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AES/EBU Digital Audio Cables:

Digital audio cables are different from analog audio cables with their electrical parameters.

 


The most important feature is impedance value in digital cables.
 Although digital systems have been around for 25 years, the standardization of it has been done recently. The spesification for digital audio was developed by the Audio Engineering Society and European Broadcast Union(AES/EBU). The two key parameters are the date rate, which depends on the sampling rate and impedance of  110 ohms±20% for twisted pair constructions and 75 ohms for coax designs.

Figure.1 AES3-1992 Installation
Figure.2 AES3id-1996 Installation
 
Analogue audio cables with low capacitance values performance better when the frequency values rise up. But for digital audio cables, system impedance is important, since it is determined as 110 ohms, digital audio cables are good analogue cables. Analogue audio cables have an impedance rate of 40 ~ 70 ohm. This large mismatch from the nominal 110 ohms results in signal reflection and jitter causing bit errors at the reciever. Also the high capacitance of analogue cables greatly increases the rise time of the digital square wave.
Digital signals are stepped wave signals. Receivers detect these signals in order to read them correctly. If the transmission is not so good, there may be some bit errors. These errors called "jitter". These jitters can cause data looses. Jitters can be measured by an oscilloscope. They called "eye paattern" because of their specific looks.

The other important specification is the data rate, which depends on the sampling rate, in digital audio cables. Sampling Rate, Bandwidth and Transmission distances are shown in the charts below.
  
Sampling Rate and Bandwidth
Use
Sampling Rate
Bandwidth
DSR
32.0 kHz
4.096 MHz
CD/DVD
44.1 kHz
5.645 MHz
DAT
48.0 kHz
6.144 MHz
DVD
96.0 kHz
12.288 MHz
DVD
192.0 kHz
24.576 MHz
Chart.1
 
Digital Audio Transmission Distances
 
2.048 MHz
4.096 MHz
5.645 MHz
6.144 MHz
 12.288 MHz
24.576 MHz
mt.
mt.
mt.
mt.
mt.
mt.
 
110 ohm
EK.203AE(26AWG)
354
280
255
239
186
140
EK.204AE(24AWG)
446
372
336
318
250
189
Ek.205AE(24AWG)
472
390
349
331
261
201
EK.206AE(22AWG)
636
514
488
453
366
300
 
75 ohm
57518205(Mini)
565
479
434
442
325
267
57518206(Mini 59)
1047
722
644
592
455
331
57518208(RG-59)
1430
1058
917
869
643
472
57518209(RG-6)
1754
1333
1176
1081
816
584
Chart.2
 
·          Note: It is accepted that min. permissable output signal amplitude is 2V according to AES3-1992, and min permissable input amplitude is 200 mV according to AES-1992 while measuring the transmission distances. Longer transmission distances are possible but depends on the quality of system parts.
 

Emek Kablo presents a large product range of 110ohm digital AES/EBU cables.