Phase shift at 20kHz of IVY i/V stage? Options  Watch this topic  Print this topic  Atom Feed  RSS Feed View » Normal Threaded

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Florianderton		#1 Posted : Saturday, December 21, 2013 10:10:11 PM(UTC)
Rank: Member Groups: Member Joined: 7/8/2013(UTC) Posts: 43 Location: Bad Ischl		Can anybody help me with this? Thanks! Florian
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Russ White		#2 Posted : Thursday, December 26, 2013 8:41:42 PM(UTC)
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)		What is the question?
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Florianderton		#3 Posted : Friday, December 27, 2013 9:12:52 AM(UTC)
Rank: Member Groups: Member Joined: 7/8/2013(UTC) Posts: 43 Location: Bad Ischl		Hi Russ! How much is the phase shift @20kHz of the output stage? Merry Christmas and a happy new year! Florian
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Russ White		#4 Posted : Friday, December 27, 2013 3:59:29 PM(UTC)
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)		With stock parts(15nf caps) a bit less than 20deg. It will depend on the filtering caps you choose to use.
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Russ White		#5 Posted : Friday, December 27, 2013 4:04:09 PM(UTC)
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)		Merry Christmas and happy new year to you as well!
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Florianderton		#6 Posted : Friday, December 27, 2013 7:42:02 PM(UTC)
Rank: Member Groups: Member Joined: 7/8/2013(UTC) Posts: 43 Location: Bad Ischl		That sounds good, so there is space to improve it? What caps can I use instead, and what are their numbers? As I guess you have already chosen an optimum - what are the disadvantages if I change the values? Thank you, Florian
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Brian Donegan		#7 Posted : Saturday, December 28, 2013 3:25:32 PM(UTC)
Rank: Administration Groups: Administration, Customer Joined: 10/24/2006(UTC) Posts: 2,868 Location: Massachusetts, USA Thanks: 2 times Was thanked: 141 time(s) in 134 post(s)		Originally Posted by: Florianderton That sounds good, so there is space to improve it? What caps can I use instead, and what are their numbers? As I guess you have already chosen an optimum - what are the disadvantages if I change the values? Thank you, Florian That's a complicated question to answer. If you want to experiment, it would be a good idea to use an analog filter simulator to see the affects of different capacitor values.
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Florianderton		#8 Posted : Saturday, December 28, 2013 4:27:28 PM(UTC)
Rank: Member Groups: Member Joined: 7/8/2013(UTC) Posts: 43 Location: Bad Ischl		So you cant just tell me a value? I dont have software for simulating, do you know if there is any freeware available? Florian
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Brian Donegan		#9 Posted : Saturday, December 28, 2013 4:42:45 PM(UTC)
Rank: Administration Groups: Administration, Customer Joined: 10/24/2006(UTC) Posts: 2,868 Location: Massachusetts, USA Thanks: 2 times Was thanked: 141 time(s) in 134 post(s)		TI has some free software for simulating differential analog filters. We recommend 15nF
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Russ White		#10 Posted : Wednesday, January 1, 2014 4:38:08 PM(UTC)
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)		As Brian said, it's complex. You could experiment with 1nf to 20nf. 1nf will get you minimal filtering so be sure you really want that, but you will have almost no phase shift at 20Khz. After a lot of testing 15nf is what we chose because it sounds great - Also, the corner is beyond 2fs - but does a good job of filtering out the natural quantization noise from these type of DACs (COD, Opus, Buf).
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Florianderton		#11 Posted : Thursday, January 2, 2014 1:48:15 PM(UTC)
Rank: Member Groups: Member Joined: 7/8/2013(UTC) Posts: 43 Location: Bad Ischl		Thank you! I have read that the phase shift is important if the sound is 'sloppy' or 'veiled' vs. 'tight' and 'clear') So thanks, I will experiment a bit) Florian
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Brian Donegan		#12 Posted : Thursday, January 2, 2014 4:03:58 PM(UTC)
Rank: Administration Groups: Administration, Customer Joined: 10/24/2006(UTC) Posts: 2,868 Location: Massachusetts, USA Thanks: 2 times Was thanked: 141 time(s) in 134 post(s)		As a matter of scale, speakers (especially complex crossovers) will have a far more complex and significant impact on phasing than this one filter.
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