Abbingdon Music Research CD-77 owner manual 3c. Infra-Red Link

An S/PDIF link was not offered as this method results in exces- sive sonic degradation

3b. DAC Input

It is possible to allow playback of a large library of music to an exceptionally high standard through the CD-77’s DAC option (See Section 2 item 12 for connection details). Under the DAC mode, the DAC section of the compact disk processor will disengage from the transport section. Instead, the digital signal from the USB input (R3) located at the rear of the CD-77 will be used as the music signal source.

It is worth noting that the isosynchronous USB connection used in the CD-77, because of the almost negligible introduction of jitter, offers a sonic performance that is virtually indistinguishable from CD playback via the integral transport.

Crowbar Muting Ciruit when not required, is out of the signal path

3c. Infra-Red Link

When using the CD-77 as part of a Home Theatre system, it is possible to connect a wireline remote control cable to the IR link (R4). The CD-77 will become “slaved” to the remote control operation of the Home Theatre system.

3d. Crowbar ‘Muting’ Circuit

During switch-on and standby/resume operation, the output of the CD-77 is ‘muted’ (turned off) in order to prevent any audible thumping noises during this period. Unlike the commonly used muting switches or transistors which are connected in series with the music signal, AMR has employed a relay which shunts across the output (a crowbar circuit). As a result, the muting circuit is completely removed from the path of the music signal when not needed yet when engaged, offers complete protection for any equipment connected to the CD-77.

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