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 Post subject: Pedja's AD844 I/V stage
PostPosted: Tue Jun 23, 2009 7:57 am 
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Joined: Mon Mar 07, 2005 10:32 pm
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Location: Split, Croatia
Hi all,

I've made an AD844 I/V stage identical to Pedja's Aya dac schematic and it works from fire up as intended, but will like to know is it possible to use AD844 diamond buffer also, a.g. to connect pin 5 (TZ) and output pin 6 without penalty? Also, how much DC offset S&B 102MkII TVC could take without damage?


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PostPosted: Tue Jun 23, 2009 11:42 am 
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It is not quite clear from your post what do you try to do, but if this is the answer that counts, you can use either buffered (pin 6) or unbuffered output (pin 5). But you shouldn't connect these pins one to another, as it will short the buffer input and output. (You can put some small cap across the diamond to improve on its stability but that would be another issue.)

Purely sonically, the buffer you have within AD844 is the good one but, things being said, all the other IC diamond buffers I tried measured better.

"Damage".. do you mean literally failure, or saturation?


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PostPosted: Tue Jun 23, 2009 2:35 pm 
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Joined: Mon Mar 07, 2005 10:32 pm
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Location: Split, Croatia
Thanks for replay Pedja... Silly me...to not having a fresh look at the simplified AD844 schematic, everything is clear now. But I've another one...why haven't you use AD's diamond buffer, since it's there anyway, in Aya dac? You see, 'cos I'm currently using S&B TX102MkIII I don't have issue regarding high output impedance from AD844 TZ node but in case I change it for some active one, would you recommend to use AD's buffer in some cases?

I meant saturation of transformers core for "damaged".


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PostPosted: Tue Jun 23, 2009 4:10 pm 
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I did used buffered output of AD844 (pin 6). Unbuffered output sounds more natural but in most cases it lacks the dynamics of the buffered output.

I would actually bet that any transformer will work better with 15 Ohm than 1 kOhm + source.

I think it is only the manufacturer who can tell you whether the core can get permanently magnetized or not, and under what conditions. Or someone who actually screwed it up that way, of course.


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PostPosted: Wed Jun 24, 2009 7:44 pm 
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Joined: Mon Mar 07, 2005 10:32 pm
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Location: Split, Croatia
[quote="Pedja"]Unbuffered output sounds more natural but in most cases it lacks the dynamics of the buffered output.

I would actually bet that any transformer will work better with 15 Ohm than 1 kOhm + source.[quote]

Since TDA1541A sounds natural in nonos to my ears, and as per your recommendation, I've decided to use buffered output...Sound very good (at least in (pair with heavily tweak Marantz CD14 with balance IC to amp), but I hope to squeeze more from it with new super-shunt regulators. Thank you! :good:


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