer has faded away
Gone forever, gone forever more

Blood red on green
Colours that I wear
I am calling out your name
Can you hear
I am calling out your name
Can you hear


I see you in a white dress, your hair blows in the wind
You’re walking barefoot in the grass, summer’s come again
Fields of sweet lavender, Provence in the sun
All is forgiven, all is one

I will sit and watch you, I will paint the scene
I will trace the outline and the colours inbetween
We’ll lie on a blanket and picnic in the sun
All is forgiven, all is one

When the light begins to fade at the end of day
There’s no need to be afraid
We can always turn away

One day we’ll remember how it used to be
How I stood alone in your affections and you were everything to me
Our time is not over, a new day has begun
And all is forgiven, all is one

When the light begins to fade at the end of day
There’s no need to be afraid
We can always turn away

I see you in a white dress, your hair blows in the wind

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Computer Audio

جمعه 15 جولای 2016
/ / /

نتایج من تا این لحظه (بعد از 30 ساعت مطالعه) این بوده در عمل بهترین گزینه USB هست (دقت کنید فقط USB 2 و USB 3 خوب هستند و گزینه USB1 مناسب نیست) بصورت Asynchronous و استفاده از یه کابل خوب مثل پیوریست و اینکه استفاده از ری کلاکر و واسط های حذف نویز اصلا خوب نیست. بهتره از مک استفاده بشه با نرم افزار بیت پرفکت Audirvana با تنظیمات مربوط. کل دیتای فایل موزیک باید تو حافظه باشه.

بعضی ها معتقدند بهتره از Toslink اپتیک برای ایزوله کردن استفاده کنیم که من حس میکنم راه حل USB (با پیشرفت بیشتر USB در آینده) راه حل بهتری خواهد بود. خود تورستن هم میگه این راه حل خیلی Jitter داره و اصلا خوب نیست.

راه دیگه هم Firewire هست که عملا نه DAC سازان رفتند سمتش و نه تو مک بوک خیلی بهش توجهی شده. این راه حل خوبه اما خیلی برای ماها عملی نیست و بیشتر بدرد استودیوها میخوره و برای پهنای باند بالا خوبه. راه حل PC با کارت صدای AES یا Firewire و سیستم لینوکس هم خیلی در موردش به نتایجی کسی نرسید که بخواد توضیحی به ما بده. عملا بهترین حالت استفاده از پورت یو اس بی MAC هست با Audirvana. خوبی دیگر Usb نسبت به Firewire در سادگی و نداشتن درایور هم هست.

هارد چه SSD چه معمولی خیلی فرقی روی ماجرا ندارند اما SSD کمی بهتره. برق یا باطری روی کامپیوتر مهمه و خودم ترجیح میدم از یک Power Supply خوب استفاده کنم.

موضوعی که مهمه اینه که تو انتخاب DAC باید به نکات زیر دقت کنیم :

  • اون DAC حتما ورودی USB 2.0 یا USB 3.0 داشته باشه
  • ورودی USB مبدل DAC حتما باید حالت Asynchronous گوردون داشته باشه مثل Wavelength یا Ayre یا Berkeley USB Alpha
  • باید ورودی USB اون DAC سیگنال رو مستقیما به چیپ DAC برسونه و نیاد اول به SPDIF تبدیلش کنه چون کل ارزش USB به همون Jitter کم Asynchronous mode هست و اگر بخواد تبدیل به SPDIF بشه دیگه کار خراب میشه.

دقت کنید نقش کابل USB برای کاهش نویز از PC به DAC بسیار مهمه.

از سایت رومی این لینک رو دیدم که مصاحبه های سال 2013 هست.

Larry Moore and Eric Hider of Ultra Fi Audio Designs

Andreas Koch of Playback Designs

Tony Lauck

Steve Nugent of Empirical Audio

Gordon Rankin of Wavelength Audio

Jon Reichbach of Sonic Studio/Amarra

Vinnie Rossi of Red Wine Audio

John Stronczer of Bel Canto Designs

Daniel Weiss of Weiss Digital Audio

Vincent Sanders and John Hughes of VRS Audio Solutions

Kent Poon of Design w Sound

Charles Hansen of Ayre Acoustics

Pete Davey of Positive Feedback Online

رومی میگه جای نظرات Dan Lavry,  Ed Meitner, Michael Ritter and Pflash Pflaumer هم خالیه. شرکت های Lavry Engineering و  EMM Labs و berkeley audio design .

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Asynchronous USB DAC Bit-Perfect NOS Tube Non-Oversampling No Filter

جمعه 15 جولای 2016
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نتایج ما از یک سورس دیجیتال خوب تو میکرو :

  1. در صورت استفاده از کامپیوتر ورودی یو اس بی USB (نسخه های 2 و بالاتر) بهتر از SPDIF و بقیه ورودی ها هست اگر USB خوب پیاده سازی بشه بصورت آسینکرون Asynchronous USB و حذف نویز کامپیوتر . اینو هم تورستن میگه هم گوردون طراح Wavelength
  2. بیت پرفکت بودن یعنی آپ سمپل نشدن NOS (Non-Oversampling) و عدم استفاده از فیلتر دیجیتال و بطور خلاصه هیچ تغییری روی دیتای دیجیتال ندادن. این موضوع رو هم Peter Qvortrup طراح Audio Note و 47Lab میگه و هم رومی و تورستن (طراح AMR) و طراح Lampizator (آقای Lukasz Fikus ) خیلی روش تاکید دارند و طراح Wavelength (آقای Gordon Rankin) هم همین اعتقاد رو داره. همه اینها با دستکاری دیتای دیجیتال و هر نوع پردازش حتی ساده مخالفند. تمام DSP ها کارشون دستکاری دیتای دیجیتال هست.
  3. عدم استفاده از op-Amp و فیلتر خروجی و در مقابل استفاده از خروجی لامپ و ترانس که Tim طراح EAR و طراح Audio Note و طراح Lampizator بهش اعتقاد دارند.
  4. برق Power Supply خوب
  5. حذف کامل جیتر Jitter

در مورد این DAC USB شرکت Wavelength Audio بیشتر بخونیم :

Cosecant USB DAC by Gordon Rankin

  – The Cosecant v3 connects the USB controller to a DAC module. The USB firmware to run that DAC module resides there so each module has its own developed code. The output of the module connector is sent directly to the 6GM8/ECC86 dual triode output tube, which drives the transformer-coupled output.
– The Cosecant has an external power supply with IEC connector to isolate the power from the DAC and its audio transformers.
– This is my own design and I wrote the software (1,800 lines of code for the USB controller to do what it does) like no one else does on the planet.
– The DAC featured in this review uses Asynchronous USB mode as do the Crimson. The USB interface is bidirectional, and has built-in error correction and buffering at both ends; it is an asynchronous interface. Clocking synch problems associated with SPDIF are not present with USB. The result is that the data on the disk is identical to what is leaving the DAC all the time. At start-up, the DAC tells the computer it can handle 16 bit audio at 32K, 44.1K and 48K. Since the USB receiver only has to handle these 3 frequencies, the clocking to the DAC has almost no jitter. SPDIF actually has to be synched to the exact frequency of the transport (i.e. if the transport is working at say 44.0896K instead of 44.1K the DAC has to sync to that frequency). Therefore the jitter problems of SPDIF are all but eliminated. The result is a zero error protocol to link between computer and DAC, with ultra low jitter.
– None of these DACs use any type of operational amplifiers (opamps) in their design. The DAC module is the only solid-state portion of the overall DAC.
– The output stage of each of these products is the key design element which is responsible for their overall sound.
– These DACs incorporate the TDA1543N2 (select top 5%) DAC chips with passive I/V using Shinko Tantulum resistors in a configuration that does not use analog or digital filters. Some people call these NOS DACs or what I call zero DACs. The data input is the data output without any up/oversampling or other manipulation, which seems to make for a very analog presentation.

Well, I admit that I was clueless on the subject but I was intrigued and I consulted my engineering recourses.  It turned out that what I proposed above was not exactly accurate: for instance regular computers do not use I2S bas interface…

To make the long story short: For a computer the USB port is a devise of the same hierarchy as sound card and there is not different for a computer to where output stream: to a driver on the sound card or to the driver the sit behind the USP port designation. With identical drivers used the ASE/EDU interface has fundamentally lower jitter interface, where the min jitter for USB is not even included in the USB standard. So, with identical design (more of the time used) the USB has no chance to be superior.

There is a catch however. With proper design, when USB is made not for utilitarian purposes but for high quality transfer, the USB has internal chance to be way more advanced. The ASE/EDU is forward-only interface where stream flows only in one direction with data mixed with clock marks. The USB is full duplex or bi-directional interface where stream flows in both ends. This enables designers to put a clock that might everything on the receiver side (DAC) and let this clock to manage the USB’s and even reader timing. USB sends data in burps by requests of by scheduled timing, this marks all might be managed by receiver side clock. In ASE/EDU the receiver shell recognize the timing marks and PLL or re-clock data. In USB there are no needs for PLL or re-clocking as the data arrives at the marks of the original clock. The USB in this case acts like an elephant that sticks a long trunk to another devise and sucks juice… according to my consultants this USB implementation is the most proper way to do the things. Or course no one knows HOW the USB is managed even if a DAC has USB port…

The Cat

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معرفي آلبوم-نغمه جادويي تيم هاردين

دوشنبه 11 جولای 2016
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سادگي و در عين حال زيبايي سبك “فولك” حيرت انگيزه .
حيفم اومد لذتي رو كه بعد از شنيدن ترانه هاي “تيم هاردين” به من دست ميده با دوستان تقسيم نكنم.


Birth name James Timothy Hardin
Also known as Tim Hardin
Born December 23, 1941
Eugene, Oregon, US
Died December 29, 1980 (aged 39)
Los Angeles, California, US
Genres Folk
Occupation(s) Singer, songwriter
Instruments Vocals, guitar, piano
Years active 1964–1980
Labels Verve, Columbia


  • 1966: Tim Hardin 1 (Verve Forecast FT/FTS 3004)
  • 1967: Tim Hardin 2 (Verve Forecast FT/FTS 3022)
  • 1967: This Is Tim Hardin (demos recorded 1963/64) (ATCO 33–210)
  • 1968: Tim Hardin 3 Live in Concert (Verve Forecast FTS 3049)
  • 1969: Tim Hardin 4 (Verve Forecast FTS 3064)
  • 1969: The Best of Tim Hardin (Verve Forecast FTS3078)
  • 1969: Suite for Susan Moore and Damion: We Are One, One, All in One (Columbia CS 9787)
  • 1971: Bird on a Wire (Columbia CK-30551)
  • 1972: Painted Head (Columbia CK-31764)
  • 1973: Nine (Antilles AN-7023)
  • 1981: Unforgiven (San Francisco Sound SFS 10810)
  • 1981: The Tim Hardin Memorial Album (Polygram PD-1-6333)
  • 1981: The Shock of Grace (CBS Columbia PC37164)
  • 1981: The Homecoming Concert (Line LICD 9.00040)
  • 1990: Reason to Believe (The Best Of) (Polydor 833954)
  • 1994: Hang on to a Dream: The Verve Recordings (Polydor 521583)
  • 1996: Simple Songs of Freedom: The Tim Hardin Collection (Legacy /Sony 64858)
  • 2000: Person to Person: The Essential, Classic Hardin 1963–1980 (Raven)
  • 2002: 20th Century Masters – The Millennium Collection: The Best of Tim Hardin (Polydor)
  • 2002: Black Sheep Boy: An Introduction to Tim Hardin (Universal International)
  • 2007: Through the Years 1964–1966 (Lilith)Tim Hardin
    Tim Hardin 
    It'll never happen again
    Cmaj7 Fmaj7        Cmaj7       Fmaj7
        I remember our first affair
    Cmaj7    Fmaj7   Cmaj7 Fmaj7  Cmaj7         Fmaj7
      All the pain, always rain   around my eyes
    It'll never happen again
    Fmaj7        Em7    Cmaj7   Dm7 
    It'll never happen again
    Em7      Fmaj7            Cmaj7 Fmaj7
       Every time I leave you alone
    Cmaj7      Fmaj7    Cmaj7            Fmaj7
    I remember times I couldn't come home
    It'll never happen again
    Fmaj7        Em7   Cmaj7  Dm7 
    It'll never happen again
    Em7           Am7   Em7                   Am7
    Why can't you be    the way I want you to be
    Em7             G                       F6  G6
    Why can't you see you got to change to love me
    Repeat first verse
    How Can We Hang On To A Dream chords
    Tim Hardin *
    Gm F Eb D
    Gm         F  Eb               D
    What can I say, she's walking away;
    Cm              F
    from what we've seen
    Gm         F Eb             D
    What can I do, still loving you;
    Cm         D
    it's all a dream
    Eb         F            Gm
    How can we hang on to a dream? 
    Eb         F                    G
    How can it really be the way it seems?
    Gm         F Eb                   D
    What can I do, she's saying we're through;
    Cm          F
    with how it was
    Gm          F  Eb                  D
    What will I try, I still don't see why;
    Cm                D
    she says what she does
    Eb         F            Gm
    How can we hang on to a dream? 
    Eb         F                    G
    How can it really be the way it seems?
    Gm F Eb D  Cm D
    Gm         F  Eb               D
    What can I say, she's walking away;
    Cm              F
    from what we've seen
    Gm         F Eb             D
    What can I do, still loving you;
    Cm         D
    it's all a dream
    Eb         F            Gm
    How can we hang on to a dream? 
    Eb         F                    G
    How can it really be the way it seems?
    Eb         F            Gm
    How can we hang on to a dream? 
    * Alternate:
    Capo III
    Gm  = Em
    F  = D
    Eb = C
    D  = B or B7
    Cm = Am
    G  = E


    Simple Song Of Freedom chords
    Tim Hardin (Bobby Darin)
    Capo I
    G               D              G  
    Come and sing a simple song of freedom  
    C                   D            G  
    Sing it like you've never sung before  
    D                    Em  
    Let it fill the air, tell the people everywhere  
    C              D                  G  
    We, the people here, don't want a war  
    G                D                 G  
    Hey there Mister Black Man can you hear me  
    C                 D               G  
    I don't want your diamond or your game  
    D                 Em  
    I just want to be someone known to you as me  
    C                 D                 G  
    And I will bet my life you want the same
    G               D              G  
    Come and sing a simple song of freedom  
    C                   D            G  
    Sing it like you've never sung before  
    D                    Em  
    Let it fill the air, tell the people everywhere  
    C              D                  G  
    We, the people here, don't want a war  
    G             D               G  
    Seven hundred million are you listening  
    C                D               G  
    most of what you read is made of lies  
    D                   Em  
    Speaking one to one ain't it everybody's sun  
       C              D               G  
    To wake to in the morning when we rise 
    G               D              G  
    Come and sing a simple song of freedom  
    C                   D            G  
    Sing it like you've never sung before  
    D                    Em  
    Let it fill the air, tell the people everywhere  
    C              D                  G  
    We, the people here, don't want a war  
    G             D                 G  
    No doubt some folks enjoy doing battle  
    C                D                   G  
    Like presidents, prime ministers and kings  
    D                            Em  
    So let us build them shelves so they might fight among themselves  
    C               D                 G  
    And leave us be those who want to sing 
    G               D              G  
    Come and sing a simple song of freedom  
    C                   D            G  
    Sing it like you've never sung before  
    D                    Em  
    Let it fill the air, tell the people everywhere  
    C              D                  G  
    We, the people here, don't want a war
    REASON TO BELIEVE		(Tim Hardin)
    C             G              Am
    If I listened long enough to you
               F      G                     C
    I'd find a way to believe that it's all true
    D                G             F             C
    Knowing that you lied straight faced while I cried
             Am     G      F      F#bass G
    Still I look to find a reason to     believe
    	G            F            G                Am G
    Someone like you makes it hard to live with   someboby eles
                F            G            Am             G
    Someone like you makes it easy to give never thinking of myself
    C             G                 Am
    If I gave you time to change my mind
               F      G                C
    I'd find a way to leave the past behind
    D                G             F             C
    Knowing that you lied straight faced while I cried
             Am     G      F      F#bass G
    Still I look to find a reason to     believe
    G            F            G                Am G
    Someone like you makes it hard to live with   someboby eles
                 F            G            Am             G
    Someone like you makes it easy to give never thinking of myself
    C             G                 Am
    If I gave you time to change my mind
               F      G                C
    I'd find a way to leave the past behind
    D                G             F             C
    Knowing that you lied straight faced while I cried
             Am     G      F      F#bass G
    Still I look to find a reason to     believe
             Am     G      F      F#bass G
    Still I look to find a reason to     believe
             Am     G      F      F#bass G
    Still I look to find a reason to     believe
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Purist Audio in Iran

یکشنبه 10 جولای 2016
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کابل های من رسید. دست آرمن درد نکنه خیلی هم خوب و سریع و عالی.

وقتتون رو برای انتخاب کابل هدر ندید ، من مطلقا Purist Audio رو پیشنهاد میکنم و کلا صداش با همه این کابل هایی که هست فرق داره. سری 30 هزار دلاریش هم به سفارش یکی از دوستان در ایران اومده و من هنوز صداشو نشنیدم اما سری نپتون خودم که هست عالیه.

Purist Audio Design 30th Anniversary USB Cable 1.0m (A to B)
Purist Audio Design Neptune Interconnects 1.0m XLR
Purist Audio Design Impresa Headphone Cables 1.5m (Furutech FP-704 1/4 Senheiser HD-800)
Purist Audio Neptune Speaker Cable 2.0m
Purist Audio Neptune AC Power Cables 1.5m (15A IEC)

اینم عکسها :

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معرفي آلبوم

شنبه 9 جولای 2016
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David Gates in 1975
Birth name David Ashworth Gates
Born December 11, 1940 (age 75)
Tulsa, Oklahoma, United States
Genres Rock and roll, soft rock, country, pop, adult contemporary
Vocals Guitar Bass Guitar Moog Synthesizer Hammond Organ Violin Viola Percussion
Years active 1957–present
Labels A&M, Elektra
Associated acts Bread

David Gates Albums


David Gates-Love Is Always Seventeen Lyrics

Seventeen – It’s been a while since I’ve seen seventeen
And the years since have been mighty lean
But there’s no use complainin’
Forty-two-has a way of creeping up on you
And my chances left are gettin’ few
But there’s till time remainin’
I’ve been waiting for someone
Who loves the way I do
Girl I’ve got my fingers crossed
In hopes it might be you…
Twenty-one…that’s how many different jobs I’ve done
I remember quittin’ every one
With no hesitatin’
And thirty-three…
That’s how many women left on me
I don’t have too good a history
But I don’t mind waitin’…
‘Cause it really doesn’t matter
How many years you’ve seen
‘Cause love is always seventeen
Wonder if you’ll be the one
To end this lonesome heart
‘Cause girl I’ve got a lot to give
And I’d sure like to start.
It really doesn’t matter
How many years you’ve seen
‘Cause love is always seventeen

David Gates&Bread – Aubrey Lyrics

And Aubrey was her name,
A not so very ordinary girl or name.
But who’s to blame?
For a love that wouldn’t bloom
For the hearts that never played in tune.
Like a lovely melody that everyone can sing,
Take away the words that rhyme it doesn’t mean a thing.

And Aubrey was her name.
We tripped the light and danced together to the moon,
But where was June.
No it never came around.
If it did it never made a sound,
Maybe I was absent or was listening to fast,
Catching all the words, but then the meaning going past,

But God I miss the girl,
And I’d go a thousand times around the world just to be
Closer to her than to me.

And Aubrey was her name,
I never knew her, but I loved her just the same,
I loved her name.
Wish that I had found the way
And the reasons that would make her stay.
I have learned to lead a life apart from all the rest.
If I can’t have the one I want, I’ll do without the best.

But how I miss the girl
And I’d go a million times around the world just to say
She had been mine for a day.


David Gates&Bread – Diary Lyrics

I found her diary underneath a tree.
And started reading about me
The words she’s written took me by surpise
You’d never read them in her eyes.
They said that she had found the love she waited for.
Wouldn’t you know it, she wouldn’t show it.

When she confronted with the writing there,
Simply pretended not to care.
I passed it off as just in keeping with
Her total disconcerting air
And though she tried to hide
The love that she denied,
Wouldn’t you know it, she wouldn’t show it.

And as I go through my life, I will give to her my wife
All the sweet things that I can find.

I found her diary underneath a tree.
And started reading about me.
The words began stick and tears to flow.
Her meaning now was clear to see.
The love she’d waited for was someone else not me
Wouldn’t you know it, she wouldn’t show it.

And as I go through my life, I will wish for her his wife
All the sweet things that she can find
All the sweet things they can find

Songwriters: GATES, DAVID
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دریچه ای تازه به موسیقی ناب

سه شنبه 5 جولای 2016
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گستردگى فضاي مجازي و سهولت دسترسي به جديدترين آلبومهاي موسيقي به تناسب شگفت زدگي مخاطب بعضا او را دچار سردرگمي و ضعف در انتخاب صحيح نموده است. نگارنده برأن است به موازات معرفي آلبومهاي اوديوفايلي با نگاهی به صداهاي ناشناخته و ضمن بهره از نظرات شما اين بخش از سايت را مجددا فعال نمايد.

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