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Hi,
i finished to assemble my IVY for my Buffalo24 by some day and i'am now testing it.
I have used the suggested values on ivy_manual_2.0.pdf and i have the following problems:
- the two OPA1632 became really really hot (i cannot touch it for more then 1 second)
- the sound it's not bad but a little bit veiled (compared to previous setup: Buffalo with output transformer)
- the THD measured with RMAA and Audigy 2 NX on 96KHz/24bit is:
--- 0.06% (spdif out -> buffalo -> ivy -> Audigy analog in)
--- 0.006% Audigy in loop
--- 0.009% (spdif out -> chinese DAC based on CS4398 -> Audigy analog in)
Ciao
Andrea
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Rank: Administration
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Something is definitely wrong. I would need to see more information. :) Pictures maybe?
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Rank: Member
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Joined: 9/2/2009(UTC)
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Location: Italy
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Rank: Member
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Joined: 9/2/2009(UTC)
Posts: 8
Location: Italy
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Sorry Russ,
have you had the time to see the pictures of my system?
any hints?
I did a test to be sure that the problem is only in my IVY.
I used a unity gain buffer with an OPA2134 in voltage follower mode in place of the IVY, using only out + and gnd of each channel on the Buffalo.
In this way (leaving the other part of the system as described/pictured in previous post) i have a THD of 0.004%, less than the audigy in loop.
Ciao
Andrea
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Rank: Administration
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Its normal for the OPA1632 to run hot, but I am not sure why the measured distortion is occurring. I can only suggest trying to remove or adjust some of the compensation caps. Especially around the BAL/SE stage since you are measuring the SE signal.
Cheers!
Russ
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Rank: Member
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Is it normal for the OPA1632 to run so hot to become untouchable?
Anyway thanks for your hints, i will try in that direction and i will let you know the results.
Ciao
Andrea
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Rank: Administration
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No it really should not get so hot you can't touch it. I have not ever seen that happen. It will get hot enough to not be comfortable. This is because the part has a high bias current.
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Rank: Member
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Maybe it's a problem of language, my "untouchable" can be near your "enough to not be comfortable".
Anyway i removed the compensation caps around the BAL/SE stage (C17 - C20) and configured IVY in "low impedance voltage input(hybrid)" as suggested in the "ivy_manual_2.0.pdf" with R1 - R8 all equal to 182Ohm (1VRMS at 0db), no C1 - C4, no R17 - R20 and C13 - C16 equal to 10nF. In this way i measure (using the same measuring setup described in previous posts) 0.003% THD and i am now satisfied with the sound i get even if i'am not sure if i like more the IVY or the transformer output stage (it seems to me to have a more detailed presentation in the transformer out setup, but i'am not a "golden ear").
Ciao
Andrea
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I like to join the line.
Mine isn't nice at all to touch either. In fact, I can feel the heat up through c9-c12. It's hot as ...., not in the range of "comfort" - untouchable it is.
The data sheet says quiescent current, 14ma pr. channel. That's pretty much energy to burn in those tiny things.
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