سورس دیجیتال Transport & DAC

یه تست جالب AMR DP-777 vs EAR DAC 4

شنبه 4 فوریه 2017
/ / /

ببینیم تورستن کارش درست تره یا تیم پاراویچینی :

http://www.hifi.ir/wp-content/uploads/2016/12/IMG_0498.jpg http://www.hifi.ir/wp-content/uploads/2016/12/IMG_0492.jpg http://www.hifi.ir/wp-content/uploads/2016/12/IMG_0493.jpg http://www.hifi.ir/wp-content/uploads/2016/12/IMG_0494.jpg http://www.hifi.ir/wp-content/uploads/2016/12/IMG_0496.jpg

اول بگم اختلاف صدای این دو خیلی زیاد نیست و عبارات رو نسبی درنظر بگیرید.

صدای AMR رو همتون بیشتر خواهید پسندید چون هم به نسبت واضح تره هم کنترل شده تره هم بیس درست تره هم های فرکانس درست تره و EAR صدای کنترل شده ای در حد AMR شیک و دقیق نمیده.

اما صدای EAR DAC 4 شنیدنی و جذاب هست و این جذابیت بیشتر حس میشه اگر شما با بلندگوی Living Voice یا بلندگوهای حسی بشنویدش. من خیلی روی تست این دو تمرکز کردم و هم تو سیستم خودم و هم تو سیستم آرمن دقیق هر دو تو شرایط خوب تست شدند.

ببینید من نمیدونم چرا اما صدای EAR DAC4 واقعا خوبه ، یعنی خیلی خوبه و صدا حالت خالی دیجیتال رو نداره . خیلی مهمه که صدا پر باشه مثل آنالوگ و این خصوصیت واقعا در بیشتر DAC  های lean امروزی نیست. مهمترین نکته اینه این DAC رو تو یک سیستم حسی که میکرو داینامیک خوبی داره بشنوید تفاوت و ارزشش مشخص تر میشه دقیقا مثل AudioNote و تو سیستم های خیلی خشک و lean نمیشه فهمید چرا این DAC اینقدر خوبه. یه وقت فکر نکنید منظورم از صدای پر و انالوگ اون کاراکتر گرم و ابری لامپ هست نه ، اتفاقا من اون کاراکتر لامپ رو دوست ندارم و دارم لامپ اینو عوض میکنم که بهتر بشه.

اما EAR وقتی کنار AMR قرار میگیره تو موسیقی های شلوغ تر و داینامیک تر خیلی از شاخص هاش مثل جداسازی سازها ، کنترل بیس و های فرکانس ، وضوح در حد AMR نیست ولی به همه این تفاسیر صداش پر و آنالوگ هست. من عاشقشم از وقتی که با Living Voice RW شنیدمش. با بلندگوی غیر حسی و امپ های Lean نمیشه قضاوتش کرد و به همین دلیل هست که وقتی سیستم شما Lean باشه همچنان به سمت Audionote و EAR نمیروید چون اصلا تو سیستم شما ارزش اینا مشخص نمیشه و این نکته خیلی مهمی هست.

اون AMR صدای دقیق تری میده و کلا هم AMR صدای معقول و درستی داره که با همه این برتری ها من EAR رو نگه میدارم و تغییرش نمیدم و فقط لامپ هاشو عوض میکنم.

من احساسم اینه کیفیت قطعات داخلی AMR بهتره اما هر دو طراحی مدار درستی دارند و هر دو مینی مال و خوب طراحی شدند. تو موسیقی های خلوت تر این EAR خیلی خوب میدرخشه اما به محض اینکه موسیقی شلوغ میشه کمی نسبت به AMR به هم میریزه و اون کنترل و تفکیک رو به نسبت از دست میده.

 

http://www.hifi.ir/wp-content/uploads/2017/02/IMG_0967.jpg

عکس بالا داخل DAC EAR رو نشون میده .

اینم از لامپ های جدید که امروز خریدمشون و فردا تست میکنیم ببینیم چطوره :

Read More

انتخاب اجزای سیستم Music Server بجای مک بوک

جمعه 13 ژانویه 2017
/ / /

بهترین حالت اینه توان مصرفی مادربرد و cpu کم باشه و با بهینه کردن لینوکس و Mpd به یه حجم خیلی کم سیستم عامل برسیم. توزیع های لینوکس به ترتیب اهمیت برای من :

Voyage MPD (http://cheap-silent-usb-linux-music-server.blogspot.com/)
AudioPhile Linux
VortexBox
Daphil
Lubuntu
Linux Mint

انتخاب های زیر فعلا مناسب بنظر میاد:

 

برای توان های خیلی کم :

https://www.board-db.org/

BeagleBone Black (ARM CPU)
PC Engines ALIX 2d2 (x86 CPU)
DHCOM pico ITX Base Board (ARM CPU)
Odroid-C1
Bela

 

 

 

برای توان های کمتر از متوسط (زیر 15 وات) مادر برد Supermicro هست که Supermicro X11SAA رو انتخاب نکردیم با اینکه N4200 بهش میخوره اما بخاطر نبود IPMI2.0 من رفتم سراغ X11SBA-F :

https://www.supermicro.com/products/motherboard/X11/X11SBA-F.cfm

اول به نماینده سوپر میکرو در ایران زنگ بزنید (آقای نجفی 88962050 شرکت آساپردازش) و اگر نداشتند میشه از اینجا بخرید :                                           http://www.serverdirect.nl/

سی پی یو اینتل پنتیوم N4200 کوادکور 6 واتی هم انتخاب نکردم چون حتما باید مادربرد سوپرمیکرو باشه رفتیم سراغ Intel N3700 که اونم 6 وات هست کواد کور اما 30% سرعتش از 4200 کمتره:

Silvermont based Pentiums Braswell (14 nm) Socket FC-BGA 1170
Intel Pentium Processor N3700

http://ark.intel.com/products/87261/Intel-Pentium-Processor-N3700-2M-Cache-up-to-2_40-GHz

The Intel Pentium N4200 is a quad-core SoC primarily for inexpensive notebooks and was announced mid 2016. It runs at 1.1-2.5 GHz (Burst) and is based on the Apollo Lake platform. Similar to the Braswell predecessor, the chip is manufactured in a 14 nm process (P1273) with FinFETs.

کیس :

Streacom F7C Alpha/Evo Chassis

رم DDR4 با ظرفیت 8Gig

هارد اینترنال برای سیستم عامل SSD با برق جدا و فیلتر SOtM SATA power filter

کارت PCIe to USB شرکت SOtM tX-PCIexp card با برق جدا از PSU خطی External

و برق خطی :

HDPLEX 100W Linear Power Supply
HDPlex 250W Internal DC-ATX

بدون هیچ دیوایس اضافی مثل DVD Rom و …

کلا زیر 15 وات میشه.

لینوکس هم بسیار اوپتیمایز و کوچیک شده با کرنل RT و خروجی صدای ALSA و نرم افزار پخش صدای بیت پرفکت MPD که هیچ دیوایسی مانند موس و کیبرد و مونیتور لازم نیست باشه و با یه گوشی موبایل کامل میشه MPD رو کنترل کرد.

مادر برد

Intel Pentium Processor N3700,
Single socket FCBGA 1170, 6W
System-on-Chip
Up to 8GB 1600MHz DDR3 Non-ECC SO-DIMM in 2 sockets
1x PCI-E 2.0 x1 (in x8),
1x Mini-PCIe (mSATA support)
Dual GbE LAN with Intel® i210-AT
1x HDMI, 1x DP, Intel HD Graphics,
VGA port for BMC
2x USB 3.0 ports (2 rear), 7x USB 2.0 (2 rear, 4 via headers, 1 Type A)
I/O: 1x SATA DOM, 2x COM, TPM 1.2 header, ALC 888S HD Audio
IPMI 2.0 with dedicated Port and KVM
Supports 12V DC power input

http://www.supermicro.com/CDS_Image/uploads/imagecache/600px_wide/intel_motherboard_active/x11sba-ln4f.jpg

کیس

 

برای توان های بیشتر میشه از اینتل Intel Xeon E3-1240 v5 که 80 وات هست و یا Intel Xeon E3-1240L v5 که 25 وات هست استفاده کرد با مادر برد Supermicro X11SSH-F که بهترین انتخابه با کیس FC9 شرکت Streacom .

 

 

http://www.audiohobby.com/raspberry-pi-for-audiophiles/

http://www.24bit96.com/usb-computer-audio-system/usb-audio-with-lowlatency-realtime-kernel-with-debian-and-mpd.html

https://www.techonia.com/960/install-linuxmint-macbook

http://www.head-fi.org/t/561961/bit-perfect-audio-from-linux#post_7596268

http://www.audiomisc.co.uk/Linux/ALSA/NoMoreSilence.html

http://www.alsa-project.org/alsa-doc/alsa-lib/pcm.html#alsa_transfers

http://www.head-fi.org/t/561961/bit-perfect-audio-from-linux#post_7596563

https://www.ap-linux.com/about/http://murga-linux.com/puppy/viewtopic.php?t=81984

http://www.audioasylum.com/cgi/vt.mpl?f=pcaudio&m=82175

http://www.computeraudiophile.com/f11-software/new-mpd-feature-%3D-cleaner-signal-3552/

https://www.raspberrypi.org/forums/viewtopic.php?t=12137

http://www.makeuseof.com/tag/install-linux-macbook-pro/

http://www.rodsbooks.com/ubuntu-efi/index.html

https://opensource.com/life/16/1/hacking-your-linux-computer-better-listening-experience

https://en.wikipedia.org/wiki/Comparison_of_single-board_computers

https://sites.google.com/site/computeraudioorg/linux-for-audio/setting-up-alsa

http://wiki.linuxaudio.org/wiki/system_configuration

https://www.alsa-project.org/main/index.php/Low_latency_howto

Read More

Linux Ubuntu Audio Setup , Macbook Pro

یکشنبه 25 دسامبر 2016
/ / /

این مک بوک صدای خوبی میده اما حریف CEC نمیشه . صدای CEC میکرو داینامیک خیلی خوبی داره که هیچ ترنسپورتی نداره. این ست ما مک بوک برکلی کابل پیوریست کلا 5000 دلار هست و ترنسپورت های زیادی رو میتونه بزنه ولی CEC رو نه.

جمع بندی های Computer Audio تا این لحظه:

خروجی باید همون USB باشه با کابل Purist Anniversary و دریافت کننده اسنکرون با کد گوردون یعنی همین Berkeley Alpha USB

مادربرد و cpu باید با کیفیت ساخت بالا باشند و هم زیر 15 وات باشن با سیستم عامل بسیار سبک لینوکسی مثل Lubuntu و پلیر MPD

https://en.wikipedia.org/wiki/Comparison_of_single-board_computers

برای برق باید یا باتری خیلی عالی با امپدانس خروجی کم باشه یا Power Supply خیلی خوب برای دو قسمت هم usb هم مادربرد CPU

برق سیستم خیلی مهمه. من هنوز به جمع بندی نهایی نرسیدم

اینم از لینک های بهینه کردن لینوکس برای صدای بیت پرفکت خوب :

سخت افزار زیر 15 وات با حذف I/O های اضافی و استفاده از کرنل RT یا همان Real Time لینوکس با بهینه کردن لینوکس و حذف پروسس های اضافی و استفاده از نرم افزار MPD با درایور بیت پرفکت ALSA و پریوریتی بالا.

http://www.audiohobby.com/raspberry-pi-for-audiophiles/

http://www.24bit96.com/usb-computer-audio-system/usb-audio-with-lowlatency-realtime-kernel-with-debian-and-mpd.html

https://www.techonia.com/960/install-linuxmint-macbook

http://www.head-fi.org/t/561961/bit-perfect-audio-from-linux#post_7596268

http://www.audiomisc.co.uk/Linux/ALSA/NoMoreSilence.html

http://www.alsa-project.org/alsa-doc/alsa-lib/pcm.html#alsa_transfers

http://www.head-fi.org/t/561961/bit-perfect-audio-from-linux#post_7596563

https://www.ap-linux.com/about/http://murga-linux.com/puppy/viewtopic.php?t=81984

http://www.audioasylum.com/cgi/vt.mpl?f=pcaudio&m=82175

http://www.computeraudiophile.com/f11-software/new-mpd-feature-%3D-cleaner-signal-3552/

https://www.raspberrypi.org/forums/viewtopic.php?t=12137

http://www.makeuseof.com/tag/install-linux-macbook-pro/

http://www.rodsbooks.com/ubuntu-efi/index.html

https://opensource.com/life/16/1/hacking-your-linux-computer-better-listening-experience

https://en.wikipedia.org/wiki/Comparison_of_single-board_computers

https://sites.google.com/site/computeraudioorg/linux-for-audio/setting-up-alsa

http://wiki.linuxaudio.org/wiki/system_configuration

https://www.alsa-project.org/main/index.php/Low_latency_howto

Read More

سیستم نهایی Computer Audio من

شنبه 26 نوامبر 2016
/ / /

من یه گراند مصنوعی هم تست کردم که نتیجه خوب نبود. گراند مصنوعی یه سیم داره به گراند وصل میشه و نویز روی گراند رو تبدیل به حرارت میکنه.

اینم شد سیستم نهایی من :

Macbook Pro mid 2014 Retina 13″ (USB output on right side of Macbook), 8Gig RAM, Core i5 + External HDD (Thunderbolt port)
MAC OS X Mavericks + CAD optimization Script + iTunes EQ off
Roon Labs Player Software (true Bit-Perfect mode with exclusive access) + AIFF File Format
Purist Audio Anniversary USB Cable 1.0m
Berkeley Alpha USB (Special Thanks to Mr.Gordon Rankin for Streamlength asynchronous code) + Purist Aquila AC Cable 1.5m
Purist Audio Neptune 75 ohm coax BNC Digital Cable 1.5m
EAR Yoshino DAC 4 D/A Converter + Purist Neptune AC Cable 1.5m (output volume at 2 o’clock)
Purist Audio Neptune XLR Analog Interconnect 1.0m
EAR Yoshino HP4 Headphone Amp (High Z Impedance is better for HD800) + Purist Neptune AC Cable 1.5m
purist Audio Impresa Headphone Cable 1.5m
Sennheiser HD800 Headphone

من یه PurePower که مولد برق AC هست رو حتما بیاد ایران اضافه میکنم و ممکنه در آینده یه سیستم مبتنی بر Mac mini یا PC رو با پاور ساپلای خطی امتحان کنم. همین ست آپ فعلی هم با صدای CEC هفته بعد تست میشه.

Read More

UpTone USB Regen

جمعه 11 نوامبر 2016
/ / /

خب من بعد از تست Qurious با Purist Audio که دیدم Purist مطبوع تره و بعدش هم رفتم سراغ Regen و این Regen دیروز رسید تهران. حدود 175 دلاره و جیم اسمیت هم ازش استفاده میکنه. با پست USPS مستقیم اومد تهران.

USB REGEN™

اینو بعد 186 ساعت آب بندی تو سیستم خودم شنیدم و هفته بعد تو سیستم آرمن هم میشنوم. تو سیستم من Regen صدای بهتری تو بیس و کلا انتقال انرژی داره و صدای کم نویز تر و ساکت تر و واضح تری میده ولی مشکل اینه صدای Regen از نظر تایمینگ و پیوستگی جریان صدا خوب نیست. من همینجوری از خودم حدس میزنم علت اینکه Berkeley نه با iUSB 3.0 صدای خوبی میده و نه با Regen به کد های آسنکرون Berkeley برمیگرده.

خود iUSB با ورودی usb دک AMR پاسخ بهتری میداد و این Reclock ها بدرد اتصال به Berkeley نمیخورند. از نظر من پرونده Computer Audio با Setup زیر کامل میشه و در آینده فقط ممکنه یه گراند CAD برای مک بوک بگیرم و یه Purepower هم به کل مجموعه اضافه کنم.

Macbook pro 2014 Retina 13″ i5 8G RAM (Roon Software + iTunes EQ off + CAD Optimization Script) -> Purist Audio Anniversary USB 1.0m -> Berkeley Alpha USB -> Purist Audio Neptune Coax 75 ohm -> EAR DAC 4 -> Purist Neptune XLR -> EAR HP4 – > Purist Headphone Cable -> Sennheiser HD800

من پیشنهادم اینه اگر سمت Computer Audio خواستید بروید این تو ذهنتون باشه اولین چیزی که باید بگیرید و بدون اون به هیچ نتیجه ای نمیرسید همین Berkeley Alpha USB هست و بعد خرید Berkeley بقیه انتخاب ها مثل PC ویندوزی باشه یا mac mini یا imac یا مک بوک و … این ها به انتخاب خودتون باشه مشکلی نیست و کابل هارو هم تست کنید و من با پیوریست انیورسری به بهترین نتیجه رسیدم شما خودتون میتونید تست کنید و انتخاب کنید.
من iUSB 3.0 و Regen رو تست کردم و شک ندارم بقیه ریکلاکر ها و واسطه ها هم مثل Itona و Wyred 4 Sound و … هیچکدوم بدرد کار ما نمیخورن وقتی Berkeley تو مدار باشه. پس جز Berkeley پول چیز دیگری ندید و من خیلی هم تاکید دارم کابل رو Purist Anniversary بگیرید چون واقعا خوبه. الان تو تست ها Curious از همه بهتر جواب داده اما من تست کردم Curious و Audioquest و بقیه کابل هایی که تست کردم به خوبی Purist جواب نداده. فقط میمونه کامپیوتر که اونو خودتون انتخاب کنید. نرم افزار هم برای مک من Roon رو پیشنهاد میدم و بعدش هم Audirvana رو و برای ویندوز هم میتونید خودتون سرچ کنید.

مهمتر اینکه کابل برق Berkeley حتما باید خوب باشه و کامل بالای 300 ساعت هم اب بندی شده باشه. بروید تا 500 ساعت اب بندی که خیال منم راحت بشه.

My Final Config after 500 hours of break-in :
Macbook Pro mid 2014 Retina 13″ (USB output on right side of Macbook), 8Gig RAM, Core i5 + External HDD (Thunderbolt port)
MAC OS X Mavericks + CAD optimization Script + iTunes EQ off
Roon Labs Player Software (true Bit-Perfect mode with exclusive access)
Purist Audio Anniversary USB Cable 1.0m
Berkeley Alpha USB (Special Thanks to Mr.Gordon Rankin for Streamlength asynchronous code) + Purist Aquila AC Cable 1.5m
Purist Audio Neptune 75 ohm coax BNC Digital Cable 1.5m
EAR Yoshino DAC 4 D/A Converter + Purist Neptune AC Cable 1.5m (output volume at 2 o’clock)
Purist Audio Neptune XLR Analog Interconnect 1.0m
EAR Yoshino HP4 Headphone Amp (High Z Impedance is better for HD800) + Purist Neptune AC Cable 1.5m
purist Audio Impresa Headphone Cable 1.5m
Sennheiser HD800 Headphone

no ground loop in system and proper AC polarity for all components.

 

http://www.hifi.ir/wp-content/uploads/2016/11/IMG_9732-1.jpg http://www.hifi.ir/wp-content/uploads/2016/11/UpTone_REGEN_PCB1.1_for_web.jpg http://www.hifi.ir/wp-content/uploads/2016/11/IMG_9733.jpg Read More

Acoustic Revive USB Cable

سه شنبه 20 سپتامبر 2016
/ / /

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

 

 

Read More

Audio CD Ripping by Apple Super Drive – dbpoweramp Software

دوشنبه 19 سپتامبر 2016
/ / /

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.

Read More

MacBook Pro 2014 vs CEC TL0

شنبه 3 سپتامبر 2016
/ / /

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.

Read More

Berkeley Alpha USB to S/PDIF Converter

دوشنبه 1 آگوست 2016
/ / /

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 .

The final production version of the Alpha USB contains dual fixed oscillators. One for each sample rate family of 44.1, 88.2, 176.4 kHz and 48, 96, 192 kHz. Only a single oscillator is operational at a time. Even very good low jitter oscillators can produce relatively high levels of low frequency phase noise.

Adding to the Alpha USB’s excellent clocking is the use of Streamlength<sup>™</sup> asynchronous USB code in conjunction with the XMOS USB receiving chip. Small companies such as Berkeley Audio Design need to leverage design talent. In this case there was no reason to reinvent the wheel. The Streamlength code was selected because it was already well developed and was very robust. Streamlength asynchronous USB code controls the data flow from the computer or music server and the newly developed crystal oscillators take control as the master clock generators. No matter what one believes about the importance, or lack thereof, of asynchronous USB and its oscillator design “requirements” it would be hard to second guess the Alpha USB’s design approach.

Another major contributing factor to isolation is how the USB interface is powered. Berkeley Audio Design elected to power the USB receiving chip in the Alpha USB via USB bus power from the computer. Power emanating from the computer’s USB port doesn’t traverse any further than the USB receiving chip inside the Alpha USB. ‘Berkeley’ uses its proprietary isolation techniques that are said to provide much better performance than traditional opto-isolation methods while keeping computer generated noise away from the sensitive output clocking and driver circuitry. Powering the audio output side of the Alpha USB is a low noise linear power supply. This noise filtered linear supply feeds clean power to the oscillators and the digital audio output circuitry.

https://www.computeraudiophile.com/ca/reviews/Berkeley-Audio-Design-Alpha-USB-Review/

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

62a43d2e_Alpha5 Read More

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

یکشنبه 31 جولای 2016
/ / /

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.

Read More

Peter Qvortrup On Digital

یکشنبه 31 جولای 2016
/ / /

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!

Read More