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Old 15th October 2011, 10:29 AM   #311
EUVL is offline EUVL  Europe
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In my own experience there is no need to ground the battery cases.
It is likely you have some input output coupling.
You may try gate stopper resistors of say 100R for each FET.
And you should also trim the current source to zero the output DC.
The input will then be automatically zeroed.

Without a schematics, it is impossible to figure out what exactly the problem is from here.

But I salute you for the courage to experiment.
You are the only one so far to do a bread broad test.


Patrick
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Old 15th October 2011, 01:17 PM   #312
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I build a breadboard version of the SEN. I send it to Mathias Kurz of Solid Core Audio to test it in an old Phillips CD player.
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Old 15th October 2011, 01:18 PM   #313
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A question & please pardon my ignorance -

Is the value of the output impedance the same as the Riv? If so, a buffer on the o/p to reduce it would need another seperate supply with it's 0 volt tied to the dac's pin 5 gnd point, same as signal 0 volt on the o/p socket?

Perhaps this been covered before, but ......
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Old 15th October 2011, 01:33 PM   #314
EUVL is offline EUVL  Europe
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> Is the value of the output impedance the same as the Riv?

Yes. If you use an Riv at 2.2k or 1.4k, I consider that low enough to not warrant an additional buffer.

> If so, a buffer on the o/p to reduce it would need another separate supply with it's 0 volt tied to the dac's pin 5 gnd point, same as signal 0 volt on the o/p socket?

Yes. A buffer would need fixed rail supplies, separate from this circuit.
And if you wish to do that, then you may also consider using the buffer as a Sallen Key filter.

See also :

Anybody using the new ESS Vout DAC (ES9022)?

> Perhaps this been covered before, but ......

Yes, in the discussion with Calvin about the Bipolar version of CEN.

As also mentioned, the bipolar version, as well as the current mirror version, has significantly more noise.
The original JFET SEN / CEN circuits are so quiet, that you hear absolutely nothing on a headphone with max volume.
The difference is not subtle.

This is all thanks to the separate current loop of bias and signal.
And the floating supply is a essential feature of that.




Patrick

.

Last edited by EUVL; 15th October 2011 at 01:39 PM.
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Old 15th October 2011, 01:40 PM   #315
EUVL is offline EUVL  Europe
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> I build a breadboard version of the SEN.
> I send it to Mathias Kurz of Solid Core Audio to test it in an old Phillips CD player.

And his feedback ?


Patrick
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Old 16th October 2011, 01:48 AM   #316
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Red face Output Impedance

Thanks, Patrick.
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Old 16th October 2011, 08:29 PM   #317
ryanj is offline ryanj  Australia
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Quote:
Originally Posted by EUVL View Post
In my own experience there is no need to ground the battery cases.
It is likely you have some input output coupling.
You may try gate stopper resistors of say 100R for each FET.
And you should also trim the current source to zero the output DC.
The input will then be automatically zeroed.

Without a schematics, it is impossible to figure out what exactly the problem is from here.

But I salute you for the courage to experiment.
You are the only one so far to do a bread broad test.


Patrick
Thanks for the encouragement.

I do have some dc offset in the output of one channel. Whats the best way around this, trimmers in series with the 560k resistors?

Ryan
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Old 16th October 2011, 09:50 PM   #318
ryanj is offline ryanj  Australia
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Sorry, the resistors I refer to are in the original cen circuit, R1 and R2.
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Old 16th October 2011, 10:54 PM   #319
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I'm still waiting for my Linear Audio issue.

I'm wondering (as I'm ordering parts right now) if there would be any benefit to upgarde the 220uF Nichicon ES to something like MUNDORF or Blackgate NX or Elna BP/NP ?

Thanks
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Old 17th October 2011, 03:01 AM   #320
EUVL is offline EUVL  Europe
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> I'm wondering (as I'm ordering parts right now) if there would be any benefit to upgarde the 220uF Nichicon ES to something like MUNDORF or Blackgate NX or Elna BP/NP ?

Can you still get Elna NP ?
Can you get a reasonably sized Mundorf (MKP?) for 100uF, or even 22uF ?

I already explained in the article why the "distortion" (i.e. non linear V-I relationship) of the caps are unimportant, as long as current in = current out (Kirchoff's law). One of two profs asked me by PM why I did not simply use ordinary Eleytrolytics (and they will work just fine).

But if you want to try Blackgate NX, please do.
And come back and tell us whether you can hear a real difference.

I would probably try a 10uF MKS-2 one day. But it has no priority.


Patrick
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