Marantz CD-6000 OSE VS Kenwood DP-7090 -which is better? - Page 2 - diyAudio
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Old 19th January 2005, 04:27 PM   #11
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Location: Bulgaria, Sofia
Default AD811 - be carefull

AD811 is a very fast and different /current feedback, or low impedance/ OP amp! You can not just swap both /with 4580/, asumming the 4580 is dual, without severe consiquencies like oscillation and bad performance. To use the AD811 you will need a very good quality PCB /layout/ and different circuit and/or component values. Not so easy to use almost a 1GHz opamp instead of 10MHz one.
Easy and drop-in replacement would be something like the OPA2134 or simply something with similar speed chars.
For faster and higher fidelity I/V look for FET-input or degenerated BiPolar-input Stage OP Amps. AD has many, including AD8066 /FET/ , AD826 /Bi, degenerated/.
Good Luck
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Old 23rd January 2005, 11:42 AM   #12
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Thanks,

for very helpful ideas.
Mario, I really hope that you will recieve your DP-7090, I am waiting it almost as much as you are I am wondering how sounds slow roll off compared to other opinions?
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Old 4th February 2005, 04:49 PM   #13
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Hey Mario,

have you aleready received your Kenwood?
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Old 5th February 2005, 04:50 PM   #14
masi is offline masi  Switzerland
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Default Kenwood DP-7090

Hi Ray

Yes, I finally got it and I’m quite impressed: a very nice and service friendly design.

The only thing I’ve done so far was adding a switch (from Pin 27 of SM5843 to ground) to choose either fast or slow roll off.
Before changing any big thing I have to get used to its sound. But I think the coupling caps (C87 & C88) are not really needed. There shouldn’t be any significant VDC at the output of the differential amp (IC 23 & IC24).

So far, I prefer the slow roll off filter with most music. But it’s maybe a matter of taste.

Have you done any mods so far? Any experiences?
Anyone else familiar with this player?

Regards,
Mario
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Old 12th February 2005, 05:52 PM   #15
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Hi,
nothing done yet, except investigating. I´m going firstly to change op amps and clock, which seems to be weak poitns in that design. Also checking power supply.
Thanks Mario for advice
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Old 17th February 2005, 11:28 AM   #16
masi is offline masi  Switzerland
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Hi,

Made a few more changes to my Kenwood:

1. removed coupling caps and muting transistors, sounds more dynamic and livelike.
2. compared the original four-DAC-setup vs. a single-DAC-setup, really liked the single DAC better.
3. compared original opamp PSU (+/- 8V) vs. a clean +/- 15V supply, again an improvement.
4. tried differnt opamps (ne5532, OPA2604, OPA2132, AD826, LM6172), hard to tell which is best, each seems to have its pros and cons.
5. added some 0.1uF C's and four more 47uF elcos around the DACs.
6. replaced the bridges with shottky diodes.
7. changed from original clock to tent XO.

Hard to tell what contributes most to the over all improvement. While mods 1. to 5. allowed for direct comparisons between an original and a modified channel, mods 6. and 7. are not easy to switch in and out, so let’s hope they're not doing any harm

What’s next?
Preferring the single-DAC-setup signal routing could be much simpler: Instead of routing LRCK, BCK and DATA from IC3 (CXD2545Q) to IC8 (D.R.I.V.E) to IC10 (SM5843) to IC9 (32FS digital filter) and finally to the DACs, one could omit IC8 omit IC9. Consequently, SM5843 must be changed from 20bit data input format to 16bit format.

In addition, pin 2 of PCM1702 (BCK) could be fed directly from a low jitter clock. See following posts:
http://www.diyaudio.com/forums/showt...533#post574533
http://www.diyaudio.com/forums/showt...934#post572934

regards,
Mario
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Old 16th March 2005, 07:14 PM   #17
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Hi,
you have done nice job Mario. It seems that you are the only one who has described his experiences with DP-7090
Maybe you will describe major differencies between opamps - which one do you like best?
It would be also interesting to know what do you think about Kenwood`s layout, design and construction.
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Old 27th March 2005, 08:29 AM   #18
masi is offline masi  Switzerland
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Hi,

Sorry for the delay, just came back from my holydays…

I really can’t say which opamp I like most, and because of that I change them every once in a while
Genreally, my experience is that the very standard NE5532 already sounds good and neutral but maybe the bass is more thick than tight. AD825/AD826/LM6172 are maybe more on the airy and clean side, they seem to be faster but possibly a little thin. OPA2604/2132 are not that revealing as AD’s or LM6172 but very pleasant or “creamy”, especially with voices, but perhaps not really neutral. In another player I’m currently using an AD810 (current feedback) as I/V converter and so far I wouldn’t complain.
I know that’s not much of a help, and I wonder myself what opamps people like most in this CDP.

Concerning its design I particularly like the mechanical part: a big case with plenty of room to stuff it with all kinds of mods, and an easy removable main PCB.
The analogue layout is as simple as possible (per channel only 4x I/V opamps, one more differential amp plus another one for the headphones) and with very little filtering (thanks to 32fs oversampling).
I’m puzzled by the digital layout: why aren’t the signals from the decoder directly fed to the oversampling filter (SM5843)? What’s the benefit of an additional chip converting 16bit signals to 20bit signals at 1fs sample rate? SM5843 would accept raw 16bit signals from the decoder. Any ideas?

Anybody having any experiences with this player, let us know

Regards,
Mario
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Old 29th March 2005, 01:24 PM   #19
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Hey,

thanks. Accuphase has also a player with 8xPCM1702 a DP-65. It is interesting to know that Accuphase is a part of Kenwoods industry. Here is a link about DP-65, specs and layout design: http://www.thevintageknob.org/ACCUPHASE/DP65/DP65.html#
Someone has said that DP-7090 has better layout(digital) than DP-65, but maybe someone can say the differencies comparing these two players, maybe there is something clever to point out

LM
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Old 15th June 2005, 11:35 PM   #20
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Quote:
SM5843 would accept raw 16bit signals from the decoder. Any ideas?
...may-be something from here, 22-bits:

"Here we find no less than four of Burr-Brown's top PCM1702 20-bit DACs per channel, each fed from the same eight-times oversampling filter also used to great effect in Arcam's Alpha 8 CD player. In this case, however, each DAC is offset by 1/32 of the sampling rate and the analogue signal summed after conversion. This confers the benefits of 'true' 32-times oversampling with a potential resolution of some 22-bits which, in a roundabout sort of way, is what Kenwood has claimed for its DRIVE innovation. Interesting idea, but daft name nonetheless." hifichoice.co.uk
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