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kesgreen  
#1 Posted : Saturday, February 9, 2013 9:35:35 PM(UTC)
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I'm using 2 Ventus EZ boards for Bal-to-SE conversion in a dual-Buffalo II/dual-Ivy III setup. Balanced output is quiet, but the SE output via the Ventus EZ boards has a faint hum and a noticeable hiss. Any idea what could cause this? Grounding issues?

PS I have already omitted the CC1 cap.

Edited by user Saturday, February 9, 2013 9:53:14 PM(UTC)  | Reason: Not specified
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SCompRacer  
#2 Posted : Saturday, February 9, 2013 10:41:04 PM(UTC)
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What grounding method did you use? Russ had suggested using a star ground with my dual mono build (all boards ground at one common point). I had EZ's in there at first and all was quiet for SE out.
Rich

http://www.twistedpearau...-Denon-DVD-3910-Mod.aspx
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kesgreen  
#3 Posted : Saturday, February 9, 2013 10:49:46 PM(UTC)
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Originally Posted by: SCompRacer Go to Quoted Post
What grounding method did you use?


Signal grounds are only connected by way of the wires connecting to each board. I assume they all share the same ground.
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SCompRacer  
#4 Posted : Sunday, February 10, 2013 12:02:06 AM(UTC)
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Originally Posted by: kesgreen Go to Quoted Post
Originally Posted by: SCompRacer Go to Quoted Post
What grounding method did you use?


Signal grounds are only connected by way of the wires connecting to each board. I assume they all share the same ground.



Well I don't really know if this would solve your problem, but a star ground is suppose to prevent ground loops which can cause hums/noise. All grounds from power supplies, DAC boards, modules and output boards are attached at one point. For lack of a better idea at the time, I used a ring terminal that I soldered all the ground wires to. It is between the LCBPS and left DAC board. It is mounted on a plastic standoff so it is not directly connected to chassis ground.

UserPostedImage

A direct link for larger image.

http://i417.photobucket....no%20Build/pesante_9.jpg

Edited by user Sunday, February 10, 2013 12:03:35 AM(UTC)  | Reason: Not specified

Rich

http://www.twistedpearau...-Denon-DVD-3910-Mod.aspx
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kesgreen  
#5 Posted : Sunday, February 10, 2013 12:50:48 AM(UTC)
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Lovely, neat wiring.

Well, I might give it a try. I don't suppose it would do any harm.
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SCompRacer  
#6 Posted : Sunday, February 10, 2013 2:57:53 AM(UTC)
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Thanks for the kind words! Russ suggested the star ground early on in my build so it came from a good source. It reminded me that we used to do a star ground with race car chassis too. Guys that had grounds all over the place could have problems, especially after computers were added and digital timing controls replaced analog ones.
Rich

http://www.twistedpearau...-Denon-DVD-3910-Mod.aspx
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kesgreen  
#7 Posted : Sunday, February 10, 2013 5:30:53 PM(UTC)
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I think I've identified the problem.

I had a pair of balanced headphones plugged in, which had a slightly iffy left channel connection. Unplugging them resulted in a nice, silent output from the Ventus EZs. I've just repaired the headphone cable, so I'm hoping I can leave them plugged in without the noise.
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kesgreen  
#8 Posted : Monday, February 11, 2013 10:07:24 PM(UTC)
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Well despite repairing the headphone cable, the hiss remains when the headphones are plugged in. A bit of a nuisance as the sockets are at the back and inaccessible without removing the DAC from its rack. Strange - I never had the problem with a single Buffalo II/Ivy III.
I suppose it's something to do with grounding or interference picked up from the headphone cable.
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