M2TECH hiFace Two - Manual (Page 30)

hi F ace T wo
192 k H z /24bit digital audio interface
REVISION 1.0 – MAY 2013
Copyright © 2013, M2Tech Srl
30
M2Tech
www.m2tech.biz
10. Interface Special Features
10.1. Precision oscillators
hi
F ace T wo uses two high precision, low phase noise oscillators as time base for data
transfer to the DAC. This way, jitter is kept at a minimum, while output transfer is virtually
isolated by the USB interface timing low stability.
10.2. Asynchronous transfer mode
hi
F ace T wo uses an asynchronous transfer mode to get data from the computer. This
way, the actual transfer timing is mastered by the hi
F ace T wo, thus avoiding all time
uncertainties and thus the jitter caused by the computer USB interface.
10.3. Output connector choice
hi
F ace T wo comes in two different versions: with RCA output connector and with 75
Ohms BNC connector. Which one to choose? It mainly depends on the input connector on
your DAC or A/V receiver. Most units have an RCA input connector, so the RCA hi
F ace
T wo is to be chosen. On the other hand, some high performance units have both RCA
and BNC input connectors, and some of them only have BNC inputs. The rule is: every
time a BNC connector is available, hi
F ace T wo BNC should be chosen, as the BNC
connection, being it a true 75 Ohms link, give slightly better performance.
Should a hybrid cable be available (that is, a cable with an RCA plug on one end and a
BNC plug on the other), it is possible to use a hi
F ace T wo BNC with a DAC provided with
an RCA input, or vice versa. A slight performance increase with respect to an all-RCA link
can be obtained.
10.4. Powering the hi hi hi hi F FF F ace ace ace ace TTTT wo wo wo wo with an external power supply
hi
F ace T wo is powered by the USB bus, so it needs no external power supply. Its internal
regulators ensure correct operation of the various sub-circuits, particularly the internal high
precision oscillators. Anyway, user may want to power the hi
F ace T wo with a power
supply giving clean current to the device. This can be done using adapting cables
purposely made for that and available on the computer market. Please use a 5V power
supply with 500mA current capability.