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I have an IVY III and Buf II with a single Placid and Placid BP. I have been using the Buf in SE fashion for a few months. I wanted to try the Buf via the BAL out to an Anthem MCA amp direct using the volume control on my Squeezbox. I noticed that the BAL out on the left channel was much lower in level. I checked the SE and they sounded OK I put the scope on the right an ran a 1khz tone into the DAC via the SPDIF and got this on the scope:  Same setup on the scope and on the left channel I have:  The neg leg of the left signal is much lower in level and they both have some high frequency noise on them. Wierdly the SE on the left channel looks fine. Here is the neg leg of the BAL out by itself:  Obviously I need to take things back apart. I looked close at the components and the solder joints and didn't see anything that stood out. Any thoughts as to where I should start? Does this look like something in the IVY or in Buf II? I'm a mechanical engineer working as an process automation/IT guy....so this electronics testing stuff is a bit new to me. Any other points where I should test the IVY to see what is going on?
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Rank: Administration
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Yeah something is definitely borked. I would need to see pics of the IVY-III to even begin to help.
I would start be checking the OPA1632s on the left side, also double check that all of the solder joints are good and no shorts.
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Rank: Administration
Groups: Administration, Customer
Joined: 10/24/2006(UTC)
Posts: 3,979
Location: Nashville, TN
Thanks: 25 times
Was thanked: 89 time(s) in 83 post(s)
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It most likely a problem with the IVY-III and not the DAC. But it is possible it could be either or both. You should test the output at the first opa1632(IC1). If it is wonky that is likely the bad chip. If it look decent there, then check the second (IC2). Edited by user Thursday, February 10, 2011 9:42:27 AM(UTC)
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Rank: Member
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Joined: 2/15/2010(UTC)
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Location: seattle
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Thanks for the quick reply. Most of the crazyness in the scope traces was due to having the scope leads looped through the AC cord and coax with the SPDIF signal. Once I got the leads routed properly the signal cleaned up. The level looked the same between both legs of the BAL out. I might have bumped a loose connection or bad solder joint.
I will get the amp back up into the listening room this weekend and see if the level in the left channel is fixed.
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Rank: Member
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1. I am not using IVY module, but I am also getting dissimilar measurement for the two B-II channels. The Out+ and Out- on one side is 65mV and the other 86mV. 2. I had also scope the SPDIF signal, it doesnt look too good. Mine is not a perfect square, and of varying horizontal distance. I measured the impedance from the player to be 73R and after terminating to B-II it is close to 36.5R. I tried changing interconnects of dissimilar type and length but getting the same results. Mind sharing how does your signal look like on the scope?  Hope you dont mind be borrowing your thread as I seem to share the same issue on the first point. Thanks Edited by user Wednesday, February 23, 2011 5:31:34 AM(UTC)
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Rank: Member
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