Практически любому современному ЦАП совершенно безразлично, какого качества и откуда на него поступает опорный сигнал. Нужно лишь одно — обеспечить надежный «захват» опорной частоты с помощью быстродействующей PLL, все равно, сами микросхемы ЦАП далее тактирует СОБСТВЕННЫЙ внутренний генератор, и не опорной частотой, а частотой ПЕРЕДИСКРЕТИЗАЦИИ, которая, как минимум, в 64 раза выше частоты пришедшего на вход, как Вы его называете, «клока».
Кстати, именно поэтому использование так называемого «внешеного клока» просто бессмысленно в целях «улучшения звучания», тем более, ОДНОГО единственного цифрового устройства в системе. Всегда, когда только возможно, источником опоры должен являться ВНУТРЕННИЙ генератор прибора! Любого. Это ВСЕГДА лучше. Внешняя опора — вынужденная технологическая мера, неизбежная при синхронизации системы из нескольких цифровых устройств. Не менее, но и, ни в коем случае, не более того!
Абсолютно никакого значения не имеет, кроме технологическо-инсталляционных удобств, и то, откуда Вы берете опору — по выделенному Word Clock, или прямо по входному сигналу.
Исключение из этого правила, пожалуй, только одно — приборы (дорогие, индустриальные) с интерфейсом MADI, но не все, а те, которые были специально сделаны так, чтобы опора передавалась сугубо по WordClock. Все это документируется в мануалах.
Содержание
- Роль входов и выходов WordClock? (1 онлайн
- DAZZER
- Devon
- DAZZER
- Devon
- DAZZER
- Word clock bnc кабель
Роль входов и выходов WordClock? (1 онлайн
DAZZER
Электронный англоаудиофил
Devon
Active Member
Половину не понял.
Кабель — обычный коаксиал 75 Ом + BNC. Не знаю, что там для антенн, я Канаре какой-то юзаю, как-то сдуру много купил, до сих пор израсходовать не могу.
Как передавать клок — в общем пофиг. Если есть возможность передавать вместе с сигналом — нет смысла усложнять систему.
Для клока лучше использовать генератор того устройства, в котором он лучше
Разъемы BNC нужны, ибо устройств может быть больше, чем два. И их тогда удобно вешать на внешний клок.
DAZZER
Электронный англоаудиофил
Devon
Active Member
Да, думаю не нужны. У тебя же на морде Юниверсала есть переключатель, откуда брать клок.
хз, я RME AIO пару дней как купил, очень доволен. На автомате лочится от чего угодно + SteadyClock.
DAZZER
Электронный англоаудиофил
Практически любому современному ЦАП совершенно безразлично, какого качества и откуда на него поступает опорный сигнал. Нужно лишь одно — обеспечить надежный «захват» опорной частоты с помощью быстродействующей PLL, все равно, сами микросхемы ЦАП далее тактирует СОБСТВЕННЫЙ внутренний генератор, и не опорной частотой, а частотой ПЕРЕДИСКРЕТИЗАЦИИ, которая, как минимум, в 64 раза выше частоты пришедшего на вход, как Вы его называете, «клока».
Кстати, именно поэтому использование так называемого «внешеного клока» просто бессмысленно в целях «улучшения звучания», тем более, ОДНОГО единственного цифрового устройства в системе. Всегда, когда только возможно, источником опоры должен являться ВНУТРЕННИЙ генератор прибора! Любого. Это ВСЕГДА лучше. Внешняя опора — вынужденная технологическая мера, неизбежная при синхронизации системы из нескольких цифровых устройств. Не менее, но и, ни в коем случае, не более того!
Абсолютно никакого значения не имеет, кроме технологическо-инсталляционных удобств, и то, откуда Вы берете опору — по выделенному Word Clock, или прямо по входному сигналу.
Исключение из этого правила, пожалуй, только одно — приборы (дорогие, индустриальные) с интерфейсом MADI, но не все, а те, которые были специально сделаны так, чтобы опора передавалась сугубо по WordClock. Все это документируется в мануалах.
Источник
Word clock bnc кабель
(02-10-2012 19:42) Art1992 писал(а): простите что не по теме, но уж очень интерестно — есть ли смысл в замене коаксиала с хорошего на очень хороший?? пожалучста приведите несколько аргументов и обьястните значимость коаксиала в тракте.
 Выразили согласие: |
DAZZER |
| Выразили согласие: |
Yuri S |
| Выразили согласие: |
Yuri S |
Overview
The term «Word Clock» is used to describe a one cycle per sample period «square wave» signal used for synchronization of digital audio equipment. The signal is typically “TTL level” which is nominally 5 volt p-p and is carried on 75 Ohm coaxial cable with BNC connectors.
History
Earlier digital audio systems employed a number of formats of interconnection, many of which were proprietary. Some were parallel; in which case each bit was carried on a separate conductor and a Word Clock signal was used to synchronize the timing of the transmission of each complete word of 16 bits, once per sample period.
In other systems; the left and right channel’s digital audio data was transmitted in a serial manner, in parallel with a Word Clock signal which was used to synchronize the receiver with the beginning of the transmission of each serial word.
As digital audio systems grew in complexity and the need for synchronization with video equipment arose, Word Clock was used as the system «clock» even though newer formats, such as the AES3 digital audio format were «self-clocking.»
Due to the fact that the Word Clock format is a relatively low frequency signal compared to the serial formats with an embedded bit clock, with two transitions per sample period as versus hundreds of transitions per sample period; the Word Clock signal did offer advantages in terms of jitter issues. With reasonable care to use of the proper cable and termination; cable reflections (one of the main sources of jitter) have the time to decay before the next transition occurs; which is not the case with serial formats.
Technology advanced; and as the speed of circuitry increased it became commonplace for digital systems to use high-speed serial transmission with the obvious advantage of fewer conductors needed to move the data from device to device. As Wordlength increased from 16, to 32, to 64 bits; the advantages of serial transmission became even greater. Contemporary digital audio equipment commonly uses serial data transmission internally as well as externally; and this makes it necessary to have an internal bit clock which is in the range of 64 to 128 times the sample frequency.
Due to advances in serial transmission technology and the fact that contemporary digital audio systems operate with a much higher frequency bit clock, the internal clock frequency is significantly higher than the one cycle per sample Word Clock frequency and better methods are available to deal with issues related to very high frequency transmission. The result is that many contemporary digital audio devices do at least as good a job, if not a better, sync’ing to an AES digital audio input than to a lower frequency Word Clock signal that requires generation of a synchronized much higher frequency bit clock. For these reasons, Lavry DA converters all “lock” to the incoming digital audio and use sophisticated methods of effectively “de-coupling” the internal clock used for conversion from the jitter in the incoming digital audio signal. Lavry AD converters also offer the option of synchronizing to AES sync, in addition to Word Clock.
Basics
See termination for important information on proper termination.
“Proper” termination requires two things:
- Both the sending end and the receiving end must have termination at exactly one place.
- The termination must be the correct value; which is the same as the characteristic impedance of the cable.
In (1) the sending end is generally a «given» as all Word Clock outputs have fixed internal termination by design. The important issue is termination of the receiving device(s).
There are three basic approaches to using Word Clock in systems larger than two devices:
a.) Use a Word Clock source with multiple outputs. The Word Clock source must have as many outputs as there are «slave» devices with Word Clock inputs. The Lavry Synchrony-16 is an example of this type of source.
b.) Use one Word Clock source and «chain» the same signal using BNC «T» connectors on the inputs of the receiving devices. The slave devices in middle of the chain must not have fixed internal termination so the only receiving device with termination is the last slave device in the chain. The last device can either have fixed internal termination or a BNC «T» connector on its input with a BNC terminator on the «T» opposite in the incoming Word Clock cable.
c.) A «mixed» approach. This can be a combination of (a) and (b) or a combination of Word Clock connections to synchronize all external AD converters and AES synchronization of the «master» AD converter to the digital audio interface.
Lavry Products
- Synchrony-16- Master Clock with 12 BNC Word Clock output and 4 BNC SuperClock outputs. Features Termination Diagnostic indicators for each output.
- LavryGold AD122-96 MkIII- BNC Word Clock input and output + XLR AES Sync input; BNC input is not internally terminated
- LavryBlue 4496 with MSYNC- BNC Word Clock output, BNC Sync input accepts Word Clock and AES3 Sync; not internally terminated
- LavryBlack AD10- BNC Sync In accepts Word Clock and AES3 Sync; fixed internal termination selectable between 75 and 110 Ohms
- LavryBlack AD11- BNC Word Clock output, BNC Clock input accepts Word Clock, AES3, and S-PDIF sync; fixed 75 Ohm internal termination.
The FireStudio works with any digital device equipped with ADAT lightpipe I/O or S/DIF I/O. This includes
digital mixers and standalone A/D devices like the DigiMax series of microphone preamps by PreSonus.
2.5.1 What is ADAT optical?
«Alesis Digital Audio Tape» or ADAT was pioneered by Alesis to simultaneously record eight tracks of digital
audio at one time. The ADAT lightpipe protocol was developed to stream eight channels of 20 or 24 bit audio
over an optical cable at 44.1kHz or 48kHz to allow for digital transfers between ADAT digital recorders.
Today «ADAT» is used as the standard abbreviation for the ADAT lightpipe protocol and is still used to
transfer eight channels of digital audio over a single fiber optic cable. The ADAT digital interface has been
adopted by many audio manufacturers as a compact way to transfer digital audio data between devices. Today
devices ranging from consoles to synthesizers are equipped with ADAT I/O.
ADAT optical uses the same type of optical cables as the TosLink two channel protocol. These cables can be
purchased at your favorite local recording store.
2.5.2 What is S/MUX?
«Sample Multiplexing» or S/MUX is used to transmit high bandwidth digital audio using lower bandwidth
technology, i.e. ADAT lightpipe. By using S/MUX, a 96 kHz digital audio stream can be transmitted through
a protocol based on lower sample rates. S/MUX works by using demultiplexing to join two or more digital
audio channels to represent a single higher bandwidth channel. As discussed earlier, the ADAT lightpipe
protocol allows for eight channels of digital audio streaming at 44.1 kHz or 48 kHz. By using S/MUX
technology, two channels are joined together to represent one channel at 88.2 kHz or 96 kHz. In this way,
you can stream four channels of digital audio at 88.2 kHz or 96 kHz over the same lightpipe connection
originally designed to stream eight channels of audio at 44.1 kHz or 48 kHz. The FireStudio is equipped with
dual S/MUX technology so that, should you choose, you can record 16 channels of audio at 88.2 kHz or 96
kHz.
2.5.3 BNC Sync and Word Clock
When using multiple devices connected through digital audio formats like S/PDIF, AES/EBU, ADAT or
TDIF, it is necessary to synchronize them to a single word clock generator. Word clock is used to keep a
perfectly timed and constant bit rate between all synced devices to avoid data errors. A word clock generator
creates digital pulses that contain no other data (i.e. audio). These pulses clock the internal oscillators of
each device and are essential to avoid frequency drift.
A word clock signal is bundled with the audio data in the ADAT Lightpipe protocol; however, many engineers
prefer to keep word clock sync and audio separate from each other.
connections come into play and the FireStudio has BNC word clock input and output for just this purpose.
You will find BNC cables used to deliver dedicated word clock in many quality studios and broadcast facilities
worldwide. BNC cables are rugged, lock into position, and can carry clock signals much farther than the
standard optical cable. A BNC word clock cable is a 75 Ω, shielded coaxial cable with standard ‘twist-lock’
BNC-type connections on each end.
FireStudio requires an impedance of 75
OPERATION
Please note: BNC cables are made in several impedances. The
to achieve consistent sync.
Ω
24 | PreSonus 2008
This is where BNC word clock
Cordial Knowledge Base
In order that two or more digital audio devices such as effects units or digital preamps can smoothly work together in a network, a master device must set the so-called word clock rate and all other devices (the «slaves») must follow this clock rate. This is so because each of these digital audio devices has an integrated clock generator that provides the basic clock rate for processing the audio data. While we’re on the subject: the act of moving media (video and film or computer animation) must also be synchronized.
Several devices interacting therefore need a synchronization of their base clock rates. This is done by means of the word clock, the base clock signal that enables the transmission of data streams between the devices. Simply setting all connected devices to the same frequency (sample rate) would not be sufficient, because the smallest inaccuracies would generate noise interference or even signal failure. Fluctuations of the signal are called jitter. An external word clock «tells» the devices when the clock pulses start and when they stop.
Any digital audio device featuring a digital output can actually be the word clock master. Topnotch external word clocks (also called digital clock or master clock), however, contribute extremely to improving the sound quality in general.
For the separate transmission of word clock signals (i.e. separate from the digital audio signals), coaxial (75 Ohm) cables with BNC connectors are used. For this purpose professional devices feature BNC word clock connections.
It is also becoming increasingly popular to transmit word clock signals by means of Ethernet cables, for example within the context of the Audio-over-Ethernet protocol. However, who uses what and how depends on the respective protocol (Ravenna, Dante, Madi etc.).
There are also other methods for word clock generation, but all of these have application-specific advantages/disadvantages — e.g. embedded sample rate clock, GPS or video signal as reference.