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Old 4th March 2008, 09:27 PM   #81
kevinkr is offline kevinkr  United States
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Hi Russ,

Actually I'm planning to do the summation in the current domain since the dacs can be treated as well matched independent sources driving a transimpedance amplifier with 0 input impedance. There should be no interaction between the sources at all and the accuracy of current summation at each I/V converter should depend solely on the trim quality of the dacs.

Paralleling current source dacs by summing currents is a common practice - some even do it with resistor I/V conversion where you can expect some interaction between the dacs.

Should this not work well I plan to design a discrete based I/V converter to do the job.
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Old 4th March 2008, 09:28 PM   #82
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Quote:
Originally posted by kevinkr
Hi Russ,

Paralleling current source dacs by summing currents is a common practice - some even do it with resistor I/V conversion where you can expect some interaction between the dacs.


Yes, I certainly agree that will work just fine.

Cheers!
Russ
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Old 2nd July 2008, 02:57 AM   #83
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Some of you may find this interesting:

http://www.diyaudio.com/forums/showt...27#post1552427

Cheers!
Russ
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Old 21st March 2009, 01:32 AM   #84
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Default COD revisited. :)

Well well well, Long time since I revisited this thread. But I have been playing around with COD again since I had some new things to test(JT2 code).

I have a couple of observations which some of you may find useful.

First... I think I have found a very very good setup for COD.

COD --> IVY basic (I will explain later) ---> JT2

Now here is the thing. The output of the COD is pretty darned clean. It does not really need heavy filtering as long as you use the fast rolloff digital filter. So, what I have done is setup IVY with just 392R feedback(I/V) resistors and no filter caps in feedback. None.

Now when I tested this (with my humble gear) the DNR and THD were pretty darn close to Buffalo. And it does sound very very good.

So any of you with a COD and IVY should consider ditching the feedback (filter) caps. I think you will discover a nice change of pace.

To me it sounds like an entirely new DAC.

Cheers!
Russ
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Old 23rd March 2009, 12:50 PM   #85
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Hi Russ,

please forgive my ignorance,

a) you are refering to caps C1-C4.
b) do we need to change the 357 Ohm resistors R1-R4 as well?


Cheers!,
Abraham Sidiropoulos
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Old 23rd March 2009, 01:33 PM   #86
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Quote:
Originally posted by Sidiropa
Hi Russ,

please forgive my ignorance,

a) you are refering to caps C1-C4.
b) do we need to change the 357 Ohm resistors R1-R4 as well?


Cheers!,
Abraham Sidiropoulos
Hi Abraham,

No Apology required.

a) Yes, remove C1-C4.
b) 357R will work just as well as 392R, I just happened to have 392R at hand, so I used them.

Cheers!
Russ
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Old 1st April 2009, 02:26 PM   #87
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Hi Russ,

should jumpers be placed instead of C1-4?

Best Regards,
Abraham
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Old 1st April 2009, 02:27 PM   #88
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Quote:
Originally posted by Sidiropa
Hi Russ,

should jumpers be placed instead of C1-4?

Best Regards,
Abraham

No, quite the opposite, just leave them open.

Cheers!
Russ
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Old 1st April 2009, 08:27 PM   #89
JeroenR is offline JeroenR  Netherlands
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Can someone please take a look at my wiring schema? I'm not too certain I got it right....

Are the modules connected ok and is the grounding ok?

Thanks!!!

Jeroen
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Old 2nd April 2009, 03:30 PM   #90
Telstar is offline Telstar  Italy
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Anyone has listening impressions of the WM8741 chip?

As with their receivers, looks like wolfson dacs are snubbed by the diy audio community (not limited to this site).
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