5
CHAPTER 1
DRAWMER DC2496 HIGH RESOLUTION
ANALOGUE TO DIGITAL CONVERTER
INTRODUCTION
The Drawmer DC2496 is an extremely sophisticated, high resolution
analogue to digital converter designed for use in demanding recording and
broadcast applications. Both analogue (balanced XLR) and digital (AES/
EBU, S/PDIF, ADAT 8 Channel light pipe and TDIF 8 Channel) I/O is
provided as standard. The audio converters are 24-bit and the digital output
can be either 16, 18, 20, 22 or 24-bit at sample rates of up to 96kHz. Noise
shaped dithering is included and Word Clock input and output is available.
NOT JUST AN A/D CONVERTER BUT ALSO DIGITAL INTERFACE FOR
RECORDING FROM ONE UNIT TO ANOTHER - WITH A BACKUP AT
THE SAME TIME!
Why 96kHz?
Digital processing has until now been confined to 48kHz sampling frequency.
In order to achieve the required bandwidth for professional audio, a very severe
low pass filter at 23kHz is required to separate analogue signal frequencies
from the clock frequency otherwise unpleasant aliasing will occur. This requires
the use of a FIR digital filter which is part of the A/D and D/A converters.
Unfortunately these filters cause what is known as
>
time smear
=
, where short
transients are smeared over a longer time period giving loss of HF detail. At
96kHz sample frequency, the low pass filter is less severe and at twice the
frequency, so time smear is considerably reduced.
A second important consideration is the increased audio bandwidth up to
40kHz. This allows harmonics which extend above human hearing to be
generated and preserved. These harmonics, although not audible themselves,
make a contribution to the sound quality.
Key Features
96k 24bit A/D with 130dB dynamic range and very low THD.
Simultaneously record 96k/48k 24bit stereo input to 48K (three) or 96K (six)
tracks to ADAT or TDIF 8 track digital tape recorder and stereo 48k 16bit
backup (to tracks 7/8) and record an independant backup copy at 48/44.1 20/
16bits to DAT (using internal Sample Rate Convertor)
Sample Rate Convertor with bit reduction and dither to reduce 96/88.2K 24bit
recordings to 48/44.1K 16/20bit for CD masters.
Built in 96/48K high quality D/A to monitor digital signals or record to analog
tape.
Dual time constant Stereo Limiter with variable time constants can apply up
to 18dB stereo gain to any input signal.
100dB range 64 element stereo signal meter with peak hold.
Selection of Noise shaped dither and bit rounding to reduce 96/48/44.1K
recordings to 22, 20, 18 or 16 bits.
Digitally copy 8 track stereo or Hi-Res ADAT/TDIF recordings to or from TDIF/
ADAT.
Auto identify Stereo or Hi-Res recordings upon ADAT or TDIF replay.
Inputs from A/D ADAT optical, TDIF, AES, SPDIF, Outputs to D/A ADAT
optical, TDIF, AES, SPDIF.
Seperate Digital Word Sync from D/A TDIF, ADAT, AES, SPDIF or BNC .
Rear panel show which sockets are active for easy hookup using Green (for
input signal) and Yellow (for word clock inputs) LEDs.
Built in 100Hz, 1kHz, 10kHz and dual sine wave generator (100Hz Left Ch,
1K Right Ch) sine tone at -40dB, -20dB and variable -24db to -6dB output
level to aid connection dificulties and troubleshooting.
Dual PLL for low jitter
Chapter
1
DC2496 HI RES A/D CONVERTER
