Audio Power DSP System Multiface 用户手册

 

 
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User's Guide HDSP System Multiface II

 © RME

 

 

 
The most important electrical properties of 'AES' and 'SPDIF' can be seen in the table below. 
AES/EBU is the professional balanced connection using XLR plugs. The standard is being set 
by the Audio Engineering Society based on the AES3-1992. For the 'home user', SONY and 
Philips have omitted the balanced connection and use either Phono plugs or optical cables 
(TOSLINK). The format called S/P-DIF (SONY/Philips Digital Interface) is described by IEC 
60958. 
 

Connection 

XLR 

RCA / Optical 

Mode Balanced 

Un-balanced 

Impedance 

110 Ohm 

75 Ohm 

Level 

0.2 V up to 5 Vss 

0.2 V up to 0.5 Vss 

Clock accuracy 

not specified 

I: 

± 50ppm 

II: 0,1% 
III: Variable Pitch 

Jitter 

< 0.025 UI (4.4 ns @ 44.1 kHz) 

not specified 

 
Besides the electrical differences, both formats also have a slightly different setup. The two 
formats are compatible in principle, because the audio information is stored in the same place in 
the data stream. However, there are blocks of additional information, which are different for both 
standards. In the table, the meaning of the first byte (#0) is shown for both formats. The first bit 
already determines whether the following bits should be read as Professional or Consumer 
information. 
 

0 Pro P/C 

Audio? 

Emphasis 

Locked 

Sample 

Freq. 

0 Con P/C 

Audio? 

Copy 

Emphasis 

Mode 

 
It becomes obvious that the meaning of the following bits differs quite substantially between the 
two formats. If a device like a common DAT recorder only has an SPDIF input, it usually under-
stands only this format. In most cases, it will switch off when being fed Professional-coded data. 
The table shows that a Professional-coded signal would lead to malfunctions for copy prohibi-
tion and emphasis, if being read as Consumer-coded data. 
 
Nowadays many devices with SPDIF input can handle Professional subcode. Devices with 
AES3 input almost always accept Consumer SPDIF (passive cable adapter necessary).