yildiray
New Head-Fier
- Joined
- Dec 31, 2013
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I agree with GearMe in that there are so many aspects of the application of a DAC chip that the specific "grade" is not particularly important.
FYI, companies like Burr-Brown don't set out to create a K version of a chip. But rather they make a production run of chips and measure them. The ones with the tightest tolerances (like most linear) are giving the highest grade ratings.
As a matter of fact, some of the connoisseurs of these vintage DAC ships will site out not just the better grades of a specific DAC chip, but which country and even which factory they were produced in. Over the years many of these same "number" and "grade" DAC chips were produced in Japan, Korea, and China. Being manufactured in different factories is part of the reason there are differences in the printing styles and wording on different DAC chips of the same "number" and "grade."
Note that the Japanese early production PCM1704 DAC chips are more highly prized than a K version of later Korean production.
Now lets look into the math on all of this...
You couldn't hear the four least significant bits on a so-called 24-bit DAC chip no matter what DAC it is in or what gear is in your system. Period. That's why recording companies never use those bits (they put in 0s for the LSBs).
Human ears can not hear the difference between a 20-bit and a 24-bit DAC, the recording companies never use the least significant bits on 24-bit commercial recordings (few even have 16-bits of resolution), and the noise floor in most DACs under $5K is so high most can't even resolve the least significant bits in a 16-bit recording. All sad but true.
In other words, all that "tight tolerance" stuff in inconsequential in most cases.
And that is not to mention the distortion you'll get from your digital source and the other components in your DAC.
Before upgrading a DAC chip to a K version I would recommend:
1. Upgrading the entire power supply in the DAC down to the individual regulators and caps at each chip.
2. Upgrading the op amps in the DAC so you could actually resolve the output from the existing DAC chips.
3. Upgrading anything else in the signal path, such as coupling caps, hook up wire, and connectors.
4. Add shielding and anti-resonant treatment to the DAC's chassis and individual ICs
5. Upgrade your digital source (transport or server). This is probably more important than any of the above.
Any and all of the above will make a more significant difference than the difference between the J and K versions of the PCM1704 DAC chips.
Actually, I would be willing to bet that it would make more of an improvement in the performance of most DACs to just do the shielding and anti-resonant treatment as opposed to any DAC chip upgrade.
And don't even get me started on tube output stages: there is so much noise in the power supplies and tubes in the output stage in most tube DACs that you couldn't hear the difference between the different grades of a DAC chip.
All these informations are great.Eventually I reach these conclusions :
1. I planed to make milled/engraving aluminium enclosure and take into account all other factors so thats right choise you verify me .
2. As i understand i can buy PCM1704U-J from Rochester Electronic :
https://www.rocelec.com/search?q=PCM1704U-J
J or K not very critical also this supplier must sell original products.Is it more sensible ?
3. My plan is OPA627 output stage + a tube preamplifier.Preamplifier planed to be with dac in same enclosure.Is it suitable for your opinion?
4. Do you have a recommendation for presicion power supply for dac ?
Thank you