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Gordon Rankin : Proper Break-in Audio Systems

چهار شنبه 7 سپتامبر 2016
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برای بهترین حالت Break-in کردن یک سیستم صوتی نظر Gordon Rankin اینه باید هر چند ساعت دستگاه خاموش بشه و سرد شد دوباره روشن بشه کار کنه . یعنی نباید شما 300 ساعت پیوسته دستگاه رو Play کنید و مثلا 4 ساعت کار کرد 1 ساعت خاموش بشه و دوباره 5 ساعت کار کرد 2 ساعت خاموش بشه.

http://www.computeraudiophile.com/f6-dac-digital-analog-conversion/new-wavelength-cosecant-v3-331/

IF you keep the unit running continously these parts will not break in at all, but will tend to move to one place. That is not the place you want them to be at. By doing the continuous thing you will not break in the device at all. It may actually take months before you get the unit correct if you do this at first.

Therefore…….. just use the damn thing as you would normally with the unit run randomly and it will reach the first break in stage at about 40-50 hours.

این بلندگوی Living Voice هم اومده و من در موردش مینویسم …

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MacBook Pro 2014 vs CEC TL0

شنبه 3 سپتامبر 2016
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خیلی تست دردناکی بود :-)))))

این CEC خوب بود ولی Macbook ما خوب صدا نمیداد. صدای CEC عمق داشت ، فول بود ، هارمونیک داشت و بالانس بود و جریان صدا راحت بود. مک بوک تیز بود بی حال بود و عمق نداشت و خسته کننده بود.

اختلاف خیلی زیاد بود.

حالا در مورد کابل Usb بخونید :

http://www.computeraudiophile.com/f8-general-forum/gordon-rankin-says-im-wrong-about-universal-serial-bus-industry-standard-cables-connectors-and-communications-protocols-between-computers-and-electronic-devices-cable-sound-20814/

الان دارم در مورد CD Ripping میخونم. اینا رو میشه استفاده کرد و برای مک dbpoweramp باید گزینه خوبی باشه:

http://www.thewelltemperedcomputer.com/KB/Ripping.htm

http://www.accuraterip.com/software.htm

How to Configure dBpoweramp for Bit-Perfect CD Audio Ripping

dbpoweramp
Exact Audio Copy (EAC)
Rip (Apple MAC)
XLD (Apple MAC)
Songbook (Apple MAC)

One of the many comparison between various rips has been made by Kent Poon.
Comparing rips made on PC and MAC using iTunes, Wavelab and EAC didn’t show any difference.
It depends on your setting. If you choose “Include pre-gap except for HTOA” mode when ripping, “Not prepended” should be chosen. If you choose “Include pre-gap for all tracks” mode, “Prepended” should be chosen.
DO NOT check the “Treat AccurateRip mismatch as an inconsistency in log” box.

در مورد سیستم usb نوشته زیر مهمه :

Gordon Rankin on why USB audio quality varies

میگه مشکل usb اینه error correction نداره. بین برندها Wavelength Audio و iFi Audio و UpTone Regen و Curious Cable روی این موضوع وقت گذاشتند. همه قسمت ها مهم میشه وقتی error correction نداریم و باید کابل با امپدانس واقعی 90 اهم باشه و فرستنده امپدانس خروجی اش مچ باشه و امپدانس ورودی ریسیور مچ باشه و بشه جلوی نویز رو بگیریم و …

خود Gordon میگه CEC داره و صدای Macbook اش بهتره (I have the CEC TL0 and it’s ok, but not nearly as good as the computer) اما باور کردن این موضوع خیلی خیلی سخته :

Via email, I posed the following question to Rankin: when I transfer a file over USB to an external hard drive it doesn’t make transfer errors – the file at the destination is the same as the source – so why should sending digital audio over USB be any different?

What came back was an epic reply. Strap yourself in – we’re going for a ride.

“While all of these interfaces (Firewire, SPDIF, USB, Ethernet, Thunderbolt so forth) have specifications. The % differential from one supplier to another in electrical, cabling, device and host seem to vary quite a bit.“

“All data moving between a host computer and a device over USB is done electrically. There are different speeds and different protocols that determine how a device and the host communicate.”

“Any interface between two points cannot be totally error free. If you use a hard drive over USB, Ethernet or Firewire there are transmission errors. That means the transmitting device is told to resend the packet that has the error in it. Most of the time this is one bit in a packet size of length X.”

“Remember, the carrier is modulated on the data so the larger X, the bigger chance of errors. Also the faster the interface the more chance that there will be an error.”

“The three main USB transmission protocols are Bulk, Interrupt and Isosynchronous. Bulk (used for data transfer to a hard drive) and Interrupt are error correcting. Isosynchronous (used for audio) is not.”

“Bulk and Interrupt are immediately NAK (negative acknowledgement). The receiver is designed to detect a bad packet immediately and the packet is resent.”

For USB audio, the receiving device is basically translating a serial stream of data with a clock interwoven throughout. At the end of the packet sits some sort of block check. If the block check does not match the data then that packet is flagged as an error.”

“With Isosynchronous USB transmission, packets are sent without any error correction / resending. But guess what? This is the USB protocol used for audio frames. The bad news is they are not error free. The good news is these Isosynchronous frames are afforded the highest priority in the system.”

“A couple of years ago, I bought an expensive Tektronix USB setup. I have had protocol analyzers since designing my first USB DACS some twelve years ago. The Tektronix is useful because it allows me to see errors better both in electrical and data packets.”

“The big thing that many people don’t realize is that not all USB ports are created equal. Not all USB cables are created equal and it’s the same for devices and even operating systems. Since getting the Tektronix I have tested probably thirty different USB cables on the fifteen computers in my lab. These computers run a variety of operating systems and the Tektronix results vary between computers even when the cable remains the same. Lets just say it’s not as pretty as I thought it would be.”

“Just a couple of things to think about in regards to USB ports. First, look to see what else is located on that tree. Each USB port can handle 127 devices. Sometimes there are additional ports hidden (inside your computer) and there are internal devices sitting on those ports – this could be the same tree that is hosting your USB DAC”.

“You can see in the lower tree, USB Hi-Speed Bus, Hub*, Hub, Apple Internal Keyboard/Trackpad, BRCM20702 Hub, Bluetooth USB Controller. On some computers, Hub* will actually be a external port and if you plugged your DAC in there you’re sharing it with all the devices below it.”

“On the PC, you can use this helpful application from Thesycon.”

“Alternatively, if you know your way around Device Manager you can go through that to find the USB tree. Although neither of these really give you a good indication of which port is on which internal hub, if you ARE able to place your DAC on a direct port you will be best served.”

“Speed plays an important part in all of this too. You may have heard the terms UAC1 and UAC2 – these are USB Audio Class protocols. UAC1 was designed for Full Speed device and host interaction. A data packet is sent every 1ms. In that packet are up to 1023 frames.”

“In high speed or UAC2 those 1024 frames each contain eight micro frames. Therefore, the amount of data we can send over UAC2 is basically eight times greater than that of UAC1. But with more data at faster speeds comes more errors and system configuration becomes harder. I almost never see an error on a UAC1 device, on a UAC2 device I can pretty much count on errors in both directions.”

“For optimum results, at least in theory, it’s best not to use a USB hard drive for your library with a USB DAC connected to the same host device. Think of it this way: your music software is reading from the hard drive in a synchronous manner and then writing to the DAC in that same synchronous manner and, as the DAC has priority, the music software might fault when reading the disk – this can lead to really bad sound.”

“Also, it’s probably best not to put the library on the system disk – because system stuff has really high priority over music playback software and again the music software can fault and bad sound will result. When a music app faults it becomes NON-bit true. One workaround for this is to choose a music app with memory buffering but in my experience even that’s not guaranteed to be 100%.”

“A good example of this is when we transitioned from Full Speed USB to High Speed USB DACs. A lot of the really expensive USB cables from audio companies failed miserably; I doubt many of these cables were even tested for High Speed compliance.”

“To summarise: the problem with USB Audio is that Isosynchronous USB frames are not error correcting. Therefore the sonic outcome of any USB system is dependent on the host to device differential.”

“Twelve years ago, I pretty much thought as many people do today: that USB was the answer to our S/PDIF quandaries. In some ways it is a good deal better. We have Asynchronous Isosynchronous so the device and host know about sample rates, bit rates, clocking options and a host of other things. But cables make a difference, computer brand and quality make a difference and even the device makes a difference.”

“I will try and capture some data errors on the Tektronix. The problem is that it does not accumulate errors. It also does not stop on errors. I have to actually push a button capture it and then pipe that to my screen.”

“What this is showing is the event table or the decoding of the USB Bus as seen by the Tektronix scope. We are using a Tektronix Differential Probe and their USB Analysis package. I made a little Male/Female HS USB board and that is plugged into a MacBook Air. I am using the Faber Acoustics Signal Scope Pro to send a 1KHz Sine wave to a Wavelength Crimson DAC @ 176.4K sampling rate. This is a program I use to test basic DACs of all kinds. This is also a pretty basic setup compared to audio transmission.”

“As per the above, a packet sent by the host to the Crimson has a CRC16 error. You can see that in the error column.”

TL;DR? What we have here is an explanation with screenshot proof that USB audio transmission isn’t bit true – enough evidence to reject any null hypothesis that assumes 1) all bits sent will all arrive intact and 2) re-transmission sorts out any detected errors. The Isosynchronous protocol used for audio data checks for errors but does not do any error correction (by way of retransmission).

Bringing it all back home, the iFi iPurifier 2 likely improves the sound of the Sonicorbiter SE because it minimises transmission errors by making lighter work for the Mytek Brooklyn’s USB receiver chip.

Furthermore, with lower noise on the line, the USB receiver chip no longer needs to kick into a higher, noise-inducing operational gear to ensure that it reads the incoming data correctly.

In other words, USB audio isn’t simply a matter of bits leaving the host PC/streamer and arriving AOK at the DAC. The quality of that which sits in-between matters.

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EAR HP4 و EAR Yoshino DAC 4 رسیدند تهران

سه شنبه 30 آگوست 2016
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بالاخره با ماجراهای زیاد اینروزهای گمرک این دو عزیز بزرگوار ترخیص شدند و آکبند آکبند تحویل من شدند.

آرمن عزیز خیلی تشکر بابت EAR و خوشحالم خیلی خوشحالم که نتیجه خیلی خوبه. ما هم دوباره به دهکده برگشتیم.

دیشب اولش دیدم صداش درنمیاد اما کمی که کار کرد و در حد 40 دقیقه گرم شد صداش در اومد. فعلا تنها چیزی که میتونم بگم اینه صدا بعد از اینکه لامپ ها به مدت 40 دقیقه گرم میشن خیلی صدا گرم و دوست داشتنیه. خیلی Full و Lush و البته EAR میدونید خیلی هم داینامیکه صداش. بنظر من کابل Purist هم خیلی خیلی تاثیر داره.

نکته خیلی جالب اینه اصلا مهم نیست شما Mp3 خیلی بی کیفیت رو از روی ویندوز (حتی بدون بیت پرفکت) پخش کنید یا فایل با کیفیت Flac رو بصورت بیت پرفکت روی مک چرا که صدا در هر دو حالت شنیدنیه .

وقتی کیفیت سورس میشه Flac و سیستم بیت پرفکت کار میکنه شما صدای جذابتر و بسیار واضح تری میشنوید اما حتی تو حالت Mp3 هم موسیقی اعتیاد آور هست. نمیدونم چی در صدا هست که حتی قبل از Break-in شدن کشش شنیدن رو زیاد میکنه.

اینم عکسها :

 

 

 

 

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اخبار

چهار شنبه 17 آگوست 2016
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اول اینکه باید از دوستی قدیمی که تشویقم کرد برم سمت یادگیری زبان تشکر کنم و بعدش از دوستی تشکر کنم که کلاس زبان ICC رو بهم معرفی کرد.

این کلاس زبان بسیار بسیار عالیه و کلا متد آموزشی اش متفاوت با بقیه کلاسهاست. یادگیری بسیار اصولی و در زمان سریع انجام میشه با کمترین صرف زمان توسط هنرجو.

تو این کلاس اصل رو بر مبنای شنیدن و تکرار در موقعیت میگذاره و شما اصلا با املا و یادداشت و نوشتن لغات کاری ندارید. فقط و فقط شنیدن هست و نه چیز دیگری. با حضور استاد اصلانی جو کلاس خیلی مثبت و شاد هست.

گرامر هم خیلی خوب و اصولی اون بین یاد داده میشه و یه دید خیلی قوی به ما میده و اصل روش هم بر مبنای مکالمه هست. برای کسانی که زمان محدودی دارند و واقعا دوست دارند زبان رو یاد بگیرند این کلاس عالیه. من قبلا دو بار سعی کردم زبان یاد بگیرم اما نشد حتی معلم خصوصی گرفتم بازم نشد و آخرش رسیدم به این متد.

مدیریت این کلاس ها با آقای اصلانی هست.

http://bamdadedanesh.ac.ir/

https://telegram.me/ICCAslani

 

این از خبر اول. خبر دوم اینکه بخشی از سفارشاتم رسیده. کابل ها که اومده بودو بعدش iUSB 3.0 اومد و Berkeley Alpha USB هم رسیده دبی و داره میاد تهران. دک و امپ هم تو راه هست. امروز هم یه هارد  تاندربرد اکسترنال گرفتم.

کابل BNC پیوریست هم تا دو هفته بعد تهرانه.

من قبلا مطلبی در مورد شیادی یکی از سایت های اینترنتی های فای نوشتم که الان باید تصحیحاتی رو اضافه کنم . اون پست رو پاک کردم و الان به عینه دیدم یک مشتری در شهرستان از این شخص بلندگو خریده و سالم و عالی تحویل هم گرفته و شخص تحویل دهنده نه کلاهبرداری کرده و نه جرمی مرتکب شده.

البته این به معنی این نیست که میشه به ایشون 100% اعتماد کرد چون همه دوستانی که من از نزدیک میشناسمشون و بهشون اعتماد دارم همشون معتقدند منش اخلاقی و اجتماعی این آدم خیلی دور از ایده ال هست و حرف ها و رفتار ها و کارهایی از ایشون سرزده که خیلی دور از اخلاق هست اما در هر صورت من لازم بود اعتراف کنم ساخته های ایشون بدست حداقل یک مشتری رسیده و کلاهبرداری ای در کار نبوده و بسته هم با بهترین بسته بندی حمل شده.

خبر بعدی اینکه فعلا خبری نیست تا رسیدن کالاها برای تست.

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Nothing Lasts Forever

دوشنبه 8 آگوست 2016
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گستره دنياي فولك و كانتري هر لحظه ما رو به كشف صدايي ناب و منحصر به فرد ترغيب ميكنه.”چارلي لندزبرو” هم براي من يه كشف جديده.صدايي كه قدرت و زيبايي اون مبهوتمون ميكنه و جالبه كه بالا رفتن سن و سال چارلي به جذابيت صداش افزوده خصوصيتي كه شامل حال بسياري از كانتري خونها ميشه.آخرين آلبوم استوديويي لندزبرو سال 2009 منتشر شده به نام “Nothing Lasts Forever ”  كه اميدوارم پايان فعاليت هنريش نباشه. حيفم اومد تجربه شنيداريم رو با شما به اشتراك نذارم.

Charlie Landsborough (born Charles Alexander Landsborough, 26 October 1941) is a British country and folk musician and singer-songwriter. He started singing professionally in the 1970s, although his major success didn’t come until 1994 with his song “What Colour is the Wind” and since the hit in 1994 he is now one of the UK’s top country acts. He is also popular in Ireland, Australia and New Zealand

Charlie Landsborough, Nothing Lasts Forever mp3Nothing Lasts Forever

2009
Charlie Landsborough, Under Blue Skies mp3Under Blue Skies
2008
Charlie Landsborough, The Storyteller mp3The Storyteller
2007
Charlie Landsborough, Heart & Soul mp3Heart & Soul
2006
Charlie Landsborough, My Heart Would Know mp3My Heart Would Know
2005
Charlie Landsborough, Reflections mp3Reflections
2003
Charlie Landsborough, Smile mp3Smile
2003
Charlie Landsborough, Movin' On mp3Movin’ On
2002
Charlie Landsborough, Once In A While mp3Once In A While
2001
Charlie Landsborough, Still Can't Say Goodbye mp3Still Can’t Say Goodbye
1999
Charlie Landsborough, What Colour Is The Wind mp3What Colour Is The Wind
1994
speed of the sound of loneliness

You come home late and you come home early
You come home big, when you’re feelin’ small
You come home straight and you come home curly
Sometimes you don’t come home at all

So what in the world’s come over you?
And what in Heaven’s name have you done?
You’ve broken the speed of the sound of loneliness
You’re out there runnin’, just to be on the run

Well, I’ve got a heart that burns with a fever
And I’ve got a worried and a jealous mind
How can a love, that will last forever
Get left so far behind?

So what in the world’s come over you?
What in Heaven’s name have you done?
You’ve broken the speed of the sound of loneliness
You’re out there runnin’, just to be on the run

It’s a mighty mean and a dreadful sorrow
Crossed the evil line today
How can you asked about tomorrow?
We ain’t got one word to say

So what in the world’s come over you?
What in Heaven’s name have you done?
You’ve broken the speed of the sound of loneliness
You’re out there runnin’, just to be on the run

So what in the world’s come over you?
And what in Heaven’s name have you done?
You’ve broken the speed of the sound of loneliness
You’re out there runnin’, just to be on the run

You’re out there runnin’, just to be on the run
You’re out there runnin’, just to be on the run

I Wish It Was Me

I wonder whose having my perfect night,
Standing where I used to be,
Tasting your sweet kind of dynamite,
Oh how I wish it was me.

Some one is having their dream come true,
Living my fantasy,
Some one is falling in love with you,
Oh how I wish it was me.

Somebody else is sailing my ship through a star spangled sky,
Some body else is melting your ways as the hours go by,
Heaven knows I wish it was me.

Some one is looking into your eyes,
Seeing what I used to see,
Lost in your spell as the evening dies,
Oh how I wish it was me.

As the hours go on by heaven knows I wish it was me.

I wonder whose having my perfect night,
Standing where I used to be,
Tasting your sweet kind of dynamite,
Oh how I wish it was me.
Oh how I wish it was me.

When You Were Sweet Sixteen

Since first I saw the love light
In your eyes
I thought the world
Held not but joy for me
And even though
We’ve drifted far apart
I never dream
But what I dreamed of you

I love you
As I never loved before
Since first I saw you on the village green
Come to me
Or my dream of love is all
I love you
As I loved you
When you were sweet
When you were sweet sixteen

Since first I saw the love light
In your eyes
I thought the world
Held not but joy for me
And even though
We’ve drifted far apart
I never dream
But what I dreamed of you

I love you
As I never loved before
Since first I saw you on the village green
Come to me
Or my dream of love is all
I love you
As I loved you
When you were sweet
When you were sweet sixteen

Walking On My Memories

Walking down the street
By the house we knew
Weeds command the garden where
Our roses grew
Children I don’t know
Climb our apple tree
And scar the bark
That bears the mark
Of your sweet love for me
No one sees an old man cry
As he starts to say goodbye
Won’t someone up there tell them please?
They’re walking on my memories
CHORUS
Sweet memories
The after glow
Of love be long ago
The window where she stood
And waved to me each day
Now fades another while I roam
The years away
See things as they were
Our love it used to be
I’m glad those smiling eyes can’t see
What time has done to me?
No one sees an old mans tears
And when his heartbreaks no one hears
Won’t someone up there tell them please?
They’re walking on my memories
Chorus 2 times and fade the 3rd time

 

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Audio Note DAC 5 vs AMR DP-777

پنجشنبه 4 آگوست 2016
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دیشب بین دک 33000 دلاری Audio Note UK و دک 5000 دلاری AMR تست گرفتیم که AMR خیلی بهتر صدا میداد. من توضیحات رو مینویسم و هنوز ذهنم نمیتونه باور کنه این اختلاف رو و بازم آخر ذهنم اینه نکنه DAC آئودیونت باید سرویس میشده یا لامپهاش عوض میشده و یا یه مشکلی بوده. در هر صورت تست دیشب خونه آرمن انجام شد و آرمن گفت شرایط تست برای هر دو مساوی هست و فقط کابل برق این دو تا با هم فرق داره. اینو بگم DAC باید برای تست خوب کار کنه و گرم بشه ، آرمن میگفت رومی هیچوقت DAC هاشو خاموش نمیکنه.

این تست هم Blind انجام شد و هم بعدش جدا DAC هارو شنیدیم. AMR خیلی تو میدرنج بهتر بود انگار صدا تو میدرنج یه Harmonic Integrity خیلی خوبی داشت و شفاف تر هم بود اما Audio Note کلا قاطی بود صداش و حالت Coherent و پایدار نداشت.

من اولش که Blind تست گرفتیم و نمیدونستم کدوم DAC داره پخش میکنه صدا رو ، گفتم انگار این DAC (منظورم Audio Note هست) تازه به برق وصل شده و صداش هنوز پایدار نشده و از نظر داینامیکی و تونالیته قاطی داره اما آرمن گفت هر دو DAC ها به یک اندازه کار کردند و روشن بودند.

در هر صورت یه راه برای اینکه بفهمیم وضعیت Audio Note چطوره داریم اونم اینکه DAC EAR 4 من رسید با AMR مقایسه اش بکنیم و اگر AMR با همین اختلاف EAR رو بزنه که معلوم میشه AMR سلطان DAC هاست و Audio Note سالم بوده اما اگر EAR DAC 4 صداش به AMR نزدیک باشه این احتمال شکل میگیره که Audio Note نیاز به سرویس داشته باشه.

در هر صورت Audio Note خیلی ناامید کننده بود. من قبلا اگر یادتون باشه نوشتم DAC Audio Note بهترین DAC تو میکرو هست :

DAC پیشنهادی

حالا منتظر میمانیم ببینیم EAR 4 وضعیت رو چطور شکل میده. حداقل چیزی که از Audio Note انتظار میرفت میدرنج خوب بود که اونم اصلا خوب نبود.

ولی حالا این تست حداقل این نتیجه رو داشته که فاکتور قیمت رو باید از ذهنمون دور کنیم و چون یک DAC قیمتش 50000 دلاره پس باید صدای خیلی بهتری از DAC مثلا 5000 دلاری بده اینطور نیست و باید تو شرایط یکسان صداهارو شنید.

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Berkeley Alpha USB to S/PDIF Converter

دوشنبه 1 آگوست 2016
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اینم داره به جمع سیستم من اضافه میشه ، دلیلش اینه EAR DAC 4 ورودی USB رو به خوبی SPDIF پخش نمیکنه و با پیشنهاد خود Gordon که ایشون تو طراحی همین Alpha USB نقش داشت تصمیم گرفتم این USB to SPDIF Converter رو بیارم . ست نهایی این میشه :

Macbook pro 2014 USB 3.0 -> Berkeley Alpha USB -> EAR DAC 4 (BNC input) -> EAR HP4 Headphone Amplifier (XLR input) -> Sennheiser HD800

All Cabling : Purist audio

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Philips TDA1541 Multi-bit DAC R-2R 1984 1985

یکشنبه 31 جولای 2016
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ظاهرا TDA1541 اگر درست پیاده سازی بشه سلطان DAC های دنیاست. بعد از این DAC میشه روی کیفیت Wolfson WM8741 و AD1865 حساب کرد. تورستن طراح AMR خیلی روی این DAC کار کرده.

این DAC EAR ما از گمرک ترخیص بشه یه تست عالی بین EAR DAC 4 و Audio Note DAC 5 و AMR DP-777 میگیریم. اولی از Wolfson WM8741 استفاده میکنه ، دومی از AD1865 و سومی از TDA1543 که این تست خیلی جالب خواهد شد. اولی 8000 دلار هست دومی 33000 دلار و سومی 5000 دلار.

در مورد مبدل مالتی بیت TDA1541 فیلیپس که در AMR CD-77 استفاده شده بخونید :

http://www.dutchaudioclassics.nl/philips-tda1541.asp

Philips TDA1541 FAQ

What is a TDA1541 DAC?
The TDA1541 series are multi-bit DACs employing a DEM (dynamic ekement matching) circuit.
What is DEM?
To put it simply, DEM (patented by R. van der Plassche) is a superior system developed by Philips technicians that employes 4 to 5 current sources inside the DAC applied in turn to achieve a 1/4 to 1/5 reduction in DAC conversion errors. At first, the TDA1541 was used in combination with the Philips-made SAA7220P/A 4x over sampling digital filter (a noise shaper circuit was not required and was not used).
When and where was the TDA1541 produced?
The TDA1541 (non -A) was launched from 1985 to 1988, and it had no grades. The TDA1541 was specified for exceptional 1/2 LSB linearity. The TDA1541A was produced from 1988 to 1998.
The silicon wafer of the TDA1541 were produced at Philips Nijmegen. Final assembly was at plants in Holland, Taiwan, China or India.
What grades does the TDA1541A have?
The TDA1541A has 4 grades: standard, The R1, the S1 single crown and the S2 double (or gold) crown.
What does the grades mean?
The (standard) TDA1541A is specified at THD+N of 0.8% (-42 dB). The TDA1541A S1 and TDA1541A S2 grades are specified at THD+N of 0.45% (-47 dB) at -60 dBFS. In addition, S2 is specified for THD+N of 0.0014 % (-97 dB) at full level, as opposed to 0.0018% claimed for non S2 grade. The S versions are guaranteed by Philips for this performance, but that does not mean that non S grades can not match the same performance level. Apart from S grades there is also R1 grade. However Philips documentation is a little confusing about it – sometimes it is slightly better specified than unmarked TDA1541A, sometimes it is inferior.

There will still be intrinsic errors in DAC linearity due to the tolerance in the alignments of the various masks during the IC production process. As further fine-tuning of the DACs is not possible, Philips has adopted a grading process to pick out those which offer the best performance. When the finished doped and etched silicon wafer emerges from the semi-conductor plant, it carries many dozens of individual DACs. A computer-controlled tester, consisting of 28 needle probes, then connects to the appropiate pads on each raw DAC die, providing power and supplying serial data from a CD player. If a DAC fails to work in this go/no-go test, the result being no analog music output, it is marked with a paint spot. Automatic machinery then slices the wafer into the individual dies and mounts those that passed the initial test in the familiar 28-pin DIL plastic package.

At this stage, the finished TDA1541 ICs are graded by a computer-controlled test station into three classes.

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Peter Qvortrup On Digital

یکشنبه 31 جولای 2016
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Audio Note DAC 5 Special Review

Peter Qvortrup On Digital

Jack: Peter, please share with us your opinion on the basic differences between CD and vinyl sound.

Peter: My view is that digital cannot resemble the original because of the inaccuracies introduced at the point of entry in the digital domain. The errors and omissions introduced by all current and past methods of conversion are so great that, at best, all we get is a card board copy of the original and it is clearly audible, as a quick comparison between a decent turntable and even the most expensive CD replay set up will quickly reveal.

This is because much like the flawed assumptions used by mathematicians to create the financial “innovations” which lie at the heart of the current financial crisis, the fundamental assumptions that created the way we digitize the analogue signal also fail to describe the content of dynamic wide band signals and the way they flow. The end result is a set of mathematical formulas that are sadly lacking in their ability to model the full range of variables in a music signal, and as a result when we come to make the analogue to digital conversion process, the bar is set at a level which is lower than it needs to be, resulting in conversion technology which does not do justice to the analogue signal it is being presented with, resulting in an anemic digital version of the analogue original.

It is therefore no major surprise that the digital medium, as we know it, lacks authority, authenticity, immediacy, instrumental medium and density, dimensionality, and overall presence when compared to its analogue version, to the point where even some digital recordings sound better on LP than the CD (the reverse is of course also occasionally true, but for sake of a proper comparison, we should always compare early all-analogue recordings on LP with their CD counterparts from the early to mid 1980s, my experience has always been that AAD recordings generally sound better than ADD, and ADD generally sounds better than DDD), which leads me to believe that the signal damage goes beyond merely the digital conversion process itself, as it would appear that the longer the signal stays in the digital domain the more damage it suffers, which may also explain some aspect of what I hear in music servers.

The high “resolution” formats like SACD and DVD-A are no better, just different versions of the same problems that beset Redbook, but unlike standard Redbook, the SACD/DVD-A converters are virtually impossible to improve upon as the 1Bit system they use do not allow removing the oversampling and digital filtering, for example, so we are reduced to playing with component choices and power supply configurations, which is like putting lipstick on a bulldog, to use a currently popular phrase!

Jack: Then Peter, how did you come to build some of the most musical sounding CD players, DACs, and Transports?

Peter: Well, from the onset I disliked CD with a vengeance, but over some years I was increasingly faced with the opposing choices or dilemma if you like, of preferring the quality of the purely analogue source but also a great need to be able to hear a lot of the music I liked that only came out on CD. So, I had no real choice but to try to work out how one makes a digital-analogue converter that does not completely sucks the life out of any musician’s best efforts, including when the recording engineers have also not done their greatest job, which of course many LPs also suffer under, but which to me at least manifests itself as far worse when it is on CD than LP.

I always felt that the main improvements were available in the DAC, so that is where our main efforts have been concentrated. However, recent development work has shown that the CD transport has equally great potential for improvement, so considerable efforts are now given to find out how far the CD transport can be taken: We now employ a valve power supply in our best CD transport for part of the circuit!

Perhaps a little history?

In 1991, I set about with my engineer at the time, Guy Adams (of Voyd Turntables fame!) to develop a digital-to-analogue converter which has a less digital signature. This work led to the use of a transformer as the I/V interface, a practice we patented across the world, and the DAC3 was born in 1993. I have always been doubtful about techniques that purport to improve the signal, so sometime in 1994 I asked Guy whether it was possible to remove the oversampling and digital filters from the converter. Guy felt it was not feasible after speaking to various people at Burr Brown, so in late 1995 I mentioned it to Andy Grove, and Andy said he would look at it, a prototype was made a week later and the sound was a revelation, although it needed some fine tuning to get rid of the out of band interference.

We released the first non-oversampling (we call it 1xoversampling) design as the DAC5 Special in July 1997, and the rest is really history. We have spent the years since then refining the circuit, I/V interfaces and power supplies.

We added dedicated 1xoversampled CD players in 1998 and started work on CD transports in 1997, the first one being the CDT Two, unfortunately the Korean manufacturers who were building all the CD products for us went under in 2000, and it took us another 4 – 5 years to develop a replacement for the CDT Two. The CDT Two/II was released in late 2004.

Jack: One last question Peter, what are Audio Note’s future plans for digital playback?

Peter: We continue to refine the circuitry and power supplies and we keep discovering incremental improvements to add to the circuits, components and materials. As an ultimate statement, Andy has been working on two major projects, the first is an all discrete 20 – 24 bit converter, and the second, which is more interesting, is a completely new conversion system which we originally designed as an out-of-house project for a company that does investigations into molecular resonance in materials; initial experiments look promising, so we shall see.

On the CD transport side, we are finishing development of the CDT Five, where a couple of valve in part of the power supply has shown that even here, valves are superior to semiconductors.

I think that covers it!

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PCM vs Delta Sigma & DSD

جمعه 29 جولای 2016
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این دو روزه خیلی با Gordon ایمیل بازی کردم. یکی از بهترین طراحان USB DAC و کلی هم راهنماییم کرد. ایشون برای خیلی از شرکت ها DAC طراحی کرده و فقط روی برند خودش فعالیت تجاری نداره. جسیکا دزل که از کاربران خیلی فعال و باهوش کلاب رومی هست از DAC این طراح استفاده میکنه و خود رومی هم نوشته شنیدم اگر کسی بتونه USB رو خوب پیاده سازی کنه نتیجه خیلی عالی هست و خود Gordon هم معتقده اگر USB DAC خوب پیاده سازی بشه خیلی بهتر از SPDIF هست. کلا از SPDIF دوری میکنه.

آقای Gordon به من گفت با مک بوک پرو خودت حتما هارد اکسترنال هم بگیر که با پورت Thunderbolt کار کنه. توصیه کرد حتما از کابل خوب استفاده کنم و خودش از Audio Quest استفاده میکنه. گفته ممکنه کابل خیلی گران هم بخرید اما اون کابل USB یا SPDIF خوب نباشه. گفت از Audirvana بدون دخالت iTunes استفاده کنم. گفت پورت سمت راست مک بوک بهتره برای گرفتن سیگنال USB و برای ریپ کردن سی دی حتما error correction برنامه itunes باید فعال باشه. گفت بین فرمت های ALAC , WAVE و FLAC و … از فرمت AIFF برای مک استفاده کنم. من قبلا خونده بودم WAVE بهتره اما گوردون گفت از AIFF استفاده کنم.

آخرش هم گفت :

Amir,

Learn by doing, not by reading.

این جمله معنی زیادی داره.

اما در مورد تبدیل آنالوگ به دیجیتال :

ببینید دیتای دیجیتال یک سری 0 و 1 هست که ما تعیین میکنیم به چه شکل اون سیگنال آنالوگ به این 0 و 1 ها تبدیل بشه . دو فرمت رایج فعلی PCM و DSD هست. تو حالت PCM ما با Analog to Digital Converter میاییم با یه فرکانسی مثلا 44.1Khz اندازه ولتاژ سیگنال آنالوگ رو میخونیم و اون عدد رو به یه عدد دیجیتال تبدیل میکنیم. عدد دیجیتال محدود و قابل شمارش هست مثلا اگر 2 بیت باشه ما 4 تا عدد داریم و اگر 3 بیت باشه ما 8 حالت داریم و اگر 16 بیت باشه ما مقادیر 0 تا 65536 رو خواهیم داشت. هر بیت فقط دو حالت 0 و 1 رو میتونه داشته باشه و با n تعداد بیت ما 2 به توان n حالت داریم .

حالا برای 16 بیت ما میتونیم 65536 حالت داشته باشیم. کاری که میکنیم اینه محدوده ولتاژ آنالوگ رو که مثلا بین -2 تا +2 ولت هست رو به 65536 قیمت تقسیم میکنیم و تو تبدیل آنالوگ به دیجیتال اندازه ولتاژ به یکی از این 65536 عدد نزدیکتره و اون عدد رو براش اختصاص میدیم. مثلا ولتاژ 0 ولت میفته روی  32768 و سیستم اینجوریه که ما با فرکانس 44.1khz کلاک میزنیم و با هر کلاک 16 بیت اطلاعات رو از روی شکل موج آنالوک تبدیل به دیجیتال میکنیم. شکل زیر 3 بیت رو نشون داده.

به عبارتی معنی PCM 16-bit 44.1khz این میشه ما هر 1 تقسیم بر 44100 ام ثانیه (میشه هر 0.000022675737 ام ثانیه) 16 بیت دیتا دیجیتال استخراج میکنیم.

برای PCM 24-bit 192khz هم همین منطق هست و فقط با فرکانس بیشتری ما 24 بیت دیتا ذخیره میکنیم. عبارت PCM مخفف Pulse Code Modulation  هست.

اما در مورد DSD این طور نیست و ما با فرکانس 2.8 مگا هرتز فقط 1 بیت ذخیره میکنیم. ببینید :

تو شکل بالا ما فقط یک بیت داریم که یا 0 هست یا 1 و با فرکانس بالا 2.8 مگا هرتز سیگنال آنالوگ رو رصد میکنه و وقتی شیب تغییرات سیگنال آنالوگ زیادتره مثل نقطه شروع شکل بالا این بیت بین 0 و 1 بیشتر نوسان میکنه و هر چقدر که به قله شکل موج سینوسی نزدیک میشیم و روند تغییر دامنه ولتاژ آهسته تر میشه میبینید اون بیت دیرتر تغییر وضعیت میده و یه جورایی فرکانس تغییر اون بیت بر اساس مشتق تابع سیگنال آنالوگ هست.

همونطور که میبینید سیستم  DSD پیچیده تر از PCM بنظر میاد. به این نوع تبدیل کردن میگیم Pulse Density Modulation یا همان PDM .

Pulse-density modulation, or PDM, is a form of modulation used to represent an analog signal with a binary signal. In a PDM signal, specific amplitude values are not encoded into codewords of pulses of different weight as they would be in pulse-code modulation (PCM). Instead, it is the relative density of the pulses that corresponds to the analog signal’s amplitude. The output of a 1-bit DAC is the same as the PDM encoding of the signal. Pulse-width modulation (PWM) is a special case of PDM where the switching frequency is fixed and all the pulses corresponding to one sample are contiguous in the digital signal. For a 50% voltage with a resolution of 8-bits, a PWM waveform will turn on for 128 clock cycles and then off for the remaining 128 cycles. With PDM and the same clock rate the signal would alternate between on and off every other cycle. The average is 50% for both waveforms, but the PDM signal switches more often. For 100% or 0% level, they are the same.

تو حالت PDM میبینید که بر اساس تغییرات ما یک بیت رو تغییر میدیم و همانطور که میدانید تو آمپلی فایر های Class D هم داره چنین اتفاقی میفته و ما با تبدیل تغییرات سیگنال آنالوگ به 1 بیت اونو کد میکنیم. یعنی منطق آمپلی فایر Class D و منطق DSD و منطق Delta Sigma همگی به این برمیگردند که ما یک بیت داریم با یک فرکانس بالا و اون بیت بر اساس سرعت تغییرات فرکانسش تغییر میکنه.

حالا میریم سراغ قسمت تبدیل دیحیتال به آنالوگ.

تو قسمت اول که آنالوگ تبدیل به دیجیتال شد ما برای PCM از مالتی بیت استفاده کردیم و برای DSD از سینگل بیت و حالا راه درستش اینه که برای بازگشت از دیجیتال به آنالوگ برای PCM از DAC مالتی بیت استفاده کنیم و برای DSD از DAC سینگل بیت .

سیستم مالتی بیت واقعی همین سیستم R-2R Ladder هست که ولتاژ هر بیت به یک مقاومت پسیو وصل میشه و تو خروجی از جمع ولتاژها سیگنال آنالوگ کاملا خطی ساخته میشه. به این حالت میگن True Multi-bit یا همان R-2R Conversion .

اینم شکل دیگر :

این حالت عالیه و رومی و تورستن هم به گفته آرمن موافق همین سیستم True Multi-bit هست. مقاله MSB و Lampizator رو بخونید جالبه :

http://www.mother-of-tone.com/conversion.htm

http://www.msbtech.com/support/dac4_vince.php?Page=supportHome

http://www.msbtech.com/support/How_DACs_Work.php?Page=supportHome

http://www.lampizator.eu/Fikus/R2R_DISCRETE.html

نکته اینه قدیما از مقاومت استفاده میشد بعدش Analog Device و Philips و Burr Brown اومدند و همین سیستم r2-r رو داخل یک چیپ پیاده سازی کردند.

The TDA chip is nothing but a ladder of several hundred resistors built in the form of integrated circuit (silicon chip) and hence miniaturized to a reasonable size, usable in home electronics. This type of DAC chips is called multibit or R2R. (resistor to resistor)

اون analog Device اومد AD1865 رو زد و Philips مدل TDA1541 رو زد و Burr Brown هم مدل PCM1704 رو زد. بعدش دیگه کلا بساط R2R برچیده شد .

The absolute peak of R2R was the chip from Burr Brown (Japan) (later acquired by Texas) called PCM1704, with close followers of Philips’ TDA1541A, (and 1547) Analog Devices AD1865 and the Burr Brown’s own PCM 63. These chips are considered the pinnacle of the PCM era and were all discontinued about 20 years ago.

این DAC ها همشون برای 44.1khz و 16 بیت بودند و برای فرکانس های بالاتر و بیت بیشتر ورژنی ندادند. البته فک کنم PCM1704 تا 96 کیلوهرتز هم میره با 24 بیت. خود Lavry برای DAC 2002 مجبور شد از همون مقاومت ها استفاده کنه برای فرکانسهای بالاتر و 24 بیت.

از AD1865 شرکت Audio Note استفاده میکنه ، از TDA1541 شرکت AMR و Zanden استفاده میکنند ، از PCM1704 هم چند شرکت محدود دیگه. شکل زیر شبکه مقاومت هارو ببینید :

لیست DAC های مالتی بیت :

CEC DA 0 3.0
Trinity DAC
Ypsilon DAC 100
Phasure NOS1 DAC
MSB Platinum
Total DAC
Audial DAC Model S (Pedja Rogic)
AMR top DAC and CD-77 (Thorsten Loesch)
Lampizator
Wavelength USB DAC
Exasound
Reimyo
CH precision

Acoustic Plan

Zanden Audio
Audio Zone DAC-1

Audio Note UK

ادامه دارد …

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Wavelength Audio Wavelink HS 24/192

پنجشنبه 28 جولای 2016
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این DAC 4 شرکت EAR احتمالا نیاز به یه رابط SPDIF داره. من بین همه این رابط ها از WaveLink HS خوشم اومده که در زیر میبینید :

 

Wavelength Audio – WaveLink HS 24/192 USB to SPDIF converter $900

  • Streamlength Asynchronous USB
  • XMOS USB receiver
  • Sampling Frequency : 44.1kHz, 48kHz, 88.2kHz, 96kHz, 176.4khZ, 192kHz
  • Bit depth: 16/24
  • Output: S/PDIF (BNC)
    Included is BNC-BNC SPDIF cable and with a mating BNC->RCA adapter
  • Thesycon USB Class 2 Audio driver (Windows)
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