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Neutrality

پنجشنبه 22 سپتامبر 2016
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مایک از Audiofederation میگه ما خیلی وقت ها توهم Neutrality تو صدا داریم و صدای Neutral رو با تجربه بیشتر میشه شناخت و ممکنه خیلی ها این اشتباه رو تو صدا داشته باشند.

طراح Audio Note UK هم قبلا ازش مطلبی نوشتم بنام Comparison by contrast که توضیح میداد برای تشخیص درست یه سیستم بهتر باید به این نکته توجه کنیم که اون سیستم بتونه موسیقی هایی که میشنویم رو متفاوت تر پخش کنه.

این موضوع تو چاپ 4 افست هم هست و دستگاهی بهتره که بتونه طیف رنگ رو با تمایز بیشتری چاپ کنه. یعنی یک سیستم خوب صوتی صدا هارو همگرا و شبیه نمیکنه .

این موضوع رو من دیروز با تست دو کابل خیلی جالب فهمیدم. اول کابل A رو زدم به سیستم و یه صدایی ازش شنیدم و بعد کابل B رو صداش رو شنیدم و بعد هر دو کابل رو سری کردم با یه رابط.

اول فکر میکردم کابل A حالت Neutral تری داره و کابل B حالت غیر Neutral تر  و بعد با سری کردن دو کابل دیدم کاراکتر نهایی صدا به کاراکتر کابل A نزدیک شد و از کاراکتر B خبری نبود .

فرض کنید دو تا شیشه دارید برای عینک و یکی کمی رنگ داره و یکی کاملا شفافه و وقتی دوتاشون رو پشت سر هم قرار میدید رنگ اونی که رنگی هست دیده میشه و اون شفافه تاثیری تو آنچه میبینیم ندارد.

کابل A هم دقیقا به همین دلیلی که نوشتم Neutral نبود و یکسری اطلاعات رو فیلتر و حذف میکرد . خیلی تجربه جالبی بود و اونی که اطلاعات صدا رو از بین میبره تو این جور تست مشخص میشه. اگر نمیشه این تست سری کردن رو برای مثلا DAC انجام داد باید از همون روش پیتر کورتف Comparison by contrast استفاده کرد.

http://www.audionote.co.uk/articles/art_audio_hell.shtml

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Acoustic Revive USB Cable

سه شنبه 20 سپتامبر 2016
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این کابل USB رو حتما بشنوید ، هم این کابل USB Acoustic Revive و هم کابل  Purist USB و هم کابل Oyaide (به قیمت عالیه) رو من پیشنهاد میکنم بشنوید هم USB و هم SPDIF . خودتون انتخاب کنید ولی دقت کنید قبل قضاوت باید این کابل ها رو بالای 100 ساعت آب بندی کنید. این Acoustic Revive رو از نزدیک ببینیدش واقعا خوش ساخته.

تو ایران من همین کابل هارو میتونم برای شنیدن پیشنهاد کنم.

https://www.acoustic-revive.com/english/pcaudio/usb_cable_01.html

http://www.6moons.com/audioreviews/acousticrevive2/1.html

http://www.oyaide.com/ENGLISH/AUDIO/products_category/digital_cable/pg746.html

 

 

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Audio CD Ripping by Apple Super Drive – dbpoweramp Software

دوشنبه 19 سپتامبر 2016
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اینطور که معلومه بهترین راه برای ریپ کردن سی دی اینه با مک و با درایو نوری خود مک بیاییم با نرم افزار dbpoweramp یک سی دی رو ریپ کنیم. تنظیماتش رو براتون میگذارم.

من لایتون 124 هم که از دید سایت Accuraterip بهترین ریپر هست گرفتم اما تو یه سایت خوندم بهترینش همین درایو اپل هست. با هر دو ریپ کردم خیلی تفاوت محسوسی حس نکردم اما حس منم اینه درایو اپل بهتره.

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انتقال دیجیتال 90 اهم USB و 75 اهم SPDIF

دوشنبه 19 سپتامبر 2016
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جمع بندی من از مطالعات این چند روزه در مورد کابل USB و کابل SPDIF :

گوردن و تورستن و رومی مطالبی رو که نوشتند تو سایتها رو تا جایی که شد خوندم و نظرات کسانی که subjective تست کردند رو هم شنیدم و این نتیجه گیری ها بدست اومده و دوستان اگر نظری دارند خوشحال میشم بشنوم. این نوشته ها هر کدوم بازتاب نظرات تورستن و گوردون و رومی هست و من تست سابجکتیوی نداشتم تا از خودم چیزی بگم.

اول اینکه انتقال سیگنال دیجیتال توسط کابل چه 90 اهم USB و چه 75 اهم SPDIF تاثیر خیلی زیادی تو کیفیت صدا داره. این تفاوت زیاد زمانی درک میشه که شما کابل های معمول بازار (هم گران هم ارزان) رو با هم تست نکنید بلکه یه کابل خوب رو با کابل های معمول بازار (حتی مدل های خیلی گران) تست کنید. بنابراین به من نگید ما دو تا کابل USB تست کردیم و تفاوتشون خیلی کم بود. باید برای مقایسه یه کابل خوب دقیق رو با کابل هایی که تو بازار هست تست کنید. اینو بگم دنیای کابل دیجیتال ربطی به دنیای کابل آنالوگ نداره. من کابل های 20 هزار تومنی پاساژ توکل جمهوری رو تست کردم واقعا فاجعه بود.

در هر صورت مهمترین قسمت کار این تولید و انتقال درست شکل موج مربعی هست طوری که هم کابل فرکانسهای بالای خوبی داشته باشه و هم انرژی اضافی High فرکانس نداشته باشه. از بابت دیتا روی کامپیوتر خیالتون راحت چون با نرم افزار dbpoweramp و دیسک درایو نوری Apple super drive میشه کل اطلاعات دیسک آئودیو رو آورد روی کامپیوتر. دیتا دقیق و درسته و فقط تو انتقالش ماجرا داریم.

گوردون با کد هایی که نوشته تو ریسیور دیجیتال TAS1020 XMOS (کد ها داخل این XMOS نوشته شده و این چیپ در ورودی Berkeley قرار داره و البته دقت کنید همه اونایی که از XMOS استفاده میکنن 90% شون از کد های دیفالت خود XMOS استفاده میکنند و اون شرکت هایی که از کد های گوردون استفاده میکنند باید پول استفاده از اون پتنت رو به گوردون بدهند مثل Ayre Acoustics Berkeley Audio  Halide Design) بنام Streamlength Asynchronous USB بصورت آسنکرون (یعنی DAC کلاک میزنه و نه کامپیوتر) میاد دیتا رو میخونه تا حد زیادی تونسته یه به بهترین شکل دیتا رو از کامپیوتر بگیره اما موضوع اینه همین دیتا هم به همراه اون 5 ولت که از کامپیوتر میاد بیرون یه شکل موج ایده ال نیست و باید برای انتقال درست اون هم از یه کابل خوب استفاده کنیم و هم از یک مک خوب.

رومی دوست داره کابل دیجیتال رو تو کارخونه با دستگاه های پیشرفته و دقیق Terminate کنن و نه بصورت دستی. ظاهرا اين كابلهاي دست ساز ديجيتال بيشترين مشكلشون اينه امپدانس كابلها وقتي به كانكتور ميرسه بدليل درست ترمينيت نشدن از عدد اصلي فاصله ميگيره.

I would prefer them to be cupper-made and made by a large company where the cable will be soldered my machine but not a human. Companies like Apogee, Belkin, Tektronix, Hewlett Packard are preferable.  I hope their production line still do cables and do not outsource everything outsourcabvle…

Romy the Cat

گوردون میگه ما کابل های 3000 دلاری دیجیتال داریم که جیتر زیادی دارند چون این کابل ها غیر از اینکه امپدانس ثابت و درستی ندارند بلکه کانکتور هاشون هم امپدانس متفاوتی دارند و شکل موج دچار اعوجاج و برگشت میشه. دقیقا برای همین اعوجاج هست که Berkeley پیشنهاد میکنه کابل رو بالای 1.5 متر بگیرید که بخاطر عدم تطبیق امپدانس اگر موج برگشت روی فرستنده تاثیر نگذاره اما همه میدونیم اگر همه چیز ایده ال باشه قاعدتا کابل هم باید کوتاه تر باشه. این مشکل امپدانس غیر دقیق باعث میشه ما ریسک نکنیم و همون 1.5 متر کابل رو بخریم و البته گوردون هم میگه دیگه طول کابل بیشتر از 2 متر هم نشه. پس بهترین حالت طول کابل چه برای USB و چه برای SPDIF همین رنج 1.5 تا 2 متر هست.

رومی رفته Belkin خریده 7 دلار و نوشته از کابل های 2000 دلاری بازار خیلی بهتر بوده.

دقت کنیم تو انتقال دیتای دیجیتال گراند و نداشتن گراند لوپ خیلی مهمه و سیستم رو باید چک کنید گراند لوپ نداشته باشید چون من گراند Berkeley وصل نبود و بعد وصل شد خیلی صدا فرق کرد.

طبق حدس های من شاید اگر کابل تک رشته باشه تو دیجیتال بهتر جواب میده و رومی و تورستن مس دوست دارند و بعضی برندها سیلور میزنند. همین کابل پیشنهادی Berkeley هم استرایت وایر تک رشته سیلور هست. همه اینها هم کواکسیال رو به XLR ترجیح میدهند اگر فرستنده و ریسیور درست طراحی شده باشه.

این نوشته گوردون هست که اشاره داره به اینکه بسته به نوع انتقال باید به انتخاب کابل دقت کرد:

Cables can have a big impact on the sound. Not all USB cables are the same. They need to both provide good data stream and also sheild the dac from noise at the PC side.

“Look there are 2 cables inside a USB cable. There is the DATA differential pair that must be designed for traffic up to at least 12Mhz and the POWER cable which is VBUS 5V’s and Ground.

I have like tons of cables now and some do sound different. But remember it will be device dependent.

All of the PCM27xx devices require VBUS to determine the computer is there. This means there is current running from the computer to the USB Device via the POWER side of the cable.

Other devices like the TAS1020 look for signal on the DATA portion of the cable only. Therefore the VBUS is not used and only the Ground connection on the POWER side is used.

On the DATA side termination on the Device side or endpoint will have an effect on transmissions. I usually get the 5M cables put them on a couple of computers with my USB analyzer on the DAC side and check for errors.

It’s not suggested to use a 5M with streaming audio. These cables were meant for low speed devices. 2M and under for audio will make all the difference in the world.

With the POWER side being used it can bleed noise from the computer into the dac.

It would be nice if you could switch the VBUS signal on the computer side from VBUS to Ground if your device doesn’t use it.

Anyways another thing about the POWER side of the cable is that noise from the computer can end up on the device. The cable should do all it can to make sure that doesn’t happen.

It’s best like all aspects of this hobby to try this stuff before you buy it.

Remember using these expensive cables on a hard drive is worthless they are in Block mode not Streaming and will not be effected by the use of costly cables.

Thanks
Gordon
J. Gordon Rankin “

در ادامه :

He said a number of things that really took me aback. The first thing he said was that yes, USB cables do sound different. They shouldn’t but they do. He says the reason is because most manufacturers are unable or unwilling to make their cables with the correct 90 Ohm impedance and be able to pass up to a 2.6 GHz perfect square wave. He says that unless those two parameters are met, the USB feedback mechanism doesn’t work because reflections get the signal confused on the computer end. Without it, there’s no way for the computer to know that it’s sending the data at the proper rate and bits get dropped. Since USB receivers have no error correction (this was news to me) a dropped bit gets interpolated at the DAC, and distortion increases. He says that this situation is not helped by the fact that Windows, including Win 8, generate 12% more hard errors in a digital audio bitstream than does Apple’s OSX! He also says to play your computer audio directly from memory for lowest error rate on either platform, and if possible, keep your music on a Firewire, eSATA or Thunderbolt drive rather than USB.
So, If you want your computer sourced digital audio system to sound it’s best, find a cable manufacturer that will guarantee his cable’s impedance at 90 Ohms* and that his cable can pass, ideally, a 2.6 GHz, or at least a 0.5 GHz perfect square wave (seems like a pretty high frequency to me), and that your music server runs OSX rather than Windows.

*Gordon also told me that virtually NONE of the cable manufacturers out there have any way of measuring the impedance of their cables and many believe that a lower than 90 Ohms is preferable because it allows them to sell longer runs. He says that because any deviation from 90 Ohms (higher or lower) is damaging to the data stream, lowering the impedance of the cable doesn’t work. Also, an apps engineer at Belden just told me that most cable companies buy their actual wire from suppliers who will customize things like sheath color and dielectric material, and it’s possible that many suppliers supply essentially the same cable to multiple audio cable makers. Fred

در ادامه هم تورستن جواب داده :

Fred,

I was hoping GR said YOU were wrong about USB Cables, but alas it turns out it was not you.
Too bad, I will support anyone who says you are wrong, because statistically speaking you are wrong precisely 87.537% of the time and not quite right the remaining 12.463% of the time.
Yes, I made that statistics up on the spot, but within common error levels I am confident I am 83.73% likely to be right.
Few cables other than printer cables from Belkin and/or similar sources are correct impedance.
Many of those “high end” ones that are handmade, even if the cable is not actually hand twisted silver or Cat6 twisted pair or variations on that theme and that are close to 90 Ohm (talk small minority in high end) give substantial breaks in impedance at the plugs…
Now USB is incredibly robust to bad cables, which is why the cheapest chinese rubbish that is miles off 90R and 1m long still prints pictures on your printer (it probably went to USB 1.1 fallback and operates at 1.5MPS, enough to not slow a printer down).
It is a bit like that SPDIF BNC Lark. Actually “75R” BNC Plugs are around 63 Ohm, 12 Ohm below nominal 75R, 13 Ohm above nominal 50 Ohm.
And of course, even if neither source nor load nor cable impedances are close to 75R, replacing evil RCA’s (which often are not much worse on a TDR than BNC’s) with Good BNC’s elevates sound quality from “rubbish” to ultra high end” in a single stroke.
Or maybe that’s just a load of old bollox and a 75R cable with 20mm worth of a 37 Ohm break (some bad RCA’s) matters Jack Schiit at the frequencies involved?
So actually, I fail to see what your beef with GR’s stuff is (I mean other than that he is usually right, when you are usually wrong).

Ciao T

https://www.google.com/search?q=audio+asylum+gordon+rankin&ie=utf-8&oe=utf-8&client=firefox-b#q=gordon+rankin+site:www.audioasylum.com

https://www.google.com/search?q=audio+asylum+Ciao+T&ie=utf-8&oe=utf-8&client=firefox-b#q=Ciao+T+site:www.audioasylum.com

برندهای زیر رو سرچ کنید هرکدوم یه اطلاعاتی دادند در مورد این بحث:

Revelation Audio Labs Prophecy USB Cable (کابل تک رشته نقره خالص با شیلد خوب)
TUBULUS Argentus USB Cable (کابل تک رشته نقره با دی الکتریک هوا)
Straightwire (کابل تک رشته نقره)
Acoustic Revive USB cable (کابل تک رشته مس با خلوص بسیار بالا)
Oyaide (کابل تک رشته نقره خالص با قیمت بسیار عالی)
Locus Design Cynosure v2 Audiophile Quality USB Cable (کابل خیلی گران)
Vertex AQ (فیلتر)
Black Cat Cable (طراح معروف کابل دیجیتال)
Curious Cables
Audiocadabra optimus dual
GoldNote Firenze Usb

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بعد از 30 ساعت

جمعه 16 سپتامبر 2016
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این DAC EAR که ما داریم کارش درسته ، قبلا نوشتم USB اش دکور هست اما تازه دیشب فهمیدم باید براش درایور نصب میکردم و بعد نصب درایو هم PCM از 16 بیت تا 24 بیت و از 44.1 تا 192 کیلو هرتز پخش میکنه و DSD هم ساپورت میکنه.

خیلی هم عالی
حالا نتیجه تست رو مینویسم.

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Three Conductor Shielded cable grounding

دوشنبه 12 سپتامبر 2016
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مشکل از اونجا شروع شد که دیدم از پریز برق وقتی جریان میکشم روی لاین گراند (ارت Earth) ولتاژ دارم حدود 30 ولت. مجبور شدم از مبدا کابل بکشم و کابل 3 در 1.5 خراسان رو گرفتم که 3 تا سیم داخلش بود همراه با شیلد. سیم مشکی برای فاز و آبی برای نول و زرد برای ارت. شیلد هم داشت. چیزی که مهمه اینه برای انتقال درست برق باید سیم های فاز و نول و ارت رو در مبدا و مقصد درست وصل کرد (یعنی سیم هارو جابجا نزنیم) و مهمتر اینکه فقط در مبدا باید شیلد رو به گراند وصل کرد. اگر هر دو سر شیلد به گراند وصل بشه گراند لوپ درست میشه که کار رو خراب میکنه.

http://diyaudioprojects.com/Power/diyMains/

 

 

http://www.hifi.ir/wp-content/uploads/2016/09/alphawire-Understanding-Shielded-Cable.pdf

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نيك كيو و روايت مرگ فرزند

شنبه 10 سپتامبر 2016
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روز قبل آلبوم جديد Nick Cave به نام Skeleton Tree در فضايي محزون و وهم آلود و متاثر از مرگ فرزندش در اثر حادثه سقوط از صخره اي در برايتون انگليس منتشر شد.نيك كيو معتقد است: وقتی فاجعه‌ای رخ می‌دهد، شما از فردی آشنا تبدیل به آدمی ناشناس می‌شوید و وقتی در آینه به خودتان نگاه می‌کنید، می‌توانید آدمی را که قبلا بودید، تشخیص دهید، اما فردی که درون آن پوست‌ومو زندگی می‌کند، شخصی کاملا متفاوت است.

Nicholas EdwardNickCave (born 22 September 1957) is an Australian musician, songwriter, author, screenwriter, composer and occasional film actor. He is best known as the frontman of Nick Cave and the Bad Seeds, established in 1983, a group known for its diverse output and ever-evolving line-up. Prior to this, he fronted the Birthday Party, one of the most extreme and confrontational post-punk bands of the early 1980s.[1] In 2006, he formed thegarage rock band Grinderman, releasing its debut album the following year.

Nick Cave and the Bad Seeds

Studio Albums:

1984 : From Her to Eternity

1985 : The Firstborn Is Dead

1986 : Kicking Against the Pricks

1986 : Your Funeral… My Trial

1988 : Tender Prey

1990 : The Good Son

1992 : Henry’s Dream

1994 : Let Love In

1996 : Murder Ballads

1997 : The Boatman’s Call

2001 : No More Shall We Part

2003 : Nocturama

2004 : Abattoir Blues/The Lyre of Orpheus

2008 : Dig, Lazarus, Dig!!!

2013 : Push the Sky Away

2016 : Skeleton Tree

 
Skeleton Tree

Sunday morning, skeleton tree
Oh, nothing is for free
In the window, a candle
Well, maybe you can see
Fallen leaves thrown across the sky
A jittery TV

Glowing white like fire
Nothing is for free
I called out, I called out
Right across the sea
But the echo comes back in, dear
And nothing is for free

Sunday morning, skeleton tree
Pressed against the sky
The jittery TV
Glowing white like fire
And I called out, I called out
Right across the sea
I called out, I called out
That nothing is for free

And it’s alright now
And it’s alright now
And it’s alright now

Distant Sky

[Verse 1: Nick Cave]
Let us go now, my one true love
Call the gasman, cut the power out
We can set out, we can set out for the distant skies
Watch the sun, watch it rising in your eyes

[Verse 2: Else Torp]
Let us go now, my darling companion
Set out for the distant skies
See the sun, see it rising
See it rising, rising in your eyes

[Verse 3: Nick Cave]
They told us our gods would outlive us
They told us our dreams would outlive us
[Verse 4: Else Torp]
Let us go now, my only companion
Set out for the distant skies
Soon the children will be rising, will be rising
This is not for our eyes

 

 Image resultWhere The Wild Roses Grow

They call me The Wild Rose
But my name was Eliza Day
Why they call me it I do not know
For my name was Eliza Day

From the first day I saw her I knew she was the one
She stared in my eyes and smiled
For her lips were the colour of the roses
That grew down the river, all bloody and wild

When he knocked on my door and entered the room
My trembling subsided in his sure embrace
He would be my first man, and with a careful hand
He wiped at the tears that ran down my face

They call me The Wild Rose
But my name was Eliza Day
Why they call me that I do not know
For my name was Eliza Day

On the second day I brought her a flower
She was more beautiful than any woman I’ve seen
I said: “Do you know where the wild roses grow
So sweet and scarlet and free?”

On the second day he came with a single red rose
He said: “Will you give me your loss and your sorrow?”
I nodded my head, as I lay on the bed
“If I show you the roses will you follow?”

They call me The Wild Rose
But my name was Eliza Day
Why they call me that I do not know
For my name was Eliza Day

On the third day he took me to the river
He showed me the roses and we kissed
And the last thing I heard was a muttered word
As he knelt above me with a rock in his fist

On the last day I took her where the wild roses grow
She lay on the bank, the wind lied as a thief
And I kissed her goodbye, said “All beauty must die”
And I lent down and planted a rose between her teeth

They call me The Wild Rose
But my name was Eliza Day
Why they call me it I do not know
For my name was Eliza Day

My name was Eliza Day
For my name was Eliza Day

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Berkeley Alpha USB , Thank you GCAudio Galen Carol

چهار شنبه 7 سپتامبر 2016
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با این شرکت Berkeley تماس گرفتم و مارو به GCAudio معرفی کرد و آقای  Galen Carol هم زحمت کشیدند این USB to SPDIF Converter رو فرستادند دبی و از دبی هم دوستی برامون آوردند.

این مبدل رو Goedon طراحی کرده و Berkeley فقط کمی بهینه اش کرده و خیلی هم خوش ساخت هست.

https://www.gcaudio.com/

رومی میگه :

Before I wrote the post that Jessie reefed I consulted with a few quite knowledgeable people in the digital field who explained to me all aspect of USB DACs. From what I understood it is clear that if (a big “if”) a USB DAC is properly implemented (that they admitthat  is not frequently happen) then USB DACs  have a lot of advantages over non-USB methods.

مثل بیشتر DAC های بازار که ورودی USB رو بیشتر برای دکور میزارن ، بهترین ورودی DAC EAR 4 همون ورودی BNC هست که ما میاییم از پورت USB مک بوک دیتا رو به iUSB 3.0 و بعدش به Berkeley Alpha USB میدیم و از خروجی Alpha دیتای SPDIF رو به DAC EAR4 میرسونیم.

فکر میکنم نتیجه خوب باشه انشاالله.

 

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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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