Accuphase DC-91: multi multi-bit

microstrip

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I don't say so, the file I linked says so and my google searches were fruitless. I had never heard of a Sony having using this Chip.

It's not just the output voltage, which is definitely marginal, it is the lack of current capability, something active preamps with robust regulated supplies deliver unwaveringly. I don't think you have heard this Dac even remotely close to its potential.

Low current capability is not an important parameter if the signal is of low voltage and the impedance of the preamplifier is very high. The main problem of using a passive load is the modulation of the supply voltage to the current sources with the output signal - there is a compromise between amplitude and linearity. I even tried 10 ohms and noise was not a problem, should remember that what is considered the best source, the tape, delivers an output of hundreds of microvolts. But yes, I am sure I have not heard the PCM63 at full capability.

Another myth to add to the unobtainium is the over. Just because it weights the triple or has ten times the power supply energy does not mean it forcefully sounds subjectively better. A few cases where this was found to be true does not create a general rule.
 

morricab

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Low current capability is not an important parameter if the signal is of low voltage and the impedance of the preamplifier is very high. The main problem of using a passive load is the modulation of the supply voltage to the current sources with the output signal - there is a compromise between amplitude and linearity. I even tried 10 ohms and noise was not a problem, should remember that what is considered the best source, the tape, delivers an output of hundreds of microvolts. But yes, I am sure I have not heard the PCM63 at full capability.

Another myth to add to the unobtainium is the over. Just because it weights the triple or has ten times the power supply energy does not mean it forcefully sounds subjectively better. A few cases where this was found to be true does not create a general rule.

Until very recently I had not heard a single preamp that was stellar sounding that did not have an ambitious power supply. I have a pre now in for review that is sounding very good indeed that is small, relatively light weight and not using any tubes in the power supply for rectification or regulation. It is heavily regulated though including the plate voltage, but doesn't have a large transformer or massive amounts of capacitance. Surprising as it competes well against some tough competition.
 

morricab

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Low current capability is not an important parameter if the signal is of low voltage and the impedance of the preamplifier is very high. The main problem of using a passive load is the modulation of the supply voltage to the current sources with the output signal - there is a compromise between amplitude and linearity. I even tried 10 ohms and noise was not a problem, should remember that what is considered the best source, the tape, delivers an output of hundreds of microvolts. But yes, I am sure I have not heard the PCM63 at full capability.

Another myth to add to the unobtainium is the over. Just because it weights the triple or has ten times the power supply energy does not mean it forcefully sounds subjectively better. A few cases where this was found to be true does not create a general rule.

Another reason to be interested in the Accuphase is that Accuphase makes very robust and well regulated power supplies that should give the 32 PCM63s a very stable environment to perform their best. As I said, my main concern is whether or not this design was "ruined" by a poor analog output stage.

It seems very few people have actually heard this DAC. It was super expensive in it's day so apparently there aren't thousands of them floating around out there...or the owners don't part with them...which is a telling sign if true.
 

LL21

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Another reason to be interested in the Accuphase is that Accuphase makes very robust and well regulated power supplies that should give the 32 PCM63s a very stable environment to perform their best. As I said, my main concern is whether or not this design was "ruined" by a poor analog output stage.

It seems very few people have actually heard this DAC. It was super expensive in it's day so apparently there aren't thousands of them floating around out there...or the owners don't part with them...which is a telling sign if true.

I presume you have read this review...but for others who may not have (like me): http://www.stereophile.com/content/...dc-91-da-processor-page-2#3wKmOWTojB7xZtbK.97
 

morricab

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LL21

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Yes, and apparently Dick Olsher had a DP-90/DC-91 combo for a long time. Dick is one of the reviewers whose sonic perspective matches fairly closely to my own...at least based on the review he has done.

I could believe that, based on your respective writing. Yes, in the review, he said he bought it and found it (at that time!) already competitive with his vinyl rig.
 

morricab

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I could believe that, based on your respective writing. Yes, in the review, he said he bought it and found it (at that time!) already competitive with his vinyl rig.

That is why I thought it interesting. They are hard to find used and even then held their value well.
 

LL21

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That is why I thought it interesting. They are hard to find used and even then held their value well.

I imagine with good bones, and some expertise/skill (like yours)...you also could look at getting such a DAC and (if appropriate) looking to enhance power supplies, emi/rfi shielding, perhaps capacitance (do I understand properly Aries Cerat has decided to give 3 FARADS to its reference level DAC?...does that make the DAC operate on essentially a battery???), look at anything in the input/output connections or other elements.
 

morricab

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I imagine with good bones, and some expertise/skill (like yours)...you also could look at getting such a DAC and (if appropriate) looking to enhance power supplies, emi/rfi shielding, perhaps capacitance (do I understand properly Aries Cerat has decided to give 3 FARADS to its reference level DAC?...does that make the DAC operate on essentially a battery???), look at anything in the input/output connections or other elements.


Maybe a power supply upgrade would help, although I would think it is likely pretty good. I would say doing an old style "lampizator" on the output stage might bring the most benefit.

Yes, the Aries top Kassandra has enough capacitance that it is "battery like" but those capacitors are a special type that have a very low ESR and are therefore able to deliver current better than a battery. It is an extreme implementation and I have not heard a Kassandra yet but I can imagine from the parts and concept as well as the execution that it should be up with the best.
 

opus112

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do I understand properly Aries Cerat has decided to give 3 FARADS to its reference level DAC?...

I went over to their webpage, its saying 2.5F total system capacitance. This isn't particularly meaningful, what's a better metric is supply impedance. Nowadays super capacitors are available in hundreds of F but only at lowish voltages (2.7V typically) and their in-circuit impedance is dominated by their ESR over most of the audio band.
 

leyenda

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I had the 90/91 in my system for about a week. As I recall, they were nice sounding but in the end did not do it for me, and I have wanted to like it for the reasons all specified here (I am a big fan of discrete jfet output stage). I did not do a direct comparison but of all the dacs I had in my system I believe it bettered (in my opinion/taste) some modern dacs such as the BADA but certainly not in the league of say the Soulution. I now use the Soekris r2r and am quite happy with digital.
 

leyenda

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Should also add that I much prefer the 90/91 to say the 100/101 combo that I very much dislike.
 

Al M.

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Here is another thing to ponder. With the advent of HQplayer and people raving about upsamping all PCM to DSD512 then the whole idea of what a DAC is goes out the window. Now you just need something to do DSD at that super speed. T+A and Lampizator have DACs that do DSD without any DAC chips. The ESS DAC is suppose to sound its best with DSD. So, using a high powered Windows computer and running HQplayer into a DAC running at DSD512 may be better than just about any other way to listen to PCM. You see folks, the times they are a changing. The Gustard will do DSD512 through its I2S interface and soon there will be a box that can send it. Fun times ahead. Many who have listened to 512 upsampled music through a great DAC are no longer listening to their turntables......yup...is that good. Of course, there are super turntables, etc.....but at what cost?

The best digital playback that I have heard was PCM as straight PCM (dCS Rossini and Vivaldi).
 

LL21

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Yes, and apparently Dick Olsher had a DP-90/DC-91 combo for a long time. Dick is one of the reviewers whose sonic perspective matches fairly closely to my own...at least based on the review he has done.

Dick Olsher also loves the Shindo line of electronics. I have heard a shindo preamp...while on Clapton, i found it mesmerizing and insanely quiet...i instantly could understand the long-term appeal of Shindo and it seemed to have an amazingly low noise floor...i also found on orchestral music i 'felt' that the midrange of strings seemed slightly forward...gently so, but there nevertheless...which was consistent with Clapton's voice coming forward more (which was an unpleasant effect).

That said, for this reason, despite all of its magic appeal, i did not pursue Shindo further than that shoot out at home.

Do you have any experience with Shindo?
 

morricab

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I had the 90/91 in my system for about a week. As I recall, they were nice sounding but in the end did not do it for me, and I have wanted to like it for the reasons all specified here (I am a big fan of discrete jfet output stage). I did not do a direct comparison but of all the dacs I had in my system I believe it bettered (in my opinion/taste) some modern dacs such as the BADA but certainly not in the league of say the Soulution. I now use the Soekris r2r and am quite happy with digital.

Thanks for your feedback. What was it about the sound that "didn't do it" for you? i am suspecting that the analog output stage of this DAC is subpar despite the high engineering pedigree. I have also heard that the first generation SACD separates (100/101) were not very good sounding.

Any experience with the older DC-81L?
 

morricab

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Dick Olsher also loves the Shindo line of electronics. I have heard a shindo preamp...while on Clapton, i found it mesmerizing and insanely quiet...i instantly could understand the long-term appeal of Shindo and it seemed to have an amazingly low noise floor...i also found on orchestral music i 'felt' that the midrange of strings seemed slightly forward...gently so, but there nevertheless...which was consistent with Clapton's voice coming forward more (which was an unpleasant effect).

That said, for this reason, despite all of its magic appeal, i did not pursue Shindo further than that shoot out at home.

Do you have any experience with Shindo?

No experience with Shindo but based on reviews I had the impression that it is more on the "dark and rich" side of the tube spectrum. I am not interested in that kind of sound. I would still like to find out for myself one day though if they really sound that way or is it system dependent.
 

LL21

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No experience with Shindo but based on reviews I had the impression that it is more on the "dark and rich" side of the tube spectrum. I am not interested in that kind of sound. I would still like to find out for myself one day though if they really sound that way or is it system dependent.

I cannot speak about dark from my memory, but i do recall it feeling a touch rich. I equally took a pass as beguiling as it could be on certain recordings (like Clapton Unplugged)...still, in the grand scheme of several albums, i felt this could be overripe in my system in too many areas.
 

leyenda

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Thanks for your feedback. What was it about the sound that "didn't do it" for you? i am suspecting that the analog output stage of this DAC is subpar despite the high engineering pedigree. I have also heard that the first generation SACD separates (100/101) were not very good sounding.

Any experience with the older DC-81L?

Sorry, no experience with the 81L. On the 90/91, I felt the sound was not extended and "uninteresting". Maybe it was the analog output stage of the DAC like you suspect. In comparison, I found the 900/901 to sound extremely good - sweet and dynamics and refine all at the same time. I should add that personal preference may come into play here, as contrary to many people, I have never been a fan of say a dCs, from the Puccini to Rossini and even the Vivaldi (I listened to Vivaldi with an unfamiliar amp in a familiar environment though, so maybe a bias statement there). So please take my comment for what it is :)
 

morricab

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Sorry, no experience with the 81L. On the 90/91, I felt the sound was not extended and "uninteresting". Maybe it was the analog output stage of the DAC like you suspect. In comparison, I found the 900/901 to sound extremely good - sweet and dynamics and refine all at the same time. I should add that personal preference may come into play here, as contrary to many people, I have never been a fan of say a dCs, from the Puccini to Rossini and even the Vivaldi (I listened to Vivaldi with an unfamiliar amp in a familiar environment though, so maybe a bias statement there). So please take my comment for what it is :)

Well we are on common ground with regard to dCs.
 

microstrip

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