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glt wrote:avr300 wrote:I'm now running it with 220nF film at the AVCC shunt output.
Still listening.. Isn't that the same value (+/-) as the bypass cap at the pin? I think the discussion is whether or not a "reservoir" size capacitor at the output of a shunt will improve sonics... Perhaps one can use 10 uF, 1 uF, .1uF, 10n, 1n in parallel in order to widen the frequency range of the bypassing. I don't know. Haven't seen any schematics ;-) I don't believe in high capacitance/big reservoir on a shunts output - it against the nature of a shunt. It has to be able to move freely. Until now I've been to lazy to rig my o'scope. I'll do it tomorrow. Edited by user Friday, February 3, 2012 1:01:57 PM(UTC)
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One thing to remember is that Trident was purposefully designed to be minimally compensated. This means it is operating toward the edge of phase margin. I used a couple of scopes to check AVCC/Trident and found that one scope (actually I found later it was the fault of the probes) would sometimes cause a Trident to oscillate, but when I switched scopes it would not.
I also had a couple of other people make similar observations.
Out of those discussions I found the following to be true:
1) Adding a decoupling cap at the output can add a larger margin - but it's not really ideal for a shunt, but also will not harm anything.
2) Adding some compensation (say 22pf) right at the -In and Out of the opamp adds a lot of compensation, but also slows down the error amp. But if your DAC is in a very high EMI environment it may be worth it.
I actually plan on writing up a small article on the DIY audio forum about these and many other things I have discovered in designing the 3rd incarnation of Trident - which will be available soon. There was a second, and it is awesome, but it proved to be too expensive to manufacture. :)
In short, I don't use a decoupling cap at the output, but It certainly won't harm anything to do so, and if you find your trident close to the edge of stability for whatever reason, then by all means give it a shot.
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Hello folks
I´ve added 100nF BG HiQ on the AVCC and the 3 Tridents and the dac definitely sounds more dynamic, harmonically richer and more textured
no way going back 4 me
best
Leif
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Well Leif - then you're not alone. To my ears it much more dynamic now. I have only applied caps to the AVCC shunt. I have been to busy to scope anything yet. Edited by user Sunday, February 5, 2012 9:02:27 AM(UTC)
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There is already much more than 100nf at the outputs. :) Edited by user Sunday, February 5, 2012 11:40:54 AM(UTC)
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sure, but even so , I trust my ears and there´s a change to the better
BGs are known to have good HF characteristics in the GHz area
who knows
for reference; what kind of gear are you (Brian and Russ) using as evaluation tools for listening?
best
Leif
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christensenleif@msn.com wrote:sure, but even so , I trust my ears and there´s a change to the better
BGs are known to have good HF characteristics in the GHz area
who knows
for reference; what kind of gear are you (Brian and Russ) using as evaluation tools for listening?
best
Leif Add 47 uf. 6,3 as well and change all Vishay Dale to Takman Carbon in analog stage . Those Vishay are better than normal metalfilm but is still shit. 
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have Panasonic FC 47µF/16vdc incoming
will try asap
pls describe perceived difference in sonics of resistors
I have preferences and normally prefer AN 2 watt tants or better still if possible: chokes
best
Leif
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Originally Posted by: Erlend Sæ  christensenleif@msn.com wrote:sure, but even so , I trust my ears and there´s a change to the better
BGs are known to have good HF characteristics in the GHz area
who knows
for reference; what kind of gear are you (Brian and Russ) using as evaluation tools for listening?
best
Leif Add 47 uf. 6,3 as well and change all Vishay Dale to Takman Carbon in analog stage . Those Vishay are better than normal metalfilm but is still shit. Nobody wants to show a pictures of this mod? Thanks in advance:)
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