Meridian America Digital Audio Processor Meridian 518 - Manual (Page 8)

Overview of 518 8
518 User Guide
Overview as Preamp (Type 0)
Conventional analogue systems use a 'preamp' or control unit to gather
together the various sources and to control the level of signal fed to the
power amplifier so you can adjust volume.
Purists know that no matter how well a piece of analogue audio
electronics is designed, there will always be unwanted and irreversible
degradation, due to the addition of noise and distortion. Preamps are by
no means immune from this.
For this reason, Meridian have for many years been developing an all-
digital system where digital audio is handled by a digital controller (like
562) instead of a preamp. In these systems the signal is kept in the digital
domain right into the DSP loudspeakers. Apart from sophisticated
loudspeaker technology, the digital signal processing (DSP) in the
speakers also replaces the volume control.
Some quality-concious audiophiles (who still don't have DSP speakers)
prefer to use very simple replacements for the analogue preamp, placing
a passive volume control between an analogue source such as a CD
player or DAC and the power amp. This architecture gives very high
sound quality, but has a number of disadvantages – like it requires a very
sensitive power amp and has difficulties with impedance matching, hum,
noise and frequency response in the passive control.
The Meridian 518 can provide an enormous improvement in the sound
quality of some systems, by allowing you to dispense with the analogue
preamp altogether – providing you have a good enough digital–analogue
converter (DAC) and can route all signals in digital form.
For these applications – where a DAC can be connected directly to a
power amp – then 518 provides a radical upgrade by removing the
troublesome passive control.
518 DAC Power Amp
CD Player
LaserDisc
DAT
Using 518 as a 'preamp'
The system is illustrated above. Up to four digital sources – like CD, DAT
or LaserDisc (often using the optical input) – are connected to the 518.
518 is then configured as Type 0 (see page 21) which makes it a system
controller with a fully-operational volume control.
The output of 518 is taken to a DAC (or digital power amp); the output of
the DAC is directly connected to the power amplifier.
The 518 performs more functions than switching and volume control. In
summary, it:
•
smooths the sound by de-jittering the incoming data stream,
•
performs resolution enhancement by word-length matching, shaped
dither DAC enhancement and the option of pre-emphasising the DAC.
For an overview of Resolution Enhancement see page 49.
Warning! Systems like this can sound incredibly good!