HHB comm CDR800 - Manual (Page 5)

Balanced analog and AES/EBU digital
signals enter the CDR–800 via the input
PC board assembly. The balanced analog
inputs are transformerless; the
+
and
−
legs of the balanced line are each fed to
5532 op amps operated noninverting as
unity gain buffers. The outputs of these
buffers are fed to the
+
and
−
inputs of a
single 5532, converting the balanced sig-
nal to an unbalanced state.
The use of 5532 op amps is a real dis-
appointment. I fail to understand why
the Japanese audio industry continues to
use these 20-plus-year-old devices when
so many high-performance dual op amps
are now available. A product as sophisti-
cated as the CDR–800 clearly deserves
better, but the Pioneer designers obvi-
ously continue to believe that high-per-
formance op amps just don’t make any
difference.
The A ES/EBU digital input also dis-
penses with the usual transformer-cou-
pled input—the balanced to unbalanced
conversion is accomplished with an
SN75157P differential line receiver. The
SN75157P is a dual device; only half of it
is used.
The signals from the balanced input
PC board are fed to the audio digital PC
board assembly, which also houses all of
the analog and digital unbalanced in-
puts. The unbalanced analog inputs for
each channel are fed to NJM072 input
signal op amps, manufactured by JRC.
These are TL072-equivalents, another ex-
tremely dated device (data on JRC op
amps can be found on their web site:
www.njr.co.jp).
I’m not familiar with the analog-to-dig-
ital converter chip—it bears the part
number AK5340–VS. HHB claims it uses
the latest 1-bit conversion system, which
is completely free of zero-crossing distor-
tion. The A/D chip design also elimi-
nates nonlinear distortions within the
passband, and does not require external
adjustments.
Digital inputs are fed directly to the
LC89585 EFM encoder ch ip. The
CDR–800 also includes a built-in sam-
pling-rate converter chip, which con-
verts 32kHz or 48kHz inputs to the CD
standard of 44.1kHz. The sampling-rate
converter functions only when needed—
inputs at the standard 44.1kHz frequency
bypass the sampling-rate converter.
On the playback end, the SM5813AP
digital filter feeds a pair of 1-bit Pioneer
36 Audio Electronics 2/00
PHOTO 4: Inside view of the CDR–800. Two
power transformers are used, and the solid
copper chassis provides excellent shielding
against EMI and RFI.