User Manual

Page 21
3.4.2 Sync Source
This button will show the currently selected Sync Source.
When you push the Sync Source button, you may select any of six possible clock
sync options. If a clock source is valid, a sample rate will appear next to that
selection. For instance, if a clock source is connected to the Hilo word clock input,
next to “Word Clock” there would appear the sample rate that the clock source is
generating.
This is where a new Sync Source can be selected. The choices include:
• Internal: Clock driven by the Hilo’s crystal oscillator
• Word Clock: Clock derived from the WORD CLOCK input
• Word Clock/2: Clock derived from the WORD CLOCK input and
doubled (i.e. 44.1 kHz to 88.2 kH z) .
• Word Clock/4: Clock derived from the WORD CLOCK input and
quadrupled (i.e. 44.1 kHz to 176.4 k Hz) .
• Digital: Clock derived from the active digital input
• LSLOT: Clock from the USB port on the computer. Generally this
is not a recommended clock source.
The box next to each clock source will display the clock rate when that port has a valid clock source attached. If th at
clock source is selected, that rate will become the current clock rate for Hilo. If Hilo detects that a specific Sync
Source is not valid, that Sync Source button will be disabled and “Not Present” will be displayed next to it.
Please note: when Hilo is connected to a computer via USB, Sync Source can only be changed by disconnecting the
USB cable. In this state the SYNC SOURCE button is crossed out, indicating a disabled parameter.
3.4.3 SynchroLock
Lynx’s SynchroLock™ technology is a very effective form of jitter reduction for
digital signals. Jitter is a type of clock error that may potentially result in distortion in
an audio signal. SynchroLock reduces jitter by a factor of 3000:1 by using the Hilo’s
high resolution crystal oscillator to generate a clock signal that is phase locked to the
external clock.
Compare this to attenuation of 100:1 or less for professional quality analog phase-lock loops (PLL) that are used by
most Pro Audio devices. As long as the clock frequencies are within +/- 100ppm of Hilo’s supported sample rates,
SynchroLock will operate on the clock signal, and insure a low-jitter clock drives the Hilo and is also sent to devices
downstream (i.e. clock slaves to the Hilo).
The SynchroLock operation is a two-stage process, starting with a fast-locking analog PLL to insure that there is clock
sync immediately when a Sync Source or Sample Rate are selected, and concluding with the digitally controlled
crystal-based secondary stage. It is normal for SynchroLock to take 1-2 minutes to achieve full lock.