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ESS Sabre Reference DAC (8-channel)
ESS Sabre Reference DAC (8-channel)
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Old 29th November 2016, 03:46 PM   #2541
cu6apum is offline cu6apum  Russian Federation
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Originally Posted by Bunpei View Post
Why don't we maintain this thread with a long and distinguished history on ES9008 and ES9018 for the latest ES9038PRO as well?
Anybody tried 9038? For me ismosys is silent as heaven, no reply on inquiry...
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Old 29th November 2016, 04:12 PM   #2542
Bunpei is offline Bunpei  Japan
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Originally Posted by cu6apum View Post
Anybody tried 9038?
My friend, Chiaki, is assembling DAC board he re-designed for ES9038PRO. His original design was for dual mono ES9018S. Ten ES9038PRO chips, a minimum quantity for one order were delivered to a personal user like us about two months ago from a local distributor in Japan.

Within a few weeks, I will have a chance to try Chiaki's prototype DAC board.
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Old 29th November 2016, 05:05 PM   #2543
Russ White is offline Russ White  United States
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I have been working with the 9038 chip.

We got initial samples which had a serious flaw - very disappointed with those - and we now have the fixed chips as well.

They are quite a departure from the 9018 in many ways - to the extent that our I/V stage is a completely new design.

One thing to note - the DS is wrong on several points. Dual mono in a production setting where you apply chip gain correction to adjust for chip to chip output differences (up to 28% difference from chip to chip) will not even come close to the datasheet numbers - because of the dynamic range lost because you must reduce the output swing in order to have headroom to apply sufficient correction.

Unfortunately - the 9018 also has the very same chip-to-chip output variance flaw - but it does not even have a way to apply correction automatically like the 9028/9038 do.

So unless you are willing to live with as much as 28% output level difference between channels - dual mono is not an option without losing dynamic range/SNR.

Cheers!
Russ
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Old 29th November 2016, 05:05 PM   #2544
cu6apum is offline cu6apum  Russian Federation
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Originally Posted by Bunpei View Post
My friend, Chiaki, is assembling DAC board he re-designed for ES9038PRO. His original design was for dual mono ES9018S. Ten ES9038PRO chips, a minimum quantity for one order were delivered to a personal user like us about two months ago from a local distributor in Japan.

Within a few weeks, I will have a chance to try Chiaki's prototype DAC board.
Hm, then another question. Can he theoretically hand me a couple chips?!
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Old 29th November 2016, 11:05 PM   #2545
Bunpei is offline Bunpei  Japan
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Originally Posted by cu6apum View Post
Can he theoretically hand me a couple chips?!
I'm afraid he can't do that. All the chips at his hand now are already assigned to his project. Some users made reservation for his DAC board.
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Old 29th November 2016, 11:17 PM   #2546
cu6apum is offline cu6apum  Russian Federation
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Originally Posted by Bunpei View Post
I'm afraid he can't do that. All the chips at his hand now are already assigned to his project. Some users made reservation for his DAC board.
Can't you by chance? I see you're one of the Masters of the Sabre family.
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Old 30th November 2016, 02:55 AM   #2547
chris719 is offline chris719  United States
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ESS Sabre Reference DAC (8-channel)
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Originally Posted by Russ White View Post
I have been working with the 9038 chip.

We got initial samples which had a serious flaw - very disappointed with those - and we now have the fixed chips as well.

They are quite a departure from the 9018 in many ways - to the extent that our I/V stage is a completely new design.

One thing to note - the DS is wrong on several points. Dual mono in a production setting where you apply chip gain correction to adjust for chip to chip output differences (up to 28% difference from chip to chip) will not even come close to the datasheet numbers - because of the dynamic range lost because you must reduce the output swing in order to have headroom to apply sufficient correction.

Unfortunately - the 9018 also has the very same chip-to-chip output variance flaw - but it does not even have a way to apply correction automatically like the 9028/9038 do.

So unless you are willing to live with as much as 28% output level difference between channels - dual mono is not an option without losing dynamic range/SNR.

Cheers!
Russ
If I understood that correctly, you're saying the full scale output current varies as much as 28% from chip to chip?

Wow...

The low master clock speeds needed for synchronous mode are also surprising - lower than AKM, TI, etc. need for running the modulator at the highest rate. For ES9018 I guess you really could never turn off the ASRC even if the clocks were synchronized.

Last edited by chris719; 30th November 2016 at 02:58 AM.
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Old 30th November 2016, 03:05 AM   #2548
Russ White is offline Russ White  United States
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That is correct - the error (as documented) is +/- 14% from nominal - and it is explicitly stated in the datasheet in the newer chips - but just to check out a hunch I measured some of my own 9018s against each other and found two that were about 20% apart... I was very disappointed to say the least. Funny I never thought to check until I saw the new datasheets.

So the situation for dual mono is pretty grim - because you have to reduce the output level on both chips - and then adjust the master trim to get them identical - only now they are not operating at the same digital scale at all and each will have different dynamic range - and you are still left with two parts that have different output impedances... you actually can't adjust for that in the digital domain satisfactorily.

So my inclination is not to use more than one chip unless you went dual stereo (or n-channel) - basically just stacking chips.
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Old 30th November 2016, 04:30 AM   #2549
chris719 is offline chris719  United States
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By dual stereo do you mean a situation where you're feeding each I/V converter with 8 total outputs (4 from each chip)?

Essentially, a stacked version of their quad-differential current mode example?
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Old 30th November 2016, 04:39 AM   #2550
Russ White is offline Russ White  United States
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Correct - but there is no reason it would have to be 2 channels - it could be 4 - or 6 or 8 etc... the idea is that you would never have a channel to channel difference in total relative output impedance. This approach would quickly reach the point of diminishing returns.

That said - it makes no sense to do any of that - at least with the 9038 which is basically 4 9028s stacked already - at least on the analog end (800R output-Z for 9028 200R for 9038 per channel - of course with +/- 14% error). There is really no need to stack - or to go dual mono. You won't really see any payoff in the real world.
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