Kenwood DP-7090
November 20 2006, updated on November 20
2007 and July 2008
This is the last model of the great XX90 Kenwood family which I haven't
yet tried to lampize so far. So when I finally laid my hands on it I
could
not wait to peek inside. 8 times PCM1702? That sets expectations
high. One of the best DAC chips ever made, and they used EIGHT of
them?!? They got a bulk discount or something? Economies of scale?
Is it 8 times better than simple one PCM1702? Or is it 8 bit
better? Apparently they claim to
squeeze 22 bits out of 20 bit chip by the way of 8x config and 32 x
over sampling. Is it high end or what?
The front panel is a direct cousin of DP 4090 // DP 5090 units,
minus the
super cool drawer with extra doors like the cheaper models have. And
minus CD-TEXT.
Everything else is identical.
The hood is a thin and flimsy one, not highendish at all. No balanced
outputs. Cheap plastic remote etc, etc. So we are dealing with a simple
standard CD machine which for some reason has 8 top DAC chips inside.
Kind of equivalent of Golf VR6.
What a joy to do lampization - this player has THE BIGGEST amount
of empty space inside (at 3U height !) and what's more - it is evenly
split for two parts - left (for power supply) and right - for tubes and
stuff. Easily accommodating fully balanced 4 tube output.
All the player fits on one PCB - a big and neat one. There is no doubt
where the burr browns reside - 8 of them in two rows makes good
impression.
Why 8 ? Nobody knows. While one is needed to make a mono DAC, we need 2
to make stereo set. Adding 2 more enables us to have mirrored balanced
signal which still makes a lot of sense. But in this player all that
has been doubled and paralleled - what for? To get more output? Or to
average errors by SQRT2 ? Sqrt 2 anybody ? Extra bit of analog
resolution? Impressing
customers at the cost of 10 bucks? I don't know. Anyway, to use this
player properly the only way is to add a balanced transformers from
sowter and utilize all 8 chips at once. THAT WOULD MAKE A KILLER
PLAYER. With tubes of course.
List of other fine players using the same DAC ...PCM1702
ACCUPHASE DC-61 12 x PCM1702
ACCUPHASE DP-55 6 x PCM1702 –
SM5843AP
ACCUPHASE DP-65 8 x PCM1702
ACCUPHASE DP-65V 8 x PCM1702
ACCUPHASE
DP-75
16 x PCM1702
ADCOM
GCD-750
4 x PCM1702
ASSEMBLAGE DAC-2 2 x PCM1702
AUDIOLABOR
531
2x PCM1702
BOW TECHNOLOGIES ZZ-Eight 4 x PCM1702
California Audio Labs CL15
PCM1702
California Audio Labs Icon Mk II 2 x PCM1702
CEC
TL5100Z
2x PCM1702
CLASSE AUDIO CDP.3 2 x PCM1702
CLASSE AUDIO
CDP.5 PCM1702
DENON
DCD-201SA
2 x PCM1702
DENON
DCD-755AR
2 x PCM1702
DENON
DCD-2700
4 x PCM1702-
DENON
DCD-2880AR
4 x PCM1702
DENON
DCD-3000
4 x PCM1702
DENON
DCD-S1
4 x PCM1702
DENON
DCD-S10
4 x PCM1702-J
KRELL
KAV-250cd
2 x PCM1702
KRELL
KAV-300cd
2 x PCM1702
LINN CD12
SONDEK
4 x PCM1702
LINN NUMERIC Mk
3
PCM1702
MARK LEVINSON No 36 4 x
PCM1702
MARK LEVINSON No 39 PCM1702
MCINTOSH
MDA4000
2 x PCM1702
NAIM AUDIO CDS
II
2 x PCM1702
NAIM AUDIO
CDX
2 x PCM1702-
NAKAMICHI
DAC-41
2 x PCM1702
PARASOUND C/DP-2000 2 x
PCM1702
PRIMARE
D30.2
4 x PCM1702
PS AUDIO DIGILINK
II
PCM1702
SONIC FRONTIERS ANTHEM 2 x
PCM1702
SONIC FRONTIERS Transdac 2 x
PCM1702
STAX DAC-TALENT
BD 4
x PCM1702
TEAC
VRDS-8
4 x PCM1702
TEAC
VRDS-9
4 x PCM1702
THETA DS PRO BASIC III PCM1702
ULTECH HDCD-10 2 x PCM1702
WADIA 16 PCM1702
WADIA 21 4 x PCM1702
WADIA 25 4 x
PCM1702
WADIA
27
PCM1702
WADIA 830 4
x PCM1702
WADIA
850 2
x PCM1702
WADIA
860 4
x PCM1702<>
FOLLOW UP
Three years later -in July 2008 I discovered the 6N2P tube
and now I would recommend to Kenwood DP7090 to hook-up their
PCM1702 DACs to 6N2P only.
Back to lampization of DP-7090
Kenwood
On the photo above you will see capacitors with a double dot - yellow
and red for better legibility, which I think should be replaced with
much better, low esr caps. Blackgates are unnecessary, but TEAPO or
JACKCON low ESR type will do. Os-cons are marvellous here ! There
is over 30 of them but the
bass and space improves a lot.
A portrait of the cheap JRC op-amp (dual one). They had to go
away, sorry.
Biggest and most expenceive SOWTER transformers installed - they play
important role. They convert current outputs of the DAC (useless
in original form) plus they summarize positive and negative signals
from symmetrical set-up plus they amplify the voltage by the factor of
turn ratio (5x). On top of that - the transformers isolate DC
offset of DAC output - the DC component. And galvanically isolate DAC
from tube grid.
After 1 year more experience I suggest to save money and go for
resistor type of I/U conversion. Just add a 100 Ohm resistor from leg 7
to 9 of tube base (no more 250 K there) and wire the isolated DAC
outputs to the leg 7. For SE system - only 2 per channel will be used,
2 will remain unused.
The Sowter transformers
they do miracles for this player. They summarize the
output of all 8 DAC chips, current OUT - LEG 11th, convert it to
voltage
and remove the digital noise and DAC error common mode component.
The signal is so powerful that it easily drives the
amplifier without any tubes at all. The transformer can also convert
the balanced signal to RCA single ended.
After the transformer installation, this player immediately jumps to
the top league together with the Grundig, Copland, Revox and Shanling.
After lampization - it is in top league. Absolutely stunning. Jaws
dropping, drooling, etc etc. You know the story. The PCM1702 DACs used
in R conversion mode are of similar quality as the TDA1541A, AD1865,
AD1862, PCM63K and other finest I out DACs.
Highly recommended. The sound is so refined, detailed, analog-like,
that the CD playback equals the best vinyl from MC cartridge and
tubed phono stage.
schematics
schematics 2
Updated 12
months later:
the second time around I decided to try a "sowterless" lampization by
means of a resistor output.
The photo above is so huge on purpose to keep resolution.
Since I wanted only RCA outputs I used every OTHER dac chip - positive
ones.
Power supply lines installed.
Here is an AC stealing point (after switch)
Installed toroidal transformer and two CRC filters. red wire supplies
AC
to lampizator, note the black fuse fitting on one wire.
Output RCA's and capacitors (paper in oil Polish military 4uF/160 plus
styroflex 5nF bypass which improves "air".
Red dots indicate the electrolytic capacitors which I upgraded as usual
with at least 2 x size, 2 x rating and ESR type (for PC motherboard).
These are responsible for power delivery to the DAC chips and to the
digital filter Os-cons or even Tantals would have been even better.
RESULT of lampizator and tuning:
The result was very good, I had
no possibility to listen longer, but
the 50 Ohm resistor gives fantastic result: very powerful, natural and
high-end sound. Probably it is more open and transparent than with
Sowters but I did not A-B them.
Thanks to Low ESR caps in P-Supply section, the bass is really awesome.
The schematics is similar to the TDA
lampizator: save for having two parallel chips not just one.
Also see other
Sowter applications:
GRUNDIG 9009
SHANLING
CD-T200
COPLAND
289
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