[Xymordos]

I was on the Chinese headphone forums and saw an discussion of a bug in the ES9018 chip. They uploaded an email from ESS to prove their point. I'm not a DIYer so I don't know exactly what they're talking about, and what the actual problem is.
 

 
 
Quote from the forums:
"ESS在2010/01/28有一份DAC scrambling THD issue的application note,是在講利用scramble the volume settings 
減輕問題,但是試過無法完全解決問題."
 
 
Translate:
"On 28th Jan 2010, ESS posted an application note on the issue of DAC scrambling THD, and talked about reducing the problem by scrambling the volume settings, but it does not solve the issue."
 
According to the forum, John Westlake said this on his own forums:
"I'll never use the ESS9018 again as an integrated DAC solution in our designs its SO FULL OF BUGS. We pull our hair out, its REALLY REALLY Buggy, some issues are more serous then others... ESS should really have re-spun the silicon to resolve the bugs."
 
The forum also contained a graph posted by another member, with him saying:
"我貼一張圖解釋這件事情並也請不要再來信詢問.因兩聲道狀況一樣所以下圖我僅擷取單一聲道.測試的板子是ESS提供的demoboard輸入是spdif,藍 
色是-35dB輸入訊號,青色是-36dB輸入的訊號.一般來說相差僅1dB的訊號測試結果應該相近.可由下圖看出青色是屬於正常的,而藍色從200Hz開始至20KHz以上 
有不正常隆起跟高次諧波失真.這個問題出現的地方有很多,也就是我說的非正常性的失真.這問題不僅是多聲道併聯才會,即便是ES9018只使用單一聲道還是會出現, 
所以這個問題無關併不併聯.ESS HQ也很明確說這是他們目前晶片技術上的副作用,他們也在2010發現這個問題所以寫了一份Application Note來解釋這個問題. 
所以很顯然在沒有客戶用AP測出這問題前他們是閉口不談,我是把這測試圖給原廠之後才給我Application Note.很多人問我是不是有辦法可以解決這問題,我在此 
也很坦白告訴各位沒辦法,因為原廠跟我說了這問題目前無解"
 
Translated:
"I posted this image explaining this, and do not PM me to ask anymore. Both channels have the same issue, so I only took one channel. The board tested is the demo board provided by ESS, input is SPDIF. Blue color is -35dB input signal, green color is -36dB input signal. Generally, a signal with a difference of only 1dB should have very similar test results. However, from the image below, green is normal, but blue starting from 200Hz to above 20kHz have an unusual bump and 'High-order harmonic distortion'. This problem appears in many places, which is what I mean by abnormal distortion. This problem appears even if ES9018 is only used for one channel only. ESS HQ also clearly stated that this is a side effect of using their chip's technology, and they discovered this problem in 2010, so they wrote an Application Note explaining this...ESS told me that this problem has no solutions."
 

 
 
 
 
 
 
Can anyone experienced in Head-Fi come out to explain this? Is the ESS9018 still a good chip to use? Thanks!

 

[goodvibes]

I'm not really surprised. I like the chip but not more so than a good Wolfson ot TI and neither as much as PMC1704 done right. I've always characterized the Sabres as detailed but smooth and seemingly with enhanced harmonics (distorion?). Maybe, maybe not. It needs to noted that the graph shows the problem is still 130db down but it may point to a bigger issue under more severe conditions. There will be a variety of distortion products not easily measured in most of these chips. I'm still of the opinion that your ear should be the deciding factor and the Sabres all sound pretty good. They are nice all in one solutions and there results will generally still be better than what most can get from outboard tailoring. Folks tend to jump on reports like this but it would certainly be minor in a portable and probably in general.

 

[StudioSound]

Does this even matter if it's below -130dB? You still have more than 21.5 bits of resolution.

It seems like this DAC spec war is getting out of hand now that we are in the range of measurable but not audible differences.

 

[Xymordos]

I did say I'm no engineer or professional, and I read that there was a bug. So I posted here with all the information I can find to see if it was a very serious issue. I see now that it isn't, and it is still safe to buy ESS based products then?

 

[Baxide]

I have been running Microsoft software on various PC hardware for decades even though I know the combination is riddled with bugs and the next MS upgrade is just round the corner. It's not something to suffer a loss of sleep over. There are friendly bugs and there are harmful bugs.

 

[runswithaliens]

Xymordos, you have started this thread quoting renowned DAC designer John Westlake who says the chip is "full of bugs".  Who do you expect on this forum is going to give a more authoritative answer than that?
 

 

[MacedonianHero]

Quote:

Xymordos, you have started this thread quoting renowned DAC designer John Westlake who says the chip is "full of bugs".  Who do you expect on this forum is going to give a more authoritative answer than that?
 

My brother owns a company designing chips for some of the big OEMs and you'd be surprised just how many chips in the market are "full of bugs".