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Which good discrete R2R multibit DAC & why NOS ?

In another thread concerning upsampling and upconversion in servers, mention was made by georgehifi :
¨Should just have a good listen to Redbook 16/44 PCM converted through a "good" discrete R2R Multibit nos dac.¨
Which would these be and why NOS ? Are there no R2R multibit DACs being made today ?
My Reimyo CDP777 although quite old has the K2 conversion and being one-box and top-loading made sense  to me at the time of purchase.
Most importantly, would adding an external R2R bring a noticible improvement or just be sidestepping ?

Thanks in advance

rost
georgehifi's avatar
georgehifi
10,312 posts
 
Yes Mojo also do good R2R Multibit dacs now.
They wrote a great article a few years ago on DSD vs PCM and the d to a conversion to do each. R2R (multibit) vs Delta Sigma (single bit)  Here's what they said.
When a PCM file is played on a native DSD single-bit converter, the single-bit DAC chip has to convert the PCM to DSD in real-time. This is one of the major reasons people claim DSD sounds better than PCM, when in fact, it is just that the chip in most modern single-bit DACs do a poor job of decoding PCM.
https://www.mojo-audio.com/blog/dsd-vs-pcm-myth-vs-truth/

Cheers George
c_avila1
185 posts
 
@veroguy  

https://www.ebay.com/itm/202167842535

I use this seller's AD1865 DAC and I really like it. I would like to know what the PCM63 DAC sounds like. 

The link below is for a PCM56P-K DAC that I'm also considering just for the sake of trying something different. 

https://www.ebay.com/itm/362843900577
georgehifi's avatar
georgehifi
10,312 posts
 
Some of the best very expensive Wadia dacs use PCM56 and PCM63 chips in them, with what they called the discrete "Sledgehammer" output boards.
They also had what I found to be the best way to link it to their transports with AT&T glass BNC optical link, using a dab of very expensive "optical indexing fluid" on both ends, so there was no air gaps to the AT&T receivers

And Accuphase used the AD1865 in great numbers their top line expensive dacs also.

Mark Levinson, Linn and Naim were a big user of the (best I felt PCM1704’s) in their top end players and dacs.

Naim got amazing sound from the CD555 and PS555 power supply combo. Even today you won’t get this pairing cheap anywhere. https://www.naimaudio.com/product/cd555

Cheers George
djones51
4,947 posts
 
The Reimyo CDP 777 used 2 PCM1704 and Nippon SM5847AF filters and JVC K2 DSP which is why it was a good CD player it wasn’t NOS and made use of good filtering and up sampling which any decent R2R implementation needs to do.
rost OP
94 posts
 
Please enlighten:

@georgehifi 
"But I can’t find what the Reimyo uses for dac chips, my guess would be the R2R PCM1704K’s, I don’t think it’s discrete R2R"
What is the difference between a discrete R2R & non discete R2R DAC ?

@djones51
" it wasn’t NOS and made use of good filtering and up sampling which any decent R2R implementation needs to do."
Please explain further, I thought R2R implied NOS or upsampling.

Thanks


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