Is CD 67 or CD 6000 better for modding?
I plan to tweak a Marantz CDP but can not decide which one. Is CD 67 better for modding or CD 6000 and is it possible and worthwhile to replace HDAM modules? If so it would probably make sense not to buy SE, OSE or KI versions. As far as I know both use the same transport and DAC and a similar output stage.
Do all CD 6000 have got dual DAC per channel or only OSE and KI? Would this be an advantage for the CD 67 not having dual DAC and therefore no ned for an additional OP to sum up the dual DAC signal?
Thank you very much!
My advice is to get a CD-63SE/KI or CD-67SE (mkII or OSE versions also OK).
The standard CD-63 and CD-67 are also OK but with the SE/KI versions you get a better and heavier chassis, and also a better transformer (OFC for SE and toroidal for KI). The CD-53 and CD-57 are the same as the 63 and 67 (same PCB) but do not have the HDAM buffers or Toslink outputs (these sections of the PCB are unpopulated). They also use lesser capacitors in the analogue filter and PSU but these are items you are likely to replace anyway so this may not matter. Given that the HDAM is something most people recommend eliminating too, a 53 or 57 can even make life easier for you! They are rarer though.
The 6000 series use the same DACs also (NPC SM5872BS delta-sigma with raw PWM differential voltage output). However two are used with another chip that slices the I2S signals from the decoder to feed two DACs - one for left and one for right. This is reported to have jitter implications, but also means that the differential to single-ended conversion has to be done twice.
In the 6000 a dual op-amp per channel (NJM2114) is used for the first conversion and the differential outputs fed to a final HDAM (discrete op-amp) circuit which also incorporates the final stages of the 4th-order low-pass filter. The 6000 OSE and KI use HDAMs for ALL stages (no monolithic op-amps).
In the 6000OSE and KI I think you can remove the piggy-back HDAM board for the first stages and use your favourite op-amps instead, but I'm not certain on this point.
The 63 and 67 use one DAC. The differential outputs are fed to a dual op-amp per channel (NJM2114), which does all the filtering (4th-order). The output is fed to an HDAM which serves only as a buffer and can be bypassed if desired. It's actually not a bad circuit but any op-amp used as a buffer (be it discrete or monolithic) will suck.
The enormous 63/67 thread has thrown up some replacement analogue-stage variations that eliminate op-amps entirely but these cannot be used on the 6000 (unless you leave the first op-amp stage in circuit which kind of defeats the object).
Also there are so many CD63s in circulation that if you blow one up you can get another cheaply enough to carry on and it needn't be an SE/KI version if you already have the chassis for one of those. As I said, the PCBs are the same and you can swap the transformer easily enough.
Differences between the 63 and 67 versions are small enough to be irrelevent once you start modding.
There's a guy (in Singapore I think) called TS Lim who mods these and suggests avoiding the 6000 series and sticking to 63 or 67 models. He suggests the 67SE as slightly preferable.
The 63KI still attracts high prices on eBay so I think the best 'bang-for-buck' is the 63SE or 67SE.
Having modded a standard 63 and a 67SE, I got better results from the latter, but I believe this is down to me being much better at it these days and taking a different approach, rather than any great difference between the two machines to start with, although my 67 is an SE. I personally think the 67 only replaced the 63 because of parent company Philips updating its chipset line (and Marantz's decision to make everything 1.5cm wider).
I hope this helps, and is of course only my opinion!
thank you very much for your detailed answer which is very helpful for me. Based on what you wrote I will get a CD 57 or 67 and tweak this.
In the meantime I found out that Marantz just came out with a CD 6002 and this one looks promising, too. It has got a Sony KSS 213 mechanism and CS 4398 DAC... might be an interesting project after the CD 67 project.
I too would go with the cd57/cd67. They give superior performance with the same mods as a cd63. This is due to the fact that the decoder and servo are on the same chip in the cd67. When you re-clock the dac, the servo also gets re-clocked. To get the same result in a cd63, you need two clocks.
Am I right that the CD 67 MK II OSE uses op-amps after the DAC and only HDAM as a buffer like the "normal" CD 67 does?
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