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Old 10th February 2006, 02:45 PM   #1
klitgt is offline klitgt  Denmark
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Default PCM1702 sensitive to ESD?

I plan to replace the PCM1702 J-grade with K-grade DAC chips in a Denon DCD2700 CDP.

1. Is this worth while?

2. Will the new 1702's die if I solder them into the PCB without anti ESD protective devices?

Anyone has anything to say about changing DACs in general?

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Old 12th February 2006, 03:18 AM   #2
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Don't bother. Most of the J-grade parts actually meet the K-grade specs. It's just that they are not *guaranteed* to do so. You won't notice any improvement, and it will cost a lot of time and money.
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Old 13th February 2006, 09:11 AM   #3
klitgt is offline klitgt  Denmark
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Oh thank's! I also suspected this, but in a Danish forum some religious persons say it is a MUST to replace the J grades.

I stay with the J's!
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Old 13th February 2006, 02:22 PM   #4
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Please remember that my opinion is just that -- an opinion. I have never directly compared the two in a strict listening test. We are a manufacturer and use the K-grade because people expect it in an expensive product. I know another manufacturer that uses a lower grade (I can't remember if it is J-grade or ungraded), and he claims there is no difference.

On the other hand, if the Danish person did a careful experiment then that could have more validity than my opinion. You would have to read many of his postings and try to decide if you think he is a careful experimenter and a good listener. I would be surprised if there is a meaningful difference between the two grades, but I have been surprised before!
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Old 13th February 2006, 02:33 PM   #5
anatech is offline anatech  Canada
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Hi klitgt,
Just a note to say I haven't killed any DACs or other chips by removing and replacing them. As long as you are careful and your equipment (plus yourself) are referenced to ground through a resistor. 1 Meg ohm is normal. Also connect the equipment chassis to the same reference.

It's important to use a controlled temperature soldering station so you don't damage the PCB. Your method is as important as your equipment.

Try not to work with the power on!

-Chris
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Old 13th February 2006, 02:37 PM   #6
anatech is offline anatech  Canada
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Hi Charles,
The PCM1702 is my current fav D/A chip. What would you say in your opinion are the better sounding chips? My Denon DCD-S10 uses two per channel, co-phased again then summed (stock).

I'm a bit out of touch these days.

-Chris
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Old 13th February 2006, 02:55 PM   #7
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I have measured plain and J 1702.
They all vary a lot, no matter what grade and it is like coing to casino.
By the way IMHO 1702 is not very good at all.
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Old 13th February 2006, 03:09 PM   #8
Hurtig is offline Hurtig  Denmark
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I have recently changed a PCM1702 that had died.... I did it at home with no special ESD-care, and I had no problems.
But remember... Often ESD failure shows long time after the problem started. Typically the device will get a partial damage, and often it works fine for months. And then some day it quit.

The discussion about J and K-grade... Remember, that these are the same devices. A THD measurement decide if the device will get a white og red dot (J or K-grade).
In real life applications it don't think you will notice any difference. Often the analog stage after the PCM1702 is much worse than the worst grade of PCM1702.

Have anyone made some serios testing of PCM1702 vs PCM1704. They are almost pin-compatible... Just remember that the digital supply is swapped.
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Old 13th February 2006, 03:31 PM   #9
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Quote:
Originally posted by Hurtig
A THD measurement decide if the device will get a white og red dot (J or K-grade).
In real life applications it don't think you will notice any difference. Often the analog stage after the PCM1702 is much worse than the worst grade of PCM1702.
Not for low level dist.
Also I believe the chips tend to change performance after time.
So grades are not worth a penny.
In some datasheets you can read about additional burn-in screening beeing offered, which means that the chip will be tested after burn-in wether it still meets grade specs or not.
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Old 13th February 2006, 03:58 PM   #10
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Default Casino.........I like that.......

The low-level performance of all the '170x DACs isn't that good. Does not matter what (if any) letter they stick on the end.

As for ESD.........they seem rugged, unlike the AD1862. Great low-level performance, a lot died in the field, though.

Jocko
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