Burr-Brown vs Cirrus Logic vs Analog Devices: What are the differences between these three DACs - Page 2 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #11 of 22 Old 02-10-09, 05:47 PM
 
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Re: Burr-Brown vs Cirrus Logic vs Analog Devices: What are the differences between these three DACs

i think a more relevant specification, though hardly available in a standardized measurement, would be the jitter rejection of the various DAC implementations. S/N for these probably already exceed the analog noise level of the surrounding circuits, leaving jitter as the more likely differentiator of sound quality.
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post #12 of 22 Old 02-10-09, 05:59 PM
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Re: Burr-Brown vs Cirrus Logic vs Analog Devices: What are the differences between these three DACs

Really? Is jitter a significant problem in the DAC itself?




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post #13 of 22 Old 02-11-09, 01:19 PM
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Re: Burr-Brown vs Cirrus Logic vs Analog Devices: What are the differences between these three DACs

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i think a more relevant specification, though hardly available in a standardized measurement, would be the jitter rejection of the various DAC implementations. S/N for these probably already exceed the analog noise level of the surrounding circuits, leaving jitter as the more likely differentiator of sound quality.
I would think that the jitter that you talk about is related to the conversion clock edge given to the DAC by circuitry outside of the DAC.

This clock recovery is an important issue for AVR's getting audio from a S/PDIF (incl Toslink) or a HDMI audio input. But outside of the DAC itself, normally a higher quality AVR has special PLL circuity, etc. for digital audio input interfaces to get better conversion clock signal to send to the DAC chip.
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post #14 of 22 Old 02-11-09, 05:11 PM
 
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Re: Burr-Brown vs Cirrus Logic vs Analog Devices: What are the differences between these three DACs

I guess I'm not sure exactly what is on-board these VLSI DAC's and what isn't -- i.e., are they monolithic chips which contain on-board crystal oscillators (clocks), or do they require the manufacturer independently implement the clocks -- or can they be made to work either with an on-board clock or an independent clock? My assumption, possibly erroneous, is that the jitter performance would be affected by an onboard clock, by whether there is onboard resampling/upsampling, etc. Does anyone know for sure?
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post #15 of 22 Old 02-12-09, 07:17 AM
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Re: Burr-Brown vs Cirrus Logic vs Analog Devices: What are the differences between these three DACs

My assumption is that most clocks would be very stable and that other components would contribute more to jitter. Without more direct knowledge of how a circuit is designed, however, I have learned from experience that basing an opinion on such assumptions is high unreliable. Are there any measurements that support the notion that jitter is a signifficant problem at all these days?




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post #16 of 22 Old 02-12-09, 08:04 AM
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Re: Burr-Brown vs Cirrus Logic vs Analog Devices: What are the differences between these three DACs

The big problem with S/PDIF (whether coax or optical Toslink) is that the clock must be recovered from the information signal. Years ago this was not always done well and audible jitter effects could be heard.

Much discussed over the years. Just do a google search on "spdif clock recovery". Here is one article that was found that way: Digital audio transmission, SPDIF, and Jitter



More recent IC's have addressed this issue. For instance the TI DIR9001 96kHz Digital Audio Receiver:

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TI wrote:
The industry-leading jitter performance of the DIR9001 makes it an ideal data and clock source for TI's high-performance digital-to-analog converter (DAC) products, such as the PCM1792A, to provide the highest performance DAC output available today.
...the DIR9001 integrates a high-performance phase-lock loop (PLL) to not only improve jitter performance but also remove the need for an external clock source when the sample frequency calculator is not used. Both features reduce the overall system cost by eliminating additional system components that competing digital audio interface receivers typically require.
  • One-Chip Digital Audio Interface Receiver (DIR) Including Low-Jitter Clock-Recovery System
  • Compliant With Digital Audio Interface Standards: IEC60958 (former IEC958), JEITA CPR-1205 (former EIAJ CP-1201, CP-340), AES3, EBU tech3250
  • Clock Recovery and Data Decode From Biphase Input Signal, Generally Called S/PDIF, EIAJ CP-1201, IEC60958, AES/EBU
  • Biphase Input Signal Sampling Frequency (fS) Range: 28 kHz to 108 kHz
  • Low-Jitter Recovered System Clock: 50 ps
  • Jitter Tolerance Compliant With IEC60958-3
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post #17 of 22 Old 02-12-09, 08:11 AM
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Re: Burr-Brown vs Cirrus Logic vs Analog Devices: What are the differences between these three DACs

So are the one chip solutions more stable and reliable in recovering the clock signals than previous designs, or does integrating the process make it more of an issue?




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post #18 of 22 Old 02-12-09, 08:22 AM
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Re: Burr-Brown vs Cirrus Logic vs Analog Devices: What are the differences between these three DACs

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So are the one chip solutions more stable and reliable in recovering the clock signals than previous designs, or does integrating the process make it more of an issue?
I would think that S/PDIF reception IC's now doing better clock recovery internally, just lets the mid to high end AVR's skip having to implement a bunch of discrete (multiple parts), PLL clock recovery circuity with newer designs.

Cost savings.
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post #19 of 22 Old 02-13-09, 06:59 AM
 
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Re: Burr-Brown vs Cirrus Logic vs Analog Devices: What are the differences between these three DACs

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Are there any measurements that support the notion that jitter is a signifficant problem at all these days?
Jitter is easily (well, not easily, but readily) measurable -- just pick up any issue of stereophile magazine -- it varies even among the modern top-tier compnents they tend to review. It can be measured at home too (at least to the point of being able to determine which of two setups exhibits less jitter). The question is whether the jitter levels that exist in modern receivers is audible. I have only one AVR, so I can't compare directly -- but I have compared various modern digital sources (sony DVD player, squeezebox, etc) and found sound quality to track well with lower jitter levels. I also was able to clearly see that coaxial S/PDIF connections exhibited less jitter than toslink connections.

Also, see if you can find robert harley's excellent explanation of how jitter affects signals in an article of The Absolute Sound -- published sometime over the past 12 months or so I think. In it, he explains how jitter causing the conversion of a signal sample at the wrong time actually is the same as the signal being reproduced at the right time with amplitude errors, which one can easily believe as being audible.
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post #20 of 22 Old 11-14-09, 04:39 AM
 
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Re: Burr-Brown vs Cirrus Logic vs Analog Devices: What are the differences between these three DACs

There are so many other variables that affect the audio not only from the Dacs in the analog circuitry,
but in their implementation also, that we can talk about this till the end of times.

Balanced Differential mode, Dual Balanced Dual Differential mode, Capacitors, Resistors, Digital Filters, etc., etc., etc... Dual layer epoxy circuit boards, copper quality, silver, gold, short circuit paths & wiring,...

* And more magic extra tweeking...

** Oh, and what about AKM Dacs too, and ESS Dacs? And of course Wolfson Microelectronics Dacs?

1. Anthem Pre/Pros like to use AKM Dacs in Dual Differential mode.
2. Oppo BDP-83SE Universal Blu-ray Player with ESS Sabre32 Premier Dacs.
3. Pioneer Elites like WM Dacs, in their A/V Receivers and Blu-ray players.
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