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-   -   PCM174U-K vs ES9018 at various I/V (IU I/U) converter - which sonic character (http://www.diyaudio.com/forums/digital-source/201170-pcm174u-k-vs-es9018-various-i-v-iu-i-u-converter-sonic-character.html)

tiefbassuebertr 25th November 2011 07:08 PM

PCM174U-K vs ES9018 at various I/V (IU I/U) converter - which sonic character
 
PCM1704UK (PCM1704) was one of the best DAC ever made, of course only in such cases where were no design errors by the ​ I / U section.
From the currently available DAC devices SABRE's 32 Bit DAC ES9018 should be the best sounded part according to the mentions of many studio guys.
Who have heard both (perhaps with various I/U topologies) and can report more details about the perception sound differences?
I have found this URLs in this case:

ES9018 vs PCM1704UK | Computer Audiophile
ES9018 DAC or NFB-11 Story
New ESS Sabre32 (ES9018) based DAC from Audio-gd....the NFB-1
BuffaloDAC
http://www.diyaudio.com/forums/exade...erface-45.html - post #441 (
2nd May 2011, 05:10)
What's your favorite DAC? - AudioKarma.org Home Audio Stereo Discussion Forums post #7

This unit used Burr Brown PCM 1704 chips, which are a multi-bit design, not a bit-streamer.

Thank you for comments concerning various impressions.

Ken Newton 26th November 2011 08:27 PM

I feel that perhaps the key implementation issue regarding the PCM1704 is the need for the I/V circuit to provide as low an resistance virtual ground as possible. The reason for this is that the PCM1704 contains a bipolar offset servo amplifier which continual attempts to null the output signal with respect to ground. In addition, an external electrolytic capacitor is required so to provide a low-pass corner frequency for the servo that is as far below the desired output signal as is practical.

Of course, the servo can have a residual affect upon the audible band, not to mention the likely audible affect of that external electrolytic capacitor. The trick to not incurring the affect of the servo amplifier and it's external feedback capacitor is have an I/V circuit which does not invoke their action in the first place. Which means an I/V which presents a nearly perfect virtual ground, such as do op-amp voltage feedback based circuits, unfortunately, with all of their their other potentially audible consequences.

In summary, I feel the best sound is obtained from the PCM1704 through an I/V which simultaneously provides a near true virtual ground but without reporting to feedback as an op-amp based circuit would do.

Joseph K 27th November 2011 06:46 PM

Good point, Ken.

This is why I have disconnected the BPO servo amp in my dac, with PCM 63.

Ciao, George

Ken Newton 28th November 2011 01:53 AM

Few good choices
 
Quote:

Originally Posted by Joseph K (Post 2797069)
Good point, Ken.

This is why I have disconnected the BPO servo amp in my dac, with PCM 63.

Ciao, George

Hi Joseph (or, is that George?),

Yes, the PCM63 makes the BPO current source available via an external pin, unlike with the PCM1704 which has that connection forever tied internally.

There are precious few production DAC chips available which lend themselves to NOS. Even those few newer DAC chips which enable the bypass of their internal oversampling filters, such as the PCM179x series, usually require that the input be externally oversampled.


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