Meridian America Meridian 518 manual Overview as Preamp Type

Overview of 518 8

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.

CD Player

LaserDisc

DAT

518 DAC Power Amp

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!

518 User Guide