Troubleshooting
109
Audible hiss at high volume settings
The input dynamic range of most current recordings is at
maximum 16 bit. The reason for this is that currently CD, DVD,
and LaserDisc use a 16-bit standard although DVD can support
up to 24-bits. The analogue sources you have cannot achieve
this kind of range. For comparison, analogue sources are likely
to be of the order of:
❍
VCR, 12 bits.
❍
FM radio, 13 bits.
❍
Reel to reel tape, 13 bits.
❍
Cassette tape, 12 bits.
❍
LP, 11 bits.
Note that there may be a difference between the dynamic range
of the source channel when it is operating, and the noise you
hear in standby. For example, LP normally has lower noise when
the stylus is not in the groove; similarly tape will be quieter when
it is stopped. CD may also be quieter when it is stopped,
producing so called ‘digital silence’.
The 561 has a 20-bit capability on its internal analogue-to-digital
converter, which is used for analogue sources. When the volume
is turned up high you may hear its dither as a hiss when the
sources are stopped. This hiss is lower than the background
noise of your recordings and should be of no consequence.
The 561 has 20-bit output precision on the analogue outputs.
Other sources of hiss may be tracked down using the Mute
option. When muted the outputs are reduced to the dither at the
selected precision.
Crackling on optical inputs
Some optical sources, in particular some LaserDisc players,
provide poor drive waveforms that do not meet the EIAJ
standard. This is because the light modulates but never goes
quite ‘black’ between pulses. If you experience crackling on the
optical input or an occasional reluctance to lock, ie provide a
sound, investigate as follows.
❍
Try other fibres.
❍
Pull the fibre part-way out and see if the problem clears up.
❍
Try another player or CD player on the optical input.
❍
Contact Meridian for up-to-date advice on this point.
