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Hi
Just wondered.. What is the purpose of C17-C20 on the version 2 of IVY.
Do I need them with Opus? I am going to use full dual mono with 3rd IVY as BAL/SE.
Øivind
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They are low pass filters and compensation for the BAL/SE opamp.
I would not omit them on the fist two IVYs (the ones after the DAC). But you can probably omit them on the third (as the filtering should not be required here), though personally I would not, but I may reduce them. 10-22pf would work great.
Cheers!
Russ
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Rank: Member
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Thanx Russ.
I get it. There is a pretty high f3 anyway so I think I keep them as designed.
One more: Should I go from unity gain to 0.5 on the third IVY as well, it seems to me that summing the BAL signal will give me 4v output?
Øivind
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Rank: Administration
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If you configure for .5 gain on the summing opamps used at the font end, you will not need to at the third IVY. The IVYs at the front end will be doing 2VRMS measured across the balanced outputs, not to GND. So summing them will get the same 2VRMS. Now, if you want to get slightly better dynamic range, you can actually increase the gain the of fully differential stages(say 6db), and reduce the gain of the summing amplifiers. :) This could get you another few db of DNR. :) To do this you would double the value of R1-4 and halve the value of C1-4. You would then have to also similarly adjust the gain resistors for the summer to further reduce their gain by the same number(say 6db). :) The circuit is very flexible. :) Cheers! Russ Edited by user Friday, August 8, 2008 5:46:28 AM(UTC)
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Rank: Member
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Joined: 7/7/2008(UTC)
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Got that too :-) I remember designing electronic crossovers some 25 years ago using good old LM074's where I used the gain up/gain down method to get some distance to the noise floor. Back then I designed RIAA's, preamps, poweramp's and even mixing consoles(32/8/2). A lot of etching and drilling and soldering and panel building and knobs and... Haven't been desiging electronics since the mid 80's so its fair to say I'm a bit rusty :-) Having a ball now diving into your designs. Like a kid in a candystore :-). I truly can relate to your approach to design, based on knowledge, not myths(enough said:-)). Thanks for sharing, guys! Cheers! Øivind Edited by user Saturday, August 9, 2008 2:03:01 AM(UTC)
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