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Old 5th November 2012, 12:58 PM   #41
qusp is offline qusp  Australia
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no, you dont need 2, each ES9018 (yes just 1x S guys please) has internally 8 parallel balanced dacs, no it does not have any single ended output, you need to perform conversion to single ended output

also the ES9018 does not output 4.2v, it has differential output of 3.05vac point to point, can be slightly higher or lower depending on the AVCC supply voltage. maybe they are adding gain? 4.2v is a pretty hot output, even for balanced, I reckon some preamps will not like that

Last edited by qusp; 5th November 2012 at 01:06 PM.
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Old 5th November 2012, 01:48 PM   #42
Coris is offline Coris  Norway
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Yes, there is gain after (I/V) DAC. The 2,1v/4,2v are measured/specified at the output pins of RCA/XLR.
I think is nothing wrong with this. 2,1v/4,2v is a kind of standard line output.

(I have my self 28ppV on my outputs (opamps)... it goes directly in a potmeter input...)
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Old 7th November 2012, 07:32 PM   #43
Coris is offline Coris  Norway
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New pictures published by Oppo. It seems that the final caps (AC coupling) have an 4 figures µF capacity and 16v. Producer of the caps: SILMIC... I could see something like 400 (last 3 figures) on one of those... It may be 1400µ... 2400µ...
It could be enough for an low end of the audio spectre... But is not possible to be seen an paralleled cap for better high end of the spectre... I can not agree with this kind of design on the output line signal path, coming from an ESS9018 DAC...
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Last edited by Coris; 7th November 2012 at 07:52 PM.
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Old 8th November 2012, 04:53 PM   #44
qusp is offline qusp  Australia
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Quote:
Originally Posted by Coris View Post
Yes, there is gain after (I/V) DAC. The 2,1v/4,2v are measured/specified at the output pins of RCA/XLR.
I think is nothing wrong with this. 2,1v/4,2v is a kind of standard line output.

(I have my self 28ppV on my outputs (opamps)... it goes directly in a potmeter input...)
no 2.1v is a standard, 4.2 is not. some complain of the already reasonably hot level without any gain.

so you are trying to squeeze best performance out of the ES9018 dac and you are adding a heap of gain then using a noisy potentiometer to throw it away? pick your gain structure, use the minimum you can and use ess excellent digital 40bit volume for slight adjustment. 28v is a huge amount of voltage gain for most systems and any pot will add more noise than the digital control as long as you dont need to attenuate too much

Last edited by qusp; 8th November 2012 at 05:00 PM.
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Old 8th November 2012, 05:20 PM   #45
Coris is offline Coris  Norway
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4,2v is specified for XLR output (2,1 x 2)

About my output on 28 Vpp (on max dynamic signal), I may say that is not here much gain involved. Is something about 1,2 (I/V is 1)... The output is like this because the chips are powered with +/-15v on final... and the slew rate is also very high.
This huge output voltage gave me a very good SNR through lines/cables (if you can believe it, not shielded, but not very longs) even though I have to use a analogue (high quality) potentiometer to adapt the line to the power amp...
Maybe this way is not very usually, but I assure you that I have absolutely not any problem with "noise" in the system (which is not audible at all), the dynamic is on top, and everything is working just excellent in my (customized) system...
But this subject is a little bit different than what is supposed to be discussed in this thread...

Last edited by Coris; 8th November 2012 at 05:25 PM.
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Old 9th November 2012, 06:35 PM   #46
Coris is offline Coris  Norway
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I just find out that the "SILMIC" caps used for AC coupling on the 105 boards are a Elna type ones...
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Old 10th November 2012, 05:50 AM   #47
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Coris, what are your thoughts on how best to improve the output stage?
Simple capacitor bypass?
Transformer?
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Old 10th November 2012, 06:42 AM   #48
qusp is offline qusp  Australia
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perhaps you should add that to wikipedia.... 4.2 even if it is 2 x the 2.1v (which is actually supposed to be 2.194vpk if its referring to ARD, or 2.1vrms) is not an XLR standard. the professional audio standard which is XLR is +4dbu which is 1.228vrms, 1.737Vpk, 3.474Vpp. 4.2v is too hot for any kind of audio standard. the ARD level would put it at 4.384vpp, but thats got nothing to do with XLR, it began at a broadcaster in Germany.

ive found a couple of references on audiophile manufacturers sites just now as 2.1 and 4.2v RMS, but ive never seen such high voltage on balanced lines outs on any pro recording gear ive used and its not mentioned anywhere on the standards pages. it does make more sense I admit if its double the power for balanced, hardly any of these places stick to a standard..



Quote:
Originally Posted by Coris View Post
4,2v is specified for XLR output (2,1 x 2)

About my output on 28 Vpp (on max dynamic signal), I may say that is not here much gain involved. Is something about 1,2 (I/V is 1)... The output is like this because the chips are powered with +/-15v on final... and the slew rate is also very high.
This huge output voltage gave me a very good SNR through lines/cables (if you can believe it, not shielded, but not very longs) even though I have to use a analogue (high quality) potentiometer to adapt the line to the power amp...
Maybe this way is not very usually, but I assure you that I have absolutely not any problem with "noise" in the system (which is not audible at all), the dynamic is on top, and everything is working just excellent in my (customized) system...
But this subject is a little bit different than what is supposed to be discussed in this thread...

Last edited by qusp; 10th November 2012 at 07:07 AM.
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Old 10th November 2012, 07:11 AM   #49
Coris is offline Coris  Norway
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Quote:
Originally Posted by David Gatti View Post
Coris, what are your thoughts on how best to improve the output stage?
Simple capacitor bypass?
Transformer?
Well, transformers to output the DAC`s signal is also an idea I have since a time ago... I really do not know how it works (sounds), but it seems that they who are using so, are satisfied. Is a really drop of signal in this way to do it, but I think is worth to be try it. Technical speaking, specially in 105 model to use transformers is very difficult (to have the player enclosure completely closed after...). Not at least, this is a very expensive choice... And is more suitable for stereo output... I think one may drop this idea.
Before conclude to bypass/remove the final caps, one may take some measurements, to appreciate better such improvement. Not least, one may hear first the sound of the player hot it is out of the manufacturer.
My main idea is to bypass those caps, but how the mod is to be done in details, is a little to earlier to say. Examining the board and see what kind of circuits/design were chosen by Oppo, is a priority, before find the best way.
One may see first what about the DC offset before those AC coupling caps, and how the final stage works.
I can see also on the boards pictures that Oppo still use some RF filters right before RCS/XLR connectors, an divider after the AC caps, and so on...
The main thought here is "less components in signal path is best". Why they chose to load this output signal path with all kind of filters and ferrite beads, caps and so on, is enough difficult to understand. The signal it may look well on the oscilloscopes displays, but is for sure not best sound out of it...
In my own design I have not any filters at all after I/V stage, and the only caps are some of few pico on the opamps feedback. I succeed to lower to 32mV the residual noise from the DAC chip (very far from audible spectrum), while audio output signal it swinging from few Vpp up to 28Vpp.

So, let`s wait the player out on marked first... and on ones each rack second...

Last edited by Coris; 10th November 2012 at 07:20 AM.
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Old 10th November 2012, 07:18 AM   #50
Coris is offline Coris  Norway
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Quote:
Originally Posted by qusp View Post
perhaps you should add that to wikipedia.... 4.2 even if it is 2 x the 2.1v (which is actually supposed to be 2.194vpk if its referring to ARD, or 2.1vrms) is not an XLR standard. the professional audio standard which is XLR is +4dbu which is 1.228vrms, 1.737Vpk, 3.474Vpp. 4.2v is too hot for any kind of audio standard. the ARD level would put it at 4.384vpp, but thats got nothing to do with XLR, it began at a broadcaster in Germany.

ive found a couple of references on audiophile manufacturers sites just now as 2.1 and 4.2v RMS, but ive never seen such high voltage on balanced lines outs on any pro recording gear ive used and its not mentioned anywhere on the standards pages. it does make more sense I admit if its double the power for balanced, hardly any of these places stick to a standard..
You may have right. Honestly I did not get in this fields details... My judgement were that so far the 2.1Vpp is a standard on SE, then 4,2 it may be a standard on differential (XLR). But I will not argue on this, if you say is a quite high output voltage. My personal opinion is that this not so big problem, and it seems to work for the most of the users of the player (BDP95 so far...). I could`t read any claim so far about this...

Last edited by Coris; 10th November 2012 at 07:24 AM.
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