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Old 27th November 2011, 05:51 AM   #41
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Hello

I did have only a partial ES9023 datasheet, but I've just found the complete datasheet on the web, so I will look at page 7 and 10.

Btw, why using the limiting resistor would made the Dac to sound less good ?

Thank

Bye

Gaetan
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Old 27th November 2011, 06:03 AM   #42
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Hi Gaetan,

Good question. I do not know why it has such a big impact on the sound as I do not know how they implemented the function in the chip.

If you want to test it add a 121K resistor from pin 6 to ground. This reduced the output in my design to ~2V RMS down from just under 2.1V RMS without it while using 3.6V rails for the 9023. It was night and day in my layout.

Dave
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Old 12th December 2011, 02:51 PM   #43
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Quote:
Originally Posted by fitzfish View Post
I'll add one more suggestion - DO NOT use the limiting resistor. While it may reduce clipping for signals we likely never will see in music, it's use is very detrimental to the sound.


Dave
Sorry late reply, thanks Dave for your recommendations.

I'm testing different caps in my ess9023 dac, all ceramics, all Oscons with small esr ceramic on Cfly. found the latter very good. still need to test good film caps, which one are you using?

I want to draw the attention to one thing I' ve discovered that brings the sound to a new level, stereo image gets wider, natural sound.. very good sound.

I wanted to get rid of the internal charge pump inverter, so I omitted the Cfly capacitor (the capacitor between CP and Cn), thus disabling de facto the switched transfer of current from Vin to NEG.
Since negative voltage is not coming from the pump, I tried connecting a quiet good source (lifepo) to NEG pin.. actually a lifepo with the minus to NEG and positive to GND.

DC offset similar to the original circuit.. 2/3 mV.
DC servo seems to track well the -3.2/3.3 from the lifepo.. the pump circuit output was a bit less (-3.1V if I remember correctly).

in my setup very good result with this simple mod.

anyone willing to try and confirm this?

PS: pay attention to DC offset.. if you leave connected alone Vneg you'll find DC at the output. you need both Vin, NEG, and omit only Cfly across Cp/Cn.

Thanks
regards
Valeriano

Last edited by Valeriano; 12th December 2011 at 03:13 PM.
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Old 12th December 2011, 03:33 PM   #44
EUVL is offline EUVL  Europe
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That is an interesting observation.
A brave one as well, or you have the internal schematics ??



Congratulations,
Patrick
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Old 12th December 2011, 05:10 PM   #45
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Quote:
Originally Posted by EUVL View Post
That is an interesting observation.
A brave one as well, or you have the internal schematics ??



Congratulations,
Patrick
Thanks Patrick!

unfortunately I have only access to the datasheet which is telling nothing about internal operation of the circuit.

I got some information about charge pump inverters (switched capacitor) using datasheet from TI and others.. since Cfly is vital to the charge transfer from Vin to NEG, I asked myself why not trying omitting this capacitor.. and directly source the negative voltage to NEG pin.

some additional info, charge pump internal oscillator is connected to the system clock, without clock pump is not working.
Vreg on the other hand is generated from Vcc regardless of the clock connected.. so no switching related operation on this reference.

I was concerned about spurious 1.5Mhz coming from the pump even without Cfly.. I don't see anything with my cheap Rigol scope.

regards
Valeriano
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Old 12th December 2011, 05:21 PM   #46
EUVL is offline EUVL  Europe
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The charge pump will not ease working even without Cfly.
I need to try this some time, though we also have no complaints about using the charge pump, if you choose the right caps.
Try some SMD film caps to compare with the MLCCs.


Patrick
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Old 12th December 2011, 07:04 PM   #47
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Patrick, did you try Wima MKS2 in 2.5 mm pitch yet ? I wanted to try that one but my ES9022 DAC did not survive the many mods and soldering. Very frustrating to build something that dies but the last mod was the final. Anyway, I could not judge the Wima anymore (well, the DAC distorted terribly as the chip was fried) but it seems a very good candidate.
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Last edited by jean-paul; 12th December 2011 at 07:07 PM.
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Old 12th December 2011, 07:09 PM   #48
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Quote:
Originally Posted by Valeriano View Post
Sorry late reply, thanks Dave for your recommendations.

I'm testing different caps in my ess9023 dac, all ceramics, all Oscons with small esr ceramic on Cfly. found the latter very good. still need to test good film caps, which one are you using?

I want to draw the attention to one thing I' ve discovered that brings the sound to a new level, stereo image gets wider, natural sound.. very good sound.

I wanted to get rid of the internal charge pump inverter, so I omitted the Cfly capacitor (the capacitor between CP and Cn), thus disabling de facto the switched transfer of current from Vin to NEG.
Since negative voltage is not coming from the pump, I tried connecting a quiet good source (lifepo) to NEG pin.. actually a lifepo with the minus to NEG and positive to GND.

DC offset similar to the original circuit.. 2/3 mV.
DC servo seems to track well the -3.2/3.3 from the lifepo.. the pump circuit output was a bit less (-3.1V if I remember correctly).

in my setup very good result with this simple mod.

anyone willing to try and confirm this?

PS: pay attention to DC offset.. if you leave connected alone Vneg you'll find DC at the output. you need both Vin, NEG, and omit only Cfly across Cp/Cn.

Thanks
regards
Valeriano
What a great idea ! I hope a negative power supply to that pin will make such a difference too. And will the chip survive this eventually ?
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Last edited by jean-paul; 12th December 2011 at 07:15 PM.
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Old 12th December 2011, 08:47 PM   #49
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Quote:
Originally Posted by jean-paul View Post
What a great idea ! I hope a negative power supply to that pin will make such a difference too. And will the chip survive this eventually ?
Thanks Jean Paul,

in my final setup I plan to use low voltage salas for positive and negative supply, I'll report back soon.
Hopefully it will survive, I see no reason why should be different than a voltage provided by a battery.

regards
Valeriano
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Old 12th December 2011, 08:52 PM   #50
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Quote:
Originally Posted by EUVL View Post
The charge pump will not ease working even without Cfly.
I need to try this some time, though we also have no complaints about using the charge pump, if you choose the right caps.
Try some SMD film caps to compare with the MLCCs.


Patrick
sure, it sounds good with MLCCs.
I'll try SMD film caps, too.

I'll be happy if you try negative supply without Cfly
thanks
Valeriano
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