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Old 14th November 2009, 12:07 AM   #1481
Havoc08 is offline Havoc08  Denmark
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It is mentioned somewhere in the thread that you should not short the dac chip. It needs alittle load, but I dont remember the exact ohms.
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Old 14th November 2009, 12:20 AM   #1482
McGyver is offline McGyver  Poland
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As I mentioned earlier Lundahls 1517 have DC resistance about 9 ohms. If it's directly connected to CS4397/8 it's practically short. You can fry the DAC in this way.
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Old 14th November 2009, 04:21 AM   #1483
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Default Is anybody interested in purchasing one of these??

I have one of these in my system- and I am using UTC A-20's. The L/R coupling caps were removed- and the transformers are wired right to the dac pins. It sounds great, but it's just a bit too "tweaky" for my taste.

I know it sounds contradictory to say this on diyaudio.com, but I'd rather be listening than tweaking.

You'll get the dac with the transformer- and the A-20's.

Let me know if any of you are interested.

Thanks
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Old 14th November 2009, 11:45 AM   #1484
Havoc08 is offline Havoc08  Denmark
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McGyver do you know the preferred impedance the dac chip would like to see?

Just scrolled through the datasheet and couldn't find anything on the subject?
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Old 14th November 2009, 12:05 PM   #1485
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The cs4398 data sheet clearly states 1k minimum. The source impedence is around 120ohms.
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Old 14th November 2009, 01:10 PM   #1486
Havoc08 is offline Havoc08  Denmark
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ahh yes.. so does the cs4397 datasheet. I found it now. Thank you.

Connecting a LL1517 with no resistors should then be considered a really bad idea .
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Old 14th November 2009, 03:04 PM   #1487
GerardA is online now GerardA  Netherlands
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Who knows the minimum DC-resistanceload the DAC can handle?
My monacor trafo's are 150 Ohm DC, with the 2 x 47 Ohm I'm at 244 Ohm.
I'd like to go lower but how low can we go?
The optimum source impedance of the monacor is 50 Ohm.
This is possible with a parallel R of about 100 Ohm, but I am not going to try that!!
Without Resitors the DAC sees 150 Ohm, will that be enough??
I know the datasheet says 1k, but as stated before I think the optimum values for the trafo are more important then for the DAC,
unless it breaks down...
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Old 14th November 2009, 03:23 PM   #1488
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Nobody knows that answer, it's your dac, try it if you must. I wouldn't add any parallel load though.

You could add a parallel load if you keep some series resistance, but it would act as a voltage divider also.
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Old 14th November 2009, 04:35 PM   #1489
Ryssen is offline Ryssen  Sweden
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Quote:
I lowered the seriesresistance from 2 x 220 to 2X 47 ohm.
Quote:
My monacor trafo's are 150 Ohm DC, with the 2 x 47 Ohm I'm at 244 Ohm.
Maybee I shouldnin go lower than 2x560 ohm with the LL1517,as they are 9 ohms.
May I dare to try around 200 ohms..
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Old 14th November 2009, 06:39 PM   #1490
ch33ta is offline ch33ta  Croatia
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Just a little favor...
I need the UTC A-20 dimensions...
Two pieces arriving soon and I planned to put them on the DAC pcb (removed opamps and anything related to them) - PICTURE (currently testing with Monacor LTR-110)
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