ESS ES9023 Sabre Premier DAC with integrated op amp - Page 2 - diyAudio
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Old 28th January 2011, 05:36 PM   #11
jkeny is offline jkeny  Ireland
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You mean we can discuss 9023 details openly but not 9022?
I emailed you datasheet
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Old 28th January 2011, 05:57 PM   #12
tomchr is offline tomchr  United States
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Quote:
Originally Posted by EUVL View Post
Everypne who has a datasheet fpr the ES9022 has signed an NDA
I've gotten datasheets for several ESS DACs directly from Shaw Electronics (US disti) without the need for an NDA, so as far as I'm concerned, there's no gag order. I'd still recommend going through the official channels to get the datasheet, though. Just because...

As far as output impedance goes - that might be a matter of THD rather than current drive capability. I'm guessing that you can only get the promised performance with a very light load (kOhm). At heavier loads, the THD might rise. That's common for op-amps and many quality op-amps tout the ability to drive, say, 600 ohm loads with a low THD.

Driving high capacitances (nF) makes me uneasy unless the manufacturer specifies a maximum. I'd stick with no more than their recommended value for sure. The phase margin slope vs cap load tends to be rather steep. At least that's the case for common op-amps designed for around 60 degrees of phase margin. That's also something that needs to be taken into consideration when driving longer cables (meters).

~Tom
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Old 28th January 2011, 06:28 PM   #13
EUVL is offline EUVL  Europe
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Why would you want to load a DAC with anything higher than 10k?
The input impedance of your preamp that low ?


Patrick
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Old 28th January 2011, 06:35 PM   #14
jkeny is offline jkeny  Ireland
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Look at the Nuforce UDAC2 thread on head-fi to get an idea of what headphones this DAC will run. AFAIK, the UDAC2 runs directly to the headphone out socket of the UDAC2. Recently had it at an audio meeting
- into AKG701s (62ohms?) it didn't sound good
- into HD600 (300R) it sounded bloody fantastic
- into HD681 (32R) it sounded fantastic

I'm not sure that the lower impedance causes it problems, more likely the current requirements needed - the AKGs being a difficult drive
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Old 28th January 2011, 06:48 PM   #15
EUVL is offline EUVL  Europe
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You should use my DAO follower with the AK701.
Perfect match. Ask those who tried them.




Patrick
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Old 28th January 2011, 07:00 PM   #16
jkeny is offline jkeny  Ireland
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I know Patrick,
But what I've heard of the AKGs I don't like them anyway - much prefer the Senn HD600. These are my impression from a headphone amp
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Old 29th January 2011, 05:15 AM   #17
EUVL is offline EUVL  Europe
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You need to hear one for yourself, powered by a low wattage power amp.

Patrick
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Old 3rd February 2011, 06:18 AM   #18
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Quote:
Originally Posted by EUVL View Post
Why would you want to load a DAC with anything higher than 10k?
I assume this was intended to read "anything lower". In my case the answer is I work pretty much exclusively with balanced interconnects and the optimum tradeoff between input impedance and noise on the receiving side of the interconnect is usually around 2-3kOhm, modulo whatever interconnect and RF filter impedance might sit between the differential receiver and the DAC. One may not have the luxury of controlling the other end of the interconnect. And increasing the receiver's input impedance can be an issue even in full DIY situations. For example, low noise op amp, low efficiency hi-fi drivers, probably no problem. Current feedback op amp, 105dB horns, problems---both from the increased noise being audible in the high efficiency speaker and the degradation in current feedback performance.

Quote:
Originally Posted by EUVL View Post
Yes, and also the QA550 thread.
Hmm, no measurements there either. Suppressed by the NDA, I presume. Looks like jkeny got you the datasheet.

Quote:
Originally Posted by tomchr View Post
I'm guessing that you can only get the promised performance with a very light load (kOhm). At heavier loads, the THD might rise... Driving high capacitances (nF) makes me uneasy unless the manufacturer specifies a maximum.
Agree. I'm hoping Dustin might provide some guidance

A review of ESS's DAC lineup is interesting (numbers are for 8 channel mode on the 8 channel parts):
  • start with an unbuffered voltage output and shared supplies
  • 9023 - -94dB THD, 112dB DNR
  • buffer the voltage output, separate analog and digital supplies
  • 9006 - -102dB THD, 120dB DNR
  • switch to 64 pin package and add more supply pins
  • 9008/9012/9018 - -108dB THD, 120dB DNR
  • go back to 48 pin package but change to current mode out
  • 9016 - -110dB THD, 124dB DNR
  • keep current mode out and switch to 64 pin package again
  • 9008 - -118dB THD, 128dB DNR
  • do some die layout improvements over the 9008?
  • 9012/9018 - -120dB THD, 129dB DNR
One possible interpretation of this data is switching from voltage to current mode out improves THD by around 10dB and DNR by 5dB and improving the die's power and ground structure yields about the same improvement again. If that intepretation is correct then one might be able to get the 9023 to something around -104dB THD and 115dB DNR by improving the supply and doing a current mode buffer on its output. The trick is be finding a low cost buffer op amp capable of matching the 9023's performance. LME49720s are getting cheap but I'm thinking this would be a nice application for LME49723s.

Obviously, if one wants performance one can throw money at it and do a real nice job with a 9018 board. But where's the challenge in that? Besides, there's a big thread on the 9018 already.
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Old 4th February 2011, 02:12 PM   #19
qusp is offline qusp  Australia
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highest transconductance, lowest inputZ and matched common mode voltage of next stage devices for current mode output yielded the most improvements with 9012/18 so far
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Old 4th February 2011, 04:15 PM   #20
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Sure, but as I remarked above I'm more interested in highest price/performance. For example, the 9006 datasheet implies the part hits -102dB THD in differential voltage mode and ESS's eval board app note says it does -104dB in differential current mode---yes, this contradicts the hypothesis above, but I hadn't noticed the app note had 9006 data as well as the 9008 when I wrote the previous post. If that's accurate one could quite reasonably say the extra 2dB isn't worth the second op amp in an application where cost is a consideration. As another example, the 9006 unbalanced current out performance spread in between the 49720 (-106dB) and 4560 (-105dB) is 1dB but the 49720 costs six times as much.

The obvious way of answering such questions for the 9023 is to do an eval board with a bunch of different options and measure them all. But at -94dB THD the 9023's already just about at the limitations of my measurement gear. Anyone got a spare AP2?
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