Eventide H8000FW Spezifikationen PDF herunterladen (Seite 86)

In effect, the H8000FW has two "speeds," a bit

like gear ratios on a car. In the normal (lower)

speed range, all presets can run, but only

sampling rates between 32kHz and 50kHz may

be used.

In the higher speed range, some presets cannot run (those which do not have the "

symbol beside their name on the program screen (e.g., Quad*16 Grafic Eq and

Stereo*32 Grafic Eq in this screen shot), but the whole sampling rate range may

be used.

Note that because the ADAT protocol does not support the higher sampling rates, ADAT inputs and outputs

are unusable at 88.2kHz and 96kHz on the H8000 and H8000A.

The H8000FW (but not H8000, H8000A) supports the SMUX protocol, allowing the

ADAT inputs to pass four channels at 96kHz.

The System Sampling Rate – A Digital Audio Primer

All digital audio systems operate by expressing the value of the audio signal at any instant

in time as a (digital) number. This number is sampled (recalculated) at regular very short

intervals. The rate at which the value is sampled is known as (wait for it) the sample rate,

sometimes known as a clock.

All the internal parts of the H8000FW family (including the A/D and D/A converters

and the digital outputs) run at a single sample rate, known as the system sampling rate. This

rate may be determined either by an internal clock, or by a single external input. If any

external input is used as an audio source, it must have exactly

the same sample rate as the

system sampling rate, or things will get out of step, causing one or more of the digital

values to be lost. This will result in clicks or distortion – a bad thing. For example, at a

sample rate of 96kHz, an 0.001% difference (10 parts per million – more accurate than

most clock sources) will cause a (probably faint) click about every second.

A very small difference in sample rates, as in the example above, results in slipping,

meaning that the sample points “slip” past each other in time. Depending on how severe

the sample rate difference is, the results may be inaudible (slight clicks will be ‘masked’ by

the signal) but will be avoided by all those interested in audio quality.

Since it is unlikely that pure chance will allow any two or more external signals to have

exactly the same sample rate, it is necessary to synchronize (lock) them, meaning that the

external signals derive their sample rate from some common reference. This may be either

a signal from the H8000FW itself, or an external signal feeding the H8000FW. It is good

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Eventide H8000FW Spezifikationen Seite 86